排序方式: 共有18条查询结果,搜索用时 15 毫秒
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为了研究低浓度空气离子对微生物的效应,利用低浓度空气离子对固体培养基上Streptomyces avermitilis作用,分析了其次生代谢产物产生时间早晚,各组分含量变化,并且初步研究有效成分含量提高的机理.用浓度为5×103/cm3的空气负离子连续十天处理固体培养基上的阿维链霉菌,经过高效液相色谱(High performance liquid chromatography,HPLC)检测后发现:经过处理,该菌株提早四天到达阿维菌素(Avermectins,AVM)产素平台期,有效成分B1a和B1b提高约20%,而无效成分含量无显著提高.经过分析,低浓度空气负离子可有效缩短该菌种的发酵周期,提高有效成分含量,刺激次生代谢过程. 相似文献
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氮离子注入选育高效发酵木糖生产L(+)-乳酸的米根霉 总被引:2,自引:0,他引:2
为了获得能够高效发酵木糖生产L( )-乳酸的菌株,采用氮离子注入诱变方法,对出发菌株米根霉RLC41-6进行改良,获得高产L( )-乳酸菌株RQ4012,发酵周期为72h,产酸能力达74.37g/L,产酸速率达1.03g/(L.h),比RLC41-6提高了1.6倍.经过多次传代实验证明该菌株具有较好的遗传稳定性. 相似文献
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Improvement of Vitamin K2 Production by Escherichia sp.with Nitrogen Ion Beam Implantation Induction
Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra.In this work,N~+ ion beam implantation was used to enhance Escherichia sp.in vitamin K_2 yield.Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K_2yield of mutant FM5-632.The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L,that is four times that of the original strain,was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×l0~(13)ions/cm~2.A further optimization increased the yield of the mutant by 39.7%,i.e.172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of(per liter):15.31 g glycerol,10 g peptone,2.89 g yeast extract,5 g K2HPO_4,1 g NaCl,0.5 g MgSO_4·7H_2O and 0.04 g cedar wood oil,incubated at 33℃,pH 7.0 and 180 rpm for 120 h. 相似文献
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Immobilized Rhizopus oryzae culturing may be a solution to the inhibited production of L(+)-lactic acid in submerged fermentation, which is caused by aggregated mycelia floc. In the present study, a R. oryzae mutant (RL6041) with a 90% conversion rate of glucose into L-lactic acid was obtained by N+ implantation under the optimized conditions of a beam energy of 15 keV and a dose of 2.6 ×10^15 ions/cm^2. Using polyurethane foam as the immobilization matrix, the optimal L-lactic acid production conditions were determined as 4 mm polyurethane foam, 150 r/min, 50 g/L ~ 80 g/L of initial glucose, 38℃ and pH 6.0. 15-cycle repeated productions of L-lactic acid by immobilized RL6041 were performed under the optimized culturing conditions and over 80% of the glucose was converted into L-lactic acid in 30 hours on average. The results show that immobilized RL6041 is a promising candidate for continuous L-lactic acid production. 相似文献
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郑之明 《河南水利与南水北调》2012,(12):99-100
优于双曲拱坝断面小,形状多变,在工程施工中,为确保坝体的几何尺寸,须随时进行放样控制。文章通过多座拱坝工程施工经验的积累,总结出一套简易可行的拱坝放样方法,在此作一介绍。 相似文献
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黄原胶发酵过程中流变学行为和气液传质的研究 总被引:3,自引:0,他引:3
在10L搅拌式发酵罐中,研究了黄原胶发酵的流变学行为和气液传质特征。发酵液呈现典型的假塑性行为,后期发酵液稠度系数K大于20Pa.snn,流变指数n低于0.2,随着胶浓度的提高,搅拌所带来的剪切力不够,使有效搅拌区域减小,发酵液几乎不随搅拌浆而转动。考察了表观粘度ηm、搅拌转速N和通气速率Ug对体积氧传质系数kLa值的影响,将kLa值与转速N和表观粘度ηm进行了无因次关联。实验条件较高搅拌下的高剪切,不仅能提高整体混合,而且能够促进细胞周边分泌的黄原胶粘液层向主体扩散,有利于强化传递。在所研究的气速范围内,通气速率的提高似乎对气液传质的贡献不大。具有较高剪切和较大有效搅拌区域的反应器被认为更适合于黄原胶发酵过程。 相似文献
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为了获得β-葡萄糖苷酶高产菌株,应用低能N+注入技术对黑曲霉菌株Au进行了诱变选育,同时研究了N+注入对菌株存活率和突变率的影响。通过几轮注入之后,最终筛选得到的高产菌株Au 0847其β-葡萄糖苷酶活力达到13.75 U/mL,比原始菌株Au提高了106.8%,且遗传性能稳定。经过进一步的发酵优化,该菌株最终β-葡萄糖苷酶活力达到30.53 U/mL。 相似文献