Using bioelectrohydrogenesis left-over residues as a future potential fertilizer for soil amendment.

In this current research, the left-over residues collected from the dark fermentation-microbial electrolysis cells (DF-MEC) integrated system solely biocatalyzed by activated sludge during the bioconversion of the agricultural straw wastes into hydrogen energy, was investigated for its feasibility to be used as a potential alternative biofertilizer to the commonly costly inorganic ones. The results revealed that the electrohydrogenesis left-over residues enriched various plant growth-promoting microbial communities including Enterobacter (8.57%), Paenibacillus (1.18%), Mycobacterium (0.77%), Pseudomonas (0.65%), Bradyrhizobium (0.12%), Azospirillum (0.11%), and Mesorhizobium (0.1%) that are generally known for their ability to produce different essential phytohormones such as indole-3-acetic acid/indole acetic acid (IAA) and Gibberellins for plant growth. Moreover, they also contain both phosphate-solubilizing and nitrogen-fixing microbial communities that remarkably provide an adequate amount of assimilable phosphorus and nitrogen required for enhanced plants or crop growth. Furthermore, macro-, and micronutrients (including N, P, K, etc.) were all analyzed from the residues and detected adequate appreciate concentrations required for plant growth promotions. The direct application of MEC-effluent as fertilizer in this current study conspicuously promoted plant growth (Solanum lycopersicum L. (tomato), Capsicum annuum L. (chilli), and Solanum melongena L. (brinjal)) and speeded up flowering and fruit-generating processes. Based on these findings, electrohydrogenesis residues could undoubtedly be considered as a potential biofertilizer. Thus, this technology provides a new approach to agricultural residue control and concomitantly provides a sustainable, cheap, and eco-friendly biofertilizer that could replace the chemical costly fertilizers.

Application of fast expectation-maximization microbial source tracking to discern fecal contamination in rivers exposed to low fecal inputs.

Community-based microbial source tracking (MST) can be used to determine fecal contamination from multiple sources in the aquatic environment. However, there is little scientific information on its application potential in water environmental management. Here, we compared SourceTracker and Fast Expectation-maximization Microbial Source Tracking (FEAST) performances on environmental water bodies exposed to low fecal pollution and evaluated treatment effects of fecal pollution in the watershed utilizing community-based MST. Our results showed that FEAST overall outperformed SourceTracker in sensitivity and stability, and was able to discern multi-source fecal contamination (mainly chicken feces) in ambient water bodies exposed to low fecal inputs. Consistent with our previous PCR/qPCR-based MST assays, FEAST analysis indicates that fecal pollution has been significantly mitigated through comprehensive environmental treatment by the local government. This study suggests that FEAST can be a powerful tool for accurately evaluating the contribution of multi-source fecal contamination in environmental water, facilitating environmental management.

Synergistic Application of Molecular Markers and Community-Based Microbial Source Tracking Methods for Identification of Fecal Pollution in River Water During Dry and Wet Seasons.

It is important to track fecal sources from humans and animals that negatively influence the water quality of rural rivers and human health. In this study, microbial source tracking (MST) methods using molecular markers and the community-based FEAST (fast expectation-maximization microbial source tracking) program were synergistically applied to distinguish the fecal contributions of multiple sources in a rural river located in Beijing, China. The performance of eight markers were evaluated using 133 fecal samples based on real-time quantitative (qPCR) technique. Among them, six markers, including universal (BacUni), human-associated (HF183-1 and BacH), swine-associated (Pig-2-Bac), ruminant-associated (Rum-2-Bac), and avian-associated (AV4143) markers, performed well in the study. A total of 96 water samples from the river and outfalls showed a coordinated composition of fecal pollution, which revealed that outfall water might be a potential input of the Fsq River. In the FEAST program, bacterial 16S rRNA genes of 58 fecal and 12 water samples were sequenced to build the "source" library and "sink," respectively. The relative contribution (<4.01% of sequence reads) of each source (i.e., human, swine, bovine, or sheep) was calculated based on simultaneous screening of the operational taxonomic units (OTUs) of sources and sinks, which indicated that community-based MST methods could be promising tools for identifying fecal sources from a more comprehensive perspective. Results of the qPCR assays indicated that fecal contamination from human was dominant during dry weather and that fecal sources from swine and ruminant were more prevalent in samples during the wet season than in those during the dry season, which were consistent with the findings predicted by the FEAST program using a very small sample size. Information from the study could be valuable for the development of improved regulation policies to reduce the levels of fecal contamination in rural rivers.

Y-Shaped Tendon Graft-A Technique in the Reconstruction of Posttraumatic Chronic Boutonniere Deformity.

PURPOSE: Current reconstruction strategies for chronic posttraumatic boutonniere deformities have variable outcomes and are prone to complications. This study aimed to describe the clinical outcomes of a Y-shaped tendon graft technique. METHODS: In this retrospective case study, we reviewed the files of 18 patients treated with the Y-shaped tendon graft between January 2010 and January 2017. The technique involves release of the central slip, lateral bands, and transverse retinacular ligaments at the proximal interphalangeal (PIP) joint, total excision of scar tissue in the central slip and at the insertion site, and construction of 3 1.5-mm unicortical holes at the base of the middle phalanx, through which a Y-shaped graft of the palmaris longus is inserted to reconstruct the central slip and stabilize the lateral bands in a dorsal position. Clinical evaluations included measuring the active range of motion in the PIP joint and distal interphalangeal (DIP) joint, grip strength, Souter score, and the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score. RESULTS: The mean age of patients was 36.1 years, and 12 of the 18 patients were men. The average follow-up period was 23 months (range, 13-38 months). The preoperative PIP joint extension deficit was 48.0° ± 5.0° compared with 10.9° ± 9.3° after surgery. The preoperative DIP joint active flexion was 34.4° ± 8.0° compared with 71.4° ± 8.6° after surgery The outcomes based on the Souter score were 11 excellent, 5 good, and 2 poor. The QuickDASH score was 17.7 ± 6.4 before surgery and 11.2 ± 7.2 after surgery. CONCLUSIONS: The Y-shaped tendon graft can be a useful procedure for the correction of chronic boutonniere deformity; in our patient series, this provided good or excellent results in 16 of 18 patients. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Regeneration of unconventional natural gas by methanogens co-existing with sulfate-reducing prokaryotes in deep shale wells in China.

Biogenic methane in shallow shale reservoirs has been proven to contribute to economic recovery of unconventional natural gas. However, whether the microbes inhabiting the deeper shale reservoirs at an average depth of 4.1 km and even co-occurring with sulfate-reducing prokaryote (SRP) have the potential to produce biomethane is still unclear. Stable isotopic technique with culture-dependent and independent approaches were employed to investigate the microbial and functional diversity related to methanogenic pathways and explore the relationship between SRP and methanogens in the shales in the Sichuan Basin, China. Although stable isotopic ratios of the gas implied a thermogenic origin for methane, the decreased trend of stable carbon and hydrogen isotope value provided clues for increasing microbial activities along with sustained gas production in these wells. These deep shale-gas wells harbored high abundance of methanogens (17.2%) with ability of utilizing various substrates for methanogenesis, which co-existed with SRP (6.7%). All genes required for performing methylotrophic, hydrogenotrophic and acetoclastic methanogenesis were present. Methane production experiments of produced water, with and without additional available substrates for methanogens, further confirmed biomethane production via all three methanogenic pathways. Statistical analysis and incubation tests revealed the partnership between SRP and methanogens under in situ sulfate concentration (~ 9 mg/L). These results suggest that biomethane could be produced with more flexible stimulation strategies for unconventional natural gas recovery even at the higher depths and at the presence of SRP.

Full-scale anaerobic reactor samples would be more suitable than lab-scale anaerobic reactor and natural samples to inoculate the wheat straw batch anaerobic digesters.

This study evaluated the effects of the inocula from natural wetland, lab-scale and full-scale anaerobic reactors on wheat straw anaerobic digestion. Three replicate batch reactors were constructed for each inoculum to investigate the reactor performances and microbial communities. Reactors seeded with full-scale reactor samples were started up most rapidly, achieved the highest methane production, and were recognized as the higher efficient reactors. The dominance of acetoclastic methanogens, including Methanosaeta and Methanoscrina, was crucial for the higher efficient reactors, whereas hydrogenotrophic methanogens were dominant in other reactors. Genus Treponema, which could enhance the cellulose degradation and conduct homoacetogenesis, was first reported to be dominant in the bacterial communities of high efficient reactors. Inoculum sources and process conditions were suggested to be the deterministic factors in shaping the microbial communities in the higher efficient reactors. These findings contribute to the startup of new anaerobic reactors.

Developmental stage has a greater effect than Cry1Ac expression in transgenic cotton on the phyllosphere mycobiome.

Transgenic Bt cotton is widely cultivated, yet its impact on the phyllosphere mycobiome is poorly understood. Hence, the objective of this study was to investigate the effects resulting from the planting of Bt cotton on fungal diversity composition. The α diversity for the Bt cotton line SGK321 was lower than that of control plants at the budding stage and the blossoming and boll-forming stage, while an obvious increase in diversity for Bt cotton XP188 was observed at the same stage. The Cry1Ac levels were higher at the seedling stage than at the budding stage and the blossoming and boll-forming stage. There was no direct relationship between the expression of the Bt protein and variation in the fungal community for Bt cotton. However, PCoA and PCA results indicated that community structure differed among developmental stages. These results indicated that developmental stage rather than Cry1Ac expression was the key factor shaping the phyllosphere mycobiome in transgenic cotton.

Proteomic and metabolomic analysis of the cellular biomarkers related to inhibitors tolerance in Zymomonas mobilis ZM4.

BACKGROUND: Toxic compounds present in both the hydrolysate and pyrolysate of lignocellulosic biomass severely hinder the further conversion of lignocellulose-derived fermentable sugars into useful chemicals by common biocatalysts like Zymomonas mobilis, which has remarkable advantages over yeast. Although the extra detoxification treatment prior to fermentation process can help biocatalysts to eliminate the inhibitory environment, it is not environment friendly and cost effective for industrial application. As also reported by previous studies, an ideal and holistic approach to solve this issue is to develop microbial strains with inhibitor tolerance. However, previously engineered strains had the limitation that they could not cope well with the synergistic effect of multiple inhibitors as they are resistant only to a single inhibitor. Hence, understanding the universal cellular responses of Z. mobilis to various inhibitors may guide the designing of rational strategies to obtain more robust engineered strains for biofuel production from lignocellulosic biomass. RESULTS: Quantitative proteomics and metabolomics approaches were used to determine the cellular responses of Z. mobilis ZM4 to representative biomass-derived inhibitors like formic acid, acetic acid, furfural, 5-hydroxymethylfurfural, and phenol. The differentially expressed proteins identified under the challenge of single and combined inhibitors were involved in cell wall/membrane biogenesis, energy production, DNA replication, DNA recombination, DNA repair, DNA transcription, RNA translation, posttranslational modification, biosynthesis of amino acids, central carbon metabolism, etc. Metabolomics analysis showed that the up- or down-regulation pattern of metabolites was changed consistently with that of relevant proteins. CONCLUSION: Fifteen up-regulated proteins (e.g., Isopropylmalate isomerase LeuC, transcription-repair-coupling factor Mfd, and phosphoglucose isomerase PGI) and thirteen down-regulated proteins (e.g., TonB-dependent transporter ZMO1522, transcription termination factor Rho, and S1/P1 nuclease ZMO0127) were identified as candidate proteins related to all the stress conditions, implying that these proteins are potential biomarkers for the improvement of Z. mobilis ZM4 to resist complex biomass-derived inhibitors. These data can be used to generate a database of inhibitor-tolerance biomarkers, which could provide a basis for engineering Z. mobilis that would be able to grow in the presence of multiple inhibitors and directly ferment the biomass-derived sugars into biofuels.

Do microbial communities in an anaerobic bioreactor change with continuous feeding sludge into a full-scale anaerobic digestion system?

Microbial communities of sludge samples from a full-scale anaerobic digestion (AD) fed with primary sludge (PS) and excess sludge (ES) were analyzed using qPCR and MiSeq. The results showed that the microbial composition of digested sludge remained relatively stable but was partially changed by microbial immigration from feeding sludge. The dominant archaea in the digested sludge were largely the same as those in the feeding sludge, but their abundances differed markedly. The dominant fungal genera in the digested sludge were different from those in PS but were similar to those in ES. Various differences in bacterial community differences between digested sludge and PS/ES were observed. Notably, this study is the first to suggest Verrucomicrobia is the predominant bacterial phylum in the digested sludge, and that numerous unreported microorganisms belonging to the order LD1-PB3 existed in this AD system and potentially played roles in the processes of hydrolysis, fermentation, and acetogenesis.

Anthropogenic protection alters the microbiome in intertidal mangrove wetlands in Hainan Island.

Intertidal mangrove wetlands are of great economic and ecological importance. The regular influence of tides has led to the microbial communities in these wetlands differing significantly from those in other habitats. In this study, we investigated the microbiomes of the two largest mangrove wetlands in Hainan Island, China, which have different levels of anthropogenic protection. Soil samples were collected from the root zone of 13 mangrove species. The microbial composition, including key functional groups, was assessed using Illumina sequencing. Bioinformatics analysis showed that there was a significant difference in the microbiomes between the protected Bamen Bay and the unprotected Dongzhai Bay. The overall microbiome was assigned into 78 phyla and Proteobacteria was the most abundant phylum at both sites. In the protected wetland, there were fewer marine-related microbial communities, such as sulfate-reducing bacteria, and more terrestrial-related communities, such as Verrucomicrobia methanotrophs. We also observed distinct microbial compositions among the different mangrove species at the protected site. Our data suggest that the different microbiomes of the two mangrove wetlands are the result of a complex interaction of the different environmental variables at the two sites.

[Community Structure of Microorganisms and Its Seasonal Variation in Beihai Lake].

Water samples were collected in summer, autumn, winter, and spring in Beihai Lake for the analysis of water quality and microbial community structure. It was found that the water quality in summer and autumn was worse than in winter and spring, and TN and TP were the most important factors affecting the water quality. The microbial community structure was investigated using MiSeq high-throughput sequencing. It was found that the phyla Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes were abundant in all the samples, whereas their relative abundances differed among the four seasons. In summer and autumn, the microbial diversities were higher, and the phylum Cyanobacteria was most abundant, with the genus Synechococcus dominant. In winter, the phylum Proteobacteria was dominant. In spring, Actinobacteria and Bacteroidetes were abundant, accounting for 51.5%-64.3% of the bacterial community. The redundancy analysis (RDA) results showed that the microbial communities were mostly affected by water temperature in Beihai Lake. Overall, the water quality of Beihai Lake was qualified for the use of landscape water. However, the abundance of Synechococcus in summer may lead to algal blooms. Thus, it is necessary to strengthen the monitoring and estimation of water quality in Beihai Lake.

Detailed comparison of bacterial communities during seasonal sludge bulking in a municipal wastewater treatment plant.

In this study, pyrosequencing combined with clone library analysis, qPCR, and fluorescent in situ hybridization (FISH) were performed to identify detailed changes of bacterial and filamentous bacterial communities in activated sludge (AS) in 3 types of typical AS samples: sludge bulking (B-AS), excessive bulking (EB-AS), and non-bulking (N-AS). Sludge bulking resulted in a decrease in total bacterial numbers from (6.4 ± 0.18) × 108 gene copies/mL in N-AS to (2.4 ± 0.22) × 108 in EB-AS and a decrease in bacterial diversity from 2757 OTUs in N-AS to 2217 OTUs in EB-AS. With the occurrence of sludge bulking, Actinobacteria and Firmicutes increased sharply, whereas Proteobacteria, which was the predominant phylum in N-AS, decreased markedly. In addition, Nitrospirae, a major lineage of the nitrite-oxidizing bacteria, had quite a low abundance in EB-AS (0.15%), while it was relatively high in N-AS (1.17%). On the other hand, filamentous bacteria accounted for 28.77% and 5.72% of total sequences in EB-AS and N-AS, respectively. More interestingly, 11 types of filamentous bacteria were always present in 3 types of typical AS samples from different stages of sludge bulking, and most of them enriched in EB-AS compared to N-AS. It is noteworthy that, in addition to the frequently reported filamentous bacteria such as Candidatus M. parvicella and Tetrasphaera, novel filamentous species of Trichococcus might exist in this bulking WWTP. Our results reveal that sludge bulking are derived from diverse taxa, which expands previous understanding and provides new insight into the underlying complications of the bulking phenomenon in AS.

Microbial Community Composition Associated with Maotai Liquor Fermentation.

The solid-state fermentation state of Chinese Maotai liquor involves the interaction of several complex microbial communities leading to the generation of the most complex liquor fermentation system in the world and contributes to the unique flavor and aroma of the liquor. In this study, total DNA was extracted from 3 fermented grain samples (FG1, FG2, and FG3) and 12 environmental samples, including Daqu (DA1, DA2, DA3, and DA4), cellar mud (CS1, CS2, and CS3), soil (SL1 and SL2), air (A1 and A2), and sorghum (SH), and the 16S and 18S rRNA genes were amplified. The distribution of typical microorganisms in the samples was analyzed using nested PCR-denaturing gradient gel electrophoresis, while quantitative PCR amplification of 16S rRNA and internal transcribed spacer genes was performed to estimate the microbial abundance present in each sample. The results indicated that Daqu was the primary source of bacteria, followed by the air, soil, and sorghum samples, while the majority of the fungi responsible for Maotai liquor fermentation were from Daqu and sorghum. Highest bacterial concentrations were found in fermented grains, followed by Daqu and sorghum, while the highest fungal concentrations were found in Daqu, followed by sorghum and an air sample from outside the liquor production area. The findings of this study may provide information regarding the mechanisms responsible for flavor development in Maotai liquor, and may be used to further optimize the traditional art of making liquor.

Seasonal Changes in Bacterial Communities Cause Foaming in a Wastewater Treatment Plant.

Bio-foaming is a major problem in solid separation in activated sludge (AS) wastewater treatment systems. Understanding the changes in bacterial communities during sludge foaming is vital for explaining foam formation. Changes in bacterial communities in the foam, corresponding foaming AS, and non-foaming AS in a seasonal foaming wastewater treatment plant (WWTP) in Northern China were investigated by high-throughput pyrosequencing and molecular quantification-based approaches. We found that bacterial communities of the foam and the corresponding foaming AS were similar but markedly different from those of the non-foaming AS. Actinobacteria was the predominant phylum in the foam and the corresponding foaming AS, whereas Proteobacteria was predominant in the non-foaming AS. Similar to the results of most previous studies, our results showed that Candidatus "Microthrix parvicella" was the predominant filamentous bacteria in the foam and the corresponding foaming AS and was significantly enriched in the foam compared to the corresponding foaming AS. Its abundance decreased gradually with a slow disappearance of sludge foaming, indicating that its overgrowth had a direct relationship with sludge foaming. In addition to Candidatus M. parvicella, Tetrasphaera and Trichococcus might play a role in sludge foaming, because they supported the changes in AS microbial ecology for foam formation. The effluent water quality of the surveyed plant remained stable during the period of sludge foaming, but the microbial consortia responsible for nitrogen and phosphorus transformation and removal markedly changed compared to that in the non-foaming AS. This study adds to the previous understanding of bacterial communities causing foaming in WWTPs.

Computational analysis of AnmK-like kinase: New insights into the cell wall metabolism of fungi.

1,6-Anhydro-N-acetylmuramic acid kinase (AnmK) is the unique enzyme that marks the recycling of the cell wall of Escherichia coli. Here, 81 fungal AnmK-like kinase sequences from 57 fungal species were searched in the NCBI database and a phylogenetic tree was constructed. The three-dimensional structure of an AnmK-like kinase, levoglucosan kinase (LGK) of the yeast Lipomyces starkeyi, was modeled; molecular docking revealed that AnmK and LGK are conserved proteins, and 187Asp, 212Asp are enzymatic residues, respectively. Analysis suggests that 1,6-anhydro-N-acetylglucosamine (anhGlcNAc) and/or 1,6-anhydro-ß-d-glucosamine (anhGlcN) would be the appropriate substrates of AnmK-like kinases. Also, the counterparts of other characteristic enzymes of cell wall recycling of bacteria were found in fungi. Taken together, it is proposed that a putative recycling of anhGlcNAc/anhGlcN, which is associated with the hydrolysis of cell walls, exists in fungi. This computational analysis will provide new insights into the metabolism of fungal cell walls.

[Impact on the microbial community of municipal sewage in the anammox system during the cooling process].

Anaerobic ammonium oxidation is an important part of the biological nitrogen removal process, and the performance of the process is determined by the microbial community structure. Low-temperature anaerobic ammonium oxidation technology has good prospects for saving a lot of energy, and anaerobic ammonium oxidation bacteria play a vital role in the removal of total nitrogen from waste water. To explore the microbial community structure changes of anammox reactor in sewage treatment during the cooling process (from 30 degrees C to 20 degrees), the total amount of the microbial, the quantity of anaerobic ammonium oxidation and the change of functional microbial community were investigated in a sewage treatment process using the phospholipid fatty acid method (PLFA), quantitative PCR and the clone library of bacterial 16S rRNA. The PLFAs results showed that the total amount of microbial was first decreased and then gradually increased with the running time, when the temperature dropped from 30 degrees C to 20 degrees C, and the NH4+ -N content in the effluent of the system was decreased. The quantitative PCR results showed that 16S rRNA gene copies of anammox bacteria increased from 1.19 x 10(8) copies x mL(-1) to 1.86 x 10(8) copies x mL(-1) in the wastewater. The PCR-DGGE results showed that when the temperature decreased, the anammox bacteria were further enriched. A shift of anammox bacteria community from single Candidatus Kuenenia sp. to a combination of Candidatus Brocadia sp. and Candidatus Kuenenia sp. was observed.

Molecular characterization of microbial communities in bioaerosols of a coal mine by 454 pyrosequencing and real-time PCR.

Microbial diversity and abundance in bioaerosols of a coal mine were analyzed based on 454 pyrosequencing and real-time polymerase chain reaction (PCR). A total of 37,191 high quality sequences were obtained and could be classified into 531, 1730 and 448 operational taxonomic units respectively for archaea, bacteria and fungi at 97% sequence similarity. The Shannon diversity index for archaea, bacteria and fungi was respectively 4.71, 6.29 and 3.86, indicating a high diversity in coal mine bioaerosols. Crenarchaeota, Proteobacteria and Ascomycota were the dominant phyla for archaea, bacteria and fungi, respectively. The concentrations of total archaea, bacteria and fungi were 1.44×10(8), 1.02×10(8) and 9.60×10(4) cells/m3, respectively. Methanotrophs observed in bioaerosols suggested possible methane oxidation in the coal mine. The identified potential pathogens to coal miners, such as Acinetobacter schindleri, Aeromonas cavernicola, Alternaria alternata, Aspergillus penicillioides, Cladosporium cladosporioides, and Penicillium brevicompactum were also observed. This was the first investigation of microbial diversity and abundance in coal mine bioaerosols. The investigation of microbial communities would be favorable in promoting the progress of methane control based on microbial technique and concern on coal miners' health.

Mathematical modeling of the fermentation of acid-hydrolyzed pyrolytic sugars to ethanol by the engineered strain Escherichia coli ACCC 11177.

Pyrolysate from waste cotton was acid hydrolyzed and detoxified to yield pyrolytic sugars, which were fermented to ethanol by the strain Escherichia coli ACCC 11177. Mathematical models based on the fermentation data were also constructed. Pyrolysate containing an initial levoglucosan concentration of 146.34 g/L gave a glucose yield of 150 % after hydrolysis, suggesting that other compounds were hydrolyzed to glucose as well. Ethyl acetate-based extraction of bacterial growth inhibitors with an ethyl acetate/hydrolysate ratio of 1:0.5 enabled hydrolysate fermentation by E. coli ACCC 11177, without a standard absorption treatment. Batch processing in a fermenter exhibited a maximum ethanol yield and productivity of 0.41 g/g and 0.93 g/L·h(-1), respectively. The cell growth rate (r x ) was consistent with a logistic equation [Formula: see text], which was determined as a function of cell growth (X). Glucose consumption rate (r s ) and ethanol formation rate (r p ) were accurately validated by the equations [Formula: see text] and [Formula: see text], respectively. Together, our results suggest that combining mathematical models with fermenter fermentation processes can enable optimized ethanol production from cellulosic pyrolysate with E. coli. Similar approaches may facilitate the production of other commercially important organic substances.

Community succession of bacteria and eukaryotes in dune ecosystems of Gurbantünggüt Desert, Northwest China.

Pyrosequencing and quantitative polymerase chain reaction of small subunit rRNA genes were used to provide a comprehensive examination of bacterial, cyanobacterial, and eukaryotic communities in the biological soil crusts (BSCs) of Gurbantünggüt Desert sand dunes (China). Three succession stages were recognized based on the analyses of eukaryotic communities: a late succession stage of BSCs in a swale with eukaryotes mainly related to the Bryophyta clade, an initial succession stage in a slope with barely any eukaryotic phototrophic microorganisms detected, and an intermediate succession type detected from both the swale and slope BSCs dominated by the phylum Chlorophyta. Moreover, the cyanobacterial community dominated all of the BSCs (48.2-69.5% of the total bacteria) and differed among the three succession stages: sequences related to Microcoleus steenstrupii and the genus Scytonema were abundant in the later succession stage, whereas both the initial and intermediate stages were dominated by Microcoleus vaginatus. Compared with swales, BSCs from slopes are exposed to a harsher environment, e.g., higher irradiance and lower water availability, and thus may be restricted from developing to a higher succession stage. Other disturbances such as wind and grazing may explain the different succession stages observed in swales or slopes. However, no clear differences were detected from non-phototrophic bacterial communities of the three succession stages, and sequences related to Alphaproteobacteria and Actinobacteria were most abundant in all the BSCs. The closest matches for the most frequent non-phototrophic bacterial genera were mainly derived from harsh environments, indicating the robustness of these genera.

Aerobic methanotroph diversity in Sanjiang wetland, Northeast China.

Aerobic methanotrophs present in wetlands can serve as a methane filter and thereby significantly reduce methane emissions. Sanjiang wetland is a major methane source and the second largest wetland in China, yet little is known about the characteristics of aerobic methanotrophs in this region. In the present study, we investigated the diversity and abundance of methanotrophs in marsh soils from Sanjiang wetland with three different types of vegetation by 16S ribosomal RNA (rRNA) and pmoA gene analysis. Quantitative polymerase chain reaction analysis revealed the highest number of pmoA gene copies in marsh soils vegetated with Carex lasiocarpa (10(9) g(-1) dry soil), followed by Carex meyeriana, and the least with Deyeuxia angustifolia (10(8) g(-1) dry soil). Consistent results were obtained using Sanger sequencing and pyrosequencing techniques, both indicating the codominance of Methylobacter and Methylocystis species in Sanjiang wetland. Other less abundant methanotrophy, including cultivated Methylomonas and Methylosinus genus, and uncultured clusters such as LP20 and JR-1, were also detected in the wetland. Methanotroph diversity was almost the same in three different vegetation covered soils, suggesting that vegetation types had very little influence on the methanotroph diversity. Our study gives an in-depth insight into the community composition of aerobic methanotrophs in the Sanjiang wetland.