Bacterial blight caused by Xanthomonas oryzae pv. oryzae has been reported as one of the most destructive diseases of rice. An antagonistic strain ATC-2 against Xanthomonas oryzae pv. oryzae was screened and identified as Streptomyces termitum by biochemical and physiological assays which was reinforced by comparison of 16S rDNA sequence on Genebank via online BLAST analysis. The antimicrobial compound was isolated from the ferments broth by column chromatography over silica gel and Sephadex LH-20 and it is determined to be aloesaponarin II by H-1 NMR and EI-MS analysis. The results of antimicrobial assays revealed that aloesaponarin II possessed strong antimicrobial activity against Xanthomonas oryzae pv. oryzae with IC50 19.2 mu g/ml.

The results of bacteriostasis experiments demonstrated that strain ACT-2 suppressed a wide range of bacterial pathogens in vitro,while no obvious antimicrobial activities towards fungal pathogens.Antibacterial stability of Streptomyces termitum strain ACT-2 fermentation broth was studied while Xanthomonas oryzae pv.oryzae physiological strain P6 was chosen as indicator bacteria.The fermentation broth could show obvious bacteriostatic activity when the tempreture was below 80 ℃ or exposured in the 4 000 lx illuminant;the diameter of inhibition zone decreased when the tempreture came up to 90 ℃.The fermentation broth was sensitive to acidity and alkalinity,the activity decreased after treatment.

从浙江省金华市郊区水稻试验田土壤筛选获得1株抗白叶枯病菌的放线菌ACT-2菌株.经形态学、16S rDNA序列分析和进化树建树分析,鉴定为白蚁链霉菌(Streptomyces termitum).生理生化实验显示,ACT-2菌株具有较强的环境适应能力.抗菌谱实验表明,ACT-2菌株对细菌类病原体具有较强的拮抗能力,对真菌类病原体效果不明显.ACT-2菌株的菌体和发酵液均对白叶枯病菌表现出明显的拮抗能力,抑菌圈直径分别达到38.00 mm和21.73mm.经发酵条件优化,ACT-2菌株在培养温度为28℃、初始pH7.5、摇床转速为180r/min、装液量为50 mL/250 mL,发酵液抑菌效果达到最大,抑菌直径达到26.20 mm.

从浙江省金华市花生地土样中筛选、分离纯化得到1株产聚-β-羟基丁酸编号为PX-95的芽胞杆菌,PHB产量为135.81 mg/L。根据形态特征、生理生化特征初步鉴定为芽胞杆菌属蜡样芽胞杆菌群,16S rDNA序列分析显示PX-95菌株与苏云金芽胞杆菌以及蜡样芽胞杆菌均具有高度同源性,最后采用扩增gyrB（DNA促旋酶B亚单位）基因的方法将其鉴定为苏云金芽胞杆菌（Bacillus thuringiensis）。

采用响应面分析法对草酸青霉（Penicillium oxalicum）L5菌株液体发酵产果胶酶条件进行了优化。结果表明:桔皮粉、米糠及硫酸铵的添加量分别为4.85%、5.89%、0.97%,摇瓶初始pH为6.0~8.0,接种量为9%时,优化后的果胶酶活达54 391.70 U,是初始酶活18 148.00 U的3倍。另外,对其果胶酶性质进行了初步探讨,结果表明:该酶较适反应温度和pH分别为50℃和5.0;30~50℃时有较好的热稳定性,pH值为5.0时稳定性最佳。

A red pigment producing bacterial strain was screened from a freshwater fish body through isolating color bacteria in nature.This strain was identified as Serratia marcescens based on morphological,physiological characters and 16S rDNA gene sequence.This pigment was demonstrated belong to prodigiosin on the basis of UV spectrum and TLC.The yield of crude prodigiosin reached at 475 mg/L.