Ned to deep-sea cluster three, is consistent with this assumption. This cluster represented uncultured members

Ned to deep-sea cluster three, is consistent with this assumption. This cluster represented uncultured members of your household Methylococcaceae and was identified almost exclusively in marine habitats [49]. Interestingly, 16S rRNA Orexin A Orexin Receptor sequences assigned towards the genus Nitrosomonas, too corresponding amoA gene sequences, had been identified in all upper sediment samples. Furthermore, amo and pmo are evolutionary related enzymes [74], and it was shown long ago that ammonia-oxidizing bacteria which include Nitrosomonas sp. can oxidize methane to methanol via the nonspecific action of the ammonia monooxygenase [75,76]. Though efficiency of methane oxidation by Nitrosomonas is considerably reduced than by accurate methanotrophs, the high-yield production of methanol from methane by ammonia-oxidizing bacteria (AOB) is feasible [77]. Hence, Nitrosomonas sp. could contribute to methane oxidation in the upper layer of sediments of the Barents Sea. Indirectly, this can be indicated by the presence of Hyphomicrobiaceae (S)-3,4-DCPG mGluR methylotrophs, capable of completing this method by oxidizing methanol developed by AOB. 4.2. Sulfur Cycle The concentration of sulfate in all sediment samples around corresponded to its content material in seawater, and also the intensity of sulfate reduction was comparable with all the intensity of carbon assimilation and exceeded the rate of methane oxidation by several orders of magnitude. The abundance of sulphate-reducing microorganisms is generally low in the uppermost oxygenated layers of sediments, while within the underlying anoxic zones it reaches a maximum and then decreases by depth and age of sediments in to the sulphate-depleted methane zone [78]. Among recognized sulfate-reducing prokaryotes, only delta-proteobacteria have been discovered. Within the upper layers of sediments, the share of sulfate reducers was low (except for station 6844). At station 6841, it elevated to 17.39 at a depth of six cm, and at a depth of 169 cm it was 12.9 . In all probability, the sulfate-depleted methane-rich zone was located deeper. Along with the above-mentioned sulfate-reducing partners of ANME archaea, the presence of the household Desulfobulbaceae was notable. This group was abundant only inside the upper sediments at stations 6841 and 6844, accounting for 2.0 and 5.five of 16S rRNA reads, respectively. Desulfobulbaceae are metabolically diverse bacteria capable of dissimilatory iron reduction [79], oxidation of elemental sulfur [80], and sulfate and sulfite reduction in the comprehensive oxidation of organic matter [81]. Cable bacteria of the genus Candidatus Electrothrix (the loved ones Desulfobulbaceae) forms filaments transferring electrons involving the sulfidic and oxic zone up to centimeter distance. They’re not capable of performing dissimilatory sulfate reduction; instead, in the sulfidic zone, they oxidize sulfide (H2 S) utilizing oxygen or nitrate as an electron acceptor [78,82,83]. Three OTUs with the household Desulfobulbaceae have been assigned to Ca. Electrothrix, but their share inside the communities didn’t exceed 0.5 . The search within the GenBank for sequences associated with probably the most abundant Desulfobulbaceae OTU, whose share was 1.7 in sample 6841 (0 cm layer) and 4.3 in sample 6844, showed that the closest hit was Ca. Electrothrix communis, however the sequenceMicroorganisms 2021, 9,13 ofidentity was only 92.75 . It is actually probable that the identified members of Desulfobulbaceae carry out the transfer of electrons amongst the aerobic and anaerobic layers from the sediments. This hypothesis is constant with their absence in deeper anoxic sedi.