Methylobacterium ajmalii sp. nov., Isolated From the International Space Station

Abstract

Four strains belonging to the family of Methylobacteriaceae were isolated from different locations on the International Space Station (ISS) across two consecutive flights. Of these, three were identified as Gram-negative, rod-shaped, catalase-positive, oxidase-positive, motile bacteria, designated as IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, whereas the fourth was identified as Methylorubrum rhodesianum. The sequence similarity of these three ISS strains, designated as IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, was <99.4% for 16S rRNA genes and <97.3% for gyrB gene, with the closest being Methylobacterium indicum SE2.11T. Furthermore, the multi-locus sequence analysis placed these three ISS strains in the same clade of M. indicum. The average nucleotide identity (ANI) values of these three ISS strains were <93% and digital DNA-DNA hybridization (dDDH) values were <46.4% with any described Methylobacterium species. Based on the ANI and dDDH analyses, these three ISS strains were considered as novel species belonging to the genus Methylobacterium. The three ISS strains showed 100% ANI similarity and dDDH values with each other, indicating that these three ISS strains, isolated during various flights and from different locations, belong to the same species. These three ISS strains were found to grow optimally at temperatures from 25 to 30°C, pH 6.0 to 8.0, and NaCl 0 to 1%. Phenotypically, these three ISS strains resemble M. aquaticum and M. terrae since they assimilate similar sugars as sole carbon substrate when compared to other Methylobacterium species. Fatty acid analysis showed that the major fatty acid produced by the ISS strains are C18:1−ω7c and C18:1−ω6c. The predominant quinone was ubiquinone 10, and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and an unidentified lipid. Therefore, based on genomic, phylogenetic, biochemical, and fatty acid analyses, strains IF7SW-B2T, IIF1SW-B5, and IIF4SW-B5, are assigned to a novel species within the genus Methylobacterium, and the name Methylobacterium ajmalii sp. nov. is proposed. The type strain is IF7SW-B2T (NRRL B-65601T and LMG 32165T).

Comprehensive Comparative Genomics and Phenotyping of Methylobacterium Species

“…Taxonomically, the first PPFM strain described in the literature was isolated from earthworm contents; at that time, it was named “ Bacillus extorquens ” ( Bassalik, 1913 ). In 1976, the genus Methylobacterium was established with Methylobacterium organophilum as the only species within it ( Patt et al, 1976 ); since then, the number of known Methylobacterium species has risen to 63 ( Hedlund et al, 2021 ; Maeng et al, 2021 ) 1 . Various attempts have been made to examine PPFMs from a taxonomic perspective ( Green and Bousfield, 1982 ; Hood et al, 1987 ; Tsuji et al, 1990 ; Tani et al, 2015 ; Kröber et al, 2021b ).…”

Spatial Characterization of Microbial Communities on Multi-Species Leafy Greens Grown Simultaneously in the Vegetable Production Systems on the International Space Station

“…In VEG-03D Methylobacterium was identified in red romaine and mizuna while Janthinobacterium was isolated in red romaine only. Recently it was reported that 4 strains of Methylobacterium, one a newly characterized strain, were isolated on the ISS with the Microbial Monitoring experiments [73]. Methylobacterium are involved in nitrogen fixation, phosphate solubilization, abiotic stress tolerance, plant growth promotion, and biocontrol activity against plant pathogens [74,75] and is a methylotrophic with the ability to utilize methanol produced by plants as a carbon source [76] Janthinobacterium is a soil bacterium with a wide range of metabolic activities, including antimicrobial properties and resistance to stressors such as UV radiation and cold temperatures providing a benefit to plants [77][78][79].…”

Advances in space microbiology

“…Our understanding of microbial diversity in the upper atmosphere and aboard spacecraft has relied mostly on the culturable microorganisms. In recent times, the advent of genomics has allowed for the identification of new species ( Bijlani et al., 2021 ; Singh et al., 2019 ; Venkateswaran et al., 2017 ) and several other microorganisms found in the ISS that are otherwise unculturable. It is well known that only 0.1%–1% of microorganisms from any environment are culturable ( Lloyd et al., 2018 ).…”