Merkel, Alexander Y.

Significance We report on cultivation and characterization of an association between Candidatus Nanohalobium constans and its host, the chitinotrophic haloarchaeon Halomicrobium LC1Hm, obtained from a crystallizer pond of marine solar salterns. High-quality nanohaloarchael genome sequence in conjunction with electron- and fluorescence microscopy, growth analysis, and proteomic and metabolomic data revealed mutually beneficial interactions between two archaea, and allowed dissection of the mechanisms for these interactions. Owing to their ubiquity in hypersaline environments, Nanohaloarchaeota may play a role in carbon turnover and ecosystem functioning, yet insights into the nature of this have been lacking. Here, we provide evidence that nanohaloarchaea can expand the range of available substrates for the haloarchaeon, suggesting that the ectosymbiont increases the metabolic capacity of the host.

Abstract This protocol describes a rapid protein extraction method for the archaeon Candidatus Vulcanisaeta moutnovskia, which can be also implemented for other archaea. The utilization of two different methods for protein extraction constitute the main step of the protocol. Method I involves the extraction with a multi-chaotropic lysis buffer containing a non-denaturing zwitterionic detergent, most efficient for extracting cytosolic proteins. Method II involves a denaturing anionic detergent allowing total disruption of the membranes and capable of extracting both membrane (hydrophobic) and non-membrane (water-soluble, hydrophilic) proteins. The big advantage of the methods is to use general laboratory chemicals to make powerful extraction buffers, resulting in high quality and quantity of proteins. The methods probably are usable for any other archaea or microbial cells, and takes about 14-22 h. Following extraction and further protein digestion, 1D-nano Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC ESI-MSMS) analysis with Triple TOF 5600 and Orbitrap technologies were used for protein identification and further quantification.

SummaryA novel moderately thermophilic, facultatively anaerobic chemoorganotrophic bacterium strainP3M‐2Twas isolated from a microbial mat developing on the wooden surface of a chute under the flow of hot water (46°C) coming out of a 2775‐m‐deep oil exploration well (Tomsk region,Russia). StrainP3M‐2Tis a moderate thermophile and facultative anaerobe growing on mono‐, di‐ or polysaccharides by aerobic respiration, fermentation or by reducing diverse electron acceptors [nitrite,Fe(III),As(V)]. Its closest cultivated relative (90.8%rRNAgene sequence identity) isIgnavibacterium album, the only chemoorganotrophic member of the phylumChlorobi. New genus and speciesMelioribacter roseusare proposed for isolateP3M‐2T. Together withI. album, the new organism represents the classIgnavibacteriaassigned to the phylumChlorobi. The revealed group includes a variety of uncultured environmental clones, the16S rRNAgene sequences of some of which have been previously attributed to the candidate divisionZB1. Phylogenetic analysis ofM. roseusandI. albumbased on their23S rRNAandRecAsequences confirmed that these two organisms could represent an even deeper, phylum‐level lineage. Hence, we propose a new phylumIgnavibacteriaewithin theBacteroidetes–Chlorobigroup with a sole classIgnavibacteria, two familiesIgnavibacteriaceaeandMelioribacteraceaeand two speciesI. albumandM. roseus. This proposal correlates with chemotaxonomic data and phenotypic differences of both organisms from other cultured representatives ofChlorobi. The most essential differences, supported by the analyses of complete genomes of both organisms, are motility, facultatively anaerobic and obligately organotrophic mode of life, the absence of chlorosomes and the apparent inability to grow phototrophically.