Deciphering a survival strategy during the interspecific competition between MSM-S1 and sp. MSM-M1.

Interspecific competition in bacteria governs colony growth dynamics and pattern formation. Here, we demonstrate an interesting phenomenon of interspecific competition between MSM-S1 and sp MSM-M1, where secretion of an inhibitor by sp is used as a strategy for survival. Although grows faster than sp., in the presence of sp. the population of reduces significantly, whereas sp. do not show any marked alteration in their population growth. Appearance of a zone of inhibition between growing colonies of two species on nutrient agar prevents the expanding front of the MSM-S1 colony from accessing and depleting nutrients in the region occupied by MSM-M1, thereby aiding the survival of the slower growing MSM-M1 colonies. To support our experimental results, we present simulations, based on a chemotactic model of colony growth dynamics. We demonstrate that the chemical(s) secreted by sp. is responsible for the observed inhibition of growth and spatial pattern of the MSM-S1 colony. Our experimental results are in excellent agreement with the numerical results and confirm that secreted inhibitors enable sp. to survive and coexist in the presence of faster growing , in a common niche.