Shelby Fife

Table of contents

What are bacteria?..................................................................page 1Archeabacteria....page 2Eubacteria.page 3

Structure of Bacteria..pages 4-5Identifying Bacteria-Gram stain.page 6

Reproduction Asexual and Sexual..page 7

Importance of Bacteria...pages 8-9

Disease causing Bacteria...page 10

Reference Page.page 11

What are Bacteria?Bacteria are a large group of unicellular microorganisms. This means that they consist of one cell and cannot be seen with out a microscope. Bacteria are found in every habit on Earth. They live in soil, acidic hot springs, radioactive waste, water, and deep in the oceans crust. They can also live in the bodies of plant and animal. Typically a few micrometers in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a milliliter of fresh water. There are thousands of bacteria in the body. The immune system in the body makes most bacteria harmless. Few are beneficial. Some are pathogenic and cause infections diseases like anthrax, syphilis, and cholera. Bacteria are classified as prokaryotes. Prokaryotes do not contain a nucleus or other membrane-bound organelles, unlike eukaryotes. Prokaryotes are broken down into two categories, eubacteria and archaebacteria.

Bacteria can also be Aerobic or Anaerobic. Aerobic bacteria are bacteria that can grow and live in the presence of oxygen. Anaerobic bacteria are bacteria that do not live or grow in the presence of oxygen.

Archaebacteria.

Archaebacteria are the oldest living organisms on earth. They live in very extreme conditions, like the bottom of the ocean and volcanic vents. Earths early atmosphere was filled with poisonous gases and was very hot. Archeabacteria were the only organisms that could survive in this harsh environment. As oxygen was introduced into Earths atmosphere, archeabacteria gave way to more modern organisms. There are three groups of archeabacteria. None of which can live in oxygen environments. Methanogens are characterized by their ability to obtain energy by converting H2 and CO2 into methane gas. They are found in marshes and in the intestinal tracts of humans and some animals. Ancient methanogens are the source of natural gas.

The second group is halophiles. In Greek this name means salt-loving. Salt kills most bacteria, but halophiles have adapted to the salty environments. They are found in the Dead Sea, the Great Salt Lake, and other areas with a high salt content. In order to survive the high salinities, halophiles have two different strategies to prevent desiccation through osmotic movement of water out of their cytoplasm. In the first, organic compounds are accumulated in the cytoplasm, known as compatible solutes. The second, adaptation involves the selective influx of potassium (K+) ions into the cytoplasm. The third group is the thermoacidophiles. These bacteria are found in extremely acidic conditions and in areas with very high temperatures. They can survive in areas with temperatures as high as 230 degrees Fahrenheit and with pHs below 2. It can survive hydrochloric acid which is incredibly strong and has a pH of 1. These locations include volcanic vents and hydrothermal vents. Hydrothermal vents are cracks in the ocean floor where scalding hot water leaks out.EubacteriaUnlike the Archaea, the Eubacteria have been known and studied for more than 150 years. Perhaps more importantly, many of them inhabit environments that are easily studied and sampled. Eubacteria have been separated into the Gram positive and Gram negative groups, based upon a standard stain technique. As it turns out, the way a cell stains is related to the type and structure of the cell wall. Gram positive cells have a single membrane with a murien or peptidoglycan wall to the outside of the single membrane. Gram negative cells have an inner membrane and an outer membrane with a murein layer sandwiched between them. The system of Margulis and Schwartz (1998) is based on the fundamental separation of gram positive and gram negative cells.

There are three types of eubacteria, Heteratrops, Photosynthetic autotrophs, and chemosynthetic autotrophs. Heteratrophs use organic carbon for growth. They are known as consumers in food chains and obtain organic carbon by eating other heterotrophs or autotrophs. They break down complex organic compounds that are produced by autotrophs. Photosynthetic autotrophs produce complex organic compounds from simple inorganic molecules using energy from light by photosynthesis. They must live in environment with sunlight. In addition to deriving energy from chemical reactions, synthesize all necessary organic compounds from carbon dioxide. Chemoautotrophs generally only use inorganic energy sources. They live in hostile environments such as deep sea vents and are the primary producers in such ecosystems. Evolutionary scientists believe that the first organisms to inhabit Earth were chemoautotrophs that produced oxygen as a by-product. Chemoautotrophs generally fall into several groups: methanogens, halophiles, sulfur reducers, nitrifiers, anammoxbacteria and thermoacidophiles.

Structure of BacteriaBacteria have a well developed cell structure that is responsible for many of their biological properties. Many of their features are not found among eukaryotes.

The cell structure of bacteria has been well studied. The cell shape can be coccus (spherical), bacillus (rod-like), spirillum (spiral), or filamentous. Some bacteria have complex life cycles involving the production of stalks and appendages and some produce elaborate structures bearing reproductive. These are often the first characteristics observed by a microbiologist to determine the identity of an unknown bacterium.

The primary function of the cell wall is to protect the cell from internal pressure. The bacterial cell wall differs from that of all other organisms by the presence of peptidoglycan, which is located outside of the cytoplasmic membrane. Peptidoglycan is responsible for the rigidity of the bacterial cell wall and for the determination of cell shape. Since the cell wall is required for bacterial survival, but is absent in eukaryotes, several antibiotics, penicillin and cephalosporin, stop bacterial infections by interfering with cell wall synthesis. This process has no effect on human cells.

Fimbrae are protein tubes that extend out from the outer. They are generally short in length and present in high numbers about the entire bacterial cell surface. Fimbrae aid in the attachment of bacterium to a surface. Pili are similar in structure to fimbrae but are much longer and present on the bacterial cell in low numbers. Pili are involved in reproduction. . Non-sex pili also aid bacteria in gripping surfaces.

An S-layer is a cell surface protein layer found in many different bacteria. It serves as the cell wall. All S-layers are made up of a two-dimensional collection of proteins and have a crystalline appearance. The exact function of layer is unknown. An S-layer could conceivably keep extra cellular proteins near the cell membrane by preventing their diffusion away from the cell. In some pathogenic species, an S-layer may help to facilitate survival within the host by conferring protection against host defense mechanisms.

Flagella are whip-like structures protruding from the bacterial cell wall and are responsible for bacterial movement. There are different forms of flagella. Peritrichous are multiple flagella found at several locations in the cell. Polar is a single flagella found at one of the cells poles. Lophotrichous is a tuft of flagella found at one cell pole. Flagella are complex structures that are composed of many different proteins. Flagellin is the protein that makes up the whip-like tube. It and a protein complex that spans the cell wall form a motor that causes the flagellum to rotate.

The most well known bacterial adaptation to stress is endospores. Endospores are bacterial survival structures that are highly resistant to many different types of chemical and environmental stresses and therefore enable the survival of bacteria in environments that would be lethal for these cells in their normal form.

Identifying bacteria- gram stain

The Gram staining method is named after the Danish bacteriologist, Hans Christian Gram. He introduced it in 1882. It is almost always the first test performed for the identification of bacteria. The primary stain of the Gram's Method is crystal violet. The microorganisms that retain the crystal violet-iodine complex appear purple brown under microscopic examination. These microorganisms that are stained by the Gram's Method are commonly classified as Gram-positive. Others that are not stained by crystal violet are referred to as Gram negative, and appear red.

Gram staining is based on the ability of bacteria cell wall to hold in the crystal violet dye. The cell walls for Gram-positive microorganisms have a higher peptidoglycan and lower lipid content than gram-negative bacteria. Iodine is subsequently added to form the crystal violet-iodine complex so that the dye cannot be removed easily. This step is referred to as fixing the dye. However, subsequent treatment with a decolorizer, which is a mixed solvent of ethanol and acetone, dissolves the lipid layer from the gram-negative cells. The removal of the lipid layer enhances the removal of the primary stain from the cells into the surrounding solvent. The solvent dehydrates the thicker Gram-positive cell walls, closing the pores as the cell wall shrinks during dehydration. As a result, the diffusion of the violet-iodine complex is blocked, and the bacteria remain stained.

Reproduction asexual and sexual

Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Bacteria can only reproduce under certain conditions. These conditions are not often met, and that is one thing that keeps bacteria from growing out of control. Bacteria can grow and divide extremely rapidly, and bacterial populations can double in 9.8 minutes. Asexual reproduction involves only one parent. The offspring generated by asexual reproduction are exact duplicates of the parent. Binary fission is the process by which a bacteria splits into two cells. Each cell gets an exact copy of the parent cell's genetic material.

Sexual reproduction involves the joining of two parent cells and the exchanging of genetic materials. In sexual reproduction, the offspring will have a mixture of the parent cells' traits. Conjugation is the process by which bacteria join and exchange genetic materials. Once genetic materials are exchanged, each bacteria cell will go through binary fission to produce an offspring with a new genetic makeup.

Binary fission

Importance of BacteriaBacteria are important in many ways: Fermentation processes, such as brewing and baking use bacteria. Cheese and butter manufacturing require the use of bacteria. Bacteria have been used for thousands of years in the preparation of foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine, and yogurt. Bacteria can actually help to fight themselves. Doctors and scientists have figured out how to use dead or weakened bacteria to prevent other bacterial diseases. This process is called vaccination. Vaccination has helped us all become a lot healthier then we were a hundred years ago. Bacteria also make, or help to make, drugs, hormones, or antibodies. Some bacteria living in the gut of cattle, horses and other herbivores secrete cellulose, an enzyme that helps in the digestion of the cellulose contents of plant cell walls. Cellulose is the major source of energy for these animals.

Bacteria are used to decompose sewage wastes. They break down organic matter to harmless, soluble sludge in settling tanks. The methane gas produced is used as energy source. Similarly toxic chemicals synthesized by living organisms and those present in the pesticides are disposed with the help of bacteria. The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing, and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Bacteria play a big role in Nitrogen fixation. Nitrogen fixation refers to the biological process by which nitrogen in the atmosphere is converted into ammonia. This process is essential for life because fixed nitrogen is required to build the basic building blocks of life, like nucleotides for DNA and amino acids for proteins.

Decomposing is one of the most important jobs bacteria do. This is also called mineralization. When an organism dies in the wild, it just sits and rots. What is happening is that bacteria are releasing carbon to the atmosphere which plants use. With no carbon dioxide there would be no photosynthesis. By decomposing the dead organisms, the bacteria release essential nutrients into the air and soil.Lastly, bacteria play a large part in many commercial industries. They help in tanning, making linen, curing tea and tobacco leaves, extracting precious metals from rock, coloring foods, coloring cosmetics, tenderizing meat, removing stains, processing paper, processing cloth, changing one chemical into another.

Disease causing bacteria

If bacteria form a parasitic association with other organisms, they are called pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, food borne illness, leprosy and tuberculosis. Bacterial diseases are also important in agriculture, with bacteria causing leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm animals.

Bacterial infections may be treated with antibiotics. They are classified as bactericidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth, where they may be contributing to the rapid development of antibiotic resistance in bacterial populations. Infections can be prevented by antiseptic measures such as sterilizating the skin prior to piercing it with the needle of a syringe. Surgical and dental instruments are also sterilized to prevent contamination by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection.

Reference page www.earthlife.net/prokaryotes/disease.html En.wikipedia.org/wiki/Bacteria

www.livescience.com/bacteria www.ucmp.berkeley.edu/bacteria/bacteria.html www.buzzle.com/articles/diferent-types-of-bacteria.html