Contribution of Louis Pasteur in biology?

Known as the founder of microbiology, Pasteur discovered the role of bacteria in fermentation. His experiments with bacteria conclusively disproved the theory of spontaneous generation and led to the theory that infection is caused by germs. Extrapolating from this knowledge, Pasteur then developed a process in which liquids such as milk were heated to kill all bacteria and moulds already present within them. This process became known as pasteurisation.

Recognising that infectious diseases are caused by microorganisms, Pasteur's research soon led others to investigate sterilisation, disinfection, vaccines, and eventually antibiotics. Pasteur created and tested vaccines for diphtheria, cholera, yellow fever, plague, rabies, anthrax, and tuberculosis. (source: today.wmit.net - 27 December)