• The microorganisms require a source of energy, carbon, nitrogen, oxygen, iron and other minerals, micronutrients, and water for growth and multiplication.
• Selection of appropriate culture medium for the microorganisms depends on the prior knowledge of the habitat of the microorganisms.
• Culture media can be categorised on the basis of chemical composition. Media are classified into two types: synthetic and complex media. While on the basis of consistency, the culture media may be solid, liquid and semi-solid. Whereas, based on their application and functions, the media may be divided into selective, differential and enrichment media.
• Sterilisation is of prime importance for any microbial study and it is the process, where all the living microorganisms, including bacterial spores are killed or removed.
• Sterilisation can be achieved by physical (heat, radiation and filtration) and chemical methods.
• The microbial growth may be affected by a number of physical factors, such as temperature, pH, oxygen, etc.
• The growth of the cultured microorganisms can be analysed by plotting the logarithm of the number of viable cells versus the incubation time, which results in a curve with four distinct phases, namely lag, exponential, stationary and death phase.
