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Hypoliths are microbial communities that live underneath translucent rocks in desert ecosystems and represent a key refuge niche in the Antarctic Dry Valleys. These cryptic microbial assemblages are crucial as they mediate numerous ecosystem processes. Here, we present the first draft genome of a hypolith isolate belonging to the α-proteobacterial class and the genus Sphingomonas. The draft genome of Sphingomonas sp. strain AntH11 shows the capacity of this organism to adapt to the extreme cold and arid conditions encountered in Antarctic desert soils. Our result also suggests that its metabolic versatility and multidrug resistance constitutes an opportunistic advantage in competition with other hypolith-colonizing microorganisms. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microbiome dynamics in anaerobic digesters are influenced by feedstock composition. • The effect of substrate change was investigated using genome-centric metagenomics. • Hydrolytic MAGs were strongly associated with the increase in food waste. • Proteiniphillum genome encoded the complete pectin degradation pathway. Bacterial community structure and dynamics in anaerobic digesters are primarily influenced by feedstock composition. It is therefore important to unveil microbial traits that explain microbiome variations in response to substrate changes. Here, gene and genome-centric metagenomics were used to examine microbiome dynamics in four laboratory-scale reactors, in which sewage sludge was co-digested with increasing amounts of food waste. A co-occurrence network revealed microbiome shifts in response to changes in substrate composition and concentration. Food waste concentration correlated with extracellular enzymes and metagenome-assembled genomes (MAGs) involved in the degradation of complex carbohydrates commonly found in fruits and plant cell walls as well as with the abundance of hydrolytic MAGs. A key role was attributed to Proteiniphillum for being the only bacteria that encoded the complete pectin degradation pathway. These results suggest that changes of feedstock composition establish new microbial niches for bacteria with the capacity to degrade newly added substrates. [ABSTRACT FROM AUTHOR]