Microbes are both useful & harmful for human being. There no. of   m/o that cause diseases in human as well as plant & other animals.

Most importance bacteria are harmless to humans, and many bacteria are essential to the existence of plant and animal life. Only small fractions of bacteria cause disease; most bacteria attack organic matter only after it is dead.
Bacteria also enrich the soil in various ways. The so-called nitrogen fixing bacteria take nitrogen gas from the atmosphere and convert it to a form (nitrate) that green plants use for growth. Bacteria are important industrially in the production of cheese, yogurt, buttermilk, vinegar, and sauerkraut; in the preparations of antibiotic such as streptomycin, which is extracted from soil bacteria.

Biotechnology and bacteria

Biotechnology or Industrial microbiology is defined as the application of organisms such as bacteria, fungi and algae to the manufacturing and services industries. These include:

  • Fermentation processes, such as brewing, baking, cheese and butter manufacturing, Bacteria, often Lactobacillus in combination with yeasts and molds, have been used for thousands of years in the preparation of fermented foods such as cheese, pickles, soy sauce, sauerkraut, vinegar, wine, and yogurt.
  • Chemical manufacturing such as ethanol, acetone, organic acid, enzymes, perfumes etc. In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrochemicals.
  • Pharmaceuticals, such as antibiotics, vaccines and steroids.