High peatland methane emissions following permafrost thaw: enhanced acetoclastic methanogenesis during early successional stages

Permafrost thaw in northern peatlands often leads to increased methane (CH4) emissions, but gaps remain in our understanding of the underlying controls responsible for increased emissions and the duration for which they persist. We assessed how shifting ecological conditions affect microbial communities, and the magnitude and stable isotopic signature (δ13C) of CH4 emissions along a thermokarst bog transect in boreal western Canada. Thermokarst bogs develop following permafrost thaw when dry, elevated peat plateaus collapse and become saturated and dominated by Sphagnum mosses. We differentiated between a young and a mature thermokarst bog stage (~30 and years ~200 since thaw, respectively). The young bog located along the thermokarst edge, was wetter, warmer and dominated by hydrophilic vegetation compared to the mature bog. Using 16S rRNA gene high throughput sequencing, we show that microbial communities were distinct near the surface and converged with depth, but lesser differences remained down to the lowest depth (160 cm). Microbial community analysis and δ13C data from CH4 surface emissions and dissolved gas depth profiles show that hydrogenotrophic methanogenesis was the dominant pathway at both sites. However, the young bog was found to have isotopically heavier δ13C-CH4 in both dissolved gases profiles and surface CH4 emissions, suggesting that acetoclastic methanogenesis was relatively more enhanced throughout the young bog peat profile. Furthermore, young bog CH4 emissions were three times greater than the mature bog. Our study suggests that interactions between ecological conditions and methanogenic communities enhance CH4 emissions in young thermokarst bogs, but these favorable conditions only persist for the initial decades after permafrost thaw.

Microbial Community Shift and Role of Bacteria in Rapid Granulation By Using Diatomite

Aerobic granular sludge (AGS) technology is a promising biological method for modern wastewater treatment. However, granulation time have become a major issue for the application of AGS technology especially in low strength wastewater. Recent studies on granulation are focusing towards rapid start-up granulation process. Diatomite, a friable light-coloured sedimentary rock was introduces in this study to enhanced the granules formation. This study highlight the effect of diatomite towards the microbial community during the transformation of seed sludge until development of granules. DNA extraction and Metagenomic analysis was conducted with three samples (seed sludge, control AGS, AGS diatomite) to compare the microbial community. The microbial community analysis revealed the alpha diversity, phylum and class level, and the abundance of EPS producing bacteria of each bacteria samples respectively. Diatomite has a significant influence towards the microbial diversity (High Shannon index alpha diversity). Also, diatomite promotes the abundance of functional bacteria especially EPS producing bacteria, which seen as a crucial elements in granulation process.

ENVIRONMENTAL PERFORMANCE OF MICROBIAL FUEL CELL BASED LIVE SLUDGE FOR VOLTAGE PRODUCTION AND CONGO RED DYE REMOVAL

: In this work, Single chamber Microbial fuel cells (SCMFCs) are a versatile technology is depends on the interaction mechanisms of bacteria, to produce bioelectricity simultaneously and treat Congo red (CR) dye from aqueous solution at different pH (6.5-8). Electricity generation from the biodegradable organic substrate (sucrose) accompanied by decolorization of azo dye was investigated in the batch test results showed that more than 99% decolorization demonstrated at UV-Visible Spectrophotometer (500 nm) was achieved within 20 days and maximum output voltage (889 mv) had been obtained in an open circuit at a pH value of 7.5. Microbial community analysis showed that species in live sludge and the impact of bacteria grown on removal and voltage.

Lysozyme Treatment Makes 16S rRNA Amplicon Sequencing Results Less Biased

Background Amplicon sequencing is widely applied in gut bacteria structure analysis. However, the proportion of Gram-positive bacteria may greatly affect the results of microbial community analysis. Lysozyme is an effective agent to extract DNA of Gram-positive bacteria. In this study, we assessed the influence of lysozyme treatment on results of Bactrocere dorsalis rectal bacteria structure. Result The results indicated that the total bacteria content can be significantly increased in lysozyme treated samples. Moreover, rectal bacteria diversity was significantly higher in lysozyme treated samples. A detail analysis revealed that abundance of Gram-positive bacteria significantly increased in samples treated with lysozyme. Conclusion This study indicates that lysozyme treatment before DNA extraction is an effective way to reduce bias in bacteria structure analysis, especially for samples with high proportion of Gram-positive bacteria.

Dehalobium species implicated in 2,3,7,8-tetrachloro-p-dioxin dechlorination in the contaminated sediments of Sydney Harbour Estuary

Polychlorinated dibenzo-p-dioxins and furans (PCDD/F) are some of the most environmentally recalcitrant and toxic compounds. They are naturally occurring and by-products of anthropogenic activity. Sydney Harbour Estuary (Sydney, Australia), is heavily contaminated with PCDD/F. Analysis of sediment cores revealed that the contamination source in Homebush Bay continues to have one of the highest levels of PCDD/F contamination in the world (5207 pg WHO-TEQ g-1) with >50% of the toxicity attributed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) the most toxic and concerning of the PCDD/F congeners. Comparison of congener profiles at the contamination source with surrounding bays and historical data provided evidence for the attenuation of 2,3,7,8-TCDD and other congeners at the source. This finding was supported by the detection of di-, mono- and unchlorinated dibenzo-p-dioxin. Microbial community analysis of sediments by 16S amplicon sequencing revealed an abundance of lineages from the class Dehalococcoidia (up to 15% of the community), including the genus Dehalobium (up to 0.5%). Anaerobic seawater enrichment cultures using perchloroethene as a more amenable growth substrate enriched only the Dehalobium population by more than six-fold. The enrichment culture then proved capable of reductively dechlorinating 2,3,7,8-TCDD to 2,3,7-TCDD and octachlorodibenzo-p-dibenzodioxin to hepta and hexa congeners. This work is the first to show microbial reductive dehalogenation of 2,3,7,8-TCDD with a bacterium from outside the Dehalococcoides genus, and one of only a few that demonstrates PCDD/F degradation in a marine environment.

Chemical and Microbial Characteristics of Blackening Disease in Lotus (Nelumbo nucifera Gaertn.) Caused by Hirschmanniella diversa Sher

The lotus (Nelumbo nucifera Gaertn.) is widely cultivated in Asia, but a blackening disease in the lotus tuber, called “kurokawa-senchu-byo”, is a serious problem caused by the Hirschmanniella diversa Sher plant-parasitic nematode. To effectively control the disease, we must elucidate the blackening mechanisms; therefore, in this study, we performed a soil chemical analysis and an evaluation of the disease level in the lotus cultivation fields, identified the chemical components of the black spots on the lotus surface, and performed a 16S rRNA gene-based microbial community analysis of the black spots. Using linear regression analysis, a positive linear relationship with a strong correlation between the damage index values and fertilizer components such as P2O5 was observed. As a result of scanning electron microscopy and energy-dispersive X-ray spectroscopy analysis, phosphorus (P) and iron (Fe) were found to be concentrated in the black spots of the lotus tubers. Furthermore, we found that the concentrations of P and Fe in the black spots were 1.5- and 2.7-fold higher, respectively, than those found in the healthy parts of the lotus tubers. A 16S rRNA gene analysis revealed that dissimilatory Fe(III)-reducing bacteria (DIRB) were predominant in the black spots, suggesting that these bacteria are important to the formation of P and Fe compounds in the black spots.