Li Dequan, Nie Fengya, Wei Lihui, Wei Benqiang, Chen Zhiyi
Department of Plant Pathology, Nanjing Agricultural University, Nanjing 210095, China.
Appl Microbiol Biotechnol. 2007 Jul;75(6):1401-8. doi: 10.1007/s00253-007-0951-7. Epub 2007 Jun 5.
Bacillus subtilis 916 was an effective biocontrol agent in control rice sheath blight caused by Rhizoctonia solani. To further improve its antagonistic ability, low-energy ion implantation was applied in Bs-916. We studied the effects of different doses of N(+) implantation. The optimum dose of ion implantation for the Bs-916 was from 15 x 2.6 x 10(14) N(+)/cm(2) to 25 x 2.6 x 10(14) N(+)/cm(2). The mutant strain designated as Bs-H74 was obtained, which showed higher inhibition activity in the screening plate. Its inhibition zone against the indicator organism increased by 30.7% compared to the parental strain. The control effect of rice sheath blight was improved by 14.6% over that of Bs-916. Thin-layer chromatography and high-performance liquid chromatography analysis indicated that lipopeptides produced by Bs-916 and the mutant strains belonged to the surfactin family. Bs-H74 produced approximately 3.0-fold surfactin compared to that of Bs-916. To determine the role of surfactin in biocontrol by Bs-916, we tested another mutant strain, Bs-M49, which produced lower levels of surfactin significantly, and found that Bs-M49 had no obvious effects against R. solani. These results suggested that the surfactin produced by Bs-916 plays an important role in the suppression of sheath blight. These observations also showed that the Bs-H74 mutant strain is a better biocontrol agent than the parental strain.
枯草芽孢杆菌916是防治由立枯丝核菌引起的水稻纹枯病的一种有效生防菌。为进一步提高其拮抗能力，对Bs-916进行了低能离子注入处理。我们研究了不同剂量的N(+)注入的影响。Bs-916离子注入的最佳剂量为15×2.6×10(14) N(+)/cm(2)至25×2.6×10(14) N(+)/cm(2)。获得了命名为Bs-H74的突变菌株，其在筛选平板上表现出更高的抑制活性。与亲本菌株相比，其对指示菌的抑菌圈增大了30.7%。对水稻纹枯病的防治效果比Bs-916提高了14.6%。薄层色谱和高效液相色谱分析表明，Bs-916及其突变菌株产生的脂肽属于表面活性素家族。与Bs-916相比，Bs-H74产生的表面活性素约为其3.0倍。为确定表面活性素在Bs-916生防中的作用，我们测试了另一个表面活性素产量显著降低的突变菌株Bs-M49，发现Bs-M49对立枯丝核菌没有明显作用。这些结果表明，Bs-916产生的表面活性素在抑制纹枯病中起重要作用。这些观察结果还表明，Bs-H74突变菌株比亲本菌株是更好的生防菌。
