Abstract

The study was focussed on the inhibitory mechanism associated with the ability of an endophytic bacterium - Bacillus altitudinis Q7, obtained from Ginkgo biloba, to inhibit the growth of Alternaria alternata in vitro. A fungus, identified as Alternaria alternata was isolated from the rotten part of an apple. One of the endophytes was identified as Bacillus altitudinis Q7. Effect of Bacillus altitudinis Q7 on Alternaria alternata was characterized by measuring membrane permeability and lipid peroxidation. Antioxidant enzymes in Alternaria alternata were determined before and after exposure to Bacillus altitudinis Q7. Results indicated that cell membranes in Alternaria alternata were damaged, lipid peroxidation was enhanced, and superoxide dismutase, peroxidase, and polyphenol oxidase were significantly inhibited. Content of lipopeptides produced by Bacillus altitudinis Q7 was higher than other metabolites. The FTIR spectra revealed that the prepared antibacterial lipopeptides is a cyclic lipopeptides. The effect of lipopeptides produced by Bacillus altitudinis Q7 at 2 mg/mL against Alternaria alternata in vitro reached 83.2%. The lipopeptide-treated group showed the same trend as Q7 fermentation broth in inhibition mode of action. Moreover, the utilization of proteins and sugars during culturing of Alternaria alternata decreased when adding lipopeptides to the growth medium. Bacillus altitudinis Q7 from Ginkgo biloba significantly inhibited the growth of Alternaria alternata and is a very promising biocontrol strain against Alternaria alternata. The study of endophytic bacteria and its metabolites is being done to identify biological control alternatives. The results provide a theoretical basis for understanding their antagonistic properties.

摘要

该研究的重点是与从银杏叶中获得的内生细菌Bacillus altitudinis Q7在体外抑制Alternaria alternata生长的能力相关的抑制机制。从苹果腐烂的部分中分离出一种真菌，鉴定为链格孢菌。其中一种内生菌被鉴定为Bacillus altitudinis Q7。的效果altitudinis芽孢杆菌上Q7链格孢的特征在于，通过测量膜的通透性和脂质过氧化。在接触高山芽孢杆菌之前和之后测定了链格孢中的抗氧化酶Q7. 结果表明，链格孢细胞膜受损，脂质过氧化作用增强，超氧化物歧化酶、过氧化物酶和多酚氧化酶受到显着抑制。Bacillus altitudinis Q7产生的脂肽含量高于其他代谢物。FTIR谱表明制备的抗菌脂肽为环状脂肽。Bacillus altitudinis Q7产生的脂肽以 2 mg/mL 的浓度在体外对Alternaria alternata 的作用达到 83.2%。脂肽处理组在抑制作用方式上表现出与Q7发酵液相同的趋势。此外，在链格孢培养过程中蛋白质和糖的利用将脂肽添加到生长培养基中时降低。来自银杏叶的Bacillus altitudinis Q7显着抑制了Alternaria alternata的生长，是非常有前途的防治Alternaria alternata 的生防菌株。正在对内生细菌及其代谢物进行研究，以确定生物防治替代品。该结果为理解它们的拮抗特性提供了理论基础。