Microbes (or microorganisms) are organisms that are too small to be seen by the unaided eye. They include bacteria, fungi, protozoa, microalgae, and viruses. Microbes live in familiar settings such as soil, water, food, and animal intestines, as well as in more extreme settings such as rocks, glaciers, hot springs, and deep-sea vents. The wide variety ofmicrobial habitats reflects an enormous diversity of biochemical and metabolic traits that have arisen by genetic variation and natural selection in microbial populations. Historically, humans have exploited some of this microbial diversity in the production of fermented foods such as bread, yogurt, and cheese. Some soil microbes release nitrogen that plants need for growth and emit gases thatmaintain the critical composition of the Earth's atmosphere. Other microbes challenge the food supply by causing yield-reducing diseases in foodproducing plants and animals. In our bodies, different microbes help to digest food, ward off invasive organisms, and engage in skirmishes and pitched battles with the human immune system in the give-and-take of the natural disease process. A genome is thetotality of genetic material in the DNA of a particular organism. Genomes differ greatly in size and sequence across different organisms. Obtaining the complete genome sequence of a microbe provides crucial information about its biology, but it is only the first step toward understanding a microbe's biological capabilities and modifying them, if needed, for agricultural purposes. Microbialbiotechnology, enabled by genome studies, will lead to breakthroughs such as improved vaccines and better disease-diagnostic tools, improved microbial agents for biological control of plant and animal pests, modifications of plant and animal pathogens for reduced virulence, development of new industrial catalysts and fermentation organisms, and development of new microbial agents for bioremediation of soiland water contaminated by agricultural runoff
FUNGI Fungi have been important in both ancient and modern biotechnological processes. Processes and products that utilize fungi include baking, brewing, and the production of antibiotics, alcohols, enzymes, organic acids, and numerous pharmaceuticals. The advent of recombinant DNA technology and large scale genomics analysis has placed yeastsand filamentous fungi in the forefront of contemporary commercial applications. Yeasts are eukaryotic microorganisms classified in the kingdom Fungi, with the 1,500 species currently described estimated to be only 1% of all yeast species. Most reproduce asexually by budding, although a few do so by binary fission. Yeasts are unicellular, although some species with yeast forms may becomemulticellular through the formation of a string of connected budding cells known as pseudohyphay or false hyphae, as seen in most molds.
Table 1. Fungal enzymes of commercial importance Enzyme Asparaginase Amylase Catalase Cellulase Dextranase ß-Glucanase Glucoamylase Glucose oxidase Hemicellulase Laccase Lipase Pectinase Protease Rennet Tannase Xylanase Main Source Aspergillus spp. And Penicillium spp.Aspergillus niger, Aspergillus. oryzae A. niger, Penicillium spp. A. niger, Trichoderma reesei, T. viride, Penicillium finiculosum Penicillium spp. A. niger, Penicillium emersonii, T. reesei, T. viride A. niger, A. oryzae A. niger, Penicillium spp. A. niger, A. oryzae, T. reesei, T. viride, P. emersonii Pyricularia oryzae Several species including A.niger, A. oryzae Several species including A.niger, Rhizopus oryzae Several species including A. niger, A. oryzae Mucor miehei, Endothia parasitica A.niger, A. oryzae A. niger, T. reesei
Table 2. Use of fungi in biotechnology Food Applications Baking Brewing Cheese-making Mushroom cultivation Oriental food fermentations Quorn myco-protein Useful Products Alkaloids Antibiotics Ethanol Enzymes Gibberellins Immunomodulators Organic...