engleski

Altered activity levels of hot spring biofilms in response to the addition of different substrates

Microbial biofilms in hot springs represent complex, self-sustaining communities with complete biogeochemical cycles and food webs. Due to the harsh environmental conditions and complex interactions of individual microorganisms in the biofilms, it is not trivial to understand the drivers behind the observed community structure and mechanisms of biogeochemical cycling in these environments. While a portion of the biofilm- dwelling microorganisms can be isolated into pure culture, pure culture activities do not necessary reflect the in situ activities and crossfeeding interactions in the biofilm community. Without the need for prior cultivation, bioorthogonal non- canonical amino acid tagging (BONCAT) can be used in combination with fluorescence activated cell sorting (FACS) to identify translationally active taxa in the community and their substrate preferences. The aim of this study was to investigate the community composition and metabolic activity of two hot spring biofilms in a range of enviromentaly relevant substrates. Translational activity was monitored by incorporation of a synthetic amino acid L- homopropargylglycine (HPG), whereupon HPG- containing proteins were detected by a copper- catalysed azide-alkyne click chemistry reaction. FACS was used to sort active members of a biofilm community whose taxonomic identification was performed using 16S rRNA gene amplicon sequencing. Although the sites were differing in geochemistry and the biofilms in overall community composition, biofilms from both sites showed a similar pattern in substrate preference. Metabolic activity was highest when biofilm material was incubated with simple organic substrates (acetate and pyruvate), whereas the preferred inorganic substrate for the chemolitotrophs and chemoorganotrophs was thiosulfate in both cases.

Hot springs, biofilms, BONCAT, FACS

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