ABSTRACT In this study, the biocontrol ability of bacterial antagonists of fungal pathogens, B. thuringiensis KYC and B. velezensis CE 100 was investigated for the inhibition of root-knot nematode, Meloidogyne incognita, and subsequent growth promotion of tomato. Based on the results of dual-culture assay, both Bacillus strains showed antagonistic activities against six different phytopathogenic fungi. The bacterial culture filtrates (BCF) of two Bacillus strains had a strong toxic effect on egg hatching and second-stage juvenile (J2) survival of M. incognita. With increasing concentration of BCF and incubation period, the hatching rate of the nematode egg was significantly inhibited and J2 mortality was remarkably increased. Moreover, the crude enzymes which were extracted from culture supernatants of two Bacillus strains caused structural damage to nematode eggs and J2 at 1, 3 and 5 days after inoculation. The pot experiment revealed that B. thuringiensis KYC and B. velezensis CE 100 significantly promoted tomato shoot growth compared to fertiliser treatment. However, root fresh weight was significantly increased in fertiliser treatment due to numerous masses in roots. The number of egg masses and root gall index in the treatment group with both Bacillus strains were significantly decreased compared to those in fertiliser treatment. Higher populations of B. thuringiensis KYC and B. velezensis CE 100 (4.12 and 6.52 × 106 CFU g−1of soil) were detected in the tomato rhizosphere. These results demonstrated the potential of B. thuringiensis KYC and B. velezensis CE 100 as biocontrol agents to control plant-pathogenic fungi and root-knot nematode and as biofertilisers to promote plant growth.

中文翻译：

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真菌病原体的细菌拮抗剂苏云金芽孢杆菌 KYC 和贝莱兹芽孢杆菌 CE 100 在控制根结线虫、南方根结线虫和随后的番茄生长促进中的作用

摘要 在这项研究中，研究了真菌病原体的细菌拮抗剂 B. thuringiensis KYC 和 B. velezensis CE 100 对根结线虫、南方根结线虫的抑制以及随后的番茄生长促进的生防能力。根据双培养试验的结果，两种芽孢杆菌菌株均对六种不同的植物病原真菌表现出拮抗活性。两种芽孢杆菌菌株的细菌培养滤液 (BCF) 对南方分枝杆菌的卵孵化和第二阶段幼体 (J2) 存活具有强烈的毒性作用。随着BCF浓度和孵化期的增加，线虫卵的孵化率受到显着抑制，J2死亡率显着增加。而且，从两种芽孢杆菌菌株的培养上清液中提取的粗酶在接种后第 1、3 和 5 天对线虫卵和 J2 造成结构损伤。盆栽试验表明，与肥料处理相比，苏云金芽孢杆菌 KYC 和 B. velezensis CE 100 显着促进番茄芽生长。然而，由于根中有大量团块，施肥处理后根鲜重显着增加。与肥料处理相比，两种芽孢杆菌菌株处理组的卵块数和根瘿指数均显着降低。在番茄根际中检测到较高数量的 B. thuringiensis KYC 和 B. velezensis CE 100（土壤的 4.12 和 6.52 × 106 CFU g−1）。这些结果证明了 B. thuringiensis KYC 和 B.