For growth and multiplication of bacteria, the mimimal nutritional requirements are water, a source of carbon, a source of nitrogen and some inorganic salts. Phototrophs are bacteria that derive energy from sunlight while chemotrophs derive theirs from chemical reactions. Beneficial microorganisms are naturally occurring bacteria, fungi, and other microbes that play a crucial role in plant productivity and health. Two types of beneficial microorganisms, mycorrhizal fungi and nitrogen-fixing bacteria, are considered beneficial to plant health.Microorganisms like bacteria and fungi, act as decomposers as they break down the dead and decaying organisms into simpler nutrients that mix with the soil. These nutrients are absorbed by plants during photosynthesis. The rate of growth or death of a particular microbial species is influenced by a variety of physical factors in its environment including temperature, osmotic pressure, pH, and oxygen concentration.

The microorganisms which thrive and grow in extreme environments where normal microorganisms can't survive are called extremophiles. The major factors which influence the growth of microorganisms are pH, water activity, temperature, oxygen level, pressure, and radiation. One of the most critical factors for microbial growth is the availability of nutrients and energy. Microbes need carbohydrates, fats, proteins, metals, and vitamins to survive, just like animals. The process of using nutrients and converting them into cellular material requires energy. All microbes have a need for three things: carbon, energy, and electrons. There are specific terms associated with the source of each of these items, to help define organisms. For growth and multiplication of bacteria; the mimimal nutritional requirements are water, a source of carbon, a source of nitrogen and some inorganic salts. Phototrophs are bacteria that derive energy from sunlight while chemotrophs derive theirs from chemical reactions. The bacteria need the nutrition and optimum physical environment to conduct its molecular, physiological activity and to multiply. The nutrients means the organic and inorganic material obtained from environment for the Bacterial Growth and multiplication.