Introductory Microbiology

Nutrition and growth of microorganisms

• Nearly 70% of the weight of cell is water and the rest is solid matter. In addition to oxygen and hydrogen the microbial cell contains four other major elements such as C, N, P and S. These six together accounts 95% of cellular dry weight. Other elements are found is lesser amounts are K, Mg, Ca, Na, Fe, Mn, Cl, Cu, Mo and Zn. Microorganisms, therefore, need a large number of elements for survival and growth. Even microorganisms differ with respect to the chemical form in which these elements are utilized as nutrients.
• Carbon is a constituent of all organic cell material and therefore represents nearly 50% of the cell dry weight. Nitrogen is found mostly in proteins, nucleic acids, co-enzymes etc. Phosphorous is a major constituent of nucleic acids while S is a constituent of mainly proteins and co-enzymes.