Biologists have found four bacterial strains of the Methylobacteriaceae family in surface samples collected from the International Space Station (ISS) during Microbial Tracking-1 flight experiments.
Transmission electron micrograph showing the general cell morphology of Methylobacterium jeotgali. Image credit: Aslam et al., doi: 10.1099/ijs.0.64625-0.
Dr. Kasthuri Venkateswaran of NASA’s Jet Propulsion Laboratory and colleagues analyzed samples collected during Microbial Tracking-1 flight experiments in 2015 and 2016.
“As part of an ongoing Microbial Tracking experiment on the ISS, eight locations are being monitored for bacterial growths and have been for the last six years,” they explained.
“These sample areas include where the crew assembles or where experiments are conducted, such as the plant growth chamber.”
The researchers isolated four Methylobacterium strains — designated as IF7SW-B2T, IIF1SW-B5, IIF4SW-B5 and I1-R3 — from the samples.
Of these, the three first strains were assigned to a novel species, named Methylobacterium ajmalii, whereas the fourth was identified as Methylorubrum rhodesianum.
“Members of the Methylobacterium genus are Gram-negative, rod-shaped bacteria,” the scientists said.
“The genus consists of 45 recognized species, which are ubiquitously present in a wide variety of habitats including air, soil, freshwater, and sediments, and can exist either in free-form or associated with plant tissues.”
“Methylobacterium species are involved in nitrogen fixation, phosphate solubilization, abiotic stress tolerance, plant growth promotion, and biocontrol activity against plant pathogens,” they added.
“For instance, a recently-discovered Methylobacterium sp. 2A was observed to result in higher density of lateral roots in inoculated potato crops, even under salt stress conditions, compared with control plants that were not inoculated with the bacteria; it was also found to exhibit biocontrol activity against several plant pathogens.”
According to the team, the newly-isolated strains might possess ‘biotechnologically useful genetic determinants’ for the growing of crops in space.
However, further experimental biology is needed to prove that it is, indeed, a potential game-changer for space farming.
“To grow plants in extreme places where resources are minimal, isolation of novel microbes that help to promote plant growth under stressful conditions is essential,” the authors said.
The findings appear in the journal Frontiers in Microbiology.
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Swati Bijlani et al. Methylobacterium ajmalii sp. nov., Isolated From the International Space Station. Front. Microbiol, published online March 15, 2021; doi: 10.3389/fmicb.2021.639396
