生防细菌X33的鉴定及产抑菌活性物质培养条件优化研究

Identification of Biocontrol Bacteria X33 and Optimization of Culture Conditions for Antibacterial Protein

在世界范围内,作物枯萎病作为一种毁灭性的土传病害受到了各国的极大关注。以尖孢镰刀菌为靶标菌,通过平板对峙的方法筛选具有生防潜力的芽孢杆菌。最终得到一株具有广谱抑菌活性的X33菌株。通过16S rDNA序列对比和生理生化特征分析,X33菌株被鉴定为多粘类芽孢杆菌(Paenibacillus polymyxa)。为提高X33菌株抗菌蛋白的产量,对培养基配方及培养条件进行优化研究。优化后的培养基配方为:甘露醇7 g·L^-1,NH4Cl 9 g·L^-1,NaCl 1 g·L^-1,牛肉膏5 g·L^-1,酵母粉5 g·L^-1。最佳发酵条件为:接种量6%,初始pH值为8,装液量100 mL·250 mL^-1,培养温度31℃,培养时间72 h。经过以上条件优化,多粘类芽孢杆菌X33的抑菌率可以达到50.44%,比优化前23%的抑菌率提高了1.19倍。

Crop blight was a devastating disease,and the biological control of the disease had got great attention.Fusarium oxysporum was used as a target to screen for Bacillus sp.with biocontrol potential.And a strain of X33 with broad-spectrum antibacterial activity was obtained.The X33 strain was identified as Paenibacillus polymyxa by physiological and biochemical characteristics and 16S rDNA sequence analysis.In order to improve the production of antibacterial protein,the fermentation medium and conditions were optimized.The optimal medium formula for X33 consisted of 7 g·L^-1 mannitol,9 g·L^-1 NH4Cl,1 g·L^-1 NaCl,5 g·L^-1 beef extract and 5 g·L^-1 yeast powder.The optimal fermentation conditions were at temperature 31℃with initial pH 8,inoculum size 6%,liquid volume 100 mL/250 mL,and the fermentation time was 72 h.Under these conditions,the inhibition rate could reach 50.44%,which was 1.19 times higher than the 23%inhibition rate before optimization.