摘要
水稻细菌性条斑病是由稻黄单胞菌稻生致病变种(Xanthomonas oryzae pv.oryzicola,Xoc)侵染引起的一种重要植物病害,迫切需要开发绿色、高效、低毒的生物农药用于防治.高地芽孢杆菌(Bacillus altitudinis)ST15对水稻黄单胞菌具有显著抑制作用,具有开发成生物农药的潜力.但ST15在摇瓶发酵中活菌和芽孢数量偏低,限制了其开发应用.为此,本文在5 L发酵罐中研究了温度、搅拌转速、通气量等因素对ST15发酵水平的影响,明确了影响活菌和芽孢数量的因素,获得了最佳发酵工艺条件:温度30 ℃、搅拌转速500 r/min、通气量4L/min、种龄12 h、接种量8％、发酵周期36 h.在此条件下,ST15活菌数量、芽孢数量和芽孢率分别达到74.54 × 108 CFU/mL、64.75 × 108 CFU/mL和86.87％,比摇瓶条件下分别提高了16.11％、42.00％和27.75％,本研究可为ST15发酵的后续中试及大规模生产提供技术支持.
Abstract
Rice bacterial leaf streak is an important plant disease caused by Xanthomonas oryzae pv.oryzicola,a pathogenic variant of X.oryzae.There is an urgent need to develop green,efficient,and low-toxicity biopesticides for its control.Bacillus altitudinis ST 15 shows a significant inhibitory effect on X.oryzae and has the potential to develop into biopesticides.However,the low number of live bacteria and spores during shake-flask fermentation limited its development and application.Therefore,the effects of temperature,stirring speed,ventilation rate,and other parameters on the fermentation of ST15 were studied in a 5 L fermentator.The factors affecting the number of live bacteria and spores were identified.The results showed that the optimal temperature,agitation speed,ventilation flow,seed age,inoculation volume,and fermentation period were 30 ℃,500 r/min,4 L/min,12 hours,8％,and 36 hours,respectively.Under this condition,the number of viable bacteria and spores,as well as the spore-producing rate of ST1 5 reached 74.54 × 108 CFU/mL,64.75 × 108 CFU/mL,and 86.91％,respectively.These values improved by 16.11％,42.00％,and 27.75％compared with those under shake-flask fermentation conditions.These findings provide technical support for the subsequent pilot and large-scale production of ST1 5.
维普
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