Is probably a consequence of co-amplification. All amoA OTUs were assigned for the genus Nitrosomonas, also identified by 16S rRNA gene profiling. The pmoA OTU9 was detected only in the deep sediments (6 cm) of station 6841, while OTU32 occurred additionally inside the upper sampled horizons at stations 6841, 6844, and 6849. The search Hydroxystilbamidine bis Data Sheet against GenBank revealed that OTU9 had 97.45 nucleotide sequence identity to pmoA sequence DQ514622 assigned to deep-sea cluster 3q [49], whilst OTU32 was closely related (95.65 identity) to sequence JN172108 from deep-sea cluster 3r [49]. The two pmoA OTUs had been 86.12 identical. Taking into account the proposed cut-off values at 10 and 17 pmoA sequence dissimilarity for species and genus delineation [50], identified OTUs possibly represented unique species on the similar genus, belonging to uncultured deep-sea cluster 3 of type 1a methanotrophs [49]. Phylogenetic evaluation of TNP-470 Inhibitor deduced amino acid sequences for pmoA OTUs also confirmed their affiliation with deep-sea cluster three (Figure four).Figure 4. Phylogenetic tree determined by the deduced amino acid sequences of pmoA OTUs and representatives of deep-sea cluster 3 [49]. OTUs identified in this function are shown in red. The help values for the internal nodes were estimated by approximate Bayes test in PhyML. GenBank accession numbers are shown in parentheses. pmoA of Methylomicrobium buryatense was applied to root the tree.Microorganisms 2021, 9,11 of4. Discussion 4.1. Methane Cycle Microbial communities of sediments in the Arctic seas are actively studied making use of molecular genetic approaches [514]; considerably fewer studies analyze the rates of microbial processes. Within this work, we characterized the microbial communities with the surface layers of sediments in the northern a part of the Barents Sea and characterized the rates of most important biogeochemical processes related with carbon and sulfur cycles. Methane is an finish product of microbial decomposition of organic matter beneath anaerobic circumstances and can accumulate in significant amounts in sediments of each fresh and marine water bodies [55]. Methane can accumulate in deep sediments within the form of gas hydrates and be released around the seabed as methane seeps. On the other hand, methane concentrations within the upper layers of sediments at most stations did not exceed 1 , and only at station 6841 it was several instances greater (two.4). Most of the autochthonous organic matter reaching the bottom appeared to be oxidized within the upper layers of sediments, as indicated by the high rate of carbon assimilation and abundance of aerobic heterotrophic bacteria (Acidobacteria, Bacteriodetes, Verrucomicrobia, alpha- and gamma-proteobacteria). In deeper horizons sampled at station 6841, the concentration of methane improved by a lot more than an order of magnitude. Nonetheless, the low rate of methanogenesis along with the close to absence of methanogens in microbial communities even in anoxic sediments indicated that methane was not formed right here but that it migrated from deeper layers towards the surface, exactly where its aerobic and anaerobic oxidation occurred [56]. Likely, methanogenesis inside the studied sediments was outcompeted by active sulfate reduction [57], and the sulfate ethane transition zone was located deeper than the studied sediment horizon. The anaerobic oxidation of methane (AOM) is actually a important sink of methane in anoxic environments. AOM coupled for the reduction of sulfate could be carried out by anaerobic methane-oxidizing archaea (ANME) [58,59]. Both active methane oxi.
