Abstract
Biofilms enhance rates of gene exchange, access to specific nutrients, and cell survivability. Haloarchaea in Deep Lake, Antarctica, are characterized by high rates of intergenera gene exchange, metabolic specialization that promotes niche adaptation, and are exposed to high levels of UV-irradiation in summer. Halorubrum lacusprofundi from Deep Lake has previously been reported to form biofilms. Here we defined growth conditions that promoted the formation of biofilms and used microscopy and enzymatic digestion of extracellular material to characterize biofilm structures. Extracellular DNA was found to be critical to biofilms, with cell surface proteins and quorum sensing also implicated in biofilm formation. Quantitative proteomics was used to define pathways and cellular processes involved in forming biofilms; these included enhanced purine synthesis and specific cell surface proteins involved in DNA metabolism; post-translational modification of cell surface proteins; specific pathways of carbon metabolism involving acetyl-CoA; and specific responses to oxidative stress. The study provides a new level of understanding about the molecular mechanisms involved in biofilm formation of this important member of the Deep Lake community.
Highlights
Halorubrum lacusprofundi is an important member of Deep Lake in Antarctica, representing ~10% of the lake population[1]
Metaproteomics analysis of Deep Lake identified novel pili and cell surface proteins synthesized by the haloarchaea, including Hrr. lacusprofundi ACAM34, that were speculated to function in aggregation or attachment[5]
The process of cell signaling, or quorum sensing, is often important in biofilm development, but while it has been linked to bacterial biofilms[19,20,21], few reports exist for equivalent analyses in Archaea; the presence of quorum sensing molecules has been described in haloarchaea[22,23] and a methanogen[24]
Summary
Halorubrum lacusprofundi is an important member of Deep Lake in Antarctica, representing ~10% of the lake population[1]. In view of Hrr. lacusprofundi producing extracellular material and forming biofilms, and the potential ecological importance of this capacity, here we used strain ACAM34 to study cell morphology, the composition of extracellular material and quorum sensing associated with biofilms, and used quantitative iTRAQ proteomics to assess the cellular pathways and processes involved. These analyses complement other ongoing studies of this species and collectively serve to expand our understanding of the ecophysiology of cold adapted Archaea[27]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
