清香型小曲白酒中微生物组成及功能微生物的分析

将PCR-DGGE技术和传统微生物培养方法相结合,分析清香型小曲白酒的微生物群落结构及功能微生物。小曲和酒醅中优势微生物种属基本一致。不同季节酒醅中微生物组成无明显变化,但微生物生长和消亡规律存在差异。小曲酒中细菌的种类较多,主要以乳酸菌和芽孢杆菌属为主,但对小曲白酒风味特征影响很小。酵母类主要包括Saccharomycopsis fibuligera、Pichia anomala、Issatchenkia orientalis和Saccharomyces cerevisiae。S.cerevisiae的作用是酒精发酵产生乙醇,Sp.fibuligera、P.anomala和I.orientalis是产酯酵母,增加酒体酯香味。霉菌种类相对较少,Rhizopus oryzae是主要糖化菌。     

生香酵母对特香型白酒风味风格的影响研究

生香酵母具有较强的氧化特性和产酯能力,特香型白酒生产中,在入池发酵的酒醅中添加生香酵母,考察其对发酵所产基酒中醇、醛、酸、酯等风味成分及其风格的影响。结果表明,总酯、四大乙酯和丙酸乙酯均有较大的增幅,各主要酯比例变化不大;总酸最大提高12．20％,乙酸、丙酸和丁酸均有较大提高;能适当增加醇类的含量;醛类变化规律不明显。经品评,添加生香酵母可使酒体醇厚、诸香协调,不会改变特香型白酒的风味风格。     

清香型大曲淀粉水解酶系解析

对清香型大曲中可能存在的淀粉代谢相关酶类及各自催化作用进行全面分析,并从Brenda数据库中搜索酿酒相关的淀粉水解酶,了解不同来源淀粉水解酶类的酶学特征,并从基因组角度分析酿酒微生物合成的淀粉代谢酶类,对酿酒微生物有更深入的认识,为选育理想的酿酒微生物提供理论依据。     

厌氧发酵制氢研究进展

厌氧发酵制氢有很多的优越性,发展潜力大。引用了大量文献资料,全面介绍了目前国内外关于厌氧发酵制氢的研究情况,包括厌氧发酵制氢的发展动态及影响因素,最后提出了未来厌氧发酵制氢的发展趋势。     

棉秆稀酸水解及微生物共发酵生产单细胞蛋白工艺优化研究

通过正交试验确定稀酸水解棉秆的最优工艺,以纤维素含量最高,木质素含量最少为优选标准,得到优化工艺条件为:硫酸体积分数1.0%、固液比1:15,于100℃条件下水解2.0h,以此发酵工艺获得稀酸水解棉杆用于后续发酵工艺研究中。采用Plackett-Burman设计法,从酵母菌接种量、酵母菌接种时间、青霉接种量、共发酵时间、起始pH值、含水量、温度、麸皮含量和装料量9个因素中筛选出装料量、麸皮含量、共发酵时间、青霉接种量4个主要影响因素,并通过响应面分析法对工艺条件进行优化,获得的最优工艺条件为:青霉接种量10%、麸皮含量4%、装料量为发酵罐头瓶体积(250mL)的1/3、共发酵时间53h,在此基础上进行验证实验,得到单细胞蛋白含量的平均值为25.38%,与模型的理论预测值(22.79%)仅相差2.59%,说明建立的模型是切实可行的。     

浓香型白酒人工窖泥培养过程中微生物变化研究

对浓香型酒人工窖泥培养过程中微生物变化趋势进行了研究,结果表明：①四个处理的好氧细菌、嫌气厌氧细菌以及处理1的好氧芽孢细菌和嫌气厌氧芽孢细菌数量在培养一个月内呈先降后升的趋势,培养30～45d达到最大值,以后又呈逐渐降低趋势,而处理2、处理3和处理4的好氧芽孢细菌和嫌气厌氧芽孢细菌数量在培养第一个月呈先降后升的趋势,第二个月呈逐渐下降趋势,第三个月又呈逐渐增加趋势。②培养90d时,处理3和处理4的好氧细菌数量、好氧芽孢细菌、嫌气厌氧细菌以及嫌气厌气芽孢细菌数量明显高于处理1和处理2。③四个处理的霉菌和酵母菌数量均是随着培养时间的延长逐渐降低。     

Microorganisms and Cellulose Digestion in the Gut of the Woodlouse Porcellio scaber

In the common woodlouse Porcellio scaber different parts of the gut were observed with respect to microbial counts, cellulose activity, and degradation of cellulose. Cellulose is mainly digested in the anterior part of the hindgut, as was indicated by the distribution of cellulolytic activity and the decrease of cellulose content inside the gut. The cellulases woodlice utilize for the degradation of litter are mainly produced by endosymbiotic bacteria in the hepatopancreas rather than by microorganisms ingested with the food. Microorganisms ingested with the litter are digested in the anterior part of the hindgut and may provide an important food source. In the posterior hindgut, bacterial proliferation ensures microbial colonization of feces.     

新疆吐鲁番坎儿井饮用水中微生物多样性分析

目的：了解新疆坎儿井微生物菌群特征。方法：采集新疆吐鲁番4种不同坎儿井饮用水，利用Illlumina-Hiseq高通量测序技术对其进行测序，Majiorbio生信云平台进行微生物群落结构多样性分析。结果：质控后细菌有效序列为446 700条、真菌有效序列为407 376条，基于97%一致性共得到2 586个OTUs。门水平上，变形菌门（Proteobacteria）为4个样品共同优势的细菌门；在属水平上，阿木尔坎儿井（样品A）、奥吾提坎儿井（样品T）共同优势菌属为嗜氢菌属（Hydrogenophaga），占比分别为34.31%，57.66%；沙依坎儿井（样品S）优势菌属为曲杆菌属（Curvibacter），占比36.33%；米依木阿吉坎儿井（样品M）优势菌属为不可鉴定的丝毛单胞菌属（unclassified_f_Comamonadaceae），占比34.84%。真菌的子囊菌门（Ascomycota）为4个样品中共同优势菌门；样品S、M、T优势菌属为油壶菌属（Olpidium），分别占比15.77%，31.84%，16.38%。样品A优势菌属为不可鉴定的真菌属（Unclassified_k_fungi），占比27.68%。结论：4种样品在细菌和真菌门、属、种水平上有共同点的同时也有差异；虽然真菌多样性比细菌高，但物种所占丰富度较小。     

The diversity of microbial communities in Chinese milk fan and their effects on volatile organic compound profiles

Milk fan is a cheese-like fermented milk product produced in Yunnan Province, China. In this study, we characterized the microbial communities of milk fan from 6 distinct geographical origins and investigated their generation of volatile organic compounds (VOC). The microbial communities found in all milk fan samples were dominated by Lactococcus, Lactobacillus, and Raoultella bacteria and Rhodotorula, Torulaspora, and Candida fungi. Samples from the Kunming and Weishan regions had greater bacterial richness, and samples from Xizhou had greater fungal community richness. Sixty prominent VOC (i.e., those having odor activity values ≥1), including esters, acids, alcohols, aldehydes, ketones, and aromatic compounds, were identified by gas chromatography-mass spectrometry analysis of milk fan samples. Pearson correlation analysis revealed that Lactobacillus, Rhodotorula, Lodderomyces, and Debaryomyces had significant correlations with various VOC, revealing a total of 13 compounds that are characteristic of the odor of milk fan. These bacteria and fungi are therefore identified as functional microorganisms that collectively create the complex VOC profile of milk fan. This study provides a comprehensive overview of the microbial community of milk fan and demonstrates its contribution to the unique aroma profile of this fermented milk product     

Improving methane production from wheat straw by digestate liquor recirculation in continuous stirred tank processes

Wheat straw is an abundant, cheap substrate that can be used for methane production. However, the nutrient content in straw is inadequate for methane fermentation. In this study, recycling digestate liquor was implemented in single-stage continuous stirred tank processes for enrichment of the nutrient content of straw with the aim of improving the methane production. The VS-based organic loading rate was set at 2 g/(L d) and the solid retention time at 40 days. When wheat straw alone was used as the substrate, the methane yields achieved with digestate liquor recycling was on average 240 ml CH₄/g VS giving a 21% improvement over the processes without recycling. However, over time, the processes suffered from declining methane yields and poor stability evidenced by low pH. To maintain process stability, wheat straw was co-digested with sewage sludge or supplemented with macronutrients (nitrogen and phosphorous). As a result, the processes with digestate liquor recycling could be operated stably, achieving methane yields ranging from 288 to 296 ml CH₄/g VS. Besides, the processes could not be operated sturdily with supplementation of macronutrients without digestate liquor recycling. The highest methane yield (296 ± 16 ml CH₄/g VS) was achieved by co-digestion with sewage sludge plus recycling of digestate liquor after filtration (retention of nutrients and microorganisms). This was comparable to the maximum expected methane yield of 293 ± 13 ml CH₄/g VS achieved in batch test. The present study therefore demonstrated that digestate liquor recycling could lead to a decreased dilution of vital nutrients from the reactors thereby rendering high process performance and stability.