Lag phase

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What is Lag Phase?

Lag phase is one of the earliest phases in the bacterial growth cycle. In this phase, the bacteria tends to adapt itself to the growth conditions. Here, the individual bacteria matures but does not divide yet. In this stage of the cycle of growth, enzymes, RNA and various molecules are synthesized. As cells are not promptly reproduced into a new medium in this stage, cells do not exhibit a lot of changes, in fact, minute changes are observed in this stage. Hence, this stage is often misunderstood. This stage of almost no division is the lag phase, ranging from merely 60 minutes to a couple of days. Although cells do not divide in this stage, they are not dormant.

This is a tentative duration of non-replication observed in bacteria initiated into a new medium. This phase is said to be an organized, dynamic and adaptive stage which safeguards bacteria against threats and fosters reproductive flexibility. It pertains to antibiotic tolerance, host-pathogen interactions, food safety, molecular biology and more.

Obtaining Bacterial Growth Curve – Lag Phase

Bacteria do not start prompt multiplication and take a while after a liquid batch culture is inoculated. This period between the beginning of multiplication and the inoculation is the lag phase. Here, the bacteria that is inoculated adapt to the conditions, activates enzymes and adapts to the ambient temperature and other conditions. It is during this phase that the bacteria increases in size, however, there is no change in the number of bacterial cells. They are just metabolically active. This period of lag phase is subject to changes, given the type of culture medium, bacterial species, temperature (incubation), etc.

Factors influencing Lag phase

There are several elements affecting the period of lag phase such as the inoculum size, physiochemical environment of the new and old growth medium, cell’s physiological history, etc. In order to gain reproducible lag times, a standardized bacterial inoculum must be deployed under steady growth conditions.

You briefly learnt about the lag phase of bacterial growth. Explored related concepts important for NEET at BYJU’S.

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Frequently Asked Questions

What are the 4 phases of bacterial growth?

The four phases of bacterial growth are log phase, lag phase, stationary phase and death phase.

What happens during the lag phase?

During the lag phase, the cells are metabolically active but they do not divide. The cells increase in size and adapt to the new environment.

What are the phases in a fungal growth curve?

There are five distinct phases in a fungal growth curve namely, the lag phase, first transition period, the log phase, second transition period and finally the stationary phase.

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