Spacy Behavior: Lack of gravity in space may affect how bacteria behave

Spacy Behavior: Lack of gravity in space may affect how bacteria behave

Bacteria in space may pose risks for astronauts on long spaceflights, and research has shown that bacteria behave differently in the microgravity environment of space. For example, in space, bacteria multiply to higher numbers and in some cases are more virulent and less susceptible to antibiotics.

Researchers have suggested that this behavior results from the lack of gravity reducing the movement of molecules outside the bacterial cells and leading to reduced nutrient availability. However, there has been little evidence to support this hypothesis.

To gain more insight into reduced extracellular molecular movement, Luis Zea from the University of Colorado, Boulder, and his colleagues conducted a new study comparing gene expression between E. coli grown at the International Space Station and E. coli grown on Earth. The authors found that in space, the bacteria expressed more genes associated with starvation conditions, including genes encoding proteins for amino acid synthesis, glucose breakdown and use of alternative carbon sources.

This pattern of gene expression is likely a reaction to reduced glucose availability, supporting the model of reduced movement of molecules in the bacteria’s extracellular environment due to decreased gravity. Future spaceflight experiments that examine a variety of other bacterial species under differing growth conditions could help explain changes in bacterial growth and virulence that could significantly affect people living in space.

Altered Extracellular Model. Gene expression data support the hypothesis that glucose concentration decreases (blue gradient) and acid builds up (gold gradient) in the boundary layer around a bacterial cell in space. Scientists have suggested that this altered extracellular environment is an effect of reduced gravity-driven forces acting on the cell and the surrounding fluid system, and this mechanism may govern bacterial behavior in space. Blue circles indicate overexpression of genes associated with glucose breakdown, while gold circles represent the overexpression of acidic condition genes.

Altered Extracellular Model. Gene expression data support the hypothesis that glucose concentration decreases (blue gradient) and acid builds up (gold gradient) in the boundary layer around a bacterial cell in space. Scientists have suggested that this altered extracellular environment is an effect of reduced gravity-driven forces acting on the cell and the surrounding fluid system, and this mechanism may govern bacterial behavior in space. Blue circles indicate overexpression of genes associated with glucose breakdown, while gold circles represent the overexpression of acidic condition genes.

“The microgravity environment of the International Space Station is now being used for myriad lines of research, for example: vaccine development, finding novel molecular targets against drug-resistant pathogens, and testing of molecules to be used against osteoporosis or cancer,” Zea says. “This new understanding of how extracellular biophysical processes initiate mechanical transduction signals in bacteria in space may serve not only to protect astronauts as they venture beyond Earth orbit, but these other lines of research as well.”

Research Article: Zea L, Prasad N, Levy SE, Stodieck L, Jones A, Shrestha S, et al. (2016) A Molecular Genetic Basis Explaining Altered Bacterial Behavior in Space. PLoS ONE 11(11): e0164359. doi:10.1371/journal.pone.0164359

Image Credit: Sweetie187, Flickr CC-BY; Zea et al (2016)

Author

Tessa is the Journal Media Manager at PLOS. She graduated from the University of California, Berkeley with degrees in Rhetoric and Music. She can be reached by email at tgregory@plos.org and on Twitter at @tessagregs.

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