To obtain the optimal extraction conditions of Poly-β-hydroxybutyrate(PHB) in Bacillus megaterium,the effect of chloroform concentration,extraction time and temperature on PHB extraction were studied.On the basis of single factor experiment,Box-Benhnken central composite method was designed for the three factors.In response to PHB extraction value,the extraction conditions were further optimized by response surface method(RSM).The results showed that when chloroform concentration was 69.7%,extraction temperature was 59.7 ℃,extraction time was 3.0 h,the productivity of PHB was 4.437 g/L,reached its maximum.

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.

Liquid-fermentation conditions of a high MEP yielding Monascus strain Mr-70 and antioxidant activity of its crude MEP were initially studied.The fermentation conditions were optimized as follows: glucose 60.0 g/L,peptone 20.0 g/L,KH2PO4 10.0 g/L,MgSO4·7H2O 1.1 g/L,pH 6.5,shaker at 200 r/min,cultured at 32 ℃ for 96 h.Under these conditions,the yield of MEP reached as much as 10.15 g/L in shaker flask.The scavenging rate of crude MEP adopting DPPH· was 82.24% within 5 mg/mL,manifested that MEP of Monascus Mr-70 had fairly strong antioxidant activity.

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 high-yield pectinase strain L5 was screened from sludge.It was identified as Penicillium oxalicum by morphological observation,and internal transcribed spacer(ITS) sequence analysis.This strain was cultured at the condition of 28 ℃,pH 6.0,160 r/min for 70 h,its pectinase activity reached to 39 940 U·mL-1·min-1.

从市售红曲米和红腐乳中分离纯化得到56株红曲霉菌株,通过摇瓶发酵试验筛选出1株胞外多糖产量为4.73 g/L的红曲霉菌株M-6;依据形态特征、生理生化特征和ITS序列将菌株M-6鉴定为红色红曲霉（Monascus rubber）。并对其部分生物学特性进行了研究。

通过优化各种转化因素,建立了根癌农杆菌(Agrobacterium tumefaciens)介导红曲霉(Monascus)的高效转化体系:红曲霉在PDA培养基培养21 d后收集孢子,制备红曲霉孢子悬浮液,浓度为106 个/mL,根癌农杆菌浓度为OD600值0.5,诱导剂AS浓度为100 μmol/L,农杆菌与红曲霉在25 ℃共培养3 d.采用此转化体系构建了含有530多个转化子的红曲霉T-DNA插入突变体库.随机选取50株转化子菌株进行分子验证和稳定性检测,证明T-DNA成功插入红曲霉基因组DNA中,并能稳定遗传.最后,通过形态观察筛选出8株变异较大的菌株,为以后的红曲霉基因功能研究奠定了一定的基础.