冬虫夏草菌的动态产孢量及抗异能力

目的：研究冬虫夏草菌的生长速度和动态产孢量，揭示产孢规律和条件，探索人工繁殖的可能及评估其在对虫害生物防治中的应用潜力；测定它的抗异活性和抗菌谱，为对其活性产物的性质研究打下基础。方法：测量虫草菌株在真菌培养基生长时的菌落直径变化，用孢子计数法跟踪测定普通培养基和水琼脂上单菌落的动态产孢量并与相近虫草菌进行对比分析，用琼脂块法测定培养菌丝对致敏菌的抗异活性，测量比较抗菌圈大小和总结抗菌谱。结果：在PDA等3种常规真菌培养基上，CY－8202的菌落扩展与进时间呈线性关系。动态产孢量的测定表明，该菌株在适宜培养基上的单菌落产孢量可达10^7以上，并随着时间的延长而增长，大约200h后增长趋于平缓。对22个致敏菌株的抗菌实验显示，CY－8202培养菌丝对革兰氏阳性的枯草杆菌、四联球菌、白色葡萄球菌以及革兰氏阴性的普通变形杆菌、伤寒杆菌、产气杆菌和沙门氏菌等7株细菌有较强的抑制能力，对3株霉菌和1株放线菌有轻微抑制，对酵母菌未见抑制影响。结论：虫草菌丝的生长和产孢力是有效侵染寄主的两个重要因素，但菌丝生长速度不宜作为生长力强弱的唯一判断指标，菌丝的穿透力更加重要；具有超量产孢能力是虫草菌株强侵染力的一个重要标志。抗异活性表明冬虫夏草菌具有分泌比虫草菌素更广谱的抗生素的能力。

Dynamic spore outputs and antibiotic activities of asexual fungi (strain CY-8202) isolated from Cordyceps sinensis

Object To study the growth speed and dynamic spore production of CY-8202, which is an asexual strain of entomopathogenic fungi isloated from Cordyceps sinensis (Berk.) Sacc., to explore the method of artificial culture of CY-8208 strain, to assay its antibiotic activity and spectrem and to provide the experimental basis for studies of its active components. Methods Variations in colony diameter of the cordyceps hypha cultured on the fungi media were measured. The spore-count was used to determine the dynamic colony spore outputs of the hypha on several fungi media and water agar. The agar-piece method was used to test its antibiotic activity.Results There were linear relationships between the colony extensions and the culture times on common fungi media such as PDA medium, etc.. The amounts of spore produced by the single colony of the fungi were more than 10⁷ and gradually increased, but the rates of increase tended to be gentle after 200h. Antimicrobial tests against 22 microbial strains showed strong inhibition of gram positve bacteria including Bacillus subtilis, Micrococcus tetragenus and Staphylococcus albus, and to gram negative bacteria, including Proteus vulgaris, Salmonella typhi, Aerobacter aerogenes and Salmonella sp., as well as weak inhibition of three mold strains and one actinomycetes strain, but no inhibition was observed in four yeast tested.Conclusion The growth activity and the spore-production ability of Cordyceps hypha are two important factors to infect validly its insect-host. For the growth activity, its strong penetration seems more important than its fast growth. The ability to product numerous spores of Cordyceps hypha may be an important mark of its strong infectivity to insect-host. The antimicrobial tests show that CY-8202 may secrete some metabolites which have a more broad-spectrum antibacterial activity than cordycepin isolated initially from Cordyceps militaris.