CLASSIFICATION OF BACTERIA
There are thousands of species of bacteria on earth, many of which have not yet been identified. When attempting to classify a bacterium, a variety of characteristics are used, including visual characteristics and laboratory tests. Bacteria are simple, unicellular organisms. Most are free-living organisms, but a few require animal or plant hosts for survival. Bacteria absorb nutrients from their environments, excrete waste products, and secrete various toxins that help them invade tissues. Bacteria have no enclosed nucleus. Their chromosomal material is in the form of a large loop, packed into the cytoplasm of the cell.
Some bacteria can be identified through a simple visual perusal. First, the operator considers the appearance of the bacterial colony (a group of the same kind of bacteria growing together, often on a petri dish.) The operator also views individual bacteria under a microscope, considering their shape, groupings, and features such as the number and location of flagella.
A variety of laboratory techniques can be used to narrow down the identity of a bacterial species if a visual survey is not sufficient. The operator can stain the bacteria using a gram stain or an acid-fast stain. The bacteria can be cultured on a specific medium which promotes the growth of certain species, as in the membrane filter method of testing for coliform bacteria. Other tests can detect bacterial by-products, while yet more advanced tests actually analyze the DNA of the bacteria.
Some bacteria can be identified through a simple visual perusal. First, the operator considers the appearance of the bacterial colony (a group of the same kind of bacteria growing together, often on a petri dish.) The operator also views individual bacteria under a microscope, considering their shape, groupings, and features such as the number and location of flagella.
A variety of laboratory techniques can be used to narrow down the identity of a bacterial species if a visual survey is not sufficient. The operator can stain the bacteria using a gram stain or an acid-fast stain. The bacteria can be cultured on a specific medium which promotes the growth of certain species, as in the membrane filter method of testing for coliform bacteria. Other tests can detect bacterial by-products, while yet more advanced tests actually analyze the DNA of the bacteria.
Nomenclature
Assignment of names to the various taxa according to international rules
Shapes
The most basic method used for identifying bacteria is based on the bacterium's shape and cell arrangement. This section will explain the three morphological categories which all bacteria fall into - cocci, bacilli, and spirilla. You should keep in mind that these categories are merely a way of describing the bacteria and do not necessarily refer to a taxonomic relationship. The most common shapes of bacteria include rod, cocci (round), and spiral forms. Cellular arrangements occur singularly, in chains, and in clusters. Some species have one to numerous projections called flagella enabling the bacteria to swim, making them motile organisms.
Cocci (or coccus for a single cell) are round cells, sometimes slightly flattened when they are adjacent to one another. Cocci bacteria can exist singly;
- in pairs (as diplococci )
- in groups of four (as tetrads )
- in chains (as streptococci )
- in clusters (as stapylococci )
- or in cubes consisting of eight cells (as sarcinae .)
Bacilli (or bacillus for a single cell) are rod-shaped bacteria. Since the length of a cell varies under the influence of age or environmental conditions, you should not use cell length as a method of classification for bacillus bacteria. Like coccus bacteria, bacilli can occur singly, in pairs, or in chains. Examples of bacillus bacteria include coliform bacteria , which are used as an indicator of wastewater pollution in water, as well as the bacteria responsible for typhoid fever.
Spirilla (or spirillum for a single cell) are curved bacteria which can range from a gently curved shape to a corkscrew-like spiral. Many spirilla are rigid and capable of movement. A special group of spirilla known as spirochetes are long, slender, and flexible.
Respiration
Although we think of respiration as breathing, respiration is actually the process by which organisms break down organic substances (such as sugars) to produce energy. All living organisms must perform some kind of respiration.
In many cases, the chemical process of respiration requires oxygen, although some organisms are able to carry out respiration in the absence of oxygen. This page will explain the three types of respiration found in microorganisms, as well as how these types of respiration affect the wastewater treatment plant.
In many cases, the chemical process of respiration requires oxygen, although some organisms are able to carry out respiration in the absence of oxygen. This page will explain the three types of respiration found in microorganisms, as well as how these types of respiration affect the wastewater treatment plant.
Biochemical reactions
it is for clinically relevant bacteria
ribosomal- rna analysis
It is the scientific study of plasma serum and other bodily fluids
example)
a) Strep pyogenes- Rheumatic fever nephritogenic strain, M types 2, 42, 49, 56, 57, and 60.
example)
a) Strep pyogenes- Rheumatic fever nephritogenic strain, M types 2, 42, 49, 56, 57, and 60.
serology
- Oxidase test
- Catalase test