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Parochlus steinenii is the only flying insect native to Antarctica. To elucidate the molecular mechanisms underlying its adaptation to cold environments, we conducted comparative genomic analyses of P. steinenii and closely related lineages. In an analysis of gene family evolution, 68 rapidly evolving gene families, involved in the innate immune system, unfolded protein response, DNA packaging, protein folding, and unsaturated fatty acid biosynthesis were detected. Some gene families were P. steinenii-specific and showed phylogenetic instability. Acyl-CoA delta desaturase and heat shock cognate protein 70 (Hsc70) were representative gene families, showing signatures of positive selection with multiple gene duplication events. Acyl-CoA delta desaturases may play pivotal roles in membrane fluidity, and expanded Hsc70 genes may function as chaperones or thermal sensors in cold environments. These findings suggest that multiple gene family expansions contributed to the adaptation of P. steinenii to cold environments., (© 2022. The Author(s).)

Two Gram-stain-negative, facultative anaerobic, chemoheterotrophic, pink-coloured, rod-shaped and non-motile bacterial strains, PAMC 26568 and PAMC 26569 T , were isolated from an Antarctic lichen. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strains PAMC 26568 and PAMC 26569 T belong to the family Acetobacteraceae and the most closely related species are Gluconacetobacter takamatsuzukensis (96.1 %), Gluconacetobacter tumulisoli (95.9 %) and Gluconacetobacter sacchari (95.7 %). Phylogenomic and genomic relatedness analyses showed that strains PAMC 26568 and PAMC 26569 T are clearly distinguished from other genera in the family Acetobacteraceae by average nucleotide identity values (<72.8 %) and the genome-to-genome distance values (<22.5 %). Genomic analysis revealed that strains PAMC 26568 and PAMC 26569 T do not contain genes involved in atmospheric nitrogen fixation and utilization of sole carbon compounds such as methane and methanol. Instead, strains PAMC 26568 and PAMC 26569 T possess genes to utilize nitrate and nitrite and certain monosaccharides and disaccharides. The major fatty acids (>10 %) are summed feature 8 (C 18 : 1  ω7 c and/or C 18 : 1  ω6 c ; 40.3-40.4 %), C 18 : 1 2OH (22.7-23.7 %) and summed feature 2 (C 14 : 0 3OH and/or C 16 : 1 iso I; 12.0 % in PAMC 26568). The major respiratory quinone is Q-10. The genomic DNA G+C content of PAMC 26568 and PAMC 26569 T is 64.6 %. Their distinct phylogenetic position and some physiological characteristics distinguish strains PAMC 26568 and PAMC 26569 T from other genera in the family Acetobacteraceae supporting the proposal of Lichenicola gen. nov., with the type species Lichenicola cladoniae sp. nov. (type strain, PAMC 26569 T =KCCM 43315 T =JCM 33604 T ).

Two Gram-stain-negative, facultative anaerobic chemoheterotrophic, pink-coloured, rod-shaped and non-motile bacterial strains, PAMC 29128 and PAMC 29148 T , were isolated from lichen. Phylogenetic analysis based on the 16S rRNA gene sequences revealed that strains PAMC 29128 and PAMC 29148 T belong to lichen-associated Rhizobiales -1 (LAR1), an uncultured phylogenetic lineage of the order Rhizobiales and the most closely related genera were Methylocapsa (<93.9 %) and Methylosinus (<93.8 %). The results of phylogenomic and genomic relatedness analyses also showed that strains PAMC 29128 and PAMC 29148 T were clearly distinguished from other species in the order Rhizobiales with average nucleotide identity values of <71.4 % and genome-to-genome distance values of <22.7 %. Genomic analysis revealed that strains PAMC 29128 and PAMC 29148 T did not contain genes involved in atmospheric nitrogen fixation or utilization of carbon compounds such as methane and methanol. Strains PAMC 29128 and PAMC 29148 T were able to utilize certain monosaccharides, disaccharides, sugar alcohols and other organic compounds as a sole carbon source. The major fatty acids (>10 %) were summed feature 8 (C 18 : 1  ω7 c and/or C 18 : 1  ω6 c ; 33.7-39.7 %), summed feature 3 (C 16 : 1 ω7 c and/or C 16:1 ω 6c ; 25.2-25.4 %) and C 19 :0 cyclo ω8 c (11.9-15.4 %). The major respiratory quinone was Q-10. The genomic DNA G+C contents of PAMC 29128 and PAMC 29148 T were 63.0 and 63.1 mol%, respectively. Their distinct phylogenetic position and some physiological characteristics support the proposal of Lichenihabitans gen. nov., with the type species Lichenihabitans psoromatis sp. nov. (type strain, PAMC 29148 T =KCCM 43293 T =JCM 33311 T ). Lichenihabitantaceae fam. nov. is also proposed.