实验室食菌螨的生活史及对果蝇繁殖的危害

观察到实验室食菌螨的生活史有卵、幼螨、第一若螨、第二若螨（休眠体）、第三若螨和成螨6种虫态。从卵至成螨的发育在23～25℃和78％～89％相对湿度下需3．0～4．5天。结果表明：孳生实验室食菌螨能明显降低果蝇的繁殖力,其危害程度随孳生数量不同而呈现明显差异。     

果蝇饲养管理的几个问题

1 防止培养基长霉 当外界温度不适应果蝇生长时(温度低于18℃)．培养基接种后的7d内,特别容易长霉。要避免长霉,应注意：①培养果蝇用的器皿要严格消毒。培养瓶洗干净后,自然凉干,再与棉塞一道进行高温干燥灭菌(120℃,30min)。②培养基要营养全面。果蝇培养基的种类很多,本实验室用的是玉米培养基,配方及配料如下：水750mL煮开,加琼脂6．2g,待琼脂溶解后加白糖62．5g,搅拌溶解后再加调成糊状的玉米糊(玉米82．5g．用冷水调成糊状,     

灰树花液体深层培养工艺研究

对灰树花进行了液体深层培养试验,结果表明：液体培养基碳源以豆粉+麸皮、玉米粉+麸皮和氮源以蛋白胨、牛肉膏等较适宜菌丝生长的物质,确定了灰树花深层培养的液体培养基配方;并研究了培养条件对菌丝生物量的影响,得出了培养液pH在5．30～6．00和通气量为1：(1．00～1．40)的条件下,菌丝生物量达到最大。     

“遗传学和进化”实验

实验4 单基因杂种杂交 (一)实验器材 1 培养管的真实遗传野生型雄果蝇;1培养管的残翅处女雌;2培养管的培养基(每管贴有一空白标签);孵化箱(调至25℃);其它器材见实验3。注释: 下列配料可为100个培养管提供足够的培养基:120克玉米粉;20克琼脂;20克黄糖;80克红糖;20克酵母;3克尼巴精(nipagin,一种霉菌抑制剂),1升凉水。配制时用约20毫升凉水,使玉米粉呈糊状。把琼脂放入剩余的凉水中加文火。逐渐加入糊状玉米、黄糖和红糖,充分搅拌混合液。沸     

分离和鉴别脑膜炎球菌的培养基

一般认为脑膜炎球菌必须在含有天然动物蛋白(血液、血清、腹水及鸡蛋)的培养基上才能生长。而我们用黄豆代替动物蛋白用于脑膜炎球菌培养和鉴别,结果满意。培养基制备方法分离用培养基(黄豆—玉米淀粉抗菌素培养基):(1)基础培养基(g):胰胨6、胨6、牛肉膏3、氯化钠3、葡萄糖1、琼脂25、蒸馏水800ml,加热溶化。(2)玉米淀粉液:玉米淀粉3g(或玉米粉5g),用10ml蒸馏水拌成糊状,再用90ml煮沸的蒸馏水边倒边搅拌,微     

爬沙虫提取液对果蝇繁殖力及寿命的影响

本实验通过研究爬沙虫提取液对果蝇繁殖力及寿命的影响,证实爬沙虫提取液具有增强果蝇的繁殖力和提高雌性果蝇寿命的作用。采用乙醚麻醉法,收集8 h内羽化的成虫,选择个体大小相近的雌雄果蝇,在不同爬沙虫浓度的培养基中培养,统计各组第一子代(first filial generation,F1)果蝇成体的数目及果蝇体重。收集各培养基中果蝇,区分雌雄,在原浓度爬沙虫培养基中培养,每日观察果蝇死亡数,直至全部死亡。结果表明:与对照组比较,各爬沙虫处理组子代果蝇雄体数目均显著增加(P<0.05),2.500%组的子代果蝇雌体数目差异显著(P<0.05)。各爬沙虫处理组刚羽化的果蝇体重极显著高于对照组(P<0.01)。2.500%剂量组果蝇雌体平均寿命极显著增加(P<0.01)。本研究为更好地利用爬沙虫的药用价值提供了参考依据。     

速生薄口螨Histiostoma feronirum Dufour与人参坏死病

本文首次报告人参坏死病的传播介体为速生薄口螨。在速生薄口螨的消化道和唾液腺均查到大量的类菌原体 MLO,大小为90～1300nm,单位膜厚度为9～11nm。与在罹病人参的筛管细胞里观察到的类菌原体 MLO 相同。在子一代和子二代速生薄口螨体内仍可查到类菌原体。将带毒活螨或螨液接种健株人参,健株人参发病。使用三氯杀螨(虫风)拌土,对人参坏死病有显著的抑制作用。初步认为速生薄口螨是人参坏死病的传播介体。     

光照、琼脂和碳源对离体培养中水曲柳根尖生长的影响

研究了光照有无、琼脂添加与否和不同碳源对离体培养的水曲柳根尖生长的影响。结果表明,不添加琼脂的液体培养基对根尖的生长较添加琼脂的固体培养基和固—液培养基好,原因是增加琼脂的量会抑制根的生长;暗培养比光培养更有利于水曲柳离体根尖的培养;蔗糖作为碳源的效果较果糖和麦芽糖好,其中以3%的蔗糖对离体根尖的生长效果最好。     

用家蝇幼虫神经节作染色体压片

家蝇（Muscadomestica）在我国广泛存在,它是一种主要卫生昆虫,能传染霍乱、伤寒及痢疾等疾病,但它也是一种很好的遗传学实验材料。本文推荐一种用于实验室饲养家蝇的方法,展示普通光学显微镜下所见的家蝇幼虫神经节细胞的染色体中期分裂期。达到取材方便,容易剥离标本,成功率高的效果。1家蝇的饲养（1）培养基成分玉米粉15g、红糖2g、蛋白陈5g、牛肉膏2g、酵母膏0．5g、苯甲酸15g、琼脂0．4g、自来水100ml。（2）培养方法用少许苯甲酸加无水乙醇溶解后,再加入培养基中,培养基煮熟smin后,分装干50Oml或1000ml已灭菌的广D瓶内,培…     

竹荪生长和基质的关系

竹荪(Dictyophora rubrovalvata)在PDA琼脂培养基上培养,菌丝体生长很慢,若在PDA培养基上分别添加酵母膏、生啤酒、天冬酰胺、核糖核酸,可促进菌丝体的生长,菌落直径生长和菌丝线性生长都加快;添加蛋白胨、椰子汁、硫胺素和肌醇效果不明显。菌丝体生长的pH值在4.4—5.4之间,最适pH值为4.7;pH值在6.7以上,菌丝体不生长。在木屑培养基中分别添加麦芽汁、玉米、高粱和黄豆粉可以增加子实体的鲜重,其中黄豆和玉米粉、黄豆和高梁粉混合使用的效果比单用一种的更好,菇产量比对照增加1—2倍。播种后基质中含水量控制在50—60％,当原基形成时,含水量提高到55—70％,空气相对湿度在95％以上,菌蕾才能发育成子实体。在自然温度条件下栽培竹荪,出菇高峰期出现在八月份,基质内平均温度为22.4℃,子实体生长的最适温度在20—22.5℃之间,在此温度下产菇率占总产值的85％。     

戊糖乳杆菌发酵培养基氮源条件的优化

对戊糖乳杆菌发酵培养基的氮源条件进行了优化。通过单因素实验及响应面分析优化利用木糖高产乳酸的戊糖乳杆菌发酵培养基的不同氮源组合。优化得到的牛肉膏与柠檬酸氢二铵复合的最佳组成为牛肉膏17.72 g/L,柠檬酸氢二铵1.91 g/L,得到乳酸实际最大产量42.37 g/L。添加玉米浆与酵母粉和无机氮源复合的最佳组成为玉米浆46.54 g/L,酵母粉21.95 g/L,柠檬酸氢二铵9.95 g/L,可得到乳酸最大产量41.06 g/L。通过响应面优化减少了有机氮源的种类。牛肉膏与柠檬酸氢二铵的复合得到了更高的乳酸产量,且减少了有机氮源用量,节约了成本。玉米浆与酵母粉的复合解决了单一玉米浆造成的木糖利用速率过低的问题,同样得到较高浓度的乳酸。     

Potentiation effect of corn extract on the production of eremofortin C, EC oxidase, and PR toxin by Penicillium roqueforti.

Eremofortin C (EC) and PR toxin are secondary metabolites of Penicillium roqueforti. Their structures are similar and differ only by an alcohol and an aldehyde group at the C-12 position. EC has been demonstrated to be the precursor of PR toxin, and EC is transformed to PR toxin by EC oxidase. These two compounds and EC oxidase are secreted by P. roqueforti in the culture medium, which is usually composed of 15% sucrose and 2% yeast extract. Recently, we discovered that the addition of corn extract to this medium increased the production of EC and PR toxin and the activity of EC oxidase in a coordinative manner. In a time-course study, we found that the peak yield of EC and PR toxin and the maximum activity of EC oxidase in the culture medium containing 7.5% sucrose, 1% yeast extract, and 20% corn extract were increased 6.2, 4.6, and 4.7-fold, respectively, as compared with those obtained in the medium without corn extract. Moreover, corn extract increased the production of EC and PR toxin and the activity of EC oxidase by P. roqueforti in a dose-dependent manner. On the other hand, when the concentrations of sucrose and yeast extract were increased while fixing the ratio of corn extract, we found that the levels of EC and PR toxin and the enzyme activity were decreased concomitantly. We thus conclude that corn extract can enhance the production of EC, PR toxin and EC oxidase by P. roqueforti when grown in a minimal medium and that the potentiation effect of corn extract is suppressed when the fungi are grown in a rich medium.     

Forward mutation assay of V79 cells to 6-thioguanine resistance in a soft agar technique that eliminates effects of metabolic co-operation

A technique involving culture in soft agar was used for the assay of forward mutation of V79 cells to 6-thioguanine (6TG) resistance. The main reason for the use of soft agar was to prevent reduction in recovery of mutants depending on the cell density plated for mutation selection, which is the chief problem in the liquid method, and which results mainly from metabolic co-operation due to cell-to-cell contact.V79 cells grew well in fortified soft agar medium (DMEM + 20% FBS) showing cloning efficiencies (>80%) as high as in liquid culture. Therefore, V79/HGPRT mutagenesis could be assayed quantitatively in soft agar culture.The frequency of 6TG-resistant colonies in agar selective medium increased linearly with increase in concentration of EMS. Toxicity and mutagenic responses were greater in soft agar than in liquid culture.In cultures of untreated and EMS-treated cells, more than 95% of the 6TG-resistant colonies isolated were aminopterin-sensitive.Use of soft agar for selection prevented the reduction in the number of mutants with increase in the size of incula on plating up to 1?2 × 10⁶ cells per 9-cm dish: in liquid culture, even with a lower plating number (2 × 10⁵ cells per 9-cm dish), a notable reduction in numbers of mutants was observed. This character was re-examined in a reconstruction experiment. The results show that, when up to 2 × 10⁶ cells were plated per 9-cm dish, 6TG-resistant cells were almost completely recovered from the soft agar medium, whereas only 10% were recovered from liquid culture.     

Ability of casamino acids to support gellan production by Sphingomonas paucimobilis ATCC 31461

The ability of casamino acids and vitamin-assay casamino acids to support gellan production by Sphingomonas paucimobilis ATCC 31461 was examined in a medium containing glucose or corn syrup as the carbon source relative to yeast extract supplementation. When glucose or corn syrup served as the carbon source, the presence of yeast extract in the growth medium stimulated gellan production by strain ATCC 31461 on casamino acids. Using vitamin-assay casamino acids as the nitrogen source, the addition of vitamins lowered gellan synthesis by glucose-grown cells regardless of yeast extract supplementation while gellan elaboration by corn syrup-grown strain ATCC 31461 cells could only be increased by supplementing vitamins into medium lacking yeast extract. Independent of carbon source, the absence of yeast extract in the medium reduced biomass production. Biomass production by the strain grown on either carbon source was increased by supplementing vitamins in the medium containing yeast extract.     

Optimization of medium composition and culture conditions for agarase production by Agarivorans albus YKW-34

Effect of medium composition and culture conditions on agarase production by Agarivorans albus YKW-34 was investigated in shake flasks. The most suitable carbon source, nitrogen source, and culture temperature were agar, yeast extract, and 25 °C, respectively, for agarase production by one-factor-at-a-time design. The nutritional components of the medium and culture conditions were analyzed by Plackett–Burman design. Among the nine factors studied, agar, yeast extract, and initial pH had significant effects on agarase production (p < 0.05). The optimum levels of these key variables were further determined using a central composite design. The highest agarase production was obtained in the medium consisting of 0.23% agar and 0.27% yeast extract at initial pH 7.81. The whole optimization strategy enhanced the agarase production from 0.23 U/ml to 0.87 U/ml. The economic medium composition and culture condition as well as the dominant occupation of agarase with high activity in culture fluid enlighten the potential application of A. albus YKW-34 for the production of agarase.     

Screening and optimization of nutritional factors for higher dextransucrase production by Leuconostocmesenteroides NRRL B-640 using statistical approach

To improve dextransucrase production from Leuconostocmesenteroides NRRL B-640 culture medium was screened and optimized using the statistical design techniques of Plackett-Burman and response surface methodology (RSM). Plackett-Burman design with six variables viz. sucrose, yeast extract, K2HPO4, peptone, beef extract and Tween 80 was performed to screen the nutrients that were significantly affecting dextransucrase production. The variables sucrose, K2HPO4, yeast extract and beef extract showed above 90% confidence levels for dextransucrase production and were considered as significant factors for optimization using response surface methodology. 2(4)-central composite design was used for RSM optimization. The experimental results were fitted to a second-order polynomial model which gave a coefficient of determination R2=0.95. The optimized composition of 30g/l sucrose, 18.9g/l yeast extract, 19.4g/l K2HPO4 and 15g/l beef extract gave an experimental value of dextransucrase activity of 10.7U/ml which corresponded well with the predicted value of 10.9U/ml by the model.     

枯草芽孢杆菌B47菌株高产抗菌物质的培养基及发酵条件优化

枯草芽孢杆菌Bacillus subtilis B47菌株为番茄内生细菌, 也是玉米小斑病拮抗菌, 能产生对玉米小斑病菌有强烈抑制作用的抗菌物质。以B47菌株发酵液的无菌滤液对玉米小斑病菌的抗菌活性为检测指标, 测定B47菌株产抗菌物质培养所需的最佳碳、氮源和无机盐, 并通过正交试验法对该菌株产抗菌物质的培养基配方和摇瓶发酵条件进行优化。研究结果表明, B47菌株产抗菌物质最佳碳、氮源和无机盐分别为蔗糖、酵母浸膏和MgSO4·7H2O, 最优培养基是YSB (Yeast extract-sucrose-beef extract)培养基, 其配方为: 蔗糖2%, 酵母浸膏2%, 牛肉浸膏1.5%, MgSO4?7H2O 0.06%, FeSO4·7H2O 0.000 9%, 最优发酵条件组合为: 30 °C, pH 7.0, 170 r/min摇床培养6 d, 接种量为1%, 装液量为40 mL/200 mL。     

糖化酶生产菌株种子制备工艺优化

目的：缩短糖化酶工业生产菌株黑曲霉A.nigerCICIM GB0506的种子制备周期。方法：对该菌的活化培养基配方及种子制备方式进行改良,并通过L9（3^4）正交试验对其液体培养方法进行优化。结果：在固体活化培养基中添加0.2%的酵母粉及1%的玉米淀粉,有利于加速菌体生长;加入40粒,粒径3-4mm的玻璃珠130r/min,摇床培养可以获得更为分散、均一的种子液;液体种子制备的较优条件为初始pH4.5,装液量90mL,琼脂加量0.1%,培养天数5d。结论：新的制备工艺使糖化酶种子制备时间较现在工业生产上使用的工艺缩短了4d,进行后续糖化酶摇瓶发酵产酶水平是原工艺的1.18倍。     

韩芝液体深层发酵培养基的优化研究

固体培养基上比较了韩芝与树舌的菌丝生长速度,二者平均分别达到0.77 cm.d-1和0.67 cm.d-1;液体培养试验了不同碳氮比、培养基组成对韩芝菌丝生长的影响,得出了菌丝生长较适宜的碳氮比范围在18~24∶1,最适宜的碳氮比在22∶1;对比试验、正交试验得出韩芝液体培养最佳的培养基配方为(g.L-1):葡萄糖10.0、玉米粉20.0、大豆粉20.0、酵母粉5.0;在此条件下,菌丝的平均产量可达23.12 g.L-1。     

Production of Gluconobacter oxydans cells from low-cost culture medium for conversion of glycerol to dihydroxyacetone

Gluconobacter oxydans could be immobilized as a biocatalyst for the conversion of glycerol to dihydroxyacetone. To reduce the production cost, the cells were produced from agricultural byproducts. Corn meal hydrolysate and corn steep liquor were employed to replace of sorbitol and yeast extract as medium for G. oxydans cell production. The optimal medium contained 80 g/L reducing sugar, 25 g/L corn steep liquor, and 10 g/L glycerol. The cell mass was about 4.22 g/L and the glycerol dehydrogenase activity was about 5.23 U/mL. For comparison, the cell mass was about 4.0 g/L and the glycerol dehydrogenase activity was about 5.35 U/mL cultured in sorbitol and yeast extract medium. These studies shown the corn meal hydrolysate and corn steep liquor medium was similar in performance to a nutrient-rich medium, but the cost of production was only 15% of that cultured in sorbitol and yeast extract medium. It was an economical process for the production of G. oxydans cells as biocatalyst for the conversion of glycerol to dihydroxyacetone in industry.