Microbial biodiversity (summerized).pptx

Microbial biodiversity

1. Microbial Biodiversity

2. Biodiversity is the measure of the variety of earth's animal, plant and microbial species; of genetic differences within species; and of the ecosystems that support the species.

3. Microbes are one of the dominant life forms which occur in the universe, but most of us are ignorant of their true profile. This is perhaps because they are so tiny as to be visible to the naked eye. For this reason only, they remained unknown till about 300 years ago.

4. Microbes are widely distributed in air, water, soil, sea, mountains, hot springs and also in bodies of living plants and animals including the human. These organisms have a high degree of adaptability . Microorganisms are exceptionally attractive models for studying fundamental life processes. They can be easily grown in culture tubes or flasks, thereby requiring less space and maintenance, than larger plants and animals.

5. Biodiversity can be subdivided into three levels as follows:

6. 1. Genetic Diversity At finer levels of organization, biodiversity includes the genetic variation within species, both among geographically separated populations and among individuals within the single population . ( Populations : Assemblages of similar organisms, Communities: Mixtures of different populations)

7. 2. Species Diversity It refers to the variety of species within a region. It measured on the basis of number of species in the region.

8. 3. Ecosystem Diversity It includes variations in the biological communities in which species live, the ecosystem in which communities exist, and the interactions among these levels .

9. In order to identify and classify the diverse kinds of microorganisms, the principal pre-requisite is to know their characteristics. The major characteristics of the microbes fall into following categories.

10. 1. Morphological characteristics It includes: Cell shape, size and structure; cell arrangement; occurrence of special structures and development of forms; staining reactions and motility and flagella arrangement. The determination of the morphological features usually requires studying individual cells of the microbes. Being very minute in size, it requires high resolution microscopy. The discovery and use of electron microscopes have given advantage in getting proper morphological features of microbes.

11. 2. Chemical characteristics Microbial cells contain variety of compounds . For example, the occurrence of lipopolysaccharide in the cell walls is distinctive of gram negative bacteria. Fungal and algal cells are very different in composition from those of bacteria.

12. 3. Cultural characteristics Each microbe has specific growth requirement. Many microorganisms can be grown in culture media, which are a mixture of nutrients used in the laboratory to support their growth and multiplication. Some can grow in a medium containing only inorganic compounds while others require organic compounds like amino acids, carbohydrates and vitamins etc. Some can grow with natural media like blood cells, malt extracts. In addition to the nutrients, microorganisms require certain characteristic environmental parameters like temperature, pH, supply of oxygen etc. for their growth in culture media.

13. 4. Metabolic characteristics The life processes of microbial cells are complex integrated series chemical reactions termed metabolism. The varieties of these reactions provide many opportunities to characterize and identify the organisms. For example, there are certain bacteria, which can independently fix atmospheric nitrogen, yet there are others which require some type of symbiotic association with angiosperms for the same purpose .

14. 5. Antigenic characteristics Certain chemical compounds of the microbial cells are called antigens. When a microbe enters the body of an animal, the animal responds with antibodies. Antibodies are highly specific for antigens, which induce their formation. This can help in the identification of the microbe.

15. 6. Genetic characteristics The double stranded chromosomal DNA of every kind of microorganism has certain features that are constant and specific for the organism and useful for the classification.

16. 7. Pathogenicity The ability of an organism to cause disease is otherwise called pathogenicity Certain microbes like bacteria and viruses are pathogenic to humans and still others such as fungi are pathogenic to plants.

17. 8. Ecological characteristics On the basis of the habitat, microorganisms show variability. The microbes, which occur in the marine environment show difference from those, occur in the fresh water environment. Some microorganisms are widely distributed in nature; others are restricted to a particular environment.