黑曲霉固态发酵豆粕的工艺条件研究

[目的]优化黑曲霉（Aspergillus oryzae）固态发酵豆粕的培养条件。[方法]采用单因素试验考察黑曲霉固态发酵豆粕的影响因素,建立优化的发酵工艺。[结果]确定的黑曲霉固态发酵豆粕的培养条件为：当固态物料中含有10%麸皮,9%玉米粉,1%葡萄糖及0.15%K2HPO4和0.01%MgSO4时,在28℃恒温条件下培养48~72 h,每隔6 h翻料1次,大豆肽含量最高可达6.159 mg/g。[结论]该研究可以为大豆肽的发酵法生产提供参考。     

生防放线菌SC1 1菌剂的研制

以放线菌SC1-1为研究对象,优化该菌株的发酵条件和生产工艺,测定其对茄子黄萎病的温室防治效果。结果表明,该菌株最佳固态发酵工艺为基质(大米粉)中加入玉米秸秆60 mg/g和小米粉30 mg/g,发酵条件为接种量0.4 mL/g、初始含水量400 mg/g、培养时间192 h、初始pH7.6。对茄子黄萎病的防效达到64%,高于对照多菌灵处理。     

Modeling the effects of solid state fermentation operating conditions on endoglucanase production using an instrumented bioreactor

Cellulase production is one of the most critical steps in the economics of second generation ethanol. Although solid-state fermentation (SSF) is an attractive process for the production of enzymes, SSF is highly limited by the difficulty in controlling the operating variables which affect microbial growth and metabolites production. In this context, this work evaluates the effects of operational conditions on endoglucanase production by a selected strain of Aspergillus niger cultivated under SSF using an instrumented lab-scale bioreactor equipped with an on-line automated monitoring and control system. The effects of air flow rate, inlet air relative humidity and substrate initial moisture on endoglucanase production were evaluated using a statistical design methodology. A correlation coefficient of 0.9106 and a calculated value of F, 5.46 folds higher than the listed value (P-value < 0.05) allowed the modeling of endoglucanase production under different process conditions. Higher endoglucanase production (56.1 U/g) was achieved for a selected condition of substrate initial moisture of 72%, air inlet humidity of 70%, and flow rate of 20 mL/min. A significant increase in endoglucanase production was also found to be achieved under forced aeration conditions (50.2 IU/g) compared to static conditions (29.8 IU/g) after 72 h of cultivation. Besides, respirometric analysis revealed that the total amount of CO₂ produced was linearly correlated with enzyme production (R² of 0.988). The bioreactor system used, as well as the methodology employed herein, was very effective in evaluating the influence of operational variables on enzymes production under SSF.     

苹果渣固态发酵产复合酶培养基优化的研究

以黑曲霉C-2为菌种,对苹果渣进行固态发酵,以纤维素酶、木聚糖酶、果胶酶的活性为测定指标,单因素试验确定水平,采用L9（3^4）正交试验对产复合酶体系的固态培养基质进行优化,同时运用极差分析、方差分析以及不同因素水平间差异显著性检验对结果进行分析,以得到较合理的培养基。优化后培养基组成为果渣：麸皮：4：1,2．0％硫酸铵,0．1％磷酸氢二钾,2．5％尿素。优化后三种酶活力比基础培养基分别提高了64．19％、17．26％、20．89％。     

Advances in research on solid-state fermented feed and its utilization: The pioneer of private customization for intestinal microorganisms

With sustainable development of biotechnology, increasing attention has been placed on utilization of solid-state fermented feed (SFF). Solid-state fermented feed has been a candidate strategy to alleviate the contradiction between supply and demand of feed resources, ensure food hygiene safety, promoting energy conservation, and emission reduction. In production of SFF, a variety of organic acids, enzymes, vitamins, peptides, and other unknown growth factors are produced, which could affect performance of animals. Solid-state fermented feed produced by different fermentation techniques has great instability on different physiological stages of different animals, which hinders the application and standardized production of SFF. Herein, we summarize the current advances in the role of the characteristics of SFF prepared by different manufacturing technique and its research progress in animal experiments on growth performance, gastrointestinal ecology, and immune system, so as to provide references for further acquiring a relatively perfect set of SFF production and evaluation systems.     

Enhancing three phenolic fractions of oats (Avena sativa L.) and their antioxidant activities by solid-state fermentation with Monascus anka and Bacillus subtilis

This work aims to improve phenolic fractions of oats and their antioxidant activities by solid-state fermentation (SSF) combining Monascus anka with Bacillus subtilis. Results revealed that the fermentation system significantly (p < 0.05) increased the total phenolic content (TPC), which was 23-fold over that in unfermented oats. The hydrolytic enzyme activities of α-amylase, β-glucosidase, and cellulase were significantly (r > 0.75, p < 0.05) correlated to the TPC, indicated an important role in the release of phenolic in oats. The proportion of free phenolic fraction in oats was increased from 39.76% to 61.62%, while that of bound phenolic fraction decreased from 42.17% to 22.78%. Moreover, the phenolic compositions of free, conjugated and bound phenolic fractions varied with fermentation. It implied that the phenolic compounds in different forms could be converted and transformed in the SSF system. Meanwhile, the DPPH· and ABTS^·+ scavenging activities of the free and conjugated phenolic fractions in oats became stronger after fermentation. It indicated that the changes of antioxidant activities of phenolic fractions might be closely related to the structural modification by microbial enzymes in the SSF system. Consequently, this study provides a prospect fermentation process for improving the phenolic release and antioxidant activities in oats.     

非酿酒酵母在葡萄酒酿造中的应用

非酿酒酵母是葡萄酒微生物领域近些年的研究热点。过去人们对非酿酒酵母认识较少,曾将其看作是葡萄酒发酵的有害微生物。随着研究者们对酿酒微生物的深入研究发现,在酿酒过程中可以利用非酿酒酵母来改善葡萄酒的品质。合理利用非酿酒酵母可以酿造出色泽更加稳定、香气较丰富独特、口感更为复杂的葡萄酒。本文综述了近些年非酿酒酵母在葡萄酒酿造中的应用研究,包括生产中常见的非酿酒酵母种属的酿造特性、非酿酒酵母影响葡萄酒风味的机制、酵母之间的相互作用等3个方面。葡萄酒生产中常见的不同属（种）非酿酒酵母的酿造特性不同,其与酿酒酵母混合发酵对葡萄酒风味的改善效果也有较大差别。了解各个属（种）的发酵特性,根据发酵目的选择合适的接种菌株极为重要;非酿酒酵母可以通过不同的代谢通路改变葡萄酒中酒精、甘油、挥发性香气物质、甘露糖蛋白/多糖、花色苷等物质的含量,从而影响葡萄酒的颜色、香气和口感。非酿酒酵母代谢通路的特异性是其影响葡萄酒风味的根本原因。除了应用非酿酒酵母来改善葡萄酒的风味外,粟酒裂殖酵母降解苹果酸和耐热克鲁维酵母高产乳酸的特性也值得生产者关注。本文通过总结非酿酒酵母在葡萄酒酿造中应用的研究进展,以科学评价非酿酒酵母在葡萄酒酿造中的作用,并为建立新的具有科学性的混合发酵策略提供参考。     

复合微生态酶制剂发酵玉米秸秆的研究

反刍动物饲用复合微生态酶制剂发酵玉米秸秆,当5种酵母菌JM-BC、JM-29、JM-34、JM-66、JM-75分别扩培后,按照1:1:1:1:1比例共5%的接种量混菌发酵36h后添加5%接种量的乳酸菌R4,复合发酵3d后,产物蛋白含量提高11.5%,ADF含量降低10.0%。发酵产物黄色,有光泽,无霉臭味,质地柔软,湿润蓬松并具有复合的酒香味和酸香味。     

高效丢糟纤维素分解复合菌系的构建与效果研究

[目的]筛选构建出对白酒丢糟分解能力强的复合菌系。[方法]从白酒丢糟堆腐物中分离筛选出产纤维素酶活性高的5株菌,混合后,在以丢糟为主要基质的培养基上固态发酵并多次传代培养,得到较稳定的纤维素分解复合菌系,测定其对丢糟的实际降解效果和产酶能力。[结果]该高效分解丢糟的复合菌系中包含4种菌株,稳定性较好。[结论]与单菌株相比,从白酒丢糟筛选并重新构建的复合菌系可大幅提高丢糟的分解能力及羧甲基纤维素酶酶活,并能在7 d内保持较好的稳定性。     

Evaluation of Fusarium oxysporum as an enzyme factory for the hydrolysis of brewer's spent grain with improved biodegradability for ethanol production

Brewer's spent grain (BG), the most abundant brewing by-product, is used in the present study as a low-cost feedstock for the production of ethanol by the mesophilic fungus Fusarium oxysporum using a consolidated bioconversion process. The production of required cellulolytic and hemicellulolytic enzymes was optimized under solid-state cultivation (SSC) concerning carbon source and initial moisture. The optimal medium contains BG and corn cobs (CC) in a ratio 7:3 while the optimal initial moisture is 66% (w/w). SSC in a laboratory horizontal bioreactor using the optimized medium allowed the large-scale production of a multienzymic system including endoglucanase, cellobiohydrolase, β-d-glucosidase, xylanase, feruloyl esterase, acetyl esterase, β-d-xylosidase and α-l-arabinofuranosidase. Chromogenic (fluorogenic) 4-methylumbelliferyl substrates were used to partially characterize the extracellular proteome of the microbe after the separation by isolectric focusing (IEF) electrophoresis. Alkali pretreatment of brewer's spent grain and different aeration levels were studied for the optimization of the ethanol production by F. oxysporum in a consecutive submerged fermentation. A yield about 65 g ethanol kg⁻¹ of dry BG was obtained with alkali pretreated BG under microaerobic conditions (0.01 vvm) corresponding to 30% of the theoretical yield based on total glucose and xylose composition of BG.