State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China.
World J Microbiol Biotechnol. 2014 Feb;30(2):469-78. doi: 10.1007/s11274-013-1469-z. Epub 2013 Aug 29.
Biological control efficacy of Brevibacillus laterosporus B4 associated with rice rhizosphere was assessed against bacterial brown stripe of rice caused by Acidovorex avenae subsp. avenae. A biochemical bactericide (chitosan) was used as positive control in this experiment. Result of in vitro analysis indicated that B. laterosporus B4 and its culture filtrates (70%; v/v) exhibited low inhibitory effects than chitosan (5 mg/ml). However, culture suspension of B. laterosporus B4 prepared in 1% saline solution presented significant ability to control bacterial brown stripe in vivo. Bacterization of rice seeds for 24 h yielded a greater response (71.9%) for controlling brown stripe in vivo than chitosan (56%). Studies on mechanisms revealed that B. laterosporus B4 suppressed the biofilm formation and severely disrupted cell membrane integrity of A. avenae subsp. avenae, causing the leakage of intracellular substances. In addition, the expression level of virulence-related genes in pathogen recovered from biocontrol-agent-treated plants showed that the genes responsible for biofilm formation, motility, niche adaptation, membrane functionality and virulence of A. avenae subsp. avenae were down-regulated by B. laterosporus B4 treatment. The biocontrol activity of B. laterosporus B4 was attributed to a substance with protein nature. This protein nature was shown by using ammonium sulfate precipitation and subsequent treatment with protease. The results obtained from this study showed the potential effectiveness of B. laterosporus B4 as biocontrol agent in control of bacterial brown stripe of rice.
生防菌短小芽孢杆菌 B4 对禾谷镰孢酸亚种引起的水稻细菌性条斑病的生防效果评估。在本实验中，使用生化杀菌剂（壳聚糖）作为阳性对照。体外分析结果表明，短小芽孢杆菌 B4 及其培养液（70%；v/v）的抑制作用低于壳聚糖（5mg/ml）。然而，在 1%生理盐水溶液中制备的短小芽孢杆菌 B4 培养悬浮液在体内控制细菌性条斑方面表现出显著的能力。将水稻种子进行 24 小时细菌化处理，对体内控制条斑的反应（71.9%）大于壳聚糖（56%）。机制研究表明，短小芽孢杆菌 B4 抑制了禾谷镰孢酸亚种的生物膜形成，并严重破坏了细胞膜的完整性，导致细胞内物质泄漏。此外，从生防剂处理的植物中回收的病原菌的毒力相关基因表达水平表明，与生物膜形成、运动性、小生境适应、膜功能和禾谷镰孢酸亚种毒力相关的基因被短小芽孢杆菌 B4 处理下调。短小芽孢杆菌 B4 的生防活性归因于一种具有蛋白质性质的物质。这一蛋白质性质是通过使用硫酸铵沉淀和随后用蛋白酶处理来显示的。本研究的结果表明，短小芽孢杆菌 B4 作为生物防治剂控制水稻细菌性条斑病的潜力。
