With the growth of microorganisms, microorganisms use nutrients in the culture medium, the number of bacteria increases, and the state of the culture medium changes from clear to turbid. Experiments show that the turbidity of culture medium is linearly proportional to the growth of microorganisms, so the degree of spectrophotometer can be used to reflect the growth of microorganisms.
In actual operation, a simple method is to use sterilized culture medium as control solution and measure od value at 600 or 660nm to reflect the growth of microorganisms. If only the OD value is used as a parameter to reflect the growth state of microorganisms in the factory, it is enough. If you are in the research room or want to send some high-quality English papers, I suggest you convert the OD value into the dry weight of bacteria, which is more accurate. In the process of converting into bacterial dry weight, you only need to measure the OD value, centrifuge the bacterial suspension, wash it with normal saline, then centrifuge, then dry the bacteria and measure the bacterial dry weight, and then you can get the corresponding relationship between the OD value and the bacterial dry weight.