Bacteria;Classification, Characteristics, Types, Structure

Bacteria – Definition, classification, characteristics, type, structure, paper, Name, Material and History– bacteria or eubacteria have various types as well as the good example that could be detrimental or can be advantageous. In this case the bacteria themselves are grouped into several types, namely based on the characteristics of the cell wall, the number and location of the flagellum, as well as the way of life, among others, as follows.

The discussion will present about (1) understanding bacteria, (2) bacterial reproduction, (3) types of bacteria, (4) metabolism in bacteria, (5) bacterial characteristics, (6) the benefits of bacteria in the food and pharmaceutical fields to be explained as follows.

Definition of Bacteria

Bacteria derived from the Latin word, bacterium (plural, bacteria) are giant groups of living organisms. They are very small (microscopic) and mostly unicellular (single-celled), with a relatively simple cell structure without nucleus / cell nucleus, cytoskeleton, and other organelles such as mitochondria and chloroplasts.

Bacteria are the most abundant of all organisms. They are spread (everywhere) in the soil, water, and as a symbiosis of other organisms. Many pathogens are bacteria. Most of them are small, usually only measuring 0.5-5 μm, although some species can reach 0.3 mm in diameter (Thiomargarita). They generally have cell walls, such as animal and fungal cells, but with very different compositions (peptidoglycan). Many move using flagella, which differ in structure from the flagella of other groups.

Bacteria are included in the prokaryotes group which is the simplest form of cells that has a size with a diameter from 1 to 10 µm. The distinguishing feature of prokaryotic and eukaryotic is the cell nucleus where prokaryotic cells do not have a clear cell membrane or nucleus. Bacteria have 2 structural divisions, namely:

• Basic structure (owned by almost all types of bacteria)

Includes: cell walls, plasma membranes, cytoplasm, ribosomes, DNA, and storage granules.

• Additional structure (owned by certain types of bacteria)

Includes: capsules, flagellum, pilus (pili), chlorosomes, gas vacuoles and endospores.

Bacteria History

The first bacterium was discovered by Anthony van Leeuwenhoek in 1674 using his own microscope. The term bacterium was introduced later by Ehrenberg in 1828, taken from the Greek word βακτηριον which means “small stick”.

Bacterial Reproduction

Bacteria can reproduce in two ways, namely asexual reproduction and sexual reproduction. Sexual bacterial reproduction is divided into three types namely, reproduction by transformation, reproduction by transduction, and reproduction by conjugation.

Asexual Reproduction

Included in this asexual reproduction are cleavage, bud formation, and filament formation.

• Division

In general, bacteria multiply by  binary division , meaning that division occurs directly, from one cell dividing into two sapling cells. Each sapling cell will form two more saplings cells, and so on.

The process of binary fission begins with the process of DNA replication into two identical DNAs, followed by the division of the cytoplasm and finally forming a dividing wall between the two daughter cells of bacteria.

• Formation of shoots or branches

Bacteria form shoots that will break free and form new bacteria. Reproduction by branch formation is preceded by the formation of shoots which grow into branches and eventually escape. Can be found in the family Streptomycetaceae bacteria .

• Filament Formation

In the formation of the filament, cells release long fibers as unbranched filaments. The chromosome material then enters the filament, then the filament breaks into pieces. Each part forms new bacteria. Especially found in abnormal circumstances, for example when the bacterium  Haemophilus influenza is cultured in wet seeding.

Sexual Reproduction

Bacteria differ from eukaryotes in the way that DNA is combined from two individuals into one cell. In eukaryotes, the sexual process by meiosis and fertilization combines the DNA of two individuals into one zygote.

However, the sexes that exist in ecuaryotes are not found in prokaryotes. Meiosis and fertilization do not occur, instead there are other processes that will collect bacterial DNA that come from different individuals. These processes are the division of transformation, transduction and conjugation.

• Transformation

In the context of bacterial genetics, transformation is a change in the genotype of bacterial cells by taking foreign DNA from the surrounding environment. For example, the  harmless Streptococcus pneumoniae bacteria  can be transformed into cells that cause pneumonia by taking DNA from a medium containing dead pathogenic strain cells.

This transformation occurs when living nonpatogenic cells take pieces of DNA that happen to contain alleles for pathogenicity (genes for a layer of cells that protect bacteria from the host immune system). This process is a genetic recombination – the rotation of the DNA segment by crossing over . This transformed cell now has one chromosome that contains DNA, which comes from two different cells.

Bacterial reproduction by transformation

• Transduction

In the DNA transfer process called transduction, phage carries the bacterial gene from one host cell to another host cell. There are two forms of transduction namely general transduction and special transduction. Both result from distortion in the reproductive cycle of phage.

Bacterial reproduction by transduction

At the end of the phytic phytic cycle, the virus nucleic acid molecule is wrapped inside a capsid, and the complete phage is released when the host cell is lysed. Sometimes a small portion of degraded host cell DNA replaces the phage genome. Viruses like this are defective because they don’t have their own genetic material. However, after release from the lysed host, phage can stick to other bacteria and inject the bacterial DNA obtained from the first cell. Some of this DNA can then replace the homologous region of the second cell chromosome.

These cell chromosomes now have a combination of DNA originating from two cells so genetic recombination has taken place. This type of transduction is called  general transduction  because bacterial genes are transferred randomly. For special transduction requires infection by temperate phage, in the lysogenic cycle the phate tempera genome is integrated as a profile into the chromosome of the host bacterium, in a specific place.

Then when the phage genome is separated from the chromosomes, this phage genome brings along a small part of the bacterial DNA next to the profile. When a virus carrying bacterial DNA like this infects other host cells, bacterial genes are injected together with the phage genome. Special transduction only transfers certain genes, namely genes that are near the profaga on the chromosome.

• Conjugation and Plasmids

Conjugation is the direct transfer of genetic material between two bacterial cells that are temporarily related. This process, has been thoroughly investigated in E. Coli. DNA transfer is a one-way transfer, in which a cell donates (donates) DNA, and the “partner” receives the gene. DNA donors, referred to as “males”, use a device called a sex pili  to attach to the recipient (recipient) of DNA and are referred to as “females”. Then a temporary cytoplasmic bridge will form between the two cells, providing a path for DNA transfer.

Plasmids are small, circular and self-replicating DNA molecules that are separated from bacterial chromosomes. Certain plasmids, such as plasmids F, can make reversible incorporation into the cell chromosome. The phaga genome replicates separately in the cytoplasm during the lytic cycle, and as an integral part of the host chromosome during the lysogenic cycle.

Plasmids have few genes, and these genes are not needed for the survival and reproduction of bacteria under normal conditions. Nevertheless, these genes from plasmids can benefit bacteria that live in a stressful environment. For example, plasmid f facilitates genetic recombination, which might be beneficial if environmental changes no longer support strains that exist in bacterial populations. Plasmids f, consisting of about 25 genes, are mostly needed to produce piliseks.

Geneticists use the symbol f + (inheritance). The plasmid f replicates synchronously with the chromosomal DNA, and division of one f + cell usually results in two offspring, all of which are f +. Cells that have no factor f are given the symbol f-, and they function as DNA recipients (“females”) during conjugation. The f + condition is a “contagious” condition in the sense that f + cells can move f- cells to f + cells when the two cells are conjugated. Plasmids f replicate in “male” cells, and a copy is transferred to “female” cells through the conjugate channels that connect these cells.

In f + marriages with f- like this, only one f plasmid is transferred. The genes from the bacterial chromosome are transferred during conjugation when the f factor of the cell donor is integrated into the chromosome. Cells equipped with the f factor in their chromosomes are called Hfr cells (  high frequency of recombination  ). Hfr cells continue to function as males during conjugation, replicating factor f DNA and transferring copies to the f-pair. But now, this factor f takes copies of some of the chromosomal DNA with it.

Random movements of bacteria usually interfere with conjugation before copies of the Hfr chromosome can be completely transferred to f-cells. For a while the recipient cell becomes partial or partial diploid, containing its own chromosome plus DNA copied from a portion of the donor’s chromosome. Recombination can occur if a portion of this newly acquired DNA is located next to the homologous region of the F-chromosome, DNA segments can be exchanged. Binary division in these cells can produce a recombinant bacterial colony with genes derived from two different cells, where one of these bacterial strains is actually Hfr and the other is F.

Bacterial reproduction by conjugation

In the 1950s, Japanese health experts began to notice that some hospital patients suffering from bacterial dysentery, which caused severe diarrhea, did not respond to antibiotics that were usually effective for the treatment of this type of infection. It seems that resistance to this antibiotic has slowly developed in strains of Shigella sp. certain, a pathogenic bacterium.

Finally, researchers began to identify specific genes that cause antibiotic resistance in Shigell and other pathogenic bacteria. Some of these genes encode enzymes that specifically destroy certain antibiotics, such as tetracycline or ampicillin. The gene that gives resistance turns out to be carried by plasmids.

Now known as plasmid R (R for resistance). Exposure to a bacterial population with a specific antibiotic both in laboratory culture and in host organisms will kill bacteria that are sensitive to antibiotics, but that does not occur with bacteria that have antibiotic R plasmids that can overcome antibiotics.

Natural selection theory predicts that, in these circumstances, more bacteria will inherit the genes that cause antibiotic resistance. The medical consequences are also readable, namely the more resistant pathogenic strains that become more and more, making the treatment of certain bacterial infections more difficult. The problem is compounded by the fact that plasmid R, like plasmid F, can move from one bacterial cell to another through conjugation.

Also Read:  Complete Class 10 Bacteria Material

Bacterial Characteristics

The general characteristics of bacteria are as follows:

1. The first common characteristic of bacteria, they are prokaryote organisms (cell nuclei not covered by special membranes) as well as unicellular (or single celled)
2. Bacteria have cell walls such as arranged plants or peptidoglycan and mucopolysaccharides.
3. Bacteria have endospores which are capsules that appear when conditions are unfavorable as a shield against heat and natural disturbances.
4. In terms of size, bacteria are generally too small, such as Mycoplasma to be seen by the naked eye, which is about 0.5 micrometers, but there is also a slightly larger one, Epulopiscium fishelsoni, which reaches a size of around 10-100 micrometers.
5. Another common characteristic of living bacteria is that they are parasitic creatures (need a host such as humans or animals) but some are free.
6. In general, bacteria do not chlorophyll.
7. Bacterial habitat can live in harsh environments such as hot water, craters, peat.
8. Judging from the appearance, bacterial cells can look like bacilli (or stems), coccus (ball-shaped), spirilum (spirals like bottle openers), kokobasil (round and stem), and Vibrio (like commas).
9. As part of protection, bacteria can secrete mucus to the surface of the cell wall. 8-10% phospholipids and proteins are constituents of cytoplasmic membranes and bacteria.

Bacterial Structure

Some structural parts are common in all bacteria such as cell walls and cell membranes. Other structures only exist in or within the cells of certain species.

Cell wall

Most bacterial cell walls contain peptidoglycan ( peptidoglycan), a network of modified sugar polymers that is cross-linked by short polypetides. This molecular structure envelops all bacteria and binds to other molecules that protrude from their surface. Bacteria can also be classified into two groups based on differences in cell wall composition. Gram-positive bacteria have simpler walls with relatively large amounts of peptidoglycan.

Gram-negative bacteria have fewer peptidoglycans and are more structurally complex, with an outer membrane containing lipopolysaccharides (carbohydrates that bind to lipids). The lipid portion of lipopolysaccharides in the walls of various gram-negative bacteria is toxic, causing fever or shock. Furthermore, the outer membrane of gram-negative bacteria helps protect bacteria from the body’s defense system. Gram-negative bacteria also tend to be more resistant to antibiotics than gram-positive species.

Ribosome

Ribosome is a cytoplasmic particle, when observed under an electron microscope, a small cytoplasmic particle is seen. Ribosomes are present in solids after protoplasts after bacterial cells are destroyed by centrifugation of 100,000 g. Bacterial ribosomes are 70S (800 KDa) in size, and can be separated into 30S and 50S subunits. The 30S subunit contains 16S RNA, while the 50S subunit contains 23S and 5S RNA.

A collection of polybosomes-membranes containing all components of a protein-synthesizing system; A polybosome is a 70S ribosome chain (monomer) attached to an mRNA. The number of ribosomes varies according to the conditions of growth: fast-growing cells in a suitable medium, contain more ribosomes compared to slow-growing cells in an inadequate medium. Histone-like proteins have now been found in small amounts associated with E. coli DNA. In bacteria, polyamine is also known, such as putreskin and spermidin.

Capsule

Cell walls of many prokaryotes are coated by capsules. Capsules are sticky layers of polysaccharides or proteins. This capsule allows prokaryotes to attach to the substrate or to other individuals in a colony. Some capsules protect bacteria from dehydration, and some protect pathogenic prokaryotes from invading the host immune system.

Cell membrane

Bacterial cell membrane composed of lipoteichoic acid (LTAs) is a glycerolfosphate polymer which ends in glycolipids, which penetrate the cytoplasmic membrane. Teikuronic acid (TAs) is a polymer consisting of N-asetyl-galactosamine (galNac) and glucoronic acid (GlcUA), bound as disaccharide repeating units (GlcUA (1,3 (GalNac) n. TAs do not contain phosphate, but are present as polymers). polyanionic acid is caused by carboxyl from uronic acid.

TAs bind via N-acetylglucosamine-1- phosphodiester to the C-6 hydroxyl group of acid. Teikuronic acid can be found in cells together with teikic acid; Teikuronic acid is synthesized when cells lose phosphate, to make the acids bound. Under the electron microscope, a transverse slice of Gram-positive cells, the cell wall as a layer above a relatively thick plasma membrane, which is sensitive to lysozyme. Proteins and polysaccharides, supporting the cell wall substructure layer. Serologic type-specific membrane proteins from group A Streptococcus form a thick, diffuse layer of the external fimbria wall, which can be damaged by trypsin without interfering with cell survival.

Pili

Pili or fimbria are hairlike protein protrusions that help cells attach to other cells or to the substrate. Fimbria is also known as pilus attachment. The gonorrhea-causing bacterium, Neisseria gonorrhoeae, uses fimbria to attach itself to its host mucous membrane. Fimbria are usually shorter and more numerous than sex pilus, the bulge that brings the two cells together before transferring DNA from one cell to another.

Mesosome

In Gram-positive bacteria there is a structure that folds into the inner plasma membrane called the mesosome. Mesosomes are usually seen as membrane-connecting cytoplasmic sacs consisting of lamella (sheet), tubular (tubular form) or vesicular structure (sac); all of which are often associated with cell division septa. The attachment of the mesosome to the chromatin DNA and membrane can be seen on thin slices under an electron microscope.

Flagella

Of the various structures that allow prokaryotes to move, the most common is flagella. Flagella are organs used by most motile bacteria for propulsion (movement). Flagella can be scattered throughout the cell surface or centered on one or both ends. Prokaryotic flagella have a tenth the width of eukaryotic flagella and are not covered by an extension of the plasma membrane. Many prokaryotes show taxis, movements toward or away from a stimulus.

Chromosome Circular

In most prokaryotes, the genome consists of one circular chromosome whose structure includes less protein than that found in the linear chromosome of eukaryotes. Prokaryotes do not have a nucleus enveloped in a chromosome membrane located in the neucloid region, an area of ​​cytoplasm that appears brighter than the cytoplasm that surrounds it in electron micrograd. Single chromosome selin, prokaryotic cells also have a small ring of DNa that replicates separately called a plasmid.

Also Read:  Types of Autotrophic Bacteria and Heterotrophic Bacteria With Their Descriptions

Benefits of Bacteria in the Field of Food

Some food ingredients are made using microorganisms as the main ingredients of the process, such as brewing beer and wine using yeast, making bread and milk products with the help of lactic acid bacteria, and making vinegar with the help of vinegar bacteria. Soybean processing in several countries uses a lot of fungi, yeast and lactic acid bacteria. Even the large amounts of lactic acid and citric acid needed by the food industry are made with the help of lactic acid and Aspergillus niger.

The production of yeast, bacteria and algae from inexpensive media contains inorganic nitrogen salts, fast food, and provides a source of protein and other compounds that are often used as supplementary food for humans and animals. Several groups of microorganisms can be used as indicators of food quality. These microorganisms are a group of bacteria whose presence in food is above a certain amount limit, which can be an indicator of an exposed condition that can introduce harmful organisms and cause proliferation of pathogenic or toxic species.

For example, E. coli type I, coliforms and faecal streptococci are used as indicators of unhygienic handling of food, including the presence of certain pathogens. This indicator microorganism is often used as an indicator of the quality of microbiology in food (Hidayati et al, 2015).

Acebacter Xylium

Each coconut produces 50-150 ml of water, so most of the coconut water is filled with water. In coconut water it has benefits other than for electrolyte sources, it can be used as a material for making nata de coco. Nata de coco is the same as yogurt, which is the result of fermentation. Bacteria that play a role for nata de coco are acebacteria xylium (Hidayati et al, 2015).

Lactobacillus Bulgarius

Yogurt is a drink that is familiar to the ears of the community, has become a daily drink because of its good taste and delicious aroma that attracted various layers of society. Derived from fermented milk made by probiotic bacteria, namely lactobacillus bulgarius and streptococcus thermophillus (Hidayati et al, 2015).

Gluconobacterium and Acetobacter

Gluconobacterium and Acetobacter are bacteria in making vinegar often used in industries that produce acetic acid from alcohol (Much, 2004). Acetobacter Xylinium is a bacterium used in making nata de coco by producing excess capsules. This bacterium can grow and develop in a sugar medium and will turn sugar into cellulose (Much, 2004).

Acetobacter bacteria can produce cellulose biofilm (nata) which is the result of the metabolism of Acetobacter sp whose processes are controlled by plasmids (Rezaee et al, 2005). In the biomedical industry, nata is widely used and for paper making that has better quality (Neelobon et al, 2007).

Lactobacillus sp.

Lactobacillus sp. used to make yogurt, butter and cheese. Lactobacillus Hetrofermentatif plays a role in making Swiss cheese because this bacterium can produce gas and photil compounds which are important as flavor forming in fermented foods (Much, 2004). In the manufacture of yogurt the bacterium Lactobacillus burgaricus has the ability of non-pathogenic intestinal microflora to join and bind to the intestines in the touching border tissue that is thought to prevent dangerous pathogens from the entrance of the gastrointestinal mucosa.

For Lactobacillus burgaricus has the effect that it must adapt to the human intestinal environment and be able to survive long in the intestinal tract. Gastric pH levels and exposure to digestive enzymes and bile salts affect the survival of Lactobacillus burgaricus, and the ability of different Lactobacillus burgaricus species to survive in the gastrointestinal environment (Oskar, 2004). Mucosal lymphoid tissue from the digestive tract has an important role as the first line of defense against pathogens ingested.

The interaction of Lactobacillus burgaricus with the mucosal epithelial lining of the digestive tract, as well as with lymphoid cells in the intestine, has been proposed as the most important mechanism by which Lactobacillus burgaricus enhances the intestinal immune function. Several factors have been identified as contributing to the immunomodulation and antimicrobial activities of Lactobacillus burgaricus, including the production of low pH, organic acids, carbon dioxide, hydrogen peroxide, bacteriocin, ethanol, and diacetyl, depletion of nutrients and competition for available living space (Oskar, 2004).

In a report that discusses the effects of yogurt and Lactobacillus burgaricus on laxation. Studies published both significant effects (G Wilhelm, 1993: 69) and no effects of yogurt or Lactobacillus burgaricus on laxation and gastrointestinal transit (Oskar, 2004).

Also Read:  Definition of Positive and Negative Gram Bacteria and their Characteristics

Benefits of Bacteria in the Pharmaceutical field

Following is the role of bacteria in producing products that can be useful in the pharmaceutical field.

Antibiotics

The modern era of the use of antibiotics to treat infectious diseases began when Alexander Fleeming in 1928 discovered penicillin produced by Penicillinum notatum (Radji, 1955).

In 1940, a research group led by Howard Flory and Ernst Chain of Oxford University succeeded in conducting the first clinical trial to prove the effectiveness of penicillin in the treatment of infectious diseases. The British scientists then conducted intensive research with US scientists so that a Pennicilium strain was found that was more productive for industrial scale.

Since then various attempts to find new antibiotics have been carried out and several new types of antibiotics have been discovered and produced on an industrial scale. In fact, antibiotics are not very difficult to find, but very little can be produced on a large scale and can be used in medicine (Radji, 1955).

Enzyme

Aspergillus foetidus and Byssochlamys fulfa produce several types of enzymes that can decompose pectin, including pectinesterase, polygalacturonase, and galactanase (Radji, 1955).

Several species of Streptococcus bacteria can produce enzymes that are useful for therapy, including streptokinase and streptodinase. Streptococcus bacterial culture cultures also contain hyaluronidase, proteinase, and several enzymes that affect nucleic acids (Radji, 1955).

Streptokinase can be used to help proteolytic enzymes in the blood and can activate blood plasminogen. So, streptokinase can help eliminate blood clots in blood clots. Streptokinase enzymes can break down DNP and DNA, which are complex compounds that are present in pus. Thus the use of the enzyme streptodornase can reduce the viscosity of pus patients (Radji, 1955).

Vitamin

Vitamins are very important compounds in helping metabolism and are often used to improve health and endurance. Vitamin B is produced by Pseudomonas denitrificans and Preptonibacterium shermanii. Ribovlavin can also be produced through a fermentation process with the help of Ashbya gossypii. Similarly, vitamin C can be produced through the process of glucose modification with the help of Acetobacter (Radji, 1955).

Dextran

Dextran is an expopolisaccharide produced by several lactic acid bacteria, including Leuconoctoc mesenteroides and Leuconostoc dextranicus . Dextran can be used in the field of medicine for blood plasma substitution. If dextran is given intravenously, a number of beneficial pharmacological effects can be obtained because dextran has an antiplatelet, antifibrin effect, and is useful as an increase in plasma volume in hypovolemia and can inhibit platelet aggregation (Radji, 1955).

Amino acid

Some microorganisms can produce several types of amino acids in sufficient quantities. For example, lysine, glutamic acid, and tryptophan are produced by Corynebacterium glutamicum (Radji, 1955).

Bacteria Classification

Based on how to get food

Based on how to obtain food, bacteria are grouped into two, namely autotrophic bacteria and heterotrophic bacteria.

• Autotrophic bacteria

Autotrophic bacteria are bacteria that can make organic material from inorganic materials. To make organic materials, energy is needed. Some bacteria get energy from light so they are called photoautotrophic bacteria. Photoautotrophic bacteria also have pigments for photosynthesis. If in green plants we know chlorophyll pigments, in bacteria the pigment for photosynthesis is called bacteriochlorophyll (which is green) and bacteriopurpurin (purple or red).

Examples of photoautrotic bacteria are Rhodobacter. Other bacteria obtain energy from the reaction of the breakdown of chemical compounds so they are called chemoautotrophic bacteria. Examples of chemoautotrophic bacteria are Nitrosomonas and Nitrobacter.

• Heterotrophic bacteria

Heterotrophic bacteria cannot make organic matter. These bacteria obtain food from organic materials that are in the vicinity by breaking down the remains of the body of other organisms. In the soil, the result of decomposition of organic materials is inorganic materials in the form of minerals. These minerals are needed by the body as nutrients.

To decompose these organic materials, some heterotrophic bacteria use the energy obtained from the reaction of the breakdown of chemical compounds. These bacteria are called kemoheterotrof bacteria.

Heterotrophic bacteria can also cause spoilage in our food. The effort to preserve food is by preventing the growth of heterotrophic bacteria in foodstuffs, for example drying, heating, smoking, freezing, cooling, and canning. Other heterotrophic bacteria are pathogenic, which can cause disease both in humans, animals and plants. An example is Bacillus anthracis which causes anthrax in livestock and humans.

Based on Oxygen Needs

Bacteria do respiration to produce energy. For the purpose of the respiratory reaction, oxygen compounds are usually needed. Based on oxygen requirements, bacteria are grouped into three, namely aerobic bacteria, anaerobic bacteria, and microaerophilic bacteria.

• Aerobic bacteria

Aerobic bacteria are bacteria that only grow when there is oxygen. If there is no oxygen, these bacteria will die. Examples of aerobic bacteria are Thiobacillus.

• Anaerobic bacteria

Anaerobic bacteria are divided into obligatory anaerobic and facultative anaerobic. Obligate anaerobic bacteria are bacteria that grow in the absence of free oxygen. If there is free oxygen, bacteria will die, for example Clostriduium. Facultative anaerobic bacteria are bacteria that can grow, both oxygen and without oxygen, for example Eschericia Coli and Salmonella.

• Microaerophilic bacteria

Microaerophilic bacteria are bacteria that grow if there is a small amount of free oxygen (> 0.2 atmosphere), for example Spirillum minus.

Based on Temperature for Growth

Bacterial growth is also strongly influenced by temperature. Each type of bacteria has a different growth temperature from one another. Based on the temperature for its growth, bacteria are divided into psychophile, mesophyll, thermofil, and hyperthermophilic bacteria.

• Psychrophile Bacteria

Psychophilic bacteria live and grow at low temperatures, which is between 0 – 30. These bacteria are found in the ocean floor, in the polar regions, and also in food ingredients causing the quality of these foods to decrease and or become rotten.

• Mesophilic bacteria

This type of bacteria lives and grows at temperatures 25 – 40 C. Mesophyll bacteria are found in many soils, water, and vertebrate bodies. One example of mesophyll bacteria is Escherichia coli.

• Thermophile Bacteria

Bacteria that are able to live and grow at a temperature of 45 -75 C are called thermophilic bacteria. This bacterium can be found in high temperature places, for example, where compost is made. In addition, thermophile bacteria are also found in temperature, soil and sea water.

• Hyperthermophilic bacteria

Hyperthermophilic bacteria live and grow at temperatures above 75 C, for example in hot springs. Some bacteria can even live at temperatures above 100 C.

Thermophile and hyperthermophil bacteria are now sought after by biotechnology experts because they can produce important enzymes used in the food and pharmaceutical industries.

Based on the Chemical Structure of the Cell Wall

Usually for identification purposes, bacteria must be colored using a Gram staining technique. This technique was first used in 1884 by  Hans Christian Gram to distinguish two types of bacteria, namely Gram positive bacteria and Gram negative bacteria. The grouping is based on differences in the chemical structure of the cell wall.

• Positive Gram Bacteria

Gram-positive bacteria have cell walls composed of layers of peptidoglycan which are relatively thick and contain teichoic acid. This type of bacteria is more susceptible to penicillin antibiotics, but more resistant to physical disorders. Examples of Gram-positive bacteria are Bacillus, Clostridium, Staphylococcus, and Strepcoccus.

Gram-positive bacteria will retain crystalline violet dyes and therefore will appear dark purple under a microscope. The gram negates bacteria will lose violet crystalline substances after being washed with alcohol and when given a coloring agent that is matched with water tochsin or safranin dyes will appear red. This color difference is caused by differences in the chemical structure of the cell wall.

If a color needs to be stained twice after the first dye (purple) is absorbed, the preparation is washed with alcohol, then mounted with a different dye, namely with a red dye. If the preparation is then washed with lau water with alcohol, two possibilities can occur. First, the additives are removed, so that what appears is the original dye (purple). In this case (bacterial) preparations we call gram-positive. The two additional dyes (red) last until the original dye is not visible. In this case (bacterial) preparations if we say gram-negative (Dwioseputro, 1984).

• Characteristics of Positive Gram Bacteria

1. Thick wall structure
2. The cell walls contain more normal lipids
3. Are more susceptible to penicillin compounds
4. Growth is significantly inhibited by dyes such as purple crystals
5. The composition required is more complicated
6. More resistant to physical disorders.

In gram staining four reagents are needed

1. 1. The main dye (violet crystal)
   2. Mordan (iodine solution) is a compound used to intensify the main color.
   3. Washers / dyes (alcohol / acetone), which are organic solvents used to fade the main dyes.

The second dye / cover paint (safranin) is used to dye the cells that have lost their primary paint after treatment with alcohol. (Suriawieia, 2002)

Diseases Caused by Positive Gram Bacteria

• Staphylococus: causes of impetigo, food poisoning, bronchitis
• Streptococus: causes of pneumonia, meningitis, dental caries
• Enterococus:  causes of enteritis
• Listeria: causes of listeriosis
• Basillus: causes of anthrax (Basillus antharx)
• Clostridium: cause of tetanus (Clostridium tetani), botulism
• Mycobacterium: causes of tuberculosis, diphtheria
• Mycoplasma: causes of acne, peumonia

• Negative Gram Bacteria

The cell wall of Gram negative bacteria consists of two layers, namely the outer layer and inner layer. The outer layer is composed of lipopolysaccharides and proteins, while the inner layer is composed of peptidoglycan. The cell wall does not contain theatricic acid. Gram-negative bacteria are resistant to penicillin antibiotics, but are less resistant to physical disorders. Salmonella, Escherichia, Azotobacter, and Acetobacter are examples of Gram negative bacteria.

Gram-negative bacteria are bacteria that cannot maintain the purple metal dye in the gram staining method. Gram-positive bacteria will retain dark purple metal dyes. After washing with alcohol, the gram-negative bacteria do not. In the gram staining test, a lead dye is added after a purple metal which makes all gram-negative bacteria, red, or pink. This test is useful for classifying these two types of bacteria based on differences in the structure of their cell walls.

Negative coloring, this method is not for coloring bacteria, but coloring the background to dark black. In this coloring microorganisms look transparent (transparent). This technique is useful for determining cell morphology and size.

• Gram-negative characteristics

1. The cell wall structure is thin, around 10-45mm, layered by three or multi layers
2. The sl walls contain more fat (11-22%), the peptidoglycan is contained in a rigid layer, before in an amount of as little as 10% of the dry weight, does not contain lactic acid.
3. Kurag is susceptible to penicillin compounds.
4. Not resistant to physical disorders. (Waluyo, 2004)

• Diseases Caused by Negative Gram Bacteria

1. Salmonella: causes of typhoid (Salmonella thyposa), salmonellosis
2. Escherichia:causes of gastroenteritis / inflammation of the gastrointestinal tract (Escherichia coli)
3. Shigell:causes of dysentery
4. Pseudomonas: causes of burn infections
5. Hellicobacter:causes of peptic ulcers
6. Haemophilus:causes of bronchitis, pneumonia (Heumophilus influenzae)
7. Bordetella:cause of whooping cough  (Bordetella pertussis)
8. Chlamydia:causes of pneumonia, urethritis, trachoma

Also Read:  Explanation of Kinds of Bacteria that Are Beneficial to Humans

Difference between Gram Positive and Negative Bacteria

Types of bacteria based on their shape

Rod shape (Basil)

Stem-shaped bacteria are known as basil (derived from the word bacillus which means stem). This form can be distinguished.

1. A single basil, a bacterium that is only in the form of a single stem. Example: Salmonella typhosa causes typhoid, Escherichiacoli bacteria found in the intestine and Lactobacillus.
2. Diplobasil is in the form of two bacterial cells bacillus attached.
3. Streptobacilli is a form of bacillary bacteria that joins elongated chain shape, for example Bacillus anthracis causes of anthrax, Streptpbacillus moniliformis, Azotobacter, nitrogen-fixing bacteria.

Round Shape (Coccus)

Spherical (ball) or coccus bacteria can be distinguished.

1. Monococcus is a single spherical bacteria, for example Monococcus gonorhoe which causes gonorrhea.
2. Diplococci, which are ball-shaped bacteria, go hand in hand, for example Diplococcus pneumoniae causes pneumonia (inflammation, lungs).
3. Sarcina is a ball-shaped bacteria in groups of four forming a cube, for example Sarcina luten.
4. Streptococcus, which is a ball-shaped bacterial group that extends in the form of chains, for example Streptococcus lactis, Streptococcus pyogenes which causes sore throats and Streptococcus thermophilis for making yogurt (sour milk).
5. Staphylococci are ball-shaped bacteria that colonize grapes, for example Staphylococcus aureus, which causes pneumonia.

Spiral Shape

There are three types of bacteria form the spiral namely:

1. Spiral, which is a group of bacteria that looks like a spiral, for example Spirillum.
2. Vibrio or coma is considered an imperfect spiral form, for example Vibrio cholerae causes cholera.
3. Spiroseta is a group of spiral-shaped bacteria that can move for example: Spirochaeta palida, the cause of syphilis.

Bacteria Classification Based on Position of Motion Equipment

• Atrik

Flagellum, not having flagellum: for example Escherichiacoly.

• Monotrik

Monotrik, one flagged at one end of the bacterial body. Example: Pseudomonas araginosa.

• Amfitrik

Amfitrik, one flagel each on both ends of the bacterial body. Example: Spirillium shortage.

• Lofotrik

Lofotrik, much flagging at one end of the bacterial body. Example: Pseudomonas flourencens.

• Peritrik

Peritrik, lots of flagging on all sides of the body of bacteria. Example: Salmonella thypii.

Bacterial Metabolism

Metabolism is all chemical processes that occur in living cells. In living cells, the chemical reaction process that produces energy is called catabolism , while the chemical reaction process that requires energy is called anabolism . Catabolic reactions are generally hydrolysis reactions that break down complex organic compounds into simpler compounds. Instead anabolic reactions or biosynthetic reactions are processes that build complex organic molecules from simpler compounds. This biosynthesis process is very needed in cell growth.

Before the metabolic process occurs, it is necessary to activate the subunit that will be used and high energy, namely ATP (adenosine triphosphate). Energy for metabolism is taken from the processes of fermentation, respiration, and photosynthesis. Energy in the process of fermentation and respiration is obtained from the carbohydrate catabolism process. Several groups of heterotrophic bacteria, including pathogenic bacteria, use organic substances as a source of carbon to obtain energy. Outrotop bacteria get energy from oxidation of inorganic compounds. This bacterium uses carbon dioxide as a carbon source for cell synthesis. However, it takes energy and coenzymes to convert carbon dioxide into cell material.

Coenzymes that play an important role in cellular metabolism include nicotinamide adenine dinucleotide (NAD ⁺ ) and nicotinamide adenine dinucleotide phosphate (NADP ⁺ ). Bacteria that carry out photosynthesis get the energy needed from light, whereas outrotop bacteria must obtain energy from chemical oxidation. In the oxidation process, electrons released from the oxidation of inorganic compounds are channeled through electron transport, which in turn will produce high energy in the form of ATP.

ATP is generally formed when oxidation-reduction reactions occur within the cell. ATP energy produced during the catabolism process will be reused in the anabolism process to build the cell components needed for cell growth.

Bacteria Names Based on Cell Walls

In the formal grouping of bacteria, it was first developed by Hans Christian Gram who divides bacteria based on cell wall characteristics through Gram staining which is divided into two namely gram negative and gram positive bacteria and non cell walled bacteria.

Positive Gram Bacteria

Gram-positive bacteria are bacteria whose cell walls absorb violet color and have a thick layer of peptidoglycan. Examples of gram-positive bacteria are as follows.

• Purple bacteria, photoautotrophic and does not produce oxygen.
• Enterobacteria, including reducing bacteria that live in decaying plants and bacteria in the human body.
• Vibrio, especially living in the ocean as bioluminescence, for example Vibrio cholera.
• Rhizobiu, living in symbiosis in the root nodules of legume plants and capable of nitrogen fixation.
• Pseudomonad, is heterotrophic and produces non-photosynthetic pigments, these bacteria cause diseases in plant animals and humans.

• Azotobacteria, live in the soil and fix nitrogen in aerobic conditions.
• Ricketsia, small rod-shaped bacteria, some species are pathogenic in humans and animals.
• Mixobacteria, secrete mucus and move by sliding.
• Chlamydia, the cell wall does not contain peptidoglycan and takes energy from its host, so it is called with high parasitic properties, for example: Chlamydia trachomati causes blindness.
• Spiroseta, a spiral-shaped bacterium that forms a flexible cell wall, this group of bacteria moves with a flagella-like structure called an axial filament, for example Treponema pallidum.
• Cynobacteria, photosynthetic bacteria that live in lakes, ponds, etc., some species of bacteria also fix nitrogen.

Negative Gram Bacteria

Gram-negative bacteria are bacteria whose cell walls absorb red color and have a thin layer of peptidoglycan, examples of gram-positive bacteria are as follows.

• Actinobacteria, are somewhat similar to fungi, these bacteria have peptidoglycan on their cell walls and do not have a core membrane, for example: several genera of Streptomyces that can produce antibiotic streptomycin.
• Streptokukos, live in the mouth and digestive tract of humans and other animals.
• Mycobacteria, containing lilindi cell wall compounds, for example: Mycobacterium tuberculosis TB disease.
• Clostridium, is anaerobic, for example: Clotridium tetani causes tetanus and Clostridum botulinum causes botulinum disease.
• Staphylococci, usually living on the nose and skin, these bacteria include opportunistic pathogenic bacteria that cause disease when the host’s immune system is down.
• Bacteria from lactic origin, able to ferment sugar and produce lactic acid as the end result, these bacteria live naturally in the mouth and vagina of humans.

Non-walled bacteria

• Mycoplasmas, these bacteria live in soil and waterways, some are parasitic in plants or animals, some species live in human mucous channels but do not cause disease.

Bacteria Names Based on Number and Location of Flagella

Each bacterial cell has a different number of flagella, based on the number and location of bacterial flagella divided into 4 namely:

• Monotric bacteria are bacteria that have one flagella at one end of the cell.
• Amfitrik bacteria are bacteria whose both ends of each cell have one flagella.
• Lophotric bacteria are bacteria which at one end of the cell have several flagella.
• Peritric bacteria are bacteria on all surfaces of the body with flagella.

Bacteria Names by Way of Life

Based on the way of life, bacteria can be divided into heterotrophic and autotrophic bacteria, among others as follows:

Heterotofrof bacteria

Bacteria that get food in the form of organic compounds from other organisms. Generally these bacteria do not have chlorophyll, this life is very dependent on the organic material that is around, because these bacteria can not convert inorganic materials into organic matter.

• Parasitic bacteria are bacteria that get food from the bodies of other organisms they are traveling in. For example: family spirochaetaceae (parasites in the intestines of two-shelled mollusks). Family treponemataceae (parasites in vertebrates and humans), another example: Borrelia burgdorferi, Borrelia recurrentis that live in animals, humans and Borrelia novyi.

• Saprofit bacteria are bacteria whose food needs are obtained from the remains of dead organisms. This type of bacteria can remodel organic matter into inorganic material. The overhaul of organic matter into inorganic material occurs through fermentation or respiration. This reshuffle process usually produces gases such as CH4, CO2, H2S, N2, H2 and NH3. Examples of saprophytic bacteria are Escherichia coli, Thibacillus denitrificans, Desulfovirio desulfuricans, Metanobacterium omelianski and Methanobacterium ruminatum, Clostridium sporageus.

• Pathogenic bacteria are parasitic bacteria that cause disease in the host / host. Examples: Salmonella thyhosa, Vibrio comma, Clostrididum tetani, Yersina pestis, Mycobacterium tuberculosis, Mycobacterium leprae, Treponema pallidum, Neisseria meningitides, Corynebacterium diphtheria, Pcudacterium tuberculosis, Mycobacterium leprae, Treponema pallidum, Neisseria meningitides, Corynebacterium diphtheria, Mycobacterium tuberculosis, Mycobacterium leprae, Treponema pallidum, Neisseria meningitides, Corynebacterium diphtheria, Pseudomonas cattelaye, P. Solanacearuum, Bovisacumumuu, a.
• Apatogen bacteria are bacteria that do not cause disease in the host, for example: Escherichia coli and Streptomyces griseus.

Autotrophic bacteria

This bacterium can make its own food from inorganic compounds, the process of conversion can occur in two ways including the following:

• Photoautotrophs are bacteria that can make their own food by using energy derived from sunlight or through photosynthesis. Photoautotrophic bacteria or photosynthetic bacteria consist of green bacteria and purple bacteria. Green bacteria have a green pigment called bacterioviridin or bacteriochlorophyll, while purple bacteria have purple, red or yellow pigments. This pigment is called bacteriopurpurin.
• Chemoautotrophs are bacteria that can make their own food using chemical energy. Examples of kemouatotrof types of bacteria are Nitrosococcus, Nitrosomonas, Nitrosocystis and Nitrospira.