基于改进PSO算法的酒精发酵过程补料优化

针对基本粒子群优化算法存在的早熟收敛问题,提出了一种保持粒子活性的改进PSO算法:当粒子失活时,对粒子进行变异或扰动操作,重新激活粒子,使粒子能够有效地进行全局和局部搜索,并将改进的PSO算法应用到酒精流加发酵过程的补料优化。实验结果表明,运用改进的PSO算法在进行流加发酵过程的补料优化时,它的寻优性能良好,而且寻优速度很快,可以提高最终产物14%的产量。     

提高发酵过程中溶解氧浓度的探讨

本文介绍了发酵过程中氧传递的各种阻力,分析了影响发酵溶氧的因素,提出了有效改善和提高发酵过程中溶解氧浓度的方法和途径。     

丙酸钙对紫花苜蓿青贮早期发酵品质的影响

为研究丙酸钙作为添加剂对紫花苜蓿青贮发酵品质的影响,试验设置了对照组和添加四个水平（5、10、15和20 g/kg）丙酸钙组对紫花苜蓿进行青贮.结果表明添加不同剂量丙酸钙均不同程度减少青贮料中乳酸含量,除添加5g/kg丙酸钙组乙酸含量低于对照组,丁酸和氨态氮含量高于对照组外,其它添加剂组青贮料中乙酸和丙酸含量高于对照组,而丁酸含量低于对照组.表明了添加5g/kg丙酸钙促进了不良微生物的发酵.综合各项化学指标的分析,在苜蓿青贮时丙酸钙适宜的添加比例为10 ～ 15g/kg.     

Improved elastase production by Bacillus sp.EL31410--further optimization and kinetics studies of culture medium for batch fermentation

An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface methodology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K2HPO4, MgSO4@7H2O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM,showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K2HPO4 0.206 g/100 ml and MgSO4@7H2O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth.     

Scale-up of rifamycin B fermentation with Amycolatoposis mediterranei

Study of the effect of dissolved oxygen and shear stress on rifamycin B fermentation with A. mediterranei XC 9-25 showed that rifamycin B fermentation with Amycolatoposis mediterranei XC 9-25 needs high dissolved oxygen and is not very sensitive to shearing stress. The scale-up of rifamycin B fermentation with A mediterranei XC 9-25 from a shaking flask to a 15 L fermentor was realized by controlling the dissolved oxygen to above 25% of saturation in the fermentation process, and the potency of rifamycin B fermentation in the 15 L fermentor reached 10 g/L after 6-day batch fermentation. By continuously feeding glucose and ammonia in the fermentation process, the potency of rifamycin B fermentaion in the 15 L fermentor reached 18.67 g/L, which was 86.65% higher than that of batch fermentation. Based on the scale-up principle of constantly aerated agitation power per unit volume, the scale-up of rifamycin B fed-batch fermentation with continuous feed from a 15 L fermentor to a 7 m3 fermentor and further to     

生淀粉糖化菌的选育及发酵条件

以黑曲霉(Aspergillus niger)523原生质体为对象,经激光、紫外线和亚硝基胍复合诱变,选育出高产生淀粉糖化酶突变株黑曲霉NL-3,其生淀粉酶活力为156μ/ml.产酶最适培养条件为:起始pH4.5,30℃,72小时.K~+、Mg~(2+)对NL—3产生淀粉糖化酶有促进作用;Z_n~(2+)对产酶有抑制作用.酶的最适作用条件为:以玉米淀粉为底物时最适温度50℃,最适pH4.5;以甘薯淀粉、马铃薯淀粉为底物时最适温度60℃,最适pH4.0—4.5.酶在60℃保温15分钟,玉米淀粉为底物的酶剩余活力80%.甘薯淀粉、马铃薯淀粉为废物的酶剩余活力98%.     

Improved elastase production by<Emphasis Type="Italic">Bacillus</Emphasis> sp. EL31410 —Further optimization and kinetics studies of culture medium for batch fermentation

An efficient culture medium producing a bacterial elastase with high yields was developed further following preliminary studies by means of response surface method. Central composite design (CCD) and response surface methodology were applied to optimize the medium constituents. A central composite design was used to explain the combined effect of three medium constituents, viz, glucose, K₂HPO₄, MgSO₄·7H₂O. The strain produced more elastase in the completely optimized medium, as compared with the partially optimized medium. The fitted model of the second model, as per RSM, showed that glucose was 7.4 g/100 ml, casein 1.13 g/100 ml, corn steep flour 0.616 g/100 ml, K₂HPO₄ 0.206 g/100 ml and MgSO₄·7H₂O 0.034 g/100 ml. The fermentation kinetics of these two culture media in the flask experiments were analyzed. It was found that the highest elastase productivity occurred at 54 hours. Higher glucose concentration had inhibitory effect on elastase production. At the same time, we observed that the glucose consumption rate was slow in the completely optimized medium, which can explain the lag period of the highest elastase production. Some metal ions and surfactant additives also affected elastase production and cell growth. Project (No. 300024) supported by the Natural Science Foundation of Zhejiang Province, China     

甜酒曲中主要的微生物菌群分离及发酵优化

酿造酒的独特风味、质量与酒曲中的微生物密切相关.从选取的民间传统酒曲中主要分离得到发酵效率高的酵母菌3株和根霉菌2株.分别用平板测量法和血球记数法测定2株根霉菌和3株酵母菌,选择生长速度最快的根霉菌M1和酵母菌S1作为菌种自制酒曲,酿制甜酒.以优质糯米为原料,经浸米、蒸饭、淋饭、拌药、下缸、糖化和发酵等工序,得到醇甜清爽、酸甜适口,风味和营养俱佳的糯米甜酒酿.在波长为620nm处用蒽酮——硫酸法测定甜酒中的总糖含量最高达13.92％.     

紫花苜蓿与意大利黑麦草混合青贮发酵品质研究

为研究不同比例紫花苜蓿与意大利黑麦草混合青贮的发酵品质,试验将两种牧草切割至1-2cm,按照鲜草质量比2：8、3：7、4：6和5：5等分为A、B、C、D四个处理组,充分混合后进行青贮。试验结果：各组青贮料的pH值和干物质含量均随青贮时间呈降低趋势,在青贮30d时,A、B组pH值约为4．1,显著低于C、D组的4．30左右（P〈0．05）;干物质含量B组显著高于C、D组（P〈0．05）,但与A组之间差异不显著（P〉0．05）;AN／TN的含量随着发酵天数的增加均持续升高,B组的AN／TN含量在青贮前3d稍高于其它三组,而3d后均低于其他三组,且在30d时与含量最高的D组差异显著（P〈0．05）,但与A、C组差异均不显著（P〉0．05）。青贮料中可溶性糖含量在青贮过程中均呈逐渐降低的趋势,其中在青贮前14d均以A组的WSC含量最高,青贮30d时,B组WSC含量最高,但各组之间差异均不显著（P〉0．05）。在青贮30d时,乳酸含量A、B组显著高于C、D组（P〈0．05）;与C、D组相比,B组乙酸和总挥发性脂肪酸含量低而乳画蔓／乙酸比值高,且差异均显著（P〈0．05）。结果表明：采用意大利黑麦草与紫花苜蓿混合青贮可以获得品质优良的青贮饲料。且以鲜草质量比3：7的混合青贮较为适宜。     

马铃薯酒精发酵的研究

用马铃薯淀粉和马铃薯浆采用不同配方分别进行酒精发酵试验。结果表明用马铃薯浆酒精发酵比马铃薯淀粉好。其最适配方为淀粉浓度１４％,酒曲添加量７％,糖化酶添加量每克淀粉１００单位,发酵时间为７２小时,其出酒率为１２．１１％。