Natronoflexus

Na.tro.no.fle’xus; N.L. neut. n. natron (arbitrarily derived from the Arabic n. natrun or natron) soda, sodium carbonate; N.L. pref. natrono-, pertaining to soda; L. masc. n. flexus, a bending, N.L. masc. n. Natronoflexus, bending/flexible cells living in soda. The genus Natronoflexus is a member of the family Marinilabiliaceae, order Bacteroidales, class Bacteroidia, and phylum Bacteroidota. It is an obligately anaerobic fermentative saccharolytic bacterium with the ability to utilize polygalacturonates and xylan as carbon and energy sources. The only species of the genus, N. pectinivorans, is a moderately salt-tolerant, chloride-independent obligate alkaliphile found in soda lakes in Central Asia. The DNA G+C content is 39.6mol% (genome). DNA G +C content (%): 39.6 (genome). Type species: Natronoflexus pectinivorans Sorokin et al. 2011, VL144.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog

Dethiobacteraceae fam. nov.

De.thi’o.bac.ter.a.ce.a.e. N.L. masc. n. Dethiobacter, the type genus of the family; L. fem. pl. n. suff. -aceae, ending to denote a family; N.L. fem. pl. n. Dethiobacteraceae, the family of the genus Dethiobacter. The family Dethiobacteraceae includes obligately anaerobic, moderately salt-tolerant, and obligately alkaliphilic bacteria able to grow chemolithoautotrophically by elemental sulfur disproportionation and fixingCO2 by the Wood–Ljungdahl pathway. The two strains currently known in pure culture are both isolated from saline soda lakes. H2 can serve as an additionalelectron donor for sulfur and thiosulfate reduction. The family consists of a single genus Dethiobacter with the type species Dethiobacter alkaliphilus. DNA G +C content (%): 48.3–48.5 (genomes of two isolates). Type genus: Dethiobacter Sorokin et al. 2008, VL123.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work publicBT/Environmental Biotechnolog

Dethiobacterales ord. nov.

De.thi’o.bac.ter.a.les. N.L.masc. n. Dethiobacter, the type genus of the order; L. fem. pl. n. suff. -ales, ending to denote an order; N.L. fem. pl. n. Dethiobacterales, the order of the genus Dethiobacter. The order Dethiobacterales is the only order of the class Dethiobacteria, which forms a deep-branching phylogenetic lineage within the phylum “Firmicutes D.” It consists of a single family Dethiobacteraceae and genus Dethiobacter, whose members are haloalkaliphilic anaerobes with a respiratory metabolism.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work publicBT/Environmental Biotechnolog

Natronospira

Na.tro.no.spi’ra. N.L. neut. n. natron (arbitrarily derived from the Arabic n. natrun or natron), soda; L. fem. n. spira, coil; N.L. fem. n. Natronospira, a soda-loving coil-shaped bacterium.The genus Natronospira was originally classified as a member of the family Ectothiorhodospiraceae, order Chromatiales, and class Gammaproteobacteria, according to the 16S rRNA-based gene sequence comparison, while according to the phylogenomic analysis it forms a separate order-level branch within the Gammaproteobacteria unrelated to the Chromatiales members. It is an aerobic heterotroph that preferably utilizes proteins and peptides for growth. Natronospira is an extremely salt-tolerant, chloride-independent obligate alkaliphile. It inhabits oxic brines of hypersaline soda lakes, particularly in southwestern Siberia. The genus currently includes a single (type) species:N. proteinivora. DNA G +C content (%): 59.8 (genome). Type species: Natronospira proteinivora Sorokin et al. 2017VP.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work publicBT/Environmental Biotechnolog

Dethiobacteria class nov.

De.thi’o.bac.ter.i.a. N.L. masc. n. Dethiobacter, type genus of the type order of the class Dethiobacterales; N.L. neut. pl. n. suff. -ia, ending to denote a class; N.L. neut. pl. n. Dethiobacteria, class of the order Dethiobacterales.The class Dethiobacteria forms a deep-branching phylogenetic lineage in the phylum “Firmicutes D” (according to the GDTB classification) and includesobligately anaerobic haloalkaliphilic bacteria with respiratory metabolism from soda lakes. It consists of a single order Dethiobacterales, family Dethiobacteraceae,and genus Dethiobacter.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog

Ecology of Methanonatronarchaeia

Methanonatronarchaeia represents a deep-branching phylogenetic lineage of extremely halo(alkali)philic and moderately thermophilic methyl-reducing methanogens belonging to the phylum Halobacteriota. It includes two genera, the alkaliphilic Methanonatronarchaeum and the neutrophilic Ca. Methanohalarchaeum. The former is represented by multiple closely related pure culture isolates from hypersaline soda lakes, while the knowledge about the latter is limited to a few mixed cultures with anaerobic haloarchaea. To get more insight into the distribution and ecophysiology of this enigmatic group of extremophilic methanogens, potential activity tests and enrichment cultivation with different substrates and at different conditions were performed with anaerobic sediment slurries from various hypersaline lakes in Russia. Methanonatronarchaeum proliferated exclusively in hypersaline soda lake samples mostly at elevated temperature, while at mesophilic conditions it coexisted with the extremely salt-tolerant methylotroph Methanosalsum natronophilum. Methanonatronarchaeum was also able to serve as a methylotrophic or hydrogenotrophic partner in several thermophilic enrichment cultures with fermentative bacteria. Ca. Methanohalarchaeum did not proliferate at mesophilic conditions and at thermophilic conditions it competed with extremely halophilic and moderately thermophilic methylotroph Methanohalobium, which it outcompeted at a combination of elevated temperature and methyl-reducing conditions. Overall, the results demonstrated that Methanonatronarchaeia are specialized extremophiles specifically proliferating in conditions of elevated temperature coupled with extreme salinity and simultaneous availability of a wide range of C1-methylated compounds and H2/formate.BT/Environmental Biotechnolog

Natrarchaeobaculum

Natr. ar. chae. o. ba' cu. lum. N.L. neut. n. natron, soda, sodium carbonate (arbitrarily derived from Arabic n. natrun or natron) ; N.L. pref. natro- pertaining to soda; Gr. masc. adj. archaîos ancient; L. neut. n. baculum, small stick, rod; N.L. neut. n. Natrarchaeobaculum soda-loving archaeal rod.The genus Natrarchaeobaculum is classified as a member of the family Natrialbaceae, order Natrialbales, class Halobacteria according to phylogenomic analyses. It includes extremely halophilic heterotrophic natronoarchaea, some of which can grow anaerobically by sulfur respiration utilizing organic acids, H2 and formate as the electron donors. The genus currently includes two species: the facultatively anaerobic type species Natrarchaeobaculum sulfurireducens and the aerobic species Natrarchaeobaculum aegyptiacus. Inhabits hypersaline soda lakes. The DNA G + C content is 62.8-64.1 % (genome sequence). Three letter abbreviation is Nab. Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.BT/Environmental Biotechnolog

Phenotypic and genomic characterization of the first alkaliphilic aceticlastic methanogens and proposal of a novel genus Methanocrinis gen.nov. within the family Methanotrichaceae

Highly purified cultures of alkaliphilic aceticlastic methanogens were collected for the first time using methanogenic enrichments with acetate from a soda lake and a terrestrial mud volcano. The cells of two strains were non-motile rods forming filaments. The mud volcano strain M04Ac was alkalitolerant, with the pH range for growth from 7.5 to 10.0 (optimum at 9.0), while the soda lake strain Mx was an obligate alkaliphile growing in the pH range 7.7–10.2 (optimum 9.3–9.5) in the presence of optimally 0.2–0.3 M total Na+. Genomes of both strains encoded all enzymes required for aceticlastic methanogenesis and different mechanisms of (halo)alkaline adaptations, including ectoine biosynthesis, which is the first evidence for the formation of this osmoprotectant in archaea. According to 16S rRNA gene phylogeny, the strains possessed 98.3–98.9% sequence identity and belonged to the obligately aceticlastic genus Methanothrix with M. harundinaceae as the most closely related species. However, a more advanced phylogenomic reconstruction based on 122 conserved single-copy archaeal protein-coding marker genes clearly indicated a polyphyletic origin of the species included in the genus Methanothrix. We propose to reclassify Methanothrix harrundinacea (type strain 8AcT) into a new genus, Methanocrinis gen. nov., with the type species Methanocrinis harrundinaceus comb. nov. We also propose under SeqCode the complete genome sequences of strain MxTs (GCA_029167045.1) and strain M04AcTs (GCA_029167205.1) as nomenclatural types of Methanocrinis natronophilus sp. nov. and Methanocrinis alkalitolerans sp. nov., respectively, which represent other species of the novel genus. This work demonstrates that the low energy aceticlastic methanogenesis may function at extreme conditions present in (halo)alkaline habitats.BT/Environmental Biotechnolog

Halapricum hydrolyticum sp. nov., a beta-1,3-glucan utilizing haloarchaeon from hypersaline lakes

Two strains of neutrophilic haloaloarchaea were selectively enriched from hypersaline lakes in southwestern Siberia using β-1,3-glucans as a substrate. The strains were nearly identical in their phenotypes and according tophylogenomic analysis, and represent a distant novel species group in the genus Halapricum of the family Haloarculaceae.The main phenotypic property of the novel isolates is the ability to hydrolyze and grow with the polysaccharides curdlan and pachyman. Such potential has, to date, not been seen in any other haloarchaea in pure cultures. The strains are obligately aerobic saccharolytics. Apart from the insoluble β-1,3-glucans, they utilized soluble α-glucans (starch, pullulan and glycogen) and a limited number of sugars. The major ether-bound polar phospholipids include PGP-Me and PG. The glyco- and sulfolipids were absent. The major respiratory menaquinone is MK-8:8. On the basis of their unique physiological properties and the results of phylogenomic analysis, the isolates are suggested to be classified into a novel species Halapricum hydrolyticum sp. nov. (type strain HArc-curdl5-1T = DSM 114193T = UQM 41587T).BT/Environmental Biotechnolog

Anaerobic carboxydotrophy in sulfur-respiring haloarchaea from hypersaline lakes

Anaerobic carboxydotrophy is a widespread catabolic trait in bacteria, with two dominant pathways: hydrogenogenic and acetogenic. The marginal mode by direct oxidation to CO2 using an external e-acceptor has only a few examples. Use of sulfidic sediments from two types of hypersaline lakes in anaerobic enrichments with CO as an e-donor and elemental sulfur as an e-acceptor led to isolation of two pure cultures of anaerobic carboxydotrophs belonging to two genera of sulfur-reducing haloarchaea: Halanaeroarchaeum sp. HSR-CO from salt lakes and Halalkaliarchaeum sp. AArc-CO from soda lakes. Anaerobic growth of extremely halophilic archaea with CO was obligatory depended on the presence of elemental sulfur as the electron acceptor and yeast extract as the carbon source. CO served as a direct electron donor and H2 was not generated from CO when cells were incubated with or without sulfur. The genomes of the isolates encode a catalytic Ni,Fe-CODH subunit CooS (distantly related to bacterial homologs) and its Ni-incorporating chaperone CooC (related to methanogenic homologs) within a single genomic locus. Similar loci were also present in a genome of the type species of Halalkaliarchaeum closely related to AArc-CO, and the ability for anaerobic sulfur-dependent carboxydotrophy was confirmed for three different strains of this genus. Moreover, similar proteins are encoded in three of the four genomes of recently described carbohydrate-utilizing sulfur-reducing haloarchaea belonging to the genus Halapricum and in two yet undescribed haloarchaeal species. Overall, this work demonstrated for the first time the potential for anaerobic sulfur-dependent carboxydotrophy in extremely halophilic archaea.Accepted Author ManuscriptBT/Environmental Biotechnolog