Community structure and carbon metabolism functions of bacterioplankton in the Guangdong coastal zone.

Coastal ecosystems are an important region for biogeochemical cycling, are a hotspot of anthropogenic disturbance and play a crucial role in global carbon cycling through the metabolic activities of bacterioplankton. Bacterioplankton can be broadly classified into two lifestyles: free-living (FL) and particle-attached (PA). However, how coastal bacterioplankton the community structure, co-occurrence networks and carbon metabolic functions with different lifestyles are differentiated is still largely unknown. Understanding these processes is necessary to better determine the contributions of coastal bacterioplankton to carbon cycling. Here, the characteristics of community structure and carbon metabolism function of bacterioplankton with two lifestyles in the coastal areas of Guangdong Province were investigated using amplicon sequencing, metagenomic, and metatranscriptomic techniques. The results show that the main bacterioplankton responsible for carbon metabolism were the Pseudomonadota, Bacteroidota, and Actinomycetota. The microbial community structure, carbon metabolic function, and environmental preferences differ between different lifestyles. FL and PA bacteria exhibited higher carbon fixation and degradation potentials, respectively. A range of environmental factors, such as dissolved oxygen, pH, and temperature, were associated with the community structure and carbon metabolic functions of the bacterioplankton. Human activities, such as nutrient discharge, may affect the distribution of functional genes and enhance the carbon degradation functions of bacterioplankton. In conclusion, this study increased the understanding of the role of microorganisms in regulating carbon export in coastal ecosystems with intense human activity. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-024-00245-x.

Ohio Coronavirus Wastewater Monitoring Network: Implementation of Statewide Monitoring for Protecting Public Health.

CONTEXT: Prior to the COVID-19 pandemic, wastewater influent monitoring for tracking disease burden in sewered communities was not performed in Ohio, and this field was only on the periphery of the state academic research community. PROGRAM: Because of the urgency of the pandemic and extensive state-level support for this new technology to detect levels of community infection to aid in public health response, the Ohio Water Resources Center established relationships and support of various stakeholders. This enabled Ohio to develop a statewide wastewater SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) monitoring network in 2 months starting in July 2020. IMPLEMENTATION: The current Ohio Coronavirus Wastewater Monitoring Network (OCWMN) monitors more than 70 unique locations twice per week, and publicly available data are updated weekly on the public dashboard. EVALUATION: This article describes the process and decisions that were made during network initiation, the network progression, and data applications, which can inform ongoing and future pandemic response and wastewater monitoring. DISCUSSION: Overall, the OCWMN established wastewater monitoring infrastructure and provided a useful tool for public health professionals responding to the pandemic.

Evaluation of intra- and inter-lab variability in quantifying SARS-CoV-2 in a state-wide wastewater monitoring network.

In December 2019, SARS-CoV-2, the virus that causes coronavirus disease 2019, was first reported and subsequently triggered a global pandemic. Wastewater monitoring, a strategy for quantifying viral gene concentrations from wastewater influents within a community, has served as an early warning and management tool for the spread of SARS-CoV-2 in a community. Ohio built a collaborative statewide wastewater monitoring network that is supported by eight labs (university, government, and commercial laboratories) with unique sample processing workflows. Consequently, we sought to characterize the variability in wastewater monitoring results for network labs. Across seven trials between October 2020 and November 2021, eight participating labs successfully quantified two SARS-CoV-2 RNA targets and human fecal indicator virus targets in wastewater sample aliquots with reproducible results, although recovery efficiencies of spiked surrogates ranged from 3 to 75%. When SARS-CoV-2 gene fragment concentrations were adjusted for recovery efficiency and flow, the proportion of variance between laboratories was minimized, serving as the best model to account for between-lab variance. Another adjustment factor (alone and in different combinations with the above factors) considered to account for sample and measurement variability includes fecal marker normalization. Genetic quantification variability can be attributed to many factors, including the methods, individual samples, and water quality parameters. In addition, statistically significant correlations were observed between SARS-CoV-2 RNA and COVID-19 case numbers, supporting the notion that wastewater surveillance continues to serve as an effective monitoring tool. This study serves as a real-time example of multi-laboratory collaboration for public health preparedness for infectious diseases.

The Ecological Differentiation of Particle-Attached and Free-Living Bacterial Communities in a Seasonal Flooding Lake-the Poyang Lake.

Particle-attached (PA) and free-living (FL) bacterial communities play essential roles in the biogeochemical cycling of essential nutrients in aquatic environments. However, little is known about the factors that drive the differentiation of bacterial lifestyles, especially in flooding lake systems. Here we assessed the compositional and functional similarities between the FL and PA bacterial fractions in a typical flooding lake-the Poyang Lake (PYL) of China. The results revealed that PA communities had significantly different compositions and functions from FL communities in every hydrological period, and the diversity of both PA and FL communities was affected mainly by the water regime rather than bacterial lifestyles. PA communities were more diverse and enriched with Proteobacteria and Bacteroidetes, while FL communities had more Actinobacteria. There was a higher abundance of photosynthetic and nitrogen-cycling bacterial groups in PA communities, but a higher abundance of members involved in hydrocarbon degradation, aromatic hydrocarbon degradation, and methylotrophy in FL communities. Water properties (e.g., temperature, pH, total phosphorus) significantly regulated the lifestyle variations of PA and FL bacteria in PYL. Collectively, our results have demonstrated a clear ecological differentiation of PA and FL bacterial communities in flooding lakes, suggesting that the connectivity between FL and PA bacterial fractions is water property-related rather than water regime-related.

Diet drives the gut microbiome composition and assembly processes in winter migratory birds in the Poyang Lake wetland, China.

The complex gut bacterial communities may facilitate the function, distribution, and diversity of birds. For migratory birds, long-distance traveling poses selection pressures on their gut microbiota, ultimately affecting the birds' health, fitness, ecology, and evolution. However, our understanding of mechanisms that underlie the assembly of the gut microbiome of migratory birds is limited. In this study, the gut microbiota of winter migratory birds in the Poyang Lake wetland was characterized using MiSeq sequencing of 16S rRNA genes. The sampled bird included herbivorous, carnivorous, and omnivorous birds from a total of 17 species of 8 families. Our results showed that the gut microbiota of migratory birds was dominated by four major bacterial phyla: Firmicutes (47.8%), Proteobacteria (18.2%), Fusobacteria (12.6%), and Bacteroidetes (9.1%). Dietary specialization outweighed the phylogeny of birds as an important factor governing the gut microbiome, mainly through regulating the deterministic processes of homogeneous selection and stochastic processes of homogeneous dispersal balance. Moreover, the omnivorous had more bacterial diversity than the herbivorous and carnivorous. Microbial networks for the gut microbiome of the herbivorous and carnivorous were less integrated, i.e., had lower average node degree and greater decreased network stability upon node attack removal than those of the omnivorous birds. Our findings advance the understanding of host-microbiota interactions and the evolution of migratory bird dietary flexibility and diversification.

Unraveling microbe-mediated degradation of lignin and lignin-derived aromatic fragments in the Pearl River Estuary sediments.

Estuaries are one of the most crucial areas for the transformation and burial of terrestrial organic carbon (TerrOC), playing an important role in the global carbon cycle. While the transformation and degradation of TerrOC are mainly driven by microorganisms, the specific taxa and degradation processes involved remain largely unknown in estuaries. We collected surface sediments from 14 stations along the longitudinal section of the Pearl River Estuary (PRE), P. R. China. By combining analytical chemistry, metagenomics, and bioinformatics methods, we analyzed composition, source and degradation pathways of lignin/lignin-derived aromatic fragments and their potential decomposers in these samples. A diversity of bacterial and archaeal taxa, mostly those from Proteobacteria (Deltaproteobacteria, Gammaproteobacteria etc.), including some lineages (e.g., Nitrospria, Polyangia, Tectomicrobia_uc) not previously implicated in lignin degradation, were identified as potential polymeric lignin or its aromatic fragments degraders. The abundance of lignin degradation pathways genes exhibited distinct spatial distribution patterns with the area adjacent to the outlet of Modaomen as a potential degradation hot zone and the Syringyl lignin fragments, 3,4-PDOG, and 4,5-PDOG pathways as the primary potential lignin aromatic fragments degradation processes. Notably, the abundance of ferulic acid metabolic pathway genes exhibited significant correlations with degree of lignin oxidation and demethylation/demethoxylization and vegetation source. Additionally, the abundance of 2,3-PDOG degradation pathways genes also showed a positive significant correlation with degree of lignin oxidation. Our study provides a meaningful insight into the microbial ecology of TerrOC degradation in the estuary.

Metagenomes of polyamine-transforming bacterioplankton along a nearshore-open ocean transect.

Short-chained aliphatic polyamines (PAs) have recently been recognized as an important carbon, nitrogen, and/or energy source for marine bacterioplankton. To study the genes and taxa involved in the transformations of different PA compounds and their potential variations among marine systems, we collected surface bacterioplankton from nearshore, offshore, and open ocean stations in the Gulf of Mexico and examined their metagenomic responses to additions of single PA model compounds (putrescine, spermidine, or spermine). Genes affiliated with PA uptake and all three known PA degradation pathways, i.e., transamination, γ-glutamylation, and spermidine cleavage, were significantly enriched in most PA-treated metagenomes. In addition, identified PA-transforming taxa were mostly the alpha and gamma classes of Proteobacteria, with less important contributions from members of Betaproteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Planctomycetes. These findings suggest that PA transformations are ubiquitous, have diverse pathways, and are carried out by a broad range of the bacterioplankton taxa in the Gulf of Mexico. Identified PA-transforming bacterial genes and taxa were different among nearshore, offshore, and open ocean sites, but were little different among individual compound-amended metagenomes at any specific site. These observations further indicate that PA-transforming taxa and genes are site-specific and with high similarities among PA compounds. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-021-00114-x.

Coordinated Diel Gene Expression of Cyanobacteria and Their Microbiome.

Diel rhythms have been well recognized in cyanobacterial metabolisms. However, whether this programmed activity of cyanobacteria could elicit coordinated diel gene expressions in microorganisms (microbiome) that co-occur with cyanobacteria and how such responses in turn impact cyanobacterial metabolism are unknown. To address these questions, a microcosm experiment was set up using Lake Erie water to compare the metatranscriptomic variations of Microcystis cells alone, the microbiome alone, and these two together (whole water) over two day-night cycles. A total of 1205 Microcystis genes and 4779 microbiome genes exhibited significant diel expression patterns in the whole-water microcosm. However, when Microcystis and the microbiome were separated, only 515 Microcystis genes showed diel expression patterns. A significant structural change was not observed for the microbiome communities between the whole-water and microbiome microcosms. Correlation analyses further showed that diel expressions of carbon, nitrogen, phosphorous, and micronutrient (iron and vitamin B12) metabolizing genes were significantly coordinated between Microcystis and the microbiome in the whole-water microcosm. Our results suggest that diel fluxes of organic carbon and vitamin B12 (cobalamin) in Microcystis could cause the diel expression of microbiome genes. Meanwhile, the microbiome communities may support the growth of Microcystis by supplying them with recycled nutrients, but compete with Microcystis for iron.

Co-occurring microorganisms regulate the succession of cyanobacterial harmful algal blooms.

Cyanobacterial harmful algal blooms (CyanoHABs) have been found to transmit from N2 fixer-dominated to non-N2 fixer-dominated in many freshwater environments when the supply of N decreases. To elucidate the mechanisms underlying such "counter-intuitive" CyanoHAB species succession, metatranscriptomes (biotic data) and water quality-related variables (abiotic data) were analyzed weekly during a bloom season in Harsha Lake, a multipurpose lake that serves as a drinking water source and recreational ground. Our results showed that CyanoHABs in Harsha Lake started with N2-fixing Anabaena in June (ANA stage) when N was high, and transitioned to non-N2-fixing Microcystis- and Planktothrix-dominated in July (MIC-PLA stage) when N became limited (low TN/TP). Meanwhile, the concentrations of cyanotoxins, i.e., microcystins were significantly higher in the MIC-PLA stage. Water quality results revealed that N species (i.e., TN, TN/TP) and water temperature were significantly correlated with cyanobacterial biomass. Expression levels of several C- and N-processing-related cyanobacterial genes were highly predictive of the biomass of their species. More importantly, the biomasses of Microcystis and Planktothrix were also significantly associated with expressions of microbial genes (mostly from heterotrophic bacteria) related to processing organic substrates (alkaline phosphatase, peptidase, carbohydrate-active enzymes) and cyanophage genes. Collectively, our results suggest that besides environmental conditions and inherent traits of specific cyanobacterial species, the development and succession of CyanoHABs are regulated by co-occurring microorganisms. Specifically, the co-occurring microorganisms can alleviate the nutrient limitation of cyanobacteria by remineralizing organic compounds.

Taxonomic and Genotypical Heterogeneity of Microcystin degrading Bacterioplankton in Western Lake Erie.

Microcystins (MCs) are among the predominant cyanotoxins that are primarily degraded by heterotrophic bacteria in various freshwater environments, including Lake Erie, a Laurentian Great Lake. However, despite the prevalence of MCs in Lake Erie basins, our knowledge about the taxonomic diversity of local MC-degrading bacteria is largely limited. The current study obtained thirty-four MC-degrading bacterial pure isolates from Lake Erie surface water and characterized their taxonomical and phenotypic identities as well as their MC-degradation rates under different pH, temperature, availability of organic substrates and with other MC-degrading isolates. Obtained MC-degrading isolates included both Gram-positive (18 isolates of Actinobacteria and Firmicutes) and Gram-negative bacteria (16 isolates of Gamma-proteobacteria); and 7 of these isolates were motile, and 13 had the capacity to form biofilms. In general, MC-degradation rates of the isolates were impacted by temperature and pH but insensitive to the presence of cyanobacterial exudates. At the optimal temperature (30-35°C) and pH (7-8), individual isolates degraded MC-LR, the most abundant MC isomer, at an average of 0.20 µg/mL/hr. With additions of cyanobacterial exudates, only Pseudomonas sp. LEw-2029, a non-motile biofilm maker, showed increased MC degradation (0.25 µg/mL/hr). Five out of nine tested dual culture mixtures showed rises in MC degradation rates than their corresponding monocultures; the highest rate reached 0.40 µg/mL/hr for the pair LEw-(1132 + 2029). PCR amplification of mlrA genes yielded negative results for all isolates; subsequent enzyme assay-Mass Spectrum analysis identified no product associated with the mlr gene-based MC degradation pathway. Collectively, our results demonstrated that a diversity of indigenous Lake Erie bacteria can degrade MCs via a novel mlr-independent pathway. Obtained MC degraders, especially Pseudomonas sp. LEw-2029, may serve as candidates for the development of biological filters to remove cyanotoxins in water treatment systems.

Unraveling bacteria-mediated degradation of lignin-derived aromatic compounds in a freshwater environment.

Terrestrial organic carbon-lignin plays a crucial role in the global carbon balance. However, limited studies presented the functional and ecological traits of lignin decomposers population in natural aquatic ecosystem. In this study, we performed a multi-omics analysis by deploying amplicon, metagenomic, and metatranscriptomic approaches to identify the key potential degraders and pathways involved lignin-derived aromatic compounds in the later stage of lignin degradation. By establishing microcosms with model lignin-derived aromatic compound (vanillic acid, VAN), based on the estimated absolute abundance (EAA) and the metagenome-assembled genomes (MAGs), novel potential lignin-derived aromatic compounds degraders were identified in the aquatic ecosystem. Furthermore, members of the phyla Proteobacteria and Actinobacteria were the potential major lignin-derived aromatic compounds degraders in the studied ecosystem. Our study demonstrated that genomes of the class Betaproteobacteria (Proteobacteria) possess a complete enzymatic system for the degradation of diarylpropanes, vanillate and protocatechuate, besides having the capacity to degrade other lignin-derived aromatic compounds. This study provides strong evidence for the ability of aquatic bacteria to degrade lignin-derived aromatic compounds and suggest that different microbes might occupy different niches in the later stage of lignin degradation.

Dynamics of bacterioplankton community structure in response to seasonal hydrological disturbances in Poyang Lake, the largest wetland in China.

Bacterioplankton communities play a critical role in biogeochemical cycling in freshwater environments, but how the hydrological regime impacts the assembly of bacterioplankton communities remains unclear. This study examined differences in bacterioplankton community structures between wet (July and September) and dry (October and November) seasons in two consecutive years (2016 and 2017) in Poyang Lake, the largest seasonal freshwater lake in China. Our results revealed no overall difference in bacterioplankton compositions and their predicted functions among spatially separated sites. However, bacterioplankton communities did show significant temporal shifts, mainly between samples in November and other months. Transitions from the dry to the wet season were observed in October in both sampling years. Meanwhile, insignificant spatial but significant temporal differences were also found for physicochemical variables. Moreover, redundancy analysis indicates that compared with water depth, water temperature was found to better explain changes in the bacterioplankton community. These findings consistently indicate that the bacterioplankton community in Poyang Lake is relatively less sensitive to annual hydrology shifts than water temperature and nutrient conditions.

Metatranscriptomic identification of polyamine-transforming bacterioplankton in the Gulf of Mexico.

The importance of short-chained aliphatic polyamines (PAs) to bacterioplankton-mediated carbon and nitrogen cycles has been repeatedly proposed. However, bacterial taxa and genes involved in the transformations of different PA compounds and their potential spatial variations remain unclear. This study collected surface bacterioplankton from nearshore, offshore, and open ocean stations in the Gulf of Mexico and examined how metatranscriptomes responded to additions of three single PA model compounds (i.e. putrescine, spermidine, or spermine). Our data showed an overrepresentation of genes affiliated with γ-glutamylation and spermidine cleavage pathways in metatranscriptomes received PA amendments and the expression level of each pathway varied among different PA compounds and sampling locations. PA-transforming taxa were affiliated with Actinobacteria, Bacteroidetes, Cyanobacteria, Planctomycetes, and Proteobacteria and their relative importance was also compound and location specific. These findings suggest that PAs are transformed via multiple pathways and by a diversity of marine bacterioplankton in the Gulf of Mexico. The relative importance of different PA transforming pathways and composition of functional microbial communities may be regulated by nutrient status of local environments.

Roseibium aestuarii sp. nov., isolated from Pearl River Estuary.

A novel bacterium, designated strain SYSU M00256-3T, was isolated from a water sample collected from Pearl River Estuary at Guangzhou, PR China. Its taxonomic position was determined by using a polyphasic approach. Cells of the strain were Gram-staining-negative, motile, aerobic and rod-shaped with peritrichous flagella. It could grow at 15-45 °C, pH 4.0-10.0 and in the presence of 0-7.5 % (w/v) NaCl. The chemotaxonomic features of strain SYSU M00256-3T included ubiquinone-10 (Q-10) as the sole respiratory quinone; phosphatidylcholine, phosphatidylmethylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid as major polar lipids; summed feature 8 (C18 : 1 ω7c and C18 : 1 ω6c) as the predominant fatty acids (>70 %). On the basis of 16S rRNA gene sequence analysis, strain SYSU M00256-3T was most closely related to the type strains of Roseibium hamelinense CGMCC 1.12584T (97.7 %) and R. aquae CGMCC 1.12426T (97.2 %), R. sediminis KCTC 52373T (96.7 %), R. denhamense CGMCC 1.12583T (96.4 %). The average nucleotide identity (ANI) values between R. aestuarii SYSU M00256-3T and R. hamelinense CGMCC 1.12584T, R. aquae CGMCC 1.12426T, R. denhamense CGMCC 1.12583T and R. sediminis KCTC 52373T were 78.0, 78.2, 77.7 and 78.8, and the dDDH value is 20.0, 20.8, 20.1 and 20.6 correspondingly. Based on the analyses of the phenotypic, genotypic and phylogenetic characteristics, strain SYSU M00256-3T is characterized to represent a novel species of the genus Roseibium, for which the name Roseibium aestuarii sp. nov. is proposed. The type strain is SYSU M00256-3T (=NBRC 112946T=CGMCC 1.16156T).

Cyanobacterial blooms alter the relative importance of neutral and selective processes in assembling freshwater bacterioplankton community.

CyanoHABs have substantial impacts on the functioning and sustainability of freshwater ecosystems by restricting light penetration, depleting dissolved oxygen, and producing various toxins. This study combined physicochemical variable measurements, 16S rRNA gene sequencing and microscopy observations to examine mechanisms that govern the assembly of bacterioplankton communities following the progress of cyanobacterial blooms in a freshwater reservoir. Throughout the sampling season, bacterioplankton distribution patterns were well predicted by a neutral model, which assumes passive dispersal and ecological drift as the predominate mechanisms for community assembly. The neutral model consistently explained the distribution of over 67% of bacterioplankton OTUs and its fit was weaker during the cyanobacterial blooms (R2 = 0.322) than the before- (R2 = 0.549) and after-bloom stages (R2 = 0.535). Variations of environmental factors, acting as selective pressures, explained shifts of non-neutral OTUs (above/under neutral prediction) (63.9%) better than neutral OTUs (34.5%). Co-occurrence network analysis organized microbial communities into modules and revealed strong positive correlations between bacterioplankton and cyanobacteria than with planktonic algae and zooplankton. Overall, our results suggest that neutral processes play significant roles in assembling bacterioplankton communities over a cyanobacterial bloom succession and its relative importance may be weakened by biotic pressures (interspecific interactions) during the bloom period. Our results also indicate that among biotic factors, cyanobacteria had greater impacts on bacterioplankton community assembly than planktonic algae and zooplankton.

Characterization of microcystin-induced apoptosis in HepG2 hepatoma cells.

Microcystins (MCs) are a class of hepatotoxins that are commonly produced by freshwater cyanobacteria. MCs harm liver cells through inhibiting protein phosphatases 1 and 2A (PP1 and PP2A) and can produce dualistic effects, i.e., cell death and uncontrolled cellular proliferation. The induction of programmed cell death, i.e., apoptosis, in MC treated hepatic cells has been described previously; however, its exact pathway remains unclear. To address this, HepG2 human hepatoma cells were exposed to MC-LR, the most prevalent isomer of MCs, and morphological and physiological responses were examined. Microscopy and Alamar Blue assay showed that HepG2 cells responded to MC-LR treatment with apoptosis characteristics, such as clumping and shrinking of cells and detachment from the monolayer culture surface. A fluorescent caspase activation assay further revealed activation of all tested apoptosis-dependent caspases (i.e., caspase-3/7, 8 and 9) after 24 h of MC-LR treatment. Furthermore, caspase-8 was found being activated 4 h after MC-LR treatment, earlier than observed activation of caspase-9 (8 h after MC-LR treatment). These data demonstrated that MC-LR can induce apoptosis of HepG2 cells through both extrinsic and intrinsic pathways and that the extrinsic pathway may be activated before the intrinsic pathway. This indicates that extrinsic pathway is more sensitive than intrinsic pathway in MC induced apoptosis. This knowledge contributes to a better understanding of MC hepatotoxicity and can be further used for developing treatments for MC exposed hepatic cells.

Aestuariisphingobium litorale gen. nov., sp. nov., a novel proteobacterium isolated from a water sample of Pearl River estuary.

Strain SYSU M10002T was isolated from a water sample collected from the coastal region of Pearl River estuary, Guangdong Province, southern China. The taxonomic position of the isolate was investigated by polyphasic taxonomic approaches. The isolate was found to be Gram-negative, non-motile, short rods and aerobic. The strain was able to grow at 14-37 °C, pH 6.0-10.0 and in the presence of up to 0.5% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SYSU M10002T is a member of the family Sphingomonadaceae, with high sequence similarity to Sphingorhabdus buctiana T5T (95.1%). Overall genomic related indices between the genome of strain SYSU M10002T and those of related strains were low to moderate (AAI values < 64.3%; POCP values < 58%), indicating that strain SYSU M10002T represents a novel lineage within the family Sphinogomonadaceae. Strain SYSU M10002T contained homospermidine as its polyamine. The major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, sphingoglycolipid, two unidentified phospholipids and an unidentified aminolipid. Ubiquinone Q-9 (44.9%) and Q-10 (43.2%) were the dominant respiratory quinones, along with a minor amount of Q-8 (11.9%). The predominant cellular fatty acids (> 10%) identified were summed feature 3 (C16:1ω7c and/or C16:1ω6c), summed feature 8 (C18:1ω7c) and C14:0 2-OH. The genomic DNA G+C content was 64.0%. Based on the analyses of the phenotypic, genotypic and phylogenetic characteristics, strain SYSU M10002T is determined to represent a novel species of a novel genus, for which the name Aestuariisphingobium litorale gen. nov., sp. nov. is proposed. The type strain of the species is SYSU M10002T (= KCTC 52944T = NBRC 112961T).

Aestuariivirga litoralis gen. nov., sp. nov., a proteobacterium isolated from a water sample, and proposal of Aestuariivirgaceae fam. nov.

A Gram-stain-negative, non-motile, short rod and aerobic bacterium, designated strain SYSU M10001T, was isolated from a water sample collected from the coastal region of Pearl River Estuary, Guangdong Province, PR China. Strain SYSU M10001T showed optimal growth at 28 °C, pH 7.0 and in the absence of NaCl. Phylogenetic analyses based on 16S rRNA gene sequences and concatenation of 20 protein markers revealed a distinct lineage for strain SYSU M10001T in the order Rhizobiales. Strain SYSU M10001T showed highest 16S rRNA gene sequence similarities to Hyphomicrobium nitrativorans NL23T (91.1 %) and Hyphomicrobium hollandicum IFAM KB-677T (91.1 %). The respiratory ubiquinone was Q-8. The polar lipids of the strain comprised diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminophospholipid, two unidentified phospholipids and three unidentified lipids. The predominant cellular fatty acids identified were C19 : 0cyclo ω8c, summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c) and C16 : 0. The G+C content was determined to be 65.5 % (genome). On the basis of differences in the phenotypic, physiological and biochemical characteristics, and results of the phylogenetic analyses, strain SYSU M10001T is proposed to represent a novel species in a novel genus for which the name Aestuariivirga litoralis gen. nov., sp. nov. The type strain of the type species Aestuariivirga litoralis is SYSU M10001T (=NBRC 112960T=KCTC 52945T). Besides, the distinct phylogenetic lineage and the distinct chemotaxonomic profile among the families in the order Rhizobiales indicated that strain SYSU M10001T should represent a new family for which the name Aestuariivirgaceae fam. nov. is proposed.

Isolation and Characterization of Microcystin-Degrading Bacteria from Lake Erie.

Heterotrophic bacteria are suggested as the major agents that degrade microcystins (MCs), a major cyanotoxins, in natural environments. However, little is known of the taxonomic and functional diversity of MC-degrading bacteria in Lake Erie of the Laurentian Great Lakes, the largest freshwater system on earth. This study obtained six bacterial pure isolates from Lake Erie with an ability to use MCs as the sole carbon and energy sources. MC degradation rates of the isolates were impacted by temperature and pH. The key gene for MC degradation (mlrA) were failed to be PCR amplified from for all 6 MC degraders, indicating they may possess a novel MC degradation pathway. In addition for potentials used in MC bioremediation, two isolates maybe can offer extra benefits as biofertilizers.

Organic carbon source and salinity shape sediment bacterial composition in two China marginal seas and their major tributaries.

Marginal sea sediments receive organic substrates of different origins, but whether and to what extent sediment microbial communities are reflective of the different sources of organic substrates remain unclear. To address these questions, sediment samples were collected in two connected China marginal seas, i.e., Bohai Sea and Yellow Sea, and their two major tributaries (Yellow River and Liao River). Sediment bacterial community composition (BCC) was examined using 16S rRNA gene pyrosequencing. In addition, physicochemical variables that describe environmental conditions and sediment features were measured. Our results revealed that BCCs changed with salinity and organic carbon (OC) content. Members of Gaiellaceae and Comamonadaceae showed a rapid decrease as salinity and phytoplankton-derived OC increased, while Piscirickettsiaceae and Desulfobulbaceae exhibited an opposite distribution pattern. Differences of riverine vs. marginal sea sediment BCCs could be mostly explained by salinity. However, within the marginal seas, sediment BCC variations were mainly explained by OC-related variables, including terrestrial-derived fatty acids (Terr_FA), phytoplankton-derived polyunsaturated fatty acids (Phyto_PUFA), stable carbon isotopes (δ13C), and carbon to nitrogen ratio (C/N). In addition to environmental variables, network analysis suggested that interactions among individual bacterial taxa might be important in shaping sediment BCCs in the studied areas.