Pune: “Typically, the number of individuals in a population is a good estimate of whether or not bacteria can evolve under certain conditions. Larger populations carry more biological variations and adapt faster to newer environments. This primarily happens as at least some of the population may cope with the sudden changes in the environment. However, this makes them more vulnerable to the new environment,” said Sutirth Dey, biologist at Indian Institute of Science, Education & Research, Pune.
He and his team members recently investigated this question in depth in their research paper, ‘Adapting in larger numbers can increase vulnerability of Escherichia coli (kind of bacteria) populations to environmental changes.’
“The lab performed experiments with E coli populations of various sizes and introduced them into a mixture of three antibiotics. They were made to evolve for 400 generations. We studied if adapting in larger numbers under constant environment makes the E coli populations more capable of facing future changes in environmental conditions,” he told Sakal Times.
The team measured the efflux activity of E coli. Efflux activity is defined as the bacteria’s ability to pump out unwanted material of the cell. “We observed that efflux activity is higher for smaller populations while it decreased for larger populations. While larger population adapts faster in alternative environments, its fitness level is worse compared to smaller population,” he said.
Evolution of drug resistance is an important topic today. This study demonstrates a novel link between population size and immediate response to environmental changes and contributes to the field of evolution.
Along with Dey, YD Chavan and SM Karve worked on the paper. This work received funding from Department of Biotechnology, Council for Scientific and Industrial Research (CSIR) and IISER Pune.
