The effect of stress on survival and bioluminescence

This study investigates how increased stress affects the fitness of free-living microorganisms and the knock-on effect as they colonise and perform in a host. Vibrionaceae were tested as they are interesting within the context of climate change as they are sensitive to temperature changes, and are able to invade harsh environments, both features connected with climate change.

Cohen et al (2018) used the same strain of marine bioluminescent bacterium Vibrio fischeri (ET00-7-1) to investigate this question exposing Vibrio fischeri to either different or fluctuating temperatures. Strain fitness was compared to ancestors (un-evolved line), distinguishing the two with the use of “neutral markers”. In both free-living (fitness) and host-associated life (bioluminescence and ability to colonise) there were significant increases in ability under stress (heat specialists>temp generalists>cold specialists>ancestors).

This is interesting as many species of Vibrionaceae are pathogenic such as Vibrio cholerae, so temperature increase may not only increase their spread and ability to colonise but also increase their virulence. However, there has been evidence that extreme temperatures effect the ability of microorganisms to engage with hosts, partially because of the effect on gene expression so this may lead to reduction in ability to colonise a host.

Cohen L.M., Mashanova V.E., Rosen M.N., Soto W. (2019) Adaptation to temperature stress by Vibrio fischeri facilitates this microbe’s symbiosis with the Hawaiian bobtail squid (Euprymna scolopes). EVOLUTION. 73, 1885-1897.