Impact of Warming on Greenhouse Gas Production and Microbial Diversity in Anoxic Peat From a Sphagnum-Dominated Bog (Grand Rapids, Minnesota, United States)

Climate warming is predicted to increase heterotrophic metabolism in northern peatland soils leading to enhanced greenhouse gas emissions. However, the specific relationships between temperature and the greenhouse gas producing microbial communities are poorly understood. Thus, in this study, the temperature dependence of carbon dioxide (CO2) and methane (CH4) production rates along with abundance and composition of microbial communities were investigated in peat from a Sphagnum-dominated peatland, S1 bog (Minnesota, United States). Whereas CH4 production rates increased with temperature up to 30°C, CO2 production did not, resulting in a lower CO2:CH4 ratio with increasing temperature. CO2 production showed both psychrophilic and mesophilic maxima at 4 and 20°C, respectively, and appears to be mediated by two anaerobic microbial communities, one that operates under psychrophilic conditions that predominate for much of the year, and another that is more active under warmer conditions during the growing season. In incubations at 10°C above the ambient range, members of the Clostridiaceae and hydrogenotrophic methanogens of the Methanobacteriaceae dominated. Moreover, a significant negative correlation between temperature and microbial diversity was observed. Results indicate that the potential consequences of warming surface peat in northern peatlands include a large stimulation in CH4 production and a significant loss of microbial diversity

Probiotic human alcohol dehydrogenase-4 expressing bacteria protects from diet-induced obesity and metabolic impairment: a new concept of disease prevention

Aim: Probiotic bacteria consumption for improving human health and for disease prevention is still controversial. There is a need to develop functional probiotic bacteria with proven efficacy for the human gastrointestinal (GI) system. The novel bacteria will lower the steady state of constant Ethanol production may lead to gut microbiota dysbiosis and liver injuries. Methods: Herein engineered probiotic bacterium B. subtilis to enhance the secretion of human alcohol dehydrogenase-4 (ADH4) by fusion of signal peptides (SPs) was constructed. As a result, higher ADH4 secretion and Ethanol removal rates were observed in phoB SP transformant SP-64, compared to other transformants. The engineered ADH4 expressing probiotic B. subtilis was delivered as spores to evaluate various physiological, biochemical, and immuno-histochemical parameters of mice under a high-fat diet (HFD)-induced obesity and metabolic impairment. Results: The treatment ameliorated significantly weight gain, improved glucose utilization, and prevented HFD-induced pancreatic damage. Lastly, SP-64 inoculation altered the gut microbiota, and increased the Firmicutes/Bacteroides ratio, supporting better fitness under HFD. Conclusions: SP-64 emerged as a potential probiotic that opens a new avenue for interventions against over-nutrition-induced metabolic disorders

Soil Metabolome Response to Whole-Ecosystem Warming at the Spruce and Peatland Responses Under Changing Environments Experiment

While peatlands have historically stored massive amounts of soil carbon, warming is expected to enhance decomposition, leading to a positive feedback with climate change. In this study, a unique whole-ecosystem warming experiment was conducted in northern Minnesota to warm peat profiles to 2 m deep while keeping water flow intact. After nearly 2 y, warming enhanced the degradation of soil organic matter and increased greenhouse gas production. Changes in organic matter quality with warming were accompanied by a stimulation of methane production relative to carbon dioxide. Our results revealed increased decomposition to be fueled by the availability of reactive carbon substrates produced by surface vegetation. The elevated rates of methanogenesis are likely to persist and exacerbate climate warming

Comparative genomic analysis indicates that niche adaptation of terrestrial Flavobacteria is strongly linked to plant glycan metabolism.

Flavobacteria are important members of aquatic and terrestrial bacterial communities, displaying extreme variations in lifestyle, geographical distribution and genome size. They are ubiquitous in soil, but are often strongly enriched in the rhizosphere and phyllosphere of plants. In this study, we compared the genome of a root-associated Flavobacterium that we recently isolated, physiologically characterized and sequenced, to 14 additional Flavobacterium genomes, in order to pinpoint characteristics associated with its high abundance in the rhizosphere. Interestingly, flavobacterial genomes vary in size by approximately two-fold, with terrestrial isolates having predominantly larger genomes than those from aquatic environments. Comparative functional gene analysis revealed that terrestrial and aquatic Flavobacteria generally segregated into two distinct clades. Members of the aquatic clade had a higher ratio of peptide and protein utilization genes, whereas members of the terrestrial clade were characterized by a significantly higher abundance and diversity of genes involved in metabolism of carbohydrates such as xylose, arabinose and pectin. Interestingly, genes encoding glycoside hydrolase (GH) families GH78 and GH106, responsible for rhamnogalacturonan utilization (exclusively associated with terrestrial plant hemicelluloses), were only present in terrestrial clade genomes, suggesting adaptation of the terrestrial strains to plant-related carbohydrate metabolism. The Peptidase/GH ratio of aquatic clade Flavobacteria was significantly higher than that of terrestrial strains (1.7±0.7 and 9.7±4.7, respectively), supporting the concept that this relation can be used to infer Flavobacterium lifestyles. Collectively, our research suggests that terrestrial Flavobacteria are highly adapted to plant carbohydrate metabolism, which appears to be a key to their profusion in plant environments

Succession of Microbial Populations and Nitrogen-fixation Associated with the Biodegradation of Sediment-oil-agglomerates Buried in a Florida Sandy Beach

The Deepwater Horizon (DWH) oil spill contaminated coastlines from Louisiana to Florida, burying oil up to 70 cm depth in sandy beaches, posing a potential threat to environmental and human health. The dry and nutrient-poor beach sand presents a taxing environment for microbial growth, raising the question how the biodegradation of the buried oil would proceed. Here we report the results of an in-situ experiment that (i) characterized the dominant microbial communities contained in sediment oil agglomerates (SOAs) of DWH oil buried in a North Florida sandy beach, (ii) elucidated the long-term succession of the microbial populations that developed in the SOAs, and (iii) revealed the coupling of SOA degradation to nitrogen fixation. Orders of magnitude higher bacterial abundances in SOAs compared to surrounding sands distinguished SOAs as hotspots of microbial growth. Blooms of bacterial taxa with a demonstrated potential for hydrocarbon degradation (Gammaproteobacteria, Alphaproteobacteria, Actinobacteria) developed in the SOAs, initiating a succession of microbial populations that mirrored the evolution of the petroleum hydrocarbons. Growth of nitrogen-fixing prokaryotes or diazotrophs (Rhizobiales and Frankiales), reflected in increased abundances of nitrogenase genes (nifH), catalyzed biodegradation of the nitrogen-poor petroleum hydrocarbons, emphasizing nitrogen fixation as a central mechanism facilitating the recovery of sandy beaches after oil contamination

Statistically significant differences in distribution of SEED subsystems between aquatic and terrestrial clades.

<p>(A) Major SEED categories, and (B) carbohydrate sub-systems, showing significant differences between aquatic and terrestrial clades. The distribution of genes across SEED categories and subsystems were normalized to the total number of genes in a particular genome and Student T-test (<i>P</i><0.05) was applied to test statistical significance.</p

Hierarchical clustering of <i>Flavobacterium</i> strains based on functional similarity.

<p><i>Flavobacterium</i> strains functionally clustered into terrestrial and aquatic clades. The distribution of genes across SEED subsystems was normalized to the total number of genes in a particular genome. Hierarchical clustering was performed using the Bray-Curtis distance matrix. Bootstrap values are shown next to the branch nodes. Open and black circles represent aquatic and terrestrial isolates, respectively.</p

Distribution of carbohydrate-utilizing enzymes.

<p>(A) Distribution of CAZy enzyme classes in the terrestrial and aquatic flavobacterial clades; and (B) Distribution of <i>Flavobacterium</i> strain glycoside hydrolases visualized using nMDS of a Bray-Curtis distance matrix. GH- glycoside hydrolases; CE-carbohydrate esterase; PL-polysaccharide lyases; CBM- carbohydrate binding modules; GT- glycosyl transferases. Asterisks indicate statistically significant differences (<i>P</i> < 0.05) between clades.</p