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In this study, bacterial and archaeal communities in sediments from the adjacent waters of Rushan Bay were studied based on 16S ribosomal RNA (rRNA) gene. Illumina sequencing and quantitative PCR (qPCR) analyses were used to analyze the bacterial and archaeal community characteristics. The ecological analyses of sequences revealed that the diversity of bacterial communities was higher than that of archaeal communities. The abundance of bacterial 16S rRNA genes was observed to be greater than that of archaeal 16S rRNA genes. Proteobacteria and Piscirickettsiaceae were the most abundant bacterial phylum and family; Thaumarchaeota dominated the archaeal communities, and MGI in Thaumarchaeota and Halobacteria in Euryarchaeota were prevalent and the predominant archaeal class in this study. Temperature and ammonium concentration were related to the bacterial communities, whereas the nitrite concentration and ammonium concentration had a correlation with the archaeal communities; meanwhile, a complex combination of environmental factors might shape the bacterial and archaeal communities in this dynamic environment. Functional Annotation of Prokaryotic Taxa (FAPROTAX) analysis showed that most bacterial sequences were involved in chemoheterotrophy, sulfate respiration, respiration of sulfur compounds, aerobic nitrite oxidation and nitrification; for the archaeal communities, the essential ecological functions were chemoheterotrophy, other ecological functions such as aerobic ammonia oxidation and methanogenesis, were also predicted to be present in this study. The comparison of bacterial and archaeal communities in different environments suggest that similar conditions are hypothesized to give rise to similar microbial communities, and environmental conditions may contribute significantly to the bacterial and archaeal community structure. [ABSTRACT FROM AUTHOR]

Abstract Certain species of microalgae are capable of growing under high concentrations of carbon dioxide (CO 2). These microalgae have potential to be used for sequestering CO 2 released as industrial pollutants using a phototrophic carbon fixation system. While some CO 2 -tolerant algal species have been identified from existing algal culture collections, this study explored a community-based approach to enrich and isolate CO 2 -tolerant microalgae. Meanwhile, we monitored the change of bacterial and microalgal communities during the CO 2 enrichment period based on the 16S and 18S rRNA gene sequences. Four different treatments were set up in the laboratory to test the effect of nutrient and CO 2 on the natural planktonic community. At the end of the enrichment experiment (17 days), green algae (Chlorophyta), especially Scenedesmus species, dominated the microalgal community when the water samples were enriched with high CO 2 (10%) and nutrient. The dominance of species in the CO 2 -enriched samples was also evident in the clonal isolation of microalgae at the end of the experiment. This study clearly demonstrates that the supplementation of high levels of CO 2 to a natural phytoplankton community is an efficient way to enrich and isolate CO 2 -tolerant microalgae. The community-based approach described here poses several advantages over the traditional culture-based screening method for isolating microalgae with specific characteristics. Graphical abstract Unlabelled Image Highlights • Enrichment of natural phytoplankton community with high CO 2 can be an efficient way for high CO 2 -tolerant strain selection. • Green algae (Scenedesmus) can become dominant when the microalgal communities are enriched with high CO 2 and nutrient. • Biotic interactions can be critical factors in the community change when the samples charged with high CO 2 and nutrient. • Green algae (Chlorophyta) tend to have low nutritional value, and are not the preferred prey for grazers. [ABSTRACT FROM AUTHOR]

Bacterial and archaeal communities play important roles in wetland ecosystems. Although the microbial communities in the soils and sediments of wetlands have been studied extensively, the comprehensive distributions of planktonic bacterial and archaeal communities and their responses to environmental variables in wetlands remain poorly understood. The present study investigated the spatiotemporal characteristics of the bacterial and archaeal communities in the water of an artificially irrigated estuarine wetland of the Liaohe River, China, explored whether the wetland effluent changed the bacterial and archaeal communities in the Liaohe River, and evaluated the driving environmental factors. Within the study, 16S rRNA quantitative PCR methods and MiSeq high-throughput sequencing were used. The bacterial and archaeal 16S rRNA gene abundances showed significant temporal variation. Meanwhile, the bacterial and archaeal structures showed temporal but not spatial variation in the wetland and did not change in the Liaohe River after wetland drainage. Moreover, the bacterial communities tended to have higher diversity in the wetland water in summer and in the scarce zone, while a relatively higher diversity of archaeal communities was found in autumn and in the intensive zone. DO, pH and PO4-P were proven to be the essential environmental parameters shaping the planktonic bacterial and archaeal community structures in the Liaohe River estuarine wetland (LEW). The LEW had a high potential for methanogenesis, which could be reflected by the composition of the microbial communities. [ABSTRACT FROM AUTHOR]

The biogeography of active microbial communities and the underlying mechanisms in marine sediments are important in microbial ecology but remain unclear. Here, using qPCR and high-throughput sequencing, we investigated bacterial and archaeal community abundances and activities by quantifying the abundance and expression of the 16S rRNA gene respectively, RNA-derived bacterial and archaeal community biogeography, assembly mechanisms and co-occurrence relationships in surface sediment samples from the Bohai Sea (BS), South Yellow Sea (SYS) and the north East China Sea (NECS) of the eastern Chinese marginal seas. The results revealed a higher heterogeneity of bacterial and archaeal community activities than of abundances and heterogeneous ecological functions among areas reflected by community compositions. Furthermore, clear geographic groups (i.e., the BS, SYS and NECS groups) were observed for all, abundant and rare active bacterial and archaeal communities, accompanied by significant distance-decay patterns. However, the abundant and rare taxa showed inconsistent geographic patterns. More importantly, deterministic processes played a greater role than stochastic processes in active bacterial and archaeal community assembly. The rare taxa had weaker abilities to disperse and/or adapt and more complex ecological processes than the abundant taxa. In addition, this study also showed that intertaxa competition was the dominant interaction between active bacterial and archaeal members, which could greatly contribute to dispersal limitation. Moreover, active bacterial and archaeal co-occurrence patterns showed significant distance-decay patterns, which were consistent with the community compositions. Unlabelled Image • A higher heterogeneity of bacterial and archaeal community activities than of abundances was observed. • Significant distance-decay patterns and clear geographic groups were observed for active microbial communities. • Deterministic processes played a greater role than stochastic processes in active microbial community assembly. • The rare taxa had weaker abilities to disperse and/or adapt and more complex ecological processes than abundant taxa. • Intertaxa competition was the dominant interaction between active microbial members, contributing to dispersal limitation. [ABSTRACT FROM AUTHOR]