贝莱斯芽胞杆菌HN-Q-8菌株发酵液稳定性测定及抑菌活性成分分析

【背景】贝莱斯芽胞杆菌(Bacillus velezensis) HN-Q-8菌株是本实验室前期获得的能有效拮抗立枯丝核菌(Rhizoctonia solani)的生防细菌。【目的】明确贝莱斯芽胞杆菌HN-Q-8菌株的抑菌活性物质。【方法】采用菌丝生长速率法检测其发酵液对5种马铃薯病原菌的拮抗能力以及稳定性,利用基质辅助激光解吸电离飞行时间质谱技术对HN-Q-8菌株活性物质进行鉴定。【结果】HN-Q-8菌株对立枯丝核菌(Rhizoctonia solani)、尖镰孢菌(Fusarium oxysporum)、茄链格孢(Alternaria solani)和致病疫霉(Phytophthora infestans)具有良好的抑菌活性,抑菌率可达50%-90%。发酵液分别经紫外照射35min、自然光照射10 h以及100°C高温处理后,相对抑菌率分别为74%、92%和98%;发酵液的抑菌活性不受胰蛋白酶和蛋白酶K的影响;但不耐强酸、强碱,其适宜pH为4.0-10.0,表明HN-Q-8菌株活性物质具有良好的稳定性。活性成分能使立枯丝核菌菌丝形态畸形扭曲,从而抑制立枯丝核菌的生长,经鉴定活性物质为丰原素(fengycin)和表面活性素(surfactin)。【结论】贝莱斯芽胞杆菌HN-Q-8菌株发酵液具有较好的稳定性和较强的抑菌活性,具有良好的开发价值和应用前景。

Determination of the stability of fermentation broth and analysis of active components of Bacillus velezensis HN-Q-8

Background] Bacillus velezensis HN-Q-8 has biocontrol effect on Rhizoctonia solani effectively. Objective] Identify the inhibition substances produced by Bacillus velezensis HN-Q-8. Methods] Both effects of strain HN-Q-8 on five pathogens of strain potato and stability of fermentation broth were detected though the growth rate method. Active substances of HN-Q-8 were identified using matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS). Results] The fermentation broth of strain HN-Q-8 exhibited strong inhibitory activity against Rhizoctonia solani, Fusarium oxysporum, Alternari solani and Phytophthora infestans, with the inhibition rates ranging from 50% to 90%. The inhibition rates of fermentation broth retained 74% after 35 min exposure to UV, and 92% after a 10 hour exposure to natural light, respectively. The fermentation broth retained 98% antifungal activity after thermal treatment at 100 °C. In addition, the antifungal activity of fermentation broth was not affected by trypsin and protease K. However, the fermentation broth could not endure both extreme acid and alkali treaments, and the suitable pH ranged from 4.0 to 10.0. The methanol extract from strain HN-Q-8 had significant inhibition effect on Rhizoctonia solani, with the two main active substances in it including fengycin and surfactin. Conclusion] The fermentation broth of strain HN-Q-8 exhibited stability and strong antifungal activity, and has promising prospects for its further study, development and application.