A large amount of marine sediment was launched on land by the Great East Japan earthquake. afterwards diverse chemoorganotrophic bacteria predominated. Geochemical analyses indicated that this concentration of metals other than Fe was lower in the uppermost layer than that in the deeper layer. Laboratory study was carried out by incubating the sediment for 57 days, and clearly indicated the dynamic transition of microbial communities in the uppermost layer exposed to atmosphere. SOB affiliated in the class Epsilonproteobacteria rapidly proliferated and dominated at the uppermost layer during the first 3 days, after that Fe(II)-oxidizing bacteria and chemoorganotrophic bacteria were sequentially dominant. Furthermore, the concentration of sulfate ion increased and the pH decreased. Consequently, SOB may have influenced the mobilization of heavy metals in the sediment by metal-bound sulfide oxidation and/or sediment acidification. These results demonstrate that SOB initiated the dynamic shift from your anaerobic to aerobic microbial communities, thereby playing a critical role in element cycling in the marine sediment. with the primer set 27F (5-AGAGTTTGATCCTGGCTCAG-3)/1525R (5-AAAGGAGGTGATCCAGCC-3). Results Microbial communities in the on-site sediment Deep sequencing of 16S rRNA genes was carried out to investigate microbial communities in the on-site sediment. The total quantity of sequences obtained from 18 sediment samples was around 7.2 hundred thousand, corresponding to an average of 39,775 sequences per library (Table S2). The -diversity indices (i.e., Chao1, Shannon, and Simpson reciprocal) were calculated by using an equal quantity of sequences (30,789) subsampled 10 occasions from initial libraries. These values were lower in the uppermost layer than in the deep layer, indicating that the uppermost layer experienced more specified and less diverse microbial communities than those in the deep layer. PCoA illustrated that microbial communities in the uppermost layers of the sediments changed drastically during the monitored period (Physique S4). Phylogenetic information of the entire structures and predominant OTUs is usually shown in Physique ?Figure11 and Table S3. Figure ?Physique11 shows that the phylum Proteobacteria dominated in both the uppermost and deep layers, which Schisandrin B supplier accounted for 42.0C72.4% and 29.9C42.2% of the relative abundance, respectively. The class Gammaproteobacteria was predominant in the uppermost layer (relative abundances: 10.9C42.0%), and analysis at the major order showed the clear bacterial succession depending on the sampling date. More specifically, the order Thiotrichales was predominant in December 2011 (10.5%), whereas the order Xanthomonadales became dominant in October 2013 (37.7%) (Physique ?(Figure1B).1B). It is worth noting that this dominant constituent of Thiotrichales detected in the sediment was only SOB belonging in the genus (Table S3). With respect to other SOB, the genus in the class Epsilonproteobacteria was dominant in December 2011 (Physique ?(Physique1C).1C). Also, (OTU 1598) in the class Betaproteobacteria accounted for 12.4% in the same RNF49 time (Table S3). These results indicate that SOB was present and may have performed sulfur oxidation in the uppermost layer of the sediment. In October 2013, chemoorganotrophic bacteria in the order Xanthomonadales and the phylum Actinobacteria became dominant in the uppermost layer (Figures 1A,B). Organic compounds including carbon products of Schisandrin B supplier SOB would serve as substrate for the chemoorganotrophs. Physique 1 Microbial community structures in the uppermost (0C2 mm depth) and deep (20C40 mm depth) layers of the on-site sediments based on the 16S rRNA gene analysis (= 3). The bars indicate average values of three replications. Sediment samples … In contrast, PCoA and phylogenetic analysis showed microbial communities in the deep layers remained nearly unchanged over 22 months (Physique S4 and Physique ?Physique1).1). The class Deltaproteobacteria was dominant (19.0C25.9%) and mainly comprised the three orders (i.e., Desulfobacterales, Desulfuromonadales and Syntrophobacterales) (Physique ?(Figure1D).1D). These taxa are known to include obligate Schisandrin B supplier anaerobic SRB, implying the fact that sulfate decrease was maintained beneath the anoxic circumstances from the deep level presumably, which is relative to findings obtained inside our prior research (Hori et al., 2014; Aoyagi et al., 2015). Geochemical properties from the on-site sediment Geochemical analyses had been executed to characterize chemical substance the different parts of the sediment and their time-dependent adjustments under oxic circumstances. Ion and IL concentrations from the deep level had been regularly high, indicating that the sediment exhibited the high deposition of organic issues as well as the salinity, and these amounts had been held for at least the time supervised around 22 a few months (Desk ?(Desk1).1). One of the most abundant steel in the deep level was Al, accompanied by Fe (Desk ?(Desk2).2). Metals, such as for example Na,.