几种发酵基质对芽孢杆菌LYC-1芽孢量的影响

利用固体发酵技术,研究了几种常见的发酵基质对芽孢杆菌LYC-1芽孢量的影响。采用单因素方差分析和LSD多重比较分析了金针菇菌糠、猴头菇菌糠、杏鲍菇菌糠、豆粕粉、玉米粉、米糠、磷酸二氢钾、和碳酸钙等基质对芽孢量的影响。结果显示:与CK(麸皮固体培养基)相比,实验组T2(猴头菇菌糠)和T6(猴头菇菌糠∶杏鲍菇菌糠=1∶1)的培养基对产芽孢量减少有显著影响,T1(金针菇菌糠)对芽孢数减少没有显著影响,芽孢数最多,为(5.58±0.19)×10^9CFU/g,金针菇菌糠可以完全替代麸皮;与T1相比较,在T1培养基中分别额外添加5.0%豆粕粉、5.0%玉米粉、4.0%米糠、0.25%磷酸二氢钾,其芽孢量在各组中最多,对芽孢杆菌LYC-1芽孢量增加都有显著影响,而不同添加量的碳酸钙对芽孢量增加都没有显著影响。

解淀粉芽孢杆菌M1摇瓶发酵条件优化及脱氮性能评价

旨在提高解淀粉芽孢杆菌M1液体发酵产芽孢量,并考察其对实际废水的反硝化脱氮效果。首先采用单因子实验研究了碳源、氮源、初始pH值、温度、转速和装液量等因子对M1液体发酵产芽孢量的影响。然后对其中显著性因子:氮源浓度、接种量、装液量、温度4个因素进行正交试验,进一步优化发酵条件。结果显示,优化后的培养基成分为:5 g/L碳源(可溶性淀粉)、10 g/L氮源(酵母粉∶蛋白胨=2∶1)、1 g/L NaCl;最佳培养条件为:初始pH6.5、发酵温度34℃、摇床转速180 r/min、培养瓶装液量30%、接种量7%。在此条件下,芽孢杆菌M1芽孢数可达到6.8×10^8 CFU/mL,高于优化前的2.08×10^8 CFU/mL。将芽孢杆菌M1投加于反应器中,与不加菌种相比,反硝化脱氮效果提升15%-34%。

钾细菌诱变选育和发酵的研究

通过钾细菌的诱变选育和发酵工艺探索 ,来提高发酵菌量和芽孢量 ,确保钾细菌肥的质量的研究。试验选用钾细菌P1为出发菌株 ,经紫外线、硫酸二乙酯交替处理 ,筛选出一株产菌量和芽孢量较高的突变株PE -R。用该菌株进行了发酵各因素的试验确定了最佳发酵条件 :接种量 2 0 %、淀粉浓度 1.2 %、氮源浓度 0 .3%、发酵初始pH7.0 - 7.2、发酵后期温度 37℃、发酵后期风量 1:1.2。试验结果表明 ,采用该工艺进行工业化生产 ,发酵菌量从 2 0× 10 10 个 /ml增加到 4 5× 10 10 个 /ml,芽孢生成量从 4 5 %增加到 95 % ,发酵时间从 2 4h缩短到 15h ,制成菌肥 1年后检测活菌保留率仍在 93 6 %。

Detection and Quantitative Analysis of Dominant Bacteria On Aging Flue-cured Tobacco Leaves

[Objective] The aim was to construct the internal motivation of flued-cured tobacco natural aging. [Method] The variation of DNA copies of Bacillus megaterium, amylase activity, PPO, peroxydase and content of starch, neutro-protein, polyphenol in different aging period were investigated using Henan flue-cured tobacco leaves. [Result] Results showed that the DNA copies of Bacillus megaterium increased initially but decreased subsequently with the aging time. The DNA copies of Bacillus per gram of tobacco leaf surface reached the maximum number at 6 months aging. The activities of four enzymes showed the same variation trend as in DNA copies, and also reached the highest level at 6 months aging. Chemical ingredients, however, displayed a downward trend. The variation of enzyme activity and content of chemical composition were reflected in the changes of DNA copies in Bacillus megaterium. [Conclusion] The result indicate that Bacillus megaterium was the internal motivation of flue-cured tobacco natural aging.

Optimization of Solid State Fermentation Conditions Using a Mixture of Bean Curd Residue and Marc with Bacillus natto

[Objective] The aim was to optimize the appropriate solid state fermentation(SSF)conditions.[Method] The optimization of solid state fermentation using a mixture substrate of bean curd residue and the marc with Bacillus natto was developed.[Result] The best fermentation condition optimized by the test of single factor and the orthogonal design respectively was mixing ratio of bean curd residue to marc 2∶1,substrate pH value 6,fermentation temperature 39 ℃,inoculum volume 10% and fermentation time 48 h.Under this optimized fermentation condition,the content of crude fiber in the substrate decreased from 107.8 mg/g before SSF to 56.2 mg/g after SSF,and the degeneration rate of crude fiber was 47.87%.[Conclusion] The bean curd residue in its palatability was enormously improved by SSF with Bacillus natto strain,which could be expected to be widely used as raw material of health foodstuff.

Speciation of chromium in soil inoculated with Cr(Ⅵ)-reducing strain,Bacillus sp.XW-4

Cr(Ⅵ)-amended soil was inoculated with Cr(Ⅵ)-reducing strain,Bacillus sp.XW-4 and incubated at 28 ℃in an incubator. Cr(Ⅵ)reduction,available Cr and Cr fractionin soils were studied.The results show that addition of Bacillus sp.XW-4 can promote Cr(Ⅵ)reduction,but inoculation of this strain has a negative effect on the decrease of available Cr content in soil.In controls (without this strain)amended with 100 and 200 mg/kg of Cr(Ⅵ),Cr(Ⅵ)contents decrease to about 41 and 92 mg/kg respectively after incubation of 4 d,while in soil inoculated with XW-4,Cr(Ⅵ)contents decrease to about 18 and 60 mg/kg,respectively.The content of available Cr in soils with inoculation of XW-4 is higher than that in controls.Chromium is partitioned into water soluble Cr,exchangeable Cr,precipitated Cr,Cr bound to organics and residual Cr.The highest content of Cr is observed in residual form and water soluble Cr is not detected for all treatments after 42 d,but the soils inoculated with Bacillus sp.XW-4 contain higher content of exchangeable Cr and lower content of precipitated Cr than the soil without the inoculum.Inoculation of Bacillus sp.XW-4 can increase chromium activity in soils.

反复冻融对枯草芽孢杆菌St-zn-34抑制链格孢菌活性的影响

【目的】以从冬枣分离的内生枯草芽孢杆菌(Bacillus subtilis St-zn-34)为供试菌株,明确反复冻融对菌体形态及其发酵滤液抑制枣缩果病初侵染病菌(Alternaria alternata)活性的变化。【方法】对供试菌株分批发酵后进行反复冻融,采用梯度稀释计数法、滤纸片法分别测定活菌数量和芽孢含量、发酵滤液抑菌活性,对供试菌株的形态变化进行电镜观察。【结果】发酵培养中pH值、活菌量、芽孢量及抑菌活性随发酵时间的增加均呈先上升后下降的趋势,其中发酵60 h发酵滤液抑菌活性最大,对此时的发酵液反复冻融,冻融3次枯草芽孢杆菌活菌量和发酵滤液抑菌活性依次减少,以后再冻融差异不显著(P>0.05),电镜观察发现随冻融次数增加,菌体变小,表面凹陷、扭曲,胶状物流出。抑菌谱检测发现发酵滤液对12种植物病原菌具有抑菌能力。不同温度和蛋白酶处理发酵滤液表明,低于60℃以下,抑菌活性与对照相比差异不显著;80℃以上抑菌活性随温度上升而下降,与对照相比差异显著;蛋白酶K可降低抑菌活性。【结论】反复冻融影响细菌形态并降低发酵滤液的抑菌活性。

Growth and Cd Accumulation of Orychophragmus violaceus as Affected by Inoculation of Cd-Tolerant Bacterial Strains

Beneficial interactions between microorganisms and plants, particularly in the rhizosphere, are a research area of global interest. Four cadmium(Cd)-tolerant bacterial strains were isolated from heavy metal-contaminated sludge and their effects on Cd mobility in soil and the root elongation and Cd accumulation of Orychophragmus violaceus were explored to identify the capability of metalresistant rhizobacteria for promoting the growth of O. violaceus roots on Cd-contaminated soils. The isolated strains, namely, Bacillus subtilis, B. cereus, B. megaterium, and Pseudomonas aeruginosa, significantly enhanced the plant Cd accumulation. The Cd concentrations in the roots and shoots were increased by up to 2.29- and 2.86-fold, respectively, by inoculation of B. megaterium, as compared with the uninoculated control. The bacterial strains displayed different effects on the shoot biomass. Compared with the uninoculated plants, the shoot biomass of the inoculated plants was slightly increased by B. megaterium and significantly decreased by the other strains. B. megaterium was identified as the best candidate for enhancing Cd accumulation in O. violaceus. Thus, this study provides novel insight into the development of plant-microbe systems for phytoremediation.