Microbiology of Water:

Many types of micro-organism such as bacteria, virus, algae, plankton and fungi etc. are present in water. Some are helpful and some cause diseases if present in drinking water.

Bacteria

Bacteria are minute single cell organism having no defined nucleus and chlorophyll. Their presence can be detected by circumstantial evidences or chemical reactions.  They belong to group of organisms known as "fission fungi" and reproduce by direct splitting of a parent cell into two daughter cells and not by any complicated reproductive process.

These are classified according to :

• Their shape (cylindrical, spherical and curved, etc.),
• Oxygen requirement (aerobic, non-aerobic and facultative), and
• Harmful/beneficial (pathogenic/non-pathogenic).

Bacteria which require oxygen for their survival are known as aerobic bacteria, whereas those which can survive in the absence of free oxygen, are known as anaerobic bacteria. And those bacteria which can survive with or without free oxygen are known as facultative bacteria.

In the cycle of life and death of all plants, animals and men, these non-pathogenic bacteria cause degradation of all organic matter and synthesis of mineralized food material by means of which all plant life on the earth is surviving. Certain bacteria are deadly to man and animals and enter their tissues causing serious water borne diseases such as cholera, typhoid, infectious hepatitis etc. These harmful bacteria are known as pathogenic bacteria or pathogens. The bacteria which are harmless are also known as non-pathogenic bacteria. Most of the bacteria of coliform group come under this category.