The effects of modeled microgravity on growth kinetics, antibiotic susceptibility, cold growth, and the virulence potential of a Yersinia pestis ymoA-deficient mutant and its isogenic parental strain.

Previously, we reported that there was no enhancement in the virulence potential (as measured by cell culture infections) of the bacterial pathogen Yersinia pestis (YP) following modeled microgravity/clinorotation growth. We have now further characterized the effects of clinorotation (CR) on YP growth kinetics, antibiotic sensitivity, cold growth, and YP's virulence potential in a murine model of infection. Surprisingly, none of the aforementioned phenotypes were altered.

Ribonucleases and bacterial virulence.

Bacterial stress responses provide them the opportunity to survive hostile environments, proliferate and potentially cause diseases in humans and animals. The way in which pathogenic bacteria interact with host immune cells triggers a complicated series of events that include rapid genetic re-programming in response to the various host conditions encountered. Viewed in this light, the bacterial host-cell induced stress response (HCISR) is similar to any other well-characterized environmental stress to which bacteria must respond by upregulating a group of specific stress-responsive genes.

The effects of low-shear mechanical stress on Yersinia pestis virulence.

Manned space exploration has created a need to evaluate the effects of spacelike stress on pathogenic and opportunistic microbes astronauts could carry with them to the International Space Station and beyond. Yersinia pestis (YP) causes bubonic, septicemic, and pneumonic plague and is capable of killing infected patients within 3-7 days. In this study, low-shear modeled microgravity (LSMMG), a spacelike stress, was used to physically stress YP; and its effects on proliferation, cold growth, and type III secretion system (T3SS) function were evaluated.

Spaceflight and modeled microgravity effects on microbial growth and virulence.

For unsuspecting bacteria, the difference between life and death depends upon efficient and specific responses to various stressors. Facing a much larger world, microbes are invariably challenged with ever-changing environments where temperature, pH, chemicals, and nutrients are in a constant state of flux. Only those that are able to rapidly reprogram themselves and express subsets of genes needed to overcome the stress will survive and outcompete neighboring microbes.