Solid state fermentation of rapeseed cake with Aspergillus niger for degrading glucosinolates and upgrading nutritional value

Background： Rapeseed cake is a good source of protein for animal feed but its utilization is limited due to the presence of anti-nutritional substances, such as glucosinolates （GIs）, phytic acid, tannins etc. In the present study, a solid state fermentation （SSF） using Aspergillus niger was carried out with the purpose of degrading glucosinolates and improving the nutritional quality of rapeseed cake （RSC）. The effects of medium composition and incubation conditions on the GIs content in fermented rapeseed cake （FRSC） were investigated, and chemical composition and amino acid in vitro digestibility of RSC substrate fermented under optimal conditions were determined. Results： After 72 h of incubation at 34℃, a 76.89% decrease in GIs of RSC was obtained in solid medium containing 70% RSC, 30% wheat bran at optimal moisture content 60% （w/w）. Compared to unfermented RSC, trichloroacetic acid soluble protein （TCA-SP）, crude protein and ether extract contents of the FRSC were increased （P〈 0.05） 103.71, 23.02 and 23.54%, respectively. As expected, the contents of NDF and phytic acid declined （P〈 0.05） by 9.12 and 44.60%, respectively. Total amino acids （TAA） and essential amino acids （EAA） contents as well as AA in vitro digestibility of FRSC were improved significantly （P 〈 0.05）. Moreover, the enzyme activity of endoglucanase, xylanase, acid protease and phytase were increased （P 〈 0.05） during SSF. Conclusions： Our results indicate that the solid state fermentation offers an effective approach to improving the quality of proteins sources such as rapeseed cake.

Optimization of Fermentation Conditions for Xylanase Production by Aspergillus niger NS-1

In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.

Production of Amylase Enzyme through Solid State Fermentation by Aspergillus niger

Traditionally, coconut dregs will be used as animal feed after the extraction of coconut oil and coconut milk from the copra. This study was carried out to discover the commercial value of coconut dregs as a solid substrate in the production of amylase through solid state fermentation （SSF） since this agro-waste is fairly rich in nutrients, providing the necessary nutrients supplementation for better microbial activity to produce enzymes. In this study, amylase is to be produced from coconut dregs by Aspergillus niger through solid state fermentation （SSF）. Three parameters were covered, which are incubation time, initial moisture content of substrate and inoculum sizes. SSF was carried out by using incubator at 37 ~C to test for enzyme activity at these following parameters： incubation time： 24, 48, 72, 96 and 120 hours; substrate moisture content： 64, 66, 68, 70 and 72% （w/w）; inoculum sizes： 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 mL spore suspension （5.5 × 10^6 spores/mL）. Enzyme activities were measured through the estimation of liberated reducing sugars after the assay of amylase enzyme by using DNS （3, 5 dinitrosalicylic acid） method. Highest enzyme activities were obtained at these following parameters： incubation time： 72 hours （31.76 U/gds）; initial moisture content ofsubstrate： 66% （26.66 U / gds） and inoculum sizes： 2.0 mL （30.56 U/gds）.

Pectinase Production by Aspergillus Niger P-6021 on Citrus Changshan-huyou Peel in Slurry-state Fermentation

The peel of Citrus changshan-huyou, coupled with wheat bran, could be utilized by Aspergillus niger P-6021 in slurry-state fermentation to produce pectinase with suitable enzyme composition for application in apple juice processing. The production of pectinase is improved by additional nitrogen source substances and mineral supplements. The ratio of carbon source substances to nitrogen source substances in the medium also has significant effect on the pectinase production by A. niger P-6021 in slurry-state fermentation. In the optimized medium composition, the maximal enzyme activity could reach 42 U.L^- 1 （polymethylgalacturonase）, 6.7 U.L^- 1 （polymethygalacturatesterase）, and 4.3 U.L^-1 （polymethylgalacturonate lyase）, respectively, after 3 days at 180 r.min^- 1 and 30℃. The crude pectinase shows significant effect to improve the yield and clarification of apple juice. Keywords Aspergillus niger, slurry-state fermentation, pectinase, Citrus changshan-huyou, apple juice

Steady State and Dynamic of Gluconic Acid Production by Aspergillus Niger

Batch and continuous fermentation ofgluconic acid production has been studied. The kinetic parameters of the fermentation process were determined from the batch experimental data. The continuous fermentation was modeled to be carried out in a stirred tank reactor. The effect of hydraulic retention time on the steady state continuous fermentation process of glucose by Aspergillus niger to produce gluconic acid was investigated. The result showed that increasing the hydraulic retention time caused the cell amount and gluconic acid concentration at the outlet stream increased but the glucose concentration at the outlet stream decreased. The steady state simulation result was useful for fermenter size determination. Dynamic behaviour of gluconic acid production through fermentation by Aspergillus niger was also studied for a fermenter with 24 h hydraulic retention time. Applying step change of inlet substrate concentration resulted in first order response of cell, substrate and product concentration with all having positive gain. On the other hand, applying step change of inlet cell concentration has resulted in positive gain for cell and product concentration and negative gain for substrate concentration with first order response for all those three parameters.

Sweet Potato Starch as a Carbon Source for Growth and Glucoamylase Production from <i>Aspergillus niger</i>

A mesophilic strain of Aspergillus niger isolated from cassava effluent samples produced extracellular glucoamylase in submerged culture containing 2% (w/v) soluble or sweet potato starch. On soluble starch medium the maximum glucoamylase activity in the culture filtrate was 9.40 U/mg compared to 8.24 U/mg on sweet potato starch culture filtrate. The mycelial dry weight for both media was 494 and 418 mg respectively. The maximum glucoamylase activity was obtained at a growth temperature of 40&deg;C and pH 4.5. The implication is that the bioprocess of utilizing sweet potato starch in the culture is attractive due to its relatively cheaper availability in Nigeria, making it even more favorable when economics is considered.

Ethanol Tolerance in <i>Aspergillus niger</i>and <i>Escherichia coli</i>Phytase

Despite yeast having its own native phytase, the high levels of phytate found in DDGS, a byproduct of ethanol (ETOH) fermentation, suggest that its activity is diminished in the presence of ETOH. Ethanol, a product of grain fermentation, is known to inactivate several hydrolytic enzymes but its effect on phytases is relatively unknown. In this study, two phytases, Aspergillus niger (PhyA) and Escherichia coli (AppA2), were tested for ETOH tolerance. The E. coli phytase displayed greater ethanol tolerance over fungal phytase in the 5% to 10% range. However, ETOH inactivation was found to be reversible for both the enzymes. These differences in ETOH tolerance do suggest that there is a potential to achieve higher ETOH tolerance in phytases by 'structure-function' studies to lower phytic acid levels in DDGS and for other applications.

不同预处理甘蔗渣混菌固态发酵制备生物发酵饲料研究

本研究以不同预处理后甘蔗渣为固态发酵培养基基质,利用可分泌纤维素酶的丝状真菌及单细胞蛋白生产菌进行混菌固态发酵,探究不同预处理甘蔗渣对生物发酵饲料品质的影响。结果显示:不同预处理的甘蔗渣对制备的生物发酵饲料营养价值影响较大,以甘蔗渣、瞬时蒸汽爆破处理后甘蔗渣及连续蒸汽爆破处理后甘蔗渣为固态发酵培养基的基质,均不利于黑曲霉、马克思克鲁维酵母对非粮生物质原料中纤维素和半纤维素的利用,制备的生物发酵饲料,其微生物蛋白含量低,营养价值低。以瞬时蒸汽爆破处理后甘蔗渣与连续蒸汽爆破处理后蔗渣组合为固态发酵培养基的基质,制备的生物发酵饲料,微生物蛋白含量高,粗蛋白质含量达到22.07%,氨基酸含量达到16.06%,马克思克鲁维酵母含量增加至7.4×10~8CFU/g,其营养价值高。

延龄草总皂苷的黑曲霉发酵工艺及提取条件研究

该文对延龄草总皂苷的最佳提取方法进行筛选,并通过紫外分光光度法与高效液相色谱法对发酵前后药液进行对比分析,在单因素实验的基础上,采用Box-Behnken响应面实验研究了黑曲霉接种量、发酵时间和发酵温度对延龄草中总皂苷提取率的影响。结果表明:延龄草总皂苷最佳提取方法为75%乙醇回流法,其最佳发酵条件为黑曲霉接种量2.25%,发酵时间6d,发酵温度27℃,在此条件下总皂苷提取率为8.620%,与预测结果基本一致。

淡豆豉的多菌种协同发酵工艺优化

目的优化淡豆豉多菌种(环状芽孢杆菌、黑曲霉、少根根霉)协同发酵工艺,为淡豆豉发酵工艺改进和创新提供参考。方法以发酵时间、发酵温度、混合菌种比例、接种量为考察因素,以总黄酮、大豆苷元、黄豆黄素、染料木素的含量为考察指标,通过单因素考查对淡豆豉多菌种协同发酵工艺进行优化。结果淡豆豉多菌种协同发酵最佳工艺条件为:发酵温度30℃,发酵时间8 d,接种量5%,混合菌种接种比例为环状芽孢杆菌∶黑曲霉∶少根根霉=1∶2∶1。结论淡豆豉多菌种协同发酵工艺可避免杂菌干扰、利于工艺标准化,可为淡豆豉工艺改进和创新以及为中药多菌种协同发酵工艺研究提供参考。

一株产L-苹果酸黑曲霉菌株的诱变筛选及发酵培养基优化

为筛选一株产L-苹果酸能力强的黑曲霉菌株,通过紫外诱变与高浓度放线菌酮迭代诱变的方法,将野生型菌株诱变为一株产L-苹果酸能力强的黑曲霉菌株,并对其种子或发酵培养基成分进行优化。结果表明,诱变所得一株产L-苹果酸能力强的黑曲霉CGMCC NO.40550菌株,其摇瓶发酵时种子培养基最适葡萄糖浓度为60 g/L、最适氮源为(NH_4)_2SO_4 4.95 g/L,黑曲霉菌球形成最优转速220 r/min;发酵培养基最适葡萄糖和最适(NH_4)_2SO_4浓度分别为180 g/L和4.95 g/L,Cu SO_4·5H_2O为其生产苹果酸最佳微量元素,最适添加量为0.065 g/L。通过单因素实验的优化,优化后的培养基更有利于L-苹果酸的合成,发酵96 h时L-苹果酸产酸量达到18.15 g/L,显著提高了245%,L-苹果酸占总酸的百分比达到71.69%。本研究为L-苹果酸的工业化生产奠定基础。

微生物固态发酵对绿豆酚类物质含量及抗氧化活性的影响

目的为提高绿豆酚类物质的生物可及性与抗氧化活性,筛选适宜发酵菌种,得到最优发酵参数。方法采用植物乳杆菌(Lactobacillus acidophilus)、嗜酸乳杆菌(Lactobacillus plantarum)、酿酒酵母菌(Saccharomyces cerevisiae)、产朊假丝酵母(Candida utilis)、黑曲霉(Aspergillus niger)、米根霉(Rhizopus oryzae)对绿豆进行固态发酵,通过测定发酵后绿豆游离多酚含量及多酚提取液的1,1-二苯基-2-三硝基苯肼自由基(1,1-diphenyl-2-picrylhydrazyl radical,DPPH·)清除率,筛选出最优发酵菌种,并对该菌种发酵工艺进行优化,分析发酵对绿豆多酚、黄酮含量及抗氧化活性的影响。结果黑曲霉为最优发酵菌种,最优发酵条件为:发酵时间10 d、发酵温度26.5℃、接菌量8 mL/100 g;在此条件下绿豆游离酚、游离黄酮含量分别为17.56 mg/g、8.01 mg/g,均为未发酵绿豆的3~4倍;游离酚、结合酚提取液的DPPH·清除率分别为91.93%、18.96%,2,2’-联氮-双-3-乙基苯并噻唑啉-6-磺酸二铵盐阳离子自由基[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)ammonium salt cationic radical,ABTS+·]清除率分别为77.86%、16.47%,铁离子还原力分别为16.96 mmol/L、1.62 mmol/L。结论黑曲霉固态发酵可显著促进绿豆酚类物质的释放或合成(P<0.05),提高绿豆酚类物质的生物利用度与抗氧化能力,以期为绿豆营养价值的提升及功能性食品的开发提供理论依据和技术支持。

基于黑曲霉固态发酵的绿豆皮降解及理化特性提升机理

实验研究了黑曲霉固态发酵对绿豆皮特性的影响,并对降解机理进行探究,结果表明黑曲霉固态发酵能有效提升绿豆皮制粉特性和理化特性,所得绿豆皮粉体积平均径减小8.53倍,比表面积增大32.46倍。阳离子交换能力、胆酸钠吸附能力及葡萄糖吸附能力均有明显提升,依次提升1.11、1.18倍和1.17倍。黑曲霉对绿豆皮的降解,先降解木质素与半纤维素,再降解纤维素。主要通过破坏纤维素、半纤维素及木质素的化学键,降解长链结构为短链结构,破坏结晶区结构,降低相对结晶度,进而破坏绿豆皮结构,使其变得疏松多孔,让绿豆皮易被粉碎为粒径更小、比表面积更大的粉体,具有更好的物质交换效率,提升绿豆皮的理化特性。

一株新分离黑曲霉对糖蜜酵母废水的脱色研究

从受糖蜜酵母废水污染的土壤中分离出2株具有脱色活性的真菌菌株,通过菌株形态分析和基因型鉴定,确定其中具有相对较大脱色潜力的菌株为黑曲霉(Aspergillus niger),将其命名为TMZ1。以碳源、氮源、初始pH为关键因素,考察了TMZ1对实际生产过程产生的糖蜜酵母废水的脱色效果,并分析了脱色机理。实验结果表明,将TMZ1接种于由18%糖蜜酵母废水、3.0%蔗糖、0.2%NaNO_(3)、0.1%KH_(2)PO_(4)、0.05%MgSO_(4)·7H_(2)O等组成的培养基中,OD值为3,初始pH为5.5,于39℃培养4 d后,脱色率可达52.9%,COD去除率为80.1%,细胞干重高达14.100 g/L。凝胶过滤色谱法分析显示,在脱色过程中大分子量和小分子量组分均得到有效去除。该菌株的脱色机理由生物吸附和生物降解共同组成,且生物降解发挥主要作用。

藜麦麸皮膳食纤维发酵工艺优化及其理化性质与结构特征研究

为了提升藜麦麸皮的利用率,改善其功能特性,该研究以藜麦麸皮为原料,采用黑曲霉(Aspergillus niger)发酵改性藜麦麸皮膳食纤维。以可溶性膳食纤维(SDF)得率为响应值,通过单因素和响应面试验优化其发酵工艺条件,并对改性前后膳食纤维理化性质及结构特征进行分析。结果表明,最佳发酵工艺条件为料液比1∶20(g∶mL)、接种量10%、发酵时间96 h。在此优化条件下,可溶性膳食纤维得率达24.8%。与未改性的藜麦麸皮膳食纤维相比,改性后藜麦麸皮可溶性膳食纤维的持水力(WHC)、持油力(OHC)、吸水膨胀力(WSC)、阳离子交换能力(CEC)分别提高74.29%、47.35%、32.73%、115.8%。傅里叶变换红外光谱(FT-IR)分析结果表明,改性后可溶性膳食纤维中官能团数量增加,但未产生新的官能团。

鲜苹果渣发酵生产饲料蛋白研究

采用混合培养法研究接菌、加氮对未灭菌和灭菌鲜苹果渣发酵生产饲料蛋白的影响。结果表明,1接菌后鲜苹果渣的纯蛋白含量显著提高,其中未灭菌鲜苹果渣接入黑曲霉UA8发酵后,纯蛋白含量较未接菌的增加了137.8%。2加氮处理后鲜苹果渣纯蛋白含量高于不加氮处理,其中未灭菌鲜苹果渣接入黑曲霉UA8后加氮发酵产物纯蛋白含量较不加氮对照增加了35.2%。3未灭菌鲜苹果渣发酵后纯蛋白含量高于灭菌处理,其中单菌有氮发酵处理中,接入黑曲霉UA8时纯蛋白含量分别为105.6和75.0g/kg,直接发酵较灭菌发酵纯蛋白增加了40.8%。4鲜苹果渣发酵后发酵产物回收率与其纯蛋白含量呈负相关,未灭菌鲜苹果渣发酵有氮和无氮处理中,接入黑曲霉UA8后,发酵产物纯蛋白含量分别为105.6和78.1g/kg,而其回收率分别为62.2%和81.0%。5不同pH时鲜苹果渣发酵产物纯蛋白含量呈pH4>pH6的趋势,未灭菌鲜苹果渣发酵中果渣酸度为pH4和pH6时,酵母菌发酵产物纯蛋白含量分别为101.2和75.9g/kg,果渣自然酸化使发酵产物纯蛋白增加了33.3%。

黑曲霉和米曲霉发酵改善豆渣口感

豆渣作为豆制品生产的副产品,富含营养。为了解决豆渣颗粒大,口感差,难以直接食用的问题,该文对利用黑曲霉和米曲霉发酵豆渣降低其粒度分布进而改善其口感、增加其可食性进行了研究。结果表明:利用黑曲霉和米曲霉在28℃,相对湿度为95%的条件下发酵,能使渣感减弱,吞咽变易,口感明显改善;对发酵10d后豆渣的外观形态、显微镜观察、粒度分布进行考察,均一致表现为发酵后豆渣颗粒显著变小;黑曲霉发酵豆渣对渣感的降低效果好于米曲霉发酵豆渣和未发酵豆渣;发酵使豆渣颗粒变小是口感改善的主要原因;口感改善的根本原因是发酵豆渣过程中所产生的纤维素酶和半纤维素酶降解了豆渣中的纤维素和半纤维素,导致豆渣颗粒变小的缘故。该研究对豆渣的综合利用提供了新途径。

酸性木聚糖酶产生菌的筛选及产酶条件

从１５０株真菌中筛选到８株产木聚糖酶活力在１００Ｕ／ｍＬ以上的菌株，其中活力最高的为黑曲霉（编号１４９）（Ａｓｐｅｒｇｉｌｕｓｎｉｇｅｒ）。该菌株产酶较适培养基为：麸皮半纤维素４％，ＮａＮＯ３１％，麸皮１％，用不加（ＮＨ４）２ＳＯ４和尿素的Ｍａｎｄｅｌｓ氏营养盐液配制。２８℃～３０℃振荡培养６０ｈ，酶活力最高可达３７５．２Ｕ／ｍＬ。该酶最适作用ｐＨ为４６，在ｐＨ３～１１之间基本稳定。该菌株发酵液中含有木聚糖酶（相对活力１００）外还有淀粉酶（１８），甘露聚糖酶（０９８），β木糖苷酶（０９４）和纤维素酶（０１７）。

黑曲霉GD-6纤维素酶液体发酵条件的研究

采用黑曲霉 (Aspergillusniger)GD 6液体发酵生产纤维素酶 ,研究了碳源、氮源、培养基起始 pH值、接种量、摇床转速、通气量对该菌株产纤维素酶活力的影响。结果表明 ,GD 6的最适发酵温度为 2 8～ 3 0℃ ,产酶pH为 5 .5～ 6.0 ,摇床最适转速为 1 5 0r/min ,最佳接种量为 1 0 %。在以 6.0 %稻草粉为碳源、1 %豆饼粉为氮源时产酶活力最高。在最适培养条件下 ,发酵周期为 1 2 0h,发酵液中CMC酶活为 1 88.6U/mL ,FP酶活为 2 7.0U/mL。

云南晒青绿毛茶的微生物固态发酵及成分变化研究

研究了添加外源优势菌种固态发酵云南晒青绿茶过程中主要成分的变化规律。结果表明,随着发酵时间的延长,主要的化学品质成分含量均发生了明显变化,以多酚类、儿茶素、茶红素、茶褐素、寡糖和多糖的变化最明显。发酵40天后,多酚类物质下降了约60%,儿茶素类下降了80%,黄酮类下降了55%,茶红素下降了90%,水溶性寡糖下降了65%,水浸出物下降了25%,而茶黄素、水溶性总糖和灰分的变化不大。但茶褐素类物质增加了4.5倍,水溶性多糖也增加了5.7倍。这说明多酚类物质、儿茶素、茶红素、茶褐素类、寡糖及多糖类物质可作为云南普洱茶的特征成分用于品质判定。实验结果还表明,利用优势菌种发酵晒青绿茶可以在短时间内生产熟普洱茶,其理化成分含量可达到陈年普洱茶的水平。实验结果同时还表明,离开了微生物和湿热作用,晒青绿茶是难以形成普洱茶特有品质风格的。