水杨酸铬(Ⅲ)配合物对肥胖小鼠肠道菌群的影响

目的探讨水杨酸铬(Ⅲ)配合物{[Cr(Ⅲ)(5-Cl-SA)(en)2]Cl·2H2O·2CH3OH}对肥胖小鼠的减肥效果和对小鼠肠道菌群结构的影响。方法昆明种小鼠随机分为正常组、模型组和药物组,定期称重并收集其粪便;给药9周后,解剖小鼠并测定多项生理生化指标;提取粪便微生物总DNA,PCR扩增16S rDNA V3可变区,并行变性梯度凝胶电泳(DGGE),分析肠道微生物多样性,利用主成分分析(PCA)研究肠道微生物群落组成的变化。结果水杨酸铬(Ⅲ)配合物可显著控制小鼠体重增长,且有减肥功效;给药9周后,小鼠各项生理指标均趋于正常。PCR-DGGE指纹图谱分析结果显示,高脂饲料和受试药物对肠道微生物的多样性影响不大,但对菌群结构影响显著。结论本研究为开发新型减肥药物提供了依据。     

Yeast involved in fermentation of Coffea arabica in East Africa determined by genotyping and by direct denaturating gradient gel electrophoresis

Samples of Coffea arabica were collected during the different stages of the fermentation from two production sites in Tanzania. The yeasts community was identified by genotyping using ITS-PCR and sequence analysis of the D1/D2 domain of the 26S rRNA gene. For confirmation, denaturating gradient gel electrophoresis (DGGE) of PCR-amplified 26S rRNA gene was performed to detect yeast directly from coffee samples without cultivation. Yeast counts were in the range 4.0 x 10(4) - 5.0 x 10(7) CFU/g with an increase during fermentation. Three yeasts species were dominant. The predominant yeast found during fermentation and drying was Pichia kluyveri. Pichia anomala was found in high numbers during drying of coffee beans. Hanseniaspora uvarum was the predominant yeast during fermentation but decreased during drying. Kluyveromyces marxianus, Candida pseudointermedia, Issatchenkia orientalis, Pichia ohmeri and Torulaspora delbrueckii occurred in concentrations of 10(3) CFU/g or below in coffee samples. Saccharomyces cerevisiae and Candida xestobii were not isolated by cultivation, but by the DGGE technique. A good agreement was found between the sequence analysis of the D1/D2 domain of the 26S rRNA gene and sequencing of the DGGE bands.     

不同屠宰工艺(剥皮和烫毛)对猪胴体表面微生物的多样性影响及关键点的控制研究

应用变性梯度凝胶电泳(Denaturinggradientgelelectrophoresis(DGGE))和经典微生物培养相结合的方法研究了剥皮和烫毛工艺中猪胴体表面污染的微生物数量和细菌多样性的变化以及3.5%乳酸处理后细菌总数和大肠菌群的变化。结果显示:不同猪胴体屠宰工艺中的微生物种类并不完全一致,微生物的污染多是由于前期的屠宰工艺引入;与剥皮工艺相比,烫毛后污染的微生物种类多,初始污染程度也较为严重;乳酸处理显著降低了剥皮工艺中的细菌总数,使出库猪胴体表面细菌总数降低到2.95logCFU/cm2,完全达到HACCP微生物的控制要求,但是没有降低烫毛工艺出库时的细菌总数,因此对不同的屠宰工艺应采取不同的关键点控制措施。     

应用DGGE技术研究玉米储藏过程中的霉菌群落时空分布特征

研究储粮过程中霉菌污染的发生规律,旨在减少霉菌及真菌毒素的污染,提高我国粮食安全。利用变性梯度凝胶电泳研究粮库中不同储藏时间和空间的玉米样品中霉菌群落的特点。结果表明,本研究中储藏玉米的霉菌污染以青霉、曲霉和毛霉为主,其霉菌群落的变化与储藏时间具有较强的相关性,而与其在粮库中的空间位置相关性较小。在储藏时间方面,储藏1a和3a的样品中霉菌群落具有较大的差异,而储藏2a样品的霉菌群落处于过渡期状态。本实验探究储藏玉米中霉菌群落的时空分布特征,可以为建立准确可靠的霉菌群落模型提供理论支持和数据支持。     

Effect of mobilizing agents on mycoremediation and impact on the indigenous microbiota

BACKGROUND: Mobilizing agents (MAs) have been suggested to improve the fungal degradation of polycyclic aromatic hydrocarbons (PAHs) in soil. Three different MAs (Tween 20, Tween 80 and soybean oil) were investigated for their ability to stimulate contaminant degradation by either Phlebia sp. DABAC 9 or Allescheriella sp. DABAC1 in a soil spiked with a mixture of PAHs. RESULTS: Phlebia sp. and Allescheriella sp. markedly differed in their growth capabilities under non‐sterile conditions and without MAs (3.0 versus 0.1 µg ergosterol g^?1 soil, respectively). However, soybean oil led to a 35‐fold increase of Allescheriella sp. growth. Contaminant degradations by Phlebia sp. DABAC 9 and Allescheriella sp. DABAC 1 were best supported by soybean oil and Tween 20, respectively. Enumeration of cultivable bacteria and denaturing gradient gel electrophoresis (DGGE) analysis of PCR‐amplified 16S rRNA showed that microbial density and biodiversity were positively affected by the mycoremediation especially with Allescheriella sp., the use of which led to an evident detoxification. CONCLUSIONS: Allescheriella sp. DABAC 1 appears to be a promising strain in the remediation of PAH‐contaminated soils. The different response of the two fungi to MAs addition confirms the stringent need for a preliminary lab‐scale assessment of fungus/MA combinations prior to application. Copyright © 2009 Society of Chemical Industry     

Effect of grazing intensities on the activity and community structure of methane-oxidizing bacteria of grassland soil in Inner Mongolia

The effects of different grazing intensities on in situ methane flux and the structure and diversity of the methanotrophic community are measured in the typical grassland of Inner Mongolia. Four grazing intensity sites founded in 1989, control (CK), low-intensity grazing (LG), middle-intensity grazing (MG) and heavy-intensity grazing (HG), were selected. Group-specific PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) of 16S rRNA genes for the type I and type II methanotrophs was used to characterize the composition of the methanotrophic community. DGGE patterns were further analyzed using the method of the Shannon-wiener index H and non-metric multi-dimensional scaling (MDS). The results showed that there were no significant differences in methane flux among different sites, yet methanotrophic communities showed significant differences. MDS analysis showed that type I methanotroph community composition at the CK site were significantly different from the three other sites. For type II methanotrophic community composition, it was similar between CK and HG site, and between LG and MG site, while that at the former two sites were significantly different from latter two ones. Additionally Shannon indices of type II methanotrophs were higher at the LG and MG sites than two other sites. Though grazing intensities had an impact on the structure of the methanotrophic community, management-induced changes in the structure of methanotrophic community did not reflect methane consumption capacity across sites. These results suggest that methane consumption is a complex process in soil, and we should be cautious when speculating on the change of methane consumption rates based on a change of methanotrophic community structure.     

Analysis of bacterial communities in pit mud from Zhijiang Baijiu distillery using denaturing gradient gel electrophoresis and high- throughput sequencing

Zhijiang Baijiu is a Chinese strong flavour liquor produced using a traditional Chinese solid state fermentation involving microorganisms in pit mud on cellar walls. In this study, pit mud samples were collected from three different cellars in a Zhijiang Baijiu distillery ranging in age from 10 to 20 and 30 years. The bacterial communities were analysed using denaturing gradient gel electrophoresis, high-throughput sequencing and quantitative real time PCR. These analyses showed that the diversity of the bacterial community in pit mud samples was relatively stable in cellars aged from 20 to 30 years old. High throughput sequencing also revealed that the relative abundance of seven core bacterial families and nearly half of the core bacterial genera were stable in 20 year-old cellars. In cellars of 10 to 30 years, the relative abundance in pit mud of Ruminococcaceae and Clostridium cluster IV increased, while that of Petrimonas and an unclassified Firmicutes decreased. Real time PCR showed that aged pit mud contained more bacteria and Clostridium kluyveri than young pit mud. It is concluded that the bacterial communities in aged pit mud are more suitable for producing high quality Baijiu. © 2019 The Institute of Brewing & Distilling     

Microbiological Analyses of Dry and Slurry Yeasts for Brewing

Classical microbiological methods in association with molecular methods (DNA amplification, Temperature Gradient Gel Electrophoresis (TGGE) and Denaturing Gradient Gel Electrophoresis (DGGE) were used. These methods, developed to rapidly analyze microbial communities on the basis of sequence‐specific separation of DNA amplicons, allowed the detection of DNA differences in the amplicons tested and the identification of the strains analyzed by the comparison of unknown sequences with sequences of known species. TGGE allowed the comparison of the different Saccharomyces cerevisiae strains used in brewing while DGGE allowed the identification of lactic acid bacteria (LAB) in beer. These methods are a reliable tool for fast comparison of strains of Saccharomyces cerevisiae collected from different craft breweries where they were used as starters to check the presence of possible yeast contaminants in the brewing process and for rapid LAB identification.     

Characterization of archaeal community in Luzhou‐flavour pit mud

The aim of this study was to investigate the archaeal community in different ages of pit mud by a combined fluorescence in situ hybridization (FISH) and polymerase chain reaction–denaturing gradient gel electrophoresis (PCR‐DGGE) method. Four probes were used to detect the major methanogenic archaea by FISH experiments, and the results showed that orders Methanosarcinales, Methanobacteriales, Methanomicrobiales and Methanococcales were detected in the various ages (50, 100 and 300 year) of pit mud, except for the 1 year‐old pit and the 100 year‐old sample, which exhibited the highest numbers of archaea. The amounts of the four methanogenic archaea significantly increased from the 50 to 100 year‐old pit mud and slightly decreased in the 300 year‐old pit mud. Results of PCR‐DGGE analysis suggest that all archaeal 16S rRNA gene sequences fall into the phylum Euryarchaeota, and Methanobacteriales and Methanomicrobiales dominated in low‐age (1 and 50 year) and old age (100 and 300 year) of pit mud, respectively. Analysis of the community diversity based on the DGGE profiles showed that the 100 and 300 year samples exhibited similar diversity indices compared with the 1 and 50 year samples. This is the first report about the archaeal community structure in different ages of pit mud determined by both FISH and PCR‐DGGE analysis. Copyright © 2015 The Institute of Brewing & Distilling