马唐生防菌Col-68发酵条件的筛选

Optimization of fermentation conditions of biocontrol strain Col-68 Colletotrichum hanaui against Digitaria sanguinalis

为了最大程度增强马唐生防菌Col-68在发酵过程中产孢能力以及次生代谢产物除草活性,试验以Col-68发酵滤液对马唐种子根、芽生长的抑制率为活性指标,综合不同培养条件下菌株产孢的差异,利用单因素筛选试验筛选出了适合该菌株发酵的不同碳氮源、碳氮比及初始碳源适宜浓度。研究结果表明,在初始pH=6.5,每300 mL锥形瓶装液120 mL,接种100μL菌原液,28℃、160 r.min-1震荡培养10 d的最佳发酵条件下,菌株活性差异显著,以蔗糖为碳源时Col-68活性、产孢量以及对马唐根长抑制率最高,蔗糖浓度在30～50 g.L-1时菌株产孢量以及对马唐根长抑制率较高,发酵最适宜利用的氮源为硝酸钠,最佳碳氮比则为2.5∶1.0。同时,不同条件下的发酵滤液对马唐根生长的抑制率均明显高于对芽生长的抑制率。

Optimization of four parameters,including initial total sugar concentration,carbon source,nitrogen source and carbon-nitrogen ratio（C/N）,was surveyed by using single factor experiment for the optimal production of sporulation of biocontrol strain Col-68 and the increasing activity of fermentation filtrate against Digitaria Sanguinalis root growth.The optimal fermentation medium was as follows：the optimal carbon source was surcose,the optimal nitrogen source was nitrate nitrogen,carbon-nitrogen ratio was 2.5∶1.0,and an initial total sugar concentration between of 30~50 g·L-1.The suitable fermentation conditions were as follows：initial pH 7.0,temperature 28℃,medium volume 120 mL·300 mL-1,inoculum volume 5%（v/v）,for 10 day.In such optimal nutrition and environmental conditions,the maximum sporulation and herbicidal activity of fermentation filtrate of were obtained.The results also showed that the inhibition of fermentation filtrate of the strain Col-68 to Digitaria Sanguinalis root growth was significantly higher than the sprout.