桂林猫儿山苏云金芽孢杆菌的筛选及抑菌性研究

Isolation of Bacillus thuringiensis Strain from Guilin Maoershan and Research on Antimicrobial Properties

[目的]探明桂林市猫儿山风景区Bt的多样性和分布概况.[方法]在该景区海拔1 800 ～2 000 m的常绿针阔叶林和海拔2 000m以上的灌丛矮林采集土壤样品共1 168份,分离Bt菌株,并对Bt分离株进行伴孢晶体蛋白分子量的测定和发酵上清液抑菌性分析.[结果]从该景区针阔叶林和灌丛矮林的146个样点共筛选出44个Bt菌株,出菌率达30.14％;其中14株Bt菌株均表达120 kD的蛋白,12株表达66 kD的蛋白.将14株Bt分离株的发酵液上清进行抑菌检测,仅有4株对草生欧文氏杆菌有抑制效果,其中9号的Bt分离株抑制率最高.9号Bt分离株发酵液上清的抑菌物质热稳定性研究结果表明抑菌物质在65℃下2h内不失活,其至少含有2种抑菌物质.[结论]为丰富我国西部地区Bt资源的开发利用奠定了基础.

[ Objective ] The aim was to study diversity and general distribution of Bacillus thuringieusis （Bt） from Guilin Maoershan. [ Method ] Total 1168 Bt strains were collected from soil samples of shrub coppice in air. above 2000 m and evergreen needle broadleaf forest in alt. 1800 -2000 m in Guilin Maoershan, and then Bt strains were collected. Finally, molecular weight determination of insecticidal crystal proteins and inhibitory analysis of supernatant were carried out for Bt isolates. [ Result ] Total of 44 Bt strains were screened out form 146 places of coniferous and broad leaf forests shrub coppice of Maoershan Scenic spots, and the screening rate reached 30.14%. The selected 14 strains of Bt parasporal crystals were expressed about the molecular weight of 120 kD and 12 strains of Bt parasporal crystal expressed molecular weight of about 66 kD. Using the fermentation broth supernatant of Bt which had been selected to test bacteriostatic, only 4 strains of Bt had inhibitory effects to Erwinia herbicola, and the highest inhibition rate among the 4 strains of Bt was sampling place of 9. After using the fermentation broth supernatant of Bt which from sampling place of 9 to research the thermal stability of antibacterial substances, the results showed that antibacterial substances at 65 ℃ without inactivation within 2 h, which contained two kinds of antibacterial substances at least. [ Conclusion ] The results lay the basis for enriching development and utilization of Bt resource in western China.