贝莱斯芽孢杆菌zk1对鹰嘴桃腐败真菌的抑菌作用

Bacteriostatic effect of Bacillus velezensis zk1 on rot-causing fungi of olecranon peach

贝莱斯芽孢杆菌是一种常用的生防菌,能有效抑制多种病原细菌和真菌。课题组前期从腐烂鹰嘴桃中分离并鉴定出4株腐败真菌,为探究贝莱斯芽孢杆菌zk1对其抑菌效果,本文用贝莱斯芽孢杆菌zk1滤液进行平板对峙试验,发现其对胶孢炭疽菌和哈茨木霉的抑菌效果较好,且对后者敏感度更高。以抑菌率为检测指标,用单因素和正交实验优化菌株zk1滤液的抑菌效果;用酸沉淀法提取滤液中的脂肽类抑菌物质,通过菌落直径、扫描电镜和透射电镜观察脂肽类粗提物的抑菌效果。结果表明,在试验范围内菌株zk1最优的发酵条件为:转速170r/min、pH6、用NB培养基在37℃条件下培养60h。10mg/mL的脂肽类粗提物对胶孢炭疽菌和哈茨木霉的抑菌率分别为57.59%和83.16%。电镜结果表明,实验组的胶孢炭疽菌菌丝体表面皱缩、干瘪,细胞内部形成大空腔、细胞器减少;哈茨木霉的菌丝体表面凹凸不平,细胞器模糊,呈现无序状态。以上结果表明脂肽类粗提物对胶孢炭疽菌和哈茨木霉有较强抑制抑制作用,这可为今后桃果致病菌的防控和延长桃果的商品货架期提供研究基础。

Bacillus velezensis is a common biocontrol bacterium,which can effectively inhibit many pathogenic bacteria and fungi.In the early stage,the team isolated and identified 4 strains of rot-causing fungi from olecranon peach.In order to explore the bacteriostatic effect of Bacillus velezensis zk1 on these fungi,in this paper,the plate confrontation test was carried out with the filtrate of Bacillus velezensis zk1.It was found that the filtrate had better antibacterial effect on anthrax and Trichoderma harziana,and had higher sensitivity to the latter.Single-factor and orthogonal experiments were used to optimize the bacteriostatic effect of zk1 strain filtrate by testing the bacteriostatic rate.Lipopeptide antibacterial substances were extracted from filtrate by acid precipitation method,and colony diameter,scanning electron microscope and transmission electronic microscopy were used to observe its antibacterial effect.The results showed that the optimal fermentation conditions of zk1 strain in the experimental range were as follows:170r/min,pH6,nutrient broth medium cultivation for 60h at 37℃.The inhibitory rates of 10mg/mL lipopeptide crude extracts against Colletotrichum gloeosporioides and Trichoderma harzianum were 57.59% and 83.16% respectively.The results of electron microscopy showed that,in the experimental group,the mycelium surface of Colletotrichum gloeosporioides was shrinked and shriveled,and there were larger cavities and less organelles in the cell.The surface of Trichoderma harzianum mycelium was uneven,and the organelles were fuzzy and disordered.These results indicated that lipopeptide crude extracts had strong inhibitory effect on Colletotrichum gloeosporioides and Trichoderma harzianum,the study provides a research basis for the prevention and control of peach pathogens and the extension of peach fruit shelf life in the future.