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Microbiology is the scientific study of microorganisms. These are organisms that cannot be seen with the naked eye. Not all organisims fit in this size criterion. Some algae and fungi are very large!. However, bacteria, viruses some fungi, some algae and protozoa fit in this size criterion.

Microorganisms studied

To solve his problem of drawing the boundaries of microbiology, Roger Stanier said that in defining microbiology and the organisms to be studied we should not only look at the size of the subjects but also the techniques used in the study.

  1. Bacteria
  2. Fungi
  3. Algae
  4. Viruses

Disciplines in microbiology

In microbiological study, isolation of organisms is carried out, pure cultures are prepared and the aseptic technique is observed. There are diffrent disciplines in microbiology. These are medical, environmental, agricultural, plant pathology, microbial ecology and sanitary microbiology

Disciplines related to Microbiology

  • Botany
  • Zoology
  • Biochemistry
  • Public health
  1. Prokaryotes
  2. Bacteria
  3. Fungi
  4. Viruses

Historical background of microbiology


This is the the process of making objects free of microorganisms. It can also be termed as the process of complete removal of all forms of life from objects.

Methods of sterilization

There mainly two methods of sterilization. These are:- Sterilization by physical means Sterilization by chemical means


Tissue preparation

animal tissues

permanent slides

Tissues in microbiology are preparered through valious steps, these involves; cutting the tissue,fixing with a suitable fixative,infitration with parafin wax,dehydrating with ethanal different concetrations and redehydrating with ethanol.the tissue are ussually held together with wax so as to be fixed od microtome for the purpiose of sectioning.the sections are floated on water bath and attached on the slide.they are then dried and infitration takesn place. tissues are the treated with a suitable stain prosses called staining.the suitable stain may be gram stain or haematixilin.the excess stain are removed by running tap water.these are hydrated using ethanol. equipments;

  • microtome
  • water bath
  • paraffin wax
  • source of heat
  • microscope
  • slides


  • ethanol
  • water
  • stains eg gram stain

Tissue culture

is a techique used to obtain oplant from minute part of the explant on sterile nutrient medium. the concept of totipotency is applied.