The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Burbank in Tasmania

Summary Management of soil moisture deficit during tuber initiation and early development was important for the optimisation of net and marketable tuber yields of cv. Russet Burbank on the typical red ferrosol cropping soils of Northern Tasmania, Australia. An effect of reduced water input during the tuber initiation period on increasing incidence of common scab disease was noted in one trial. In subsequent trials disease inoculum levels were not sufficient to show differences between treatments despite a history of disease at the site. For optimisation of marketable yield and probable assistance in the management of common scab disease it is recommended that irrigation scheduling to known soil moisture deficits be adopted during this period of growth on this soil type.     

铜绿金龟子肠道链霉菌Streptomyces sp. BCa1 菌体的抗菌成分研究

为从昆虫来源的放线菌次级代谢产物中寻找药物先导分子，对铜绿金龟子幼虫肠道链霉菌Streptomyces sp. BCa1菌丝体化学成分进行了研究。通过活性跟踪，从其菌丝体的氯仿甲醇萃取物中分离得到主要成分1。利用高分辨质谱、一维和二维核磁波谱技术，将该主要成分1鉴定为具有双重旋转对称结构的不饱和大环内酯类抗生素阿扎霉素（elaiophylin），具有显著的抗金黄色葡萄球菌活性。该类化合物为首次从昆虫来源的放线菌中发现。     

D-101大孔吸附树脂分离放线菌Streptomyces lavendulae gCLA4活性成分条件的研究

为了优化大孔吸附树脂分离放线菌Streptomyces lavendulae gCLA4发酵液中活性成分的条件,以洗脱液对猕猴桃溃疡菌(Pseudomonas syringae pv.actinidiae)抑菌活性的强弱为评价指标,采用D-101大孔吸附树脂对放线菌Streptomyces lavendulae gCLA4的发酵液进行吸附和洗脱试验。结果表明:当发酵液上样量为100mL,pH为6,洗脱流速为150mL/h,解析溶剂为φ=80%的丙酮水溶液,洗脱体积为40mL时,洗脱液的抑菌圈直径最大,吸附解析效果最好。说明,D-101大孔吸附树脂可用于分离放线菌Streptomyces lavendulae gCLA4发酵液中的活性成分。     

中生菌素产生菌的紫外诱变育种

以中生菌素产生菌C5为出发菌株,经过紫外诱变处理,获得突变株UV-69,其摇瓶发酵效价比出发菌株提高30.2%。传代试验表明,该突变株的高产性能遗传特性较稳定。在15t发酵罐上连续5批验证,平均发酵效价比原生产水平提高47.8%。     

放线菌处理皂河水体的应用研究

利用放线菌5406对皂河黑臭水体进行处理,以接种量、pH值、摇床或静置3个因素在8种条件下对皂河水体的COD、氨氮、正磷酸盐的去除效果进行了研究。结果表明,放线菌接种量为10%时,在30℃、pH7.0及摇床条件下对废水的处理效果较好,对COD的去除率可以达到75%,对氨氮、正磷酸盐的去除率均达到95%以上。放线菌对COD、氨氮、正磷酸盐的去除在时间上呈现出不一致性。     

吉他霉素生产菌培养条件优化

研究淀粉、豆饼粉及丝素粉等3个培养基主要成分对吉他霉素生产菌北里链霉菌发酵结果的影响,同时考察种龄及前体添加对效价的影响。对3个培养基成分采用三因素三水平正交实验设计,对种龄及前体物质则采用梯度实验。最后得到一个相对最优的北里链霉菌培养条件。     

Elimination of common scab sensitive progeny from a potato breeding population using thaxtomin A as a selective agent

Common scab is one of the most important soil‐borne diseases of potato and is difficult to control. Selection of potato breeding lines for resistance to common scab is also cumbersome due to environmental factors influencing symptom development and an erratic spatial distribution of the scab pathogens (Streptomyces spp.) in the field. The bacterial phytotoxin thaxtomin A, which causes scab symptoms, can be used to screen large numbers of potato seedlings for tolerance in vitro, but few studies have investigated whether the results correspond to resistance to common scab observed in the field. In this study, 120 F1 potato progeny from a single cross were screened in vitro by exposing the seedlings to thaxtomin A added to the culture medium. Eighteen genotypes were selected based on high sensitivity or tolerance using shoot growth as the criterion, multiplied in vitro, and tested for resistance to common scab caused by S. turgidiscabies and S. scabies in a glasshouse and in three different fields. Evaluation of ca. 6500 tubers showed that the 18 potato genotypes differed in scab indices and disease severity (P < 0·0001). The relative shoot height in vitro (thaxtomin A used at 0·5 μg mL^?1) and the scab index in the field showed significant correlation (r_s = ?0·463, P = 0·0528, n = 18), also consistent with the results obtained under controlled conditions in the glasshouse. Hence, the in vitro bioassay may be used to discard scab‐susceptible genotypes and elevate the overall levels of common scab resistance in the potato breeding populations.     

链霉菌高拷贝质粒pIJ101DNA的研究 Ⅲ.在变铅青链霉菌中的启动子活性

链霉菌高拷贝质粒pIJ101上的两个片段(1.18kb和0.54kb)在大肠杆菌中具有明显的启动子活性。把这两个片段克隆到链霉菌启动子探针载体pIJ424和pIJ425(修饰了克隆位点)上,转化到变铅青链霉菌中,然后用梯度平板测定转化子对卡那霉素的抗性水平发现:在变铅青链霉菌中,1.18kb的片段在两个方向都有启动子活性,而0.54kb的片段则明显没有。     

卑霉素摇瓶发酵工艺研究

根据代谢发酵控制原理,采用二次回归正交旋转组合设计,对卑霉素摇瓶发酵培养基组分及其接种量、装量和初始pH摇瓶发酵条件进行了优化。结果表明,卑霉素摇瓶发酵培养基的最优配方为:豆饼粉45 g/L,可溶性淀粉5 g/L,甘露醇24 g/L,葡萄糖5 g/L,硫酸铵2 g/L,硫酸镁0.05 g/L;最优发酵条件为:摇瓶装量100 mL/L,接种量8%,C aCO35 g/L(调节pH值),在温度28℃、发酵周期40 h的优化条件下,得到卑霉素的效价值为77.12μg/mL,较对照(64.11μg/mL)提高了20.29%。     

6株土壤链霉菌的抑真菌活性及其发酵液对采后香蕉果实炭疽病的防效

测定了从海南土壤中分离获得的6株链霉菌(Streptomycessp.)LA5、BM9、BM10、BM11、BM19和BW的抑真菌活性及其发酵液对采后香蕉果实炭疽病的防效。香蕉果实接种香蕉炭疽病菌[Colletotrichummusae(BerkeleyetCurtis)vonArx]0h(指接种后立即浸果处理)和24h后,用6菌株的无菌发酵液浸果。结果表明,这6株放线菌活菌及其无菌发酵液对香蕉炭疽病菌均有较强的抑制作用;接种0h后蘸果处理中,LA5菌株的防效最好,达80.0%,与50%多菌灵800倍液的防效相当;接种24h后蘸果处理中以BW菌株防效最好,达75.0%,显著高于50%多菌灵500倍液的防效(64.6%)。