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Step-Controlled Povarov-Type Reaction with 1,2-Dihydroquinolines as Precursors of Dienophiles: Direct Synthesis of Spirocyclic Bi-tetrahydroquinolines and Functionalized 1,2-Dihydroquinolines
No full textA novel Povarov-type reaction for straightforward synthesis of novel spiro bi-tetrahydroquinolines with readily available 1,2-DHQs (1,2-dihydroquinolines) and aromatic imines was developed. The reaction could be selectively stopped at the first stage under a Bronsted acid catalyst to afford the corresponding functionalized 1,2-DHQs conveniently
Gut region influences the diversity and interactions of bacterial communities in pikas (Ochotona curzoniae and Ochotona daurica)
No full textThe mammalian microbial communities in the gastrointestinal tract (GIT) play important roles in host nutrition and health. However, we still lack an understanding of how these communities are organized across GIT in natural environments. Here, using 16S rRNA gene sequencing, we analyzed the bacterial community diversity, network interactions and ecosystem stability across five gut regions (mouth, stomach, small intestine, cecum and colon) emanating from two common pika species in China, including Plateau pikas (Ochotona curzoniae) inhabiting high-altitude regions, as well as Daurian pikas (O. daurica) occupying low-altitude areas. The relative abundances of dominant Bacteroidetes and Firmicutes exhibited an increasing trend from mouth to colon. Cecum and colon harbored higher bacterial diversity compared with other anatomical regions. Gut region significantly influenced the structure of bacterial communities in the GIT. Network analysis indicated that topological features showed marked variations among gut regions. Interestingly, the ecosystem stability of bacterial communities increased gradually from mouth to colon. Our results suggest that gut region influences the diversity, structure and network interactions of bacterial communities in pikas. For hindgut-fermenting herbivorous mammals, relatively higher bacterial diversity and ecosystem stability in the cecum may provide a favorable condition for the fermentation of indigestible plant polysaccharides
Effects of Cu2+ and humic acids on degradation and fate of TBBPA in pure culture of Pseudomonas sp strain CDT
No full textSoil contamination with tetrabromobisphenol A (TBBPA) has caused great concerns; however, the presence of heavy metals and soil organic matter on the biodegradation of TBBPA is still unclear. We isolated Pseudomonas sp. strain CDT, a TBBPA-degrading bacterium, from activated sludge and incubated it with C-14-labeled TBBPA for 87 days in the absence and presence of Cu2+ and humic acids (HA). TBBPA was degraded to organic-solvent extractable (59.4% +/- 2.2%) and non-extractable (25.1% +/- 1.3%) metabolites, mineralized to CO2 (4.8% +/- 0.8%), and assimilated into cells (10.6% +/- 0.9%) at the end of incubation. When Cu2+ was present, the transformation of extractable metabolites into non-extractable metabolites and mineralization were inhibited, possibly due to the toxicity of Cu2+ to cells. HA significantly inhibited both dissipation and mineralization of TBBPA and altered the fate of TBBPA in the culture by formation of HA-bound residues that amounted to 22.1% +/- 3.7% of the transformed TBBPA. The inhibition from HA was attributed to adsorption of TBBPA and formation of bound residues with HA via reaction of reactive metabolites with HA molecules, which decreased bioavailability of TBBPA and metabolites in the culture. When Cu2+ and HA were both present, Cu2+ significantly promoted the HA inhibition on TBBPA dissipation but not on metabolite degradation. The results provide insights into individual and interactive effects of Cu2+ and soil organic matter on the biotransformation of TBBPA and indicate that soil organic matter plays an essential role in determining the fate of organic pollutants in soil and mitigating heavy metal toxicity. (C) 2017 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V
Soil pH is a major driver of soil diazotrophic community assembly in Qinghai-Tibet alpine meadows
No full textThe biological nitrogen input is essential for nutrient enrichment in natural grassland ecosystems. This process is carried out by diazotrophic microbes. However, the patterns and assembly processes of diazotrophic communities in grassland soil are not fully understood, especially in alpine meadows of high-altitude Qinghai-Tibet Plateau (QTP). In this study, the diversity patterns and community assembly processes of soil diazotrophic communities were investigated in QTP alpine meadows. The results showed that different diazotrophic taxa responded differentially to the increase of soil pH, and alpha-diversity increased linearly with pH values. Diazotrophic community turnover was enhanced by the increased variation in soil pH, moreover, it also showed strong response to mean annual temperature. Null model analysis showed that deterministic processes were most important in shaping the phylogenetic community structure and assembly of diazotrophs. Diazotrophic communities of each sampling site tended to be phylogenetically clustered, while communities at high pH soils (pH 7.00 to 8.00) showed more clustering than those of low pH (pH 5.02 to 7.00). The soil pH is a main driver in structuring soil diazotrophic community assembly by regulating the relative importance of deterministic and stochastic processes in QTP alpine meadows. (C) 2017 Elsevier Ltd. All rights reserved
New microbial resource: microbial diversity, function and dynamics in Chinese liquor starter
No full textTraditional Chinese liquor (Baijiu) solid state fermentation technology has lasted for several thousand years. The microbial communities that enrich in liquor starter are important for fermentation. However, the microbial communities are still under-characterized. In this study, 454 pyrosequencing technology was applied to comprehensively analyze the microbial diversity, function and dynamics of two most-consumed liquor starters (Jiang-and Nong-flavor) during production. In total, 315 and 83 bacterial genera and 72 and 47 fungal genera were identified in Jiang-and Nong-flavor liquor starter, respectively. The relatively high diversity was observed when the temperature increased to 70 and 62 degrees C for Jiang-and Nong-flavor liquor starter, respectively. Some thermophilic fungi have already been isolated. Microbial communities that might contribute to ethanol fermentation, saccharification and flavor development were identified and shown to be core communities in correlation-based network analysis. The predictively functional profile of bacterial communities showed significant difference in energy, carbohydrate and amino acid metabolism and the degradation of aromatic compounds between the two kinds of liquor starters. Here we report these liquor starters as a new functionally microbial resource, which can be used for discovering thermophilic and aerobic enzymes and for food and feed preservation
Metatranscriptomics Reveals the Functions and Enzyme Profiles of the Microbial Community in Chinese Nong-Flavor Liquor Starter
No full textChinese liquor is one of the world's best-known distilled spirits and is the largest spirit category by sales. The unique and traditional solid-state fermentation technology used to produce Chinese liquor has been in continuous use for several thousand years. The diverse and dynamic microbial community in a liquor starter is the main contributor to liquor brewing. However, little is known about the ecological distribution and functional importance of these community members. In this study, metatranscriptomics was used to comprehensively explore the active microbial community members and key transcripts with significant functions in the liquor starter production process. Fungi were found to be the most abundant and active community members. A total of 932 carbohydrate-active enzymes, including highly expressed auxiliary activity family 9 and 10 proteins, were identified at 62 degrees C under aerobic conditions. Some potential thermostable enzymes were identified at 50, 62, and 25 degrees C (mature stage). Increased content and overexpressed key enzymes involved in glycolysis and starch, pyruvate and ethanol metabolism were detected at 50 and 62 degrees C. The key enzymes of the citrate cycle were up-regulated at 62 degrees C, and their abundant derivatives are crucial for flavor generation. Here, the metabolism and functional enzymes of the active microbial communities in NF liquor starter were studied, which could pave the way to initiate improvements in liquor quality and to discover microbes that produce novel enzymes or high-value added products
Assessment and potential sources of metals in the surface sediments of the Yellow River Delta, Eastern China
No full textThe Yellow River Delta is the most intact estuary wetland in China and suffers from great pressure of metals. Seventy-seven surface sediment samples were collected in the delta, and contents of Cu, Pb, Cd, Cr, Zn, Ni, and Mn were analyzed by inductively coupled plasma spectrometry and those of Hg and As by atomic fluorescence spectrometry. The results showed that means of metal contents (ppm, dry weight) were as follows: Hg, 0.04; Cr, 61.72; Cu, 20.97; Zn, 60.73; As, 9.47; Pb, 21.91; Cd, 0.12; Ni, 27.24; and Mn, 540.48. 43.8% of Hg and 14.3% of Cd were from the allogenic source while others from the authigenic source. The results of the geoaccumulation indexes appeared that 6.5% of sites from the estuarine and the Gudao areas were moderately polluted by Hg. All ecological risk index values of Hg and 37.7% of Cd were more than 40, which were the main factors of strongly and moderately potential ecological risks of 37.7% of sites in the delta. High Cd contents may be due to the alkaline conditions of the delta and the unreasonable management of the farmland, while the abnormal distribution of Hg to the wet or dry deposition and the erosion of the seawater. It was suggested to monitor Hg content in the atmosphere of the Yellow River Delta. The results were expected to update the pollution status of metals in the delta and created awareness of preserving the sound condition of the Yellow River Delta
The differentiation of soil bacterial communities along a precipitation and temperature gradient in the eastern Inner Mongolia steppe
No full textUnderstanding the differentiation of soil bacterial communities under precipitation and temperature gradients is crucial for assessing the impacts of environmental filters on ecosystem structure and function. Here we investigated spatial variations of bacterial communities along a precipitation and temperature transect in the eastern Inner Mongolia steppe, China. The aims are to understand the biogeographic pattern and key drivers shaping soil bacterial communities along the transect. Our results shoved that the soil bacterial community along the 451-km transect exhibited the distance-decay relationship, decreasing in community similarity with geographic distance. Obvious changes in the bacterial community structure occurred at an annual precipitation from 215 to 261 mm, which was close to the boundary between arid and semi-arid systems. The relative abundances of Proteobacteria, Bacteroidetes, and Acidobacteria increased with precipitation, while those of Actinobacteria, Chloroflexi, and Gemmatimonadetes decreased. Environmental filtering was observed to be the key in shaping bacterial biogeographic patterns, and climate conditions exert indirect effects on soil bacterial communities mainly through direct effects on soil properties. Soil pH and plant coverage were important to soil bacterial communities in both arid and semi-arid steppes. Our findings provided insights for understanding the linkages among geographic distance, environmental filters, and soil bacterial communities in Eurasian steppe ecosystems. (C) 2017 Elsevier B.V. All rights reserved
Microbial diversity in Chinese temperate steppe: unveiling the most influential environmental drivers
No full textTemperate steppe is extremely sensitive to the current global changes. However, what are the main environmental variables driving microbial diversity in temperate steppe are still unclear, something that impairs doing predictions about the expected effects of global changes on microbe-mediated ecological functions. This is why, in this study, the relationship between soil microbial diversity and environmental variables in Chinese temperate steppe is investigated. In this study, significant correlations between soil bacterial alpha-diversity and mean annual precipitation and the aridity index were observed at the whole region scale. No clear correlations between microbial alpha-diversities and other measured environmental variables were found at the whole temperate steppe region and sub-regions. On the other hand, beta-diversity was strongly related to spatial variables and climate variables for bacteria, while spatial variables and soil organic matters were more related with fungal beta-diversity. In addition, the mean annual temperature was highly correlated with microbial beta-diversity at different spatial scales, suggesting that it could be a good single predictor of soil microbial assemblage in temperate steppe. beta-Diversities are more explained by combined effect of local environmental variables based on variation partitioning analysis, reflecting the community assemblage is more likely driven by species sorting through environmental filtering
甘薯淀粉加工废渣生产蛋白饲料的工艺
No full text以甘薯淀粉加工废渣为原料,研究了以酿酒酵母、产朊假丝酵母以及双菌混合培养生产菌体蛋白的工艺。结果表明:以酿酒酵母为菌种,其最佳培养条件为自然pH值、薯渣含水率75%、培养温度32℃、接种量10%、尿素1.5%、纤维素酶0.5%、异淀粉酶0.5%,薯渣中真蛋白质量分数达12.01%;以产朊假丝酵母为菌种,除尿素添加量为1%外,其利用甘薯渣生产菌体蛋白的最适培养条件与酿酒酵母一致,薯渣中真蛋白质量分数达16.36%;以酿酒酵母和产朊假丝酵母进行混合接种培养时,其最佳接种配比为1∶1,此时薯渣中真蛋白质量分数达18.08%