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利用纤维废弃物生产L-乳酸的研究 总被引:4,自引:0,他引:4
为了使对环境造成污染的纤维废弃物得到资源化利用,采用纤维素酶对纤维废料进行酶解,并用米根霉发酵生产L-乳酸.研究结果表明,0.3 mol/L稀磷酸对纤维废弃物进行预处理后,纤维素酶酶解60h,取糖化液进行米根霉发酵,可得到较佳转化率;在固定摇床转速为120r/min、种龄12 h的条件下,米根霉发酵生产L-乳酸的最佳条件为:装液量(250 mL瓶)50mL,接种量8%;经稀磷酸预处理纤维废料分别糖化发酵时,糖对L-乳酸转化率高于未经稀磷酸预处理的,而在同时糖化发酵过程中,经稀磷酸预处理纤维废料发酵效果不明显. 相似文献
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利用纤维素类物质——玉米芯生产L-乳酸的研究 总被引:4,自引:0,他引:4
以纤维素类物质——玉米芯为底物,利用纤维素酶和米根霉对L-乳酸的同时糖化发酵工艺进行了系统地研究。运用单因素试验和正交设计理论确定了最佳摇瓶发酵培养基及条件。最佳发酵培养基组成(g/L):玉米芯150,NH4Cl0.2,ZnSO4·7H2O0.08,MgSO4·7H2O0.25,NaH2PO40.3,KH2PO40.3,一次性添加20g/LCaCO3控制pH;最佳发酵条件是:发酵温度34℃,摇床转速200r/min,发酵72h,产酸量可达24.80g/L。 相似文献
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采用基因工程方法和进化工程相结合的策略对酿酒酵母进行遗传改造,获得高效表达L-乳酸的酿酒酵母适应工程菌.以酵母丙酮酸脱羧酶基因1为同源序列构建乳酸脱氢酶编码基因整合片段,并与酵母自王表达质粒pUT332共转化酿酒酵母菌,筛选具有乳酸脱氢酶活性的转化子.再通过进一步适应进化筛选高产乳酸的酿酒酵母工程菌.结果表明,工程菌的培养介质组成(g/L)为糖蜜总糖120、玉米黄浆水1000、K2HPO46,起始pH 5.0;发酵条件为发酵时间4d,接种量10%,搅拌速度650 r/min,通气量1.5 L/min,发酵温度30℃. 相似文献
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To reduce the production cost of biodegradable plastics, the fermentation performance of L-lactic acid for a new fermentation medium, fresh cassava roots (FCRs) as a substrate slurried with tofu liquid waste (TLW) as basal medium, was investigated by batch fermentation of Streptococcus bovis. The fermentation properties of the three substrates, namely, FCR, tapioca (cassava starch) and glucose, which were independently mixed with TLW, were compared with those independently mixed with the standard basal medium, trypto-soya broth (TSB). Experiments were conducted at various sugar concentrations of the substrates with CaCO(3) as a neutralizer. The maximum L-lactic acid concentrations (C(La)) obtained using the three substrates in TLW were about 75% of those obtained using TSB caused by less nutrients in the TLW. The L-lactic acid productivities (P(La)) and the specific growth rates of S. bovis (mu) in TLW were about 1/4 to 1/3 and 1/5 to 1/4 of those in TSB, respectively. The maximum C(La), P(La) and mu were obtained at 10% w/w sugar concentration. Total yields (eta) were nearly constant up to 10% w/w sugar concentration for TSB and TLW, that is, 80% to 85% and 50% to 60%, respectively. But their total yields decreased in more than 10% w/w sugar concentration in both basal media, because of substrate inhibition. The fermentation properties (C(La), P(La), mu, and eta) were found to be in the order of: FCR > tapioca > glucose for all concentrations of the three substrates. The fermentation properties for FCR and tapioca were higher than those for glucose, in TLW or TSB, because S. bovis in a medium containing starch (FCR and tapioca) has more amylase activity than in a medium containing glucose. The nutrients in FCR with poor nutrient basal medium (TLW) more strongly affected the fermentation properties than those in FCR with rich nutrient basal medium (TSB). The proposed fermentation medium of FCR slurried with TLW is worth studying in order to reduce production cost of biodegradable plastics. 相似文献
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海藻酸钙法固定化乳酸菌发酵制备L-乳酸的研究 总被引:1,自引:0,他引:1
在单因素实验的基础上,利用响应曲面法,对海藻酸钙法固定化植物乳杆菌发酵生产L-乳酸的条件进行优化.建立了显著影响因素和响应值之间的函数关系,得到回归方程.结果表明,最适合乳酸发酵的固定化细胞制作条件为:海藻酸钠浓度2%、包埋量20mL菌悬液/mL凝胶、固定化增殖时间22h、颗粒直径1mm左右、氯化钙浓度2%. 相似文献
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玉米淀粉深层发酵生产L-乳酸 总被引:9,自引:0,他引:9
本文报道了使用米根霉(RhizopusOryzae)TL-527-9菌株用玉米淀粉深层发酵生产L-乳酸。探讨了不同碳源、氮源、底物浓度、液化条件、通气量、种龄对L-乳酸生成的影响,在3M3发酵罐中,当玉米淀粉投料浓度为13%时,7罐平均产L-乳酸9.41g/100ml,对糖转化率79.55%。发酵液经分离提取精制,L-乳酸纯度达98%以上。同时在研究过程中利用高压液相色谱测定了L-乳酸代谢变化。本结果表明米根霉TL-527-9菌株具有L-乳酸产率高和发酵快的特点。 相似文献
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玉米淀粉深层发酵生产L-乳酸 总被引:7,自引:0,他引:7
本文报道了使用米根霉(RhizopusOryzae)TL-527-9菌株用玉米淀粉深层发酵生产L-乳酸。探讨了不同碳源、氮源、底物浓度、液化条件、通气量、种龄对L-乳酸生成的影响,在3M3发酵罐中,当玉米淀粉投料浓度为13%时,7罐平均产L-乳酸9.41g/100ml,对糖转化率79.55%。发酵液经分离提取精制,L-乳酸纯度达98%以上。同时在研究过程中利用高压液相色谱测定了L-乳酸代谢变化。本结果表明米根霉TL-527-9菌株具有L-乳酸产率高和发酵快的特点。 相似文献
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Controlled release of pesticides is eco-friendly and cost-effective. Thiram is a pesticide for fighting fungi and protection of cultivated products. This research aimed at controlled release of thiram pesticide from Poly (L-lactic acid) (PLLA) nanofibrous matrix. Solutions of PLLA (9% w/v) in chloroform-methanol (80–20 v/v) containing 5, 10, 15, 20, and 25% (w/w) thiram relative to the PLLA were electrospun. FESEM, FTIR, and XRD were employed to characterize the electrospun nanofibers. UV spectrophotometry was employed to study the release of thiram from PLLA nanofibers in deionized water. The results showed that the controlled release of thiram from PLLA nanofibers without annealing followed Fick mechanism, but after annealing, non-Fick mechanism prevailed. It was also observed that annealing led to lower level and lower initial rate of controlled release. It is concluded that electrospun PLLA-thiram nanofibers can be used for the controlled release of thiram in long-term periods in agriculture. 相似文献
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Pinpanit Boonchuay Charin Techapun Phisit Seesuriyachan Thanongsak Chaiyaso 《Food science and biotechnology》2014,23(5):1515-1523
Production of xylooligosaccharides (XOs) from corncob using the thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 was investigated using KOH pretreatment, followed by enzymatic hydrolysis. The optimal reaction time for production of XOs was 12 h, after which xylobiose comprised a majority of products, and a low xylose content was observed. The optimal conditions for production of XOs were studied using a central composite design. At an enzyme concentration of 129.43 U/g of substrate, 53.80°C, and pH 6.17, the yield of XOs reached 162.97 mg/g of substrate or 752.15 mg/g of hemicellulose in KOH-pretreated corncob. The prebiotic properties of XOs derived from corncob were also investigated using in vitro fermentation of those XOs with the known probiotic strains Lactobacillus casei TISTR1463, L. lactis TISTR1464, and L. plantarum TISTR1465. XOs derived from corncob were comparable to commercial XOs for an ability to enhance the growth of the specified probiotic lactobacilli. 相似文献
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从L-乳酸菌酸菜发酵液中初步分离肽类抑菌物质 总被引:1,自引:0,他引:1
从L-乳酸菌酸菜发酵液中经硫酸铵盐析、透析、CM Sephadex C-25凝胶柱层析等操作,分离提取肽类抑菌物质,通过琼脂扩散法检测其活性为1.83×103IU/g,经尿素-SDS-聚丙烯酰胺凝肢电泳,发现有三条清晰条带,相对分子量分别为3500、14000、22000.结果说明该酸菜发酵液中确实存在抑菌活性物质,为从酸菜发酵液中分离产生抑菌活性物质的菌株,并进行纯培养发酵生产天然防腐剂奠定了基础. 相似文献
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《食品与发酵工业》2019,(24):134-139
为了解决基酒中乳酸乙酯酯含量不足,风味欠缺的问题,该文以黑曲霉(Aspergillus niger)T103为出发菌株,分别以L/D-乳酸为底物测定其酯化力,发现相较于D-乳酸,黑曲酯化酶对L-乳酸酯化能力更强,并通过对7株乳酸菌发酵产L-乳酸性能的比较,发现各菌株在以玉米为原料的发酵培养基上所产L-乳酸比例明显高于以大米为原料的发酵培养基,进一步发现不同初始糖度对产L-乳酸的比例没有明显影响,并初步确定了最佳L-乳酸发酵液制备工艺:以凝结芽孢杆菌(Bacillus coagulans)B1为出发菌株,接种于以玉米为原料,糖度为18°Bx的乳酸发酵培养基中,发酵13 d,乳酸总量可达89.19 g/L,其中L-乳酸所占比例高达99%。该文为今后乳酸菌的强化发酵和高乳酸乙酯调味酒的制备奠定了基础。 相似文献
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Efficient L-lactic acid production from xylose was achieved using a pyruvate decarboxylase-deficient Candida utilis strain expressing an L-lactate dehydrogenase, an NADH-preferring mutated xylose reductase (XR), a xylitol dehydrogenase and a xylulokinase. The recombinant strain showed 53% increased L-lactic acid production compared with the reference strain expressing native XR (NADPH-preferring). 相似文献
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