On the physiology of Vibrio natriegens and the possible costs of growing "too fast"*

Vibrio natriegens is a marine bacterium with one of the fastest known growth rates: in optimal conditions its population can double in as little as 10 minutes. However, even though it is able to grow so fast, V. natriegens is not a dominant species in the marine environments where it was isolated from. To see whether this may arise from possible tradeoffs between fast growth with other physiological characteristics, we characterized various aspects of V. natriegens' growth physiology, including yield, death, and lag times when switching between nutrients. We compared these results with those of Vibrio splendidus sp. 1A01, a closely related Vibrio species which grows 25% more slowly than V. natriegens even at its optimal growth temperature, which is 10°C lower than that of V. natriegens. No apparent physiological trade-off for V. natriegens could be identified, as V. natriegens performed at least as well as V. 1A01 in all aspects examined. One ability V. natriegens lacks compared to V. 1A01 is the degradation of chitin, a polysaccharide of N-acetylglucosamine (GlcNAc) that is common in the marine environment, even though V. natriegens grows better than V. 1A01 on the monomer GlcNAc itself. Interestingly, When V. natriegens is introduced in a V. 1A01 chitin culture, it strongly inhibits the growth of the whole population, including its own. Our experiments suggest a "tragedy of the commons" scenario wherein the fast growth of V. natriegens on the monomer GlcNAc prevents V. 1A01 from growing, eventually limiting its ability to degrade chitin and generate monomers for both species. Thus, an indirect negative consequence of fast growth may be that it deprives the cells of the possibility to benefit from other species in environments that they cannot excel in.