Bacteria are found everywhere in air, soil, water. They are most adaptative organisms which can grow in very cold climate like arctic region, hot spring, desert, on and inside organisms body.This note contains information about its occurrence, types and gram positive and gram negative bacteria.

Cell Structure of Bacteria

The detailed structure of bacteria can be studied only under the electron microscope. This note contains information about cell structures of bacteria.

Nutrition in Bacteria

Most of the bacteria do not contain chlorophyll. They are unable to synthesis their own food but a small group of bacteria are capable of synthesizing their own food. So, nutrition in bacteria is both autotrophic and heterotrophic. This note contains information about types of nutrition in bacteria.

Economic Importance of Bacteria

Bacteria have both harmful and beneficial effect. This note contains brief description about harmful and useful effects of bacteria.

Respiration in Bacteria

Both aerobic and anaerobic respiration occurs in bacteria. This note contains information about respiration in bacteria.

Introduction to Cyanobacteria (Blue-green algae)

Cyanobacteria is also known as blue-green algae. This note contains information about classification and general characteristics of cyanobacteria.


Terrestrial species of Nostoc can be found in damp soil. Few species of Nostoc are also found in the rice field in which they increase the soil fertility by fixing atmospheric free nitrogen. This note contains information about occurrence, structure, cell structure of Nostoc.

Reproduction in Nostoc

Nostoc is reproduced only by vegetative and asexual methods. The sexual reproduction is completely absent. This note contains information about the vegetative and asexual method of reproduction.