BACTERIA

I. Competency Standart The student will be able to apply the principles of classification of living things to learn the diversity and the use of biodiversity for life.

II. Basic Competence The students will be able to describe the characteristic of bacteria.

Material Concepts

The characteristic of bacteria

The shapes of bacteria

BACTERIA The cell structure of bacteria

The reproduction of bacteria

The clasificatin of bacteria

The roles of bacteria towards humans life

INTRODUCTION We often hear this term pronounced almost everyday in our life. Now the

question is, where can we find bacteria?As a matter of fact, we encounter these organism almost every second regarding their abundant existence on the air, water soil, our skin, our mouth and so on. In a nutshell, we can find these living organism everywhere on most object. A gram of sol can contain a hundred millions of bacteria itself was derived from Greek, Bacterion, which means rod. However, the shape of bacteria is not only rod-shape but there are also others like spherical-shaped and round-shaped.

THE CHARACTERISTIK OF BACTERIA 1. Bacteria generally range size 10m in length and 0,5-1 m in width. 2. Bacteria are unicellular, which means that their body containsone cell

only. They life in colonies or solitaire. 3. The cell has no chloroplast that does not enable bacteria to produce their

own food. 4. Bacteria reproduce asexually by means of ninary fission. 5. Bacteria have an outer cell wall composed of peptidoglycan, a molecule

that contains chains of unique amino disaccharide joined by peptide chains.

6. Some bacteria move by means of flagella but some others do not.

7. Bacteria produce an endospore whenever the environmental conditions turn to extreme. This endospore is resistan upon an extreme heat and other bad circumstances.

8. Bacteria can life and be found anywhere like in swamps, fresh water, tropical area and even in the Pole.

THE SHAPE OF BACTERIA

Bacteria cells are of many different shape but there are three shapes most commonly exist : the spherical or coccus type, the straightrod or bacillus type, and the curved-rod or spirillum type. 1. Coccus type

These bacteria are bulb-shaped since they look like a ball. Based on the colonies, these bacteria are classified as the following:

a. Monococcus type, this bacterium live by itself since it does not have companion colonies. For example, Neisseria gonorrhoeae, a bacterium that causes gonorrhea disease.

b. Dyplococcus type, a pair of cells remains double after a cell divides itself. For example, Diplococcus Pneumoniae, bacteria that cause pneumonia diseases.

c. Tetracoccus type, colonies of bacteria consisted of several groups in which each group comprises four bacteria.

d. Streptococcus type, colonies of bacteria that produce a filamentous chain cells.

e. Sacrina type, colonies of bacteria, which live in-groups and produce an eight-celled, cubical colony.

f. Staphylococcus type, a colony of bacteria that create an irregular cluster of cells in grape-shaped.

2. Bacillus type The shape of bacteria in this category is rod shaped. Bacillus type bacteria are divided into the following categories :

a. Monobacillus type, the kind of bacterium live alone and does not create a colony.

b. Diphobacillus type, the bacteria make a pair of cell remain double.

c. Streptobacillus type, bacteria that produce a filamentous chain of cells.

3. Spiral / helical shaped type (spirillum) The bacteria look like a long curved spiral. An example of this bacterium is vibrion, a bacterium that look like a coma.

THE CELL STRUCTURE OF BACTERIA 1. The cell wall

The function of this cell wall is to prevent a bacterium from bursting or collapsing due to osmotic changes. Beside that, this cell wall shapes

the body of the bacterium. The cell wall is composed of peptidoglycan, a molecule that contains chains of unique amino disaccharide joined by peptide chains. Based on the structure of protein and polysaccharide in the cell wall, bacteria are conmmonly distinguished by using the Gramstain produce. Gram positive bacteria retain a dye iodine complex and appear purple the light microscope. On the other hand, gram negative bacteria do not retain the complex and appear pink.

2. Capsule In some bacteria, the cell wall is surrounded by an attahached

capsule that protects the bacteria from viruse infection as well as the attack from the host defense.

3. Flagella Some bacteria move by means of flagella. The flagellum has a

filament composed of three stands of the protein flagellin wound in helix. The filament is inserted into a hook that is anchored by a basal body. The rotation of the flagellum causes the cell to spin and move forward. Flagella attach at the outer plasma membrane or at the outer membrane of the cell. Based on the position and the amount of flagella, bacteria are divided into monotric, amphitric, lophotric and peritric.

4. Cell Membrane This membrane is constructed of protein and fat molecule just like the other membranes.

5. Mesosome Mesosome was made from the cell membrane that indented into the cytoplasm. It is attached at the cell membranes and functions as the energy provider for the bacteria as well as the central of new cell wall replication.

6. Photosynthesis lamella For bacteria that are able to do photosynthesis process, they have the co calld photosynthesis lamella. These organelles contains chlorophyll for helping the bacteria to do photosynthesis process.

7. Cytoplasm Chytoplasm is the content of a cell between the nucleus region of bacteria and the plasma membrane. Cythoplasm contains organic molecules such as carbonhydrate, protein, fat and other minerals. This is where metabolic process takes place.

8. DNA DNA as the bacterial chromosome is located at a dense area called nucleoid.

9. Plasmid Besides chromosome DNA, bacteria also have non chromosome DNA or circular DNA located at the outside of chromosome DNA known as plasmid. Plasmid is a self duplicating ring of accessory DNA in the cythoplasm of bacteria. The size of plasmid 1/1000 times of chromosome DNA.

10. Ribosomes

Ribosome carry out protein synthesis in a bacterial cell. They are consisted of RNA and protein.

11. Endospore Whenever bacteria are faced with unfavorable environmental condition, they form endospore. Endospore is a new and thicker cell wall rounding up the former plasma membrane and cytoplasm. Endospore are resistant to extreme heat, cold or toxin.

THE REPRODUCTION OF BACTERIA 1. Binary Fisson

Bacteria reproduce asexually by means of binary fission. Binary fission can be described as a process in which a single circular chromosome replicates and then two copies separate as the cell enlarges. Newly formed plasma membrane and cell wall separate the cell into two cells.

2. Genetic Recombination In bacteria, genetic recombination can occur in three ways.

a. Conjugation The process of which the donor cells passes DNA to the recipient cell by way of a sex pilus, which tempory joins two cells. Conjugation takes place only between bacteria in the same or closely related species.

b. Tranformation Transformation occurs when a bacterium picks up free pieces of DNA secreted by live bacteria or relased by dead bacteria.

c. Transduction This is process when bacteriophages carry portion of bacteria DNA from one cell to another.

THE CLASSIFICATION OF BACTERIA BASED ON THE NUTRITION With respect to the nutrient requirements, bacteria are classified into the following.

1. Heterotrophic Bacteria Heterotrophic bacteria are bacteria that can not synthesize organic

compounds from inorganic substances and therefore they have to take the food from their surrounding. These bacteria gain the organic substance from the waste products of other organism or the inside substance of other organism. Scientist call these bacteria as saprotrophic bacteria.

Saphotrophic reduce and decompose dead organism and their waste products from complex organic compounds to simpler chemical substances that can be recycled by other organism. Thus, bacteria are actually nutrient suppliers for the plantations so that plantation can accomplish photosynthesis process. An example of saprotrophic bacterium is Escherichia Coli that lives inside humans intestines

2. Autotrophic Bacteria Authotrophic bacteria can make organic molecules from inorganic

nutrients. Thus, they can utilize carbin dioxide as a carbon source and synthtesis all their molecules from it.

The process of synthesizing the inorganic molecules into the organcic ones are divided into the following : a. By using the sunlight energy

Bacteria use the sunlight energy to synthesize the inorganic molecules into the organic molecules through photosynthesis process. Therefore, these bacteria are called photoautotoph. Example of these bacteria are green bacteria, which contain green pigment called bacteriochlorophyll and purple bacteria, which contain purple / yellow / red pigment.

b. By using chemical energy Bacteria oxide inorganic compounds such as nitrites, hydrogen gas and hydrogen sulfide to obtain the chemical energy. Bacteria then use this chemical energy to synthesize and produce organic molecules. Example of such bacteria are Nitrosococcus and Nitrobacter.

THE CALACCIFICATION OF BACTERIA BASED ON THE NEED FOR OXYGEN

To gain for their growing, bacteria exert respiration by the process of fission of the food molecules. During the fission process, there are some bacteria that indispensably need the presence of oxygen and there are some others that do not need the presence of oxygen.

Based on the need of the presence of oxygen, bacteria are divided into two categories as follows :

1. Aerobic bacteria These bacteria do need the presence of oxyen during the fission

process of the food molecules. They also require a constant supply of oxygen to carry out cellular respiration. Such bacteria are fond of living in humid circumstances. An example of these is Nitrosomonas

2. Anaerobic bacteria These bacteria are obligate anaerobs because they are unable to

grow in the presence of oxygen. Example of such bacteria are Microsococcus denitrificans, and Clostridium tetan. The later is the cause of tetanus disease.

THE ROLES OF BACTERIA TOWARDS HUMANS LIFE Most people do assume that bacteria bring disadvantages only towards

human beings. Yet, such an assumption is not quite true cognizant to the fact that there are some bacteria which have been proven to be very much useful for humans. a. Bacteria that bring advantages upon humans.

As decomposers One of the most essential functions of bacteria is that they are the ones

that decompose and reduce dead organism and their waste products from complex organic compounds to simpler chemical substances that can be recycled by other organism such as the plantations. Thus, bacteria are deeply involved in soil with nitrogen compounds. Indirectly, bacteria can help plantations to do photosynthesis process by providing the nutrients that the plants need.

As a matter of fact, bacteria also exist in our body as decomposers. Escheria coli are the bacteria that live inside our body. They live mostly in our large intenstines to decompose our waste products of the digestion process. These bacteria also help humans in synthesizing vitamin K.

Bacteria are especially important to mammalian herbivores, which depend on a diet of plants full of hard to digest cellulose. Cows, goats, deer, sheep, antelope, giraffe and others have a special part of the stomach called the rumen in which bacterial digestion takes place.

As antibiotic producers Some bacteria, especially from Actinomycetes group, are antibiotic

producers. Antibiotic is a substances that has the capacity to kill or inhibit growth of infectious microorganism. Thus, it can be to help humans preventing pathogenic bacteria, which may create diseases. Some bacteria that produce antibiotics are :

1. Sreptomyces griceus (producing streptomycin) 2. Streptomyces aurefaciens (producing Auremycin) 3. Sreptomyces venezuele (producing chloromycin and

chloramphenicol)

As acid substances producers Bacteria also produce acid substances, which is basically needed by

humans. The following are those bacteria that produce acid substances : 1. Clostridium butiricum (producers of butyrate acid) 2. Propioni bacterium (producers of propionate acid) 3. Acetobacter (producers of acetate acid)

Helping the process of emulsion process Such a bacterium like Lactobacilus bulgaricus can be used in the

process of yogurt production. Beside that, bacterial action is also involved in the production of butter, cheese, sauerkraut, pickles, vinegar and soy sauce.

As Nitrogen fixers As a matter of fact, bacteria play a significant role in enriching the soil

with nitrogen compounds. Since plants can not use atmosphere nitrogen, nitrogen-fixing bacteria in the soil are essential in order to convert nitrogen from the air into nitrogen compounds that can be used by plants. Bacterium that can do such a job of fixing nitrogen is Rhizobium leguminosorum. As the legume begins to grow in the soil, secretes chemical substances conducive to Rhizobium growth, attracting bacteria from the soil, which the rapidly colonize the plant. The rizhobia infect the plant roots and produce nodules that are colonized by millions of bacteria. The growth of the bacteria colonies is stimulated by hormones produces by the plants root. The plant produces carbohydrates, which provide the

bacteria with carbon and energy, and the bacteria fix the nitrogen, which is used by the plant.

Helping humans in oxidizing sewage Most of the waste products of industrial production are oxidized by

aerobic bacteria, which are enormously existing in the air. Besides that, some anaerobic bacteria can help in decompiosing waste products of dead organism and oxidizing them into methane gas, which is very useful for humans being.

In recents years, scientist nave been able to change the genetic content of microorganism to enable them to produce useful chemicals. This genetic engineering has produce bacteria thar efficiently manufacture growth hormone, insulin and interferon a potential cancer-fighting drug. In a nutshell, bacteria may become the most important producers of medicine in the future.

b. Bacteria that bring disadvantages towars humans beings Although bacteria do help a lot humans life, but they also creates

disadvantages as the following : As pathogens

As pathogenic organism, bacteria are filling roles as parasites. Bacteria cause several of disease towards animals, plantations and humans.

As pathogens in plantations and animals There are lots of diseases attack animals and plants such as the following : 1. Anthrax : this disease is caused by bacterium named Bacillius

antraxis. This bacterium infects cows, buffaloes, and sheep. 2. Bruselosis : this disease is caused by bacterium called Brucella

abortus. Such a disease commonly attacks cows. 3. Swollen jaw : it is caused by Acttynomices bovis and this bacterium

commonly infects cows.

Bacteria also creates various disease towards plantations such as crown gall on fruit tress in which this disease is caused by Xanthomonas citri and the same disease also infects coffe tree, the bacterium is called Agrobacterium tumefaciens.

As foodstuff exhauster As a matter of fact, ther are mountainous bacteria live in foodstuff

as saprotrophic and their existence mostly create damages. They destroy the foodstuff by producing toxin, which is turn, endangering the health of humans who consume the products. The following examples are those bacteria that destroy foodstuff :

a. Pseudomonas cocovenanans : they produce some kind of diseased-tuber acid. These bacteria are commonly found in fermented soybean cake.

b. Clostrodium botulinum : they produce botulinine toxin. Such bacteria usually live in canned-food.

c. Leuconostoc mesentrodies : they produce phlegm especially for spoiled food.

As pathogens in humans body Bacteria cause various kinds of infections towards human being. Disease such as pneumonia, rheumatic fever, scarlet fever, food poisoning, gonorrhea, syphilis and meningitis are caused bacteria.

c. Preventive action towards the threat of bacteria Owing to the fact that bacteria do create problem towards human

beings, people, henceforth, need to take preventive actions upon such a problem. Scientists suggest the following action to tackle the problems related with bacteria:

1. The use of vaccine In recent years, scientist have already invented some vaccine to

conquer the infections caused by bacteria. They are as follows : a. BCG vaccine (Bacillus Calmette Guerin) in which thi

vaccine is used to cure tuberculosis disease. b. DPTP vaccine (Diphteria, Pertusis, Tetanus, Propholacsis)

in which it can be used to cure diphtheria disease, whooping, cough, and tetanus disease.

c. TCD vaccine (Thypus, Cholera, Dysentry) that can be applied to medicate thypus disease, cholera and dysentery disease.

d. Cothipha vaccine that can be applied to medicate cholera disease, thypus and parathypus disease.

2. Protection towards preserved-food One of the ways to protect foodstuff from the infectin of

bacteria is by preserving the foodstuff. To preserve foodstuff, there are several methods suggested by scientist such as sterilization, pasteurization, coagulation, refrigation, radiation and the use of chemical substances.

EVALUATION

I. Chose one right answer

1. One way to prove that bacteria are living organism is done by.. a. Observasing by using microscope the presents of respiration process. b. Breeding in the right medium. c. Observing by using electron microscope the presence of DNA. d. Observasing by using electron microscope the shape of their structure. e. Analysing the chemical elements that build their body.

2. The specific content of bacteria cell wall is.. a. Peptidoglycan b. Pectin c. Cellulose d. Lignin e. Chitin

3. Rhizobium bacteria that make symbiosis with beans plant are useful because they..

a. Refine soil particles b. Break anorganic compound into organic compounds c. Break organic compound dinto anorganic compounds d. Changing free nitrogen into nitrate e. Change nitrate into free nitrogen.

4. Blue algae can make photosynthesis so these algae live in way. a. Heterotrophic b. Saprophytic c. Autotrophic d. Parasitic e. Chemoautotrophic

5. Cyanophyta that can be used as source of protein is.. a. Anabaena b. Nostoc c. Spirulina d. Azolla pinnata e. Oscilatoria

II. Answer briefly and clearly

1. Explain why monera is the simplest living organism ! 2. Why cant bacteria be seen by using naked eyes ? 3. When is a bacteria called positive gram ?