Protozoa
Protozoa are parasitic and animal-like protists because of their motility. Their sizes range from 10 to 52 micrometers. They moved by flagella, hair-like structures called cilia and foot-like structures called pseudopodia (Fig. 13). Protozoa absorb food by their cell membranes e.g., amoebas, surround food and engulf it. All protozoa digest their food in stomach-like compartments called vacuoles. Protozoa can reproduce by binary fission or multiple fission. Some protozoa reproduce sexually, some asexually, while some use a combination. They cause many diseases in human such as malaria, amoebiasis and leishmaniasis etc.
The scope and relevance of microbiology
Microbes influence human society in countless ways. Sometimes, the influence of microorganisms on human life is beneficial, whereas at other times, it is detrimental. For example, microorganisms are required for the production of bread, cheese, yogurt, alcohol, wine, beer, antibiotics (e.g., penicillin, streptomycin, and chloramphenicol), vaccines, vitamins and enzymes. Many products of microbes contribute to public health as aids to nutrition, other products are used to interrupt the spread of disease, and still others hold promise for improving the quality of life in the years ahead. Microbes are also an important and essential component of an ecosystem. Molds and bacteria play key roles in the cycling of important nutrients in plant nutrition particularly those of carbon, nitrogen and sulphur. Bacteria referred to as nitrogen fixers live in the soil where they convert vast quantities of nitrogen in air into a form that plants can use. Microorganisms also play major roles in energy production. Natural gas (methane) is a product of bacterial activity, arising from the metabolism of methanogenic bacteria. Microorganisms are also being used to clean up pollution caused by human activities, a process called bioremediation (the introduction of microbes to restore stability to disturbed or polluted environments). Bacteria and fungi have been used to consume spilled oil, solvents, pesticides and other environmentally toxic substances.
Agricultural microbiology – try to combat plant diseases that attack important food crops, work on methods to increase soil fertility and crop yields etc. Currently there is a great interest in using bacterial or viral insect pathogens as substitute for chemical pesticides.
Microbial ecology – biogeochemical cycles – bioremediation to reduce pollution effects
Food and dairy microbiology – try to prevent microbial spoilage of food and transmission of food borne diseases such as botulism and salmonellolis. Use microorganisms to make foods such as cheese, yogurt, pickles and beers.
Industrial microbiology – used to make products such as antibiotics, vaccines, steroids, alcohols and other solvents, vitamins, amino acids and enzymes.
Microbial physiology and Biochemistry – study the synthesis of antibiotics and toxins, microbial energy production, microbial nitrogen fixation, effects of chemical and physical agents on microbial growth and survival etc.
Microbial genetics and Molecular biology – nature of genetic information and how it regulated the development and function of cells and organisms. Development of new microbial strains that are more efficient in synthesizing useful products.
Genetic engineering – arisen from work of microbial genetics and molecular biology. Engineered microorganisms are used to make hormones, antibiotics, vaccines and other products. New genes can be inserted into plants and animals.