贝莱斯芽孢杆菌XC1的筛选、鉴定及其对苹果连作障碍的影响

从连作苹果园健康苹果树根际土壤中筛选出1株对苹果连作障碍镰孢属病原菌具有较强拮抗作用的细菌XC1,该菌对尖孢镰孢菌的抑菌率最高,达到79.83%。根据其形态、生理生化特征和基于16S rDNA、gyrA基因的系统发育分析,鉴定该菌为贝莱斯芽孢杆菌(Bacillus velezensis)。目前菌株XC1已保藏于中国微生物菌种保藏管理委员会普通微生物中心,保藏号为CGMCC No.20057。苹果连作土盆栽试验表明,XC1菌肥处理能显著促进平邑甜茶(Malus hupehensis Rehd.)幼苗的生长,其株高、地径、鲜质量和干质量分别比对照提高了54.8%、34.8%、121.1%和96.0%;显著提高连作土壤中的蔗糖酶、脲酶、过氧化氢酶和中性磷酸酶的活性,分别为对照的1.57倍、2.71倍、1.21倍和1.79倍;显著减少连作土壤中真菌的数量,提高细菌和放线菌的数量,且对尖孢镰孢菌(Fusarium oxysporum)有很好的抑制作用,尖孢镰孢菌的基因拷贝数比对照降低了76.4%。这说明贝莱斯芽孢杆菌抑制连作障碍病原菌的效果明显,可改善土壤环境,促进平邑甜茶幼苗的生长,能在一定程度上减轻苹果连作障碍。

Screening and Identification of Bacillus velezensis XC1 and Its Influence on Apple Replant Disease

In this study,a strain XC1 was screened from the rhizosphere soil of healthy apple trees in the replanted apple orchard,which could antagonize the main pathogenic fungi(Fusarium solani,F.proliferatum,F.oxysporum,F.moniliforme)of apple replant disease.Among them,the inhibitory rate of F.oxysporum was the highest,reaching 79.83%.Through morphological,physiological and biochemical characteristics,16S rDNA and gyrA sequence analysis,the bacterium was identified as Bacillus velezensis,which is a new biocontrol bacterium with development potential.At present,strain XC1 has been collected by the China General Microbiological Culture Collection Center,with the preservation number CGMCC No.20057.The pot experiment showed that compared with the control(replanted soil),XC1 treatment could significantly promote the seedlings growth of Malus hupehensis Rehd.and its plant height,ground diameter,fresh and dry mass were 54.8%,34.8%,121.1%and 96.0%higher than those of the control respectively;the activities of sucrase,urease,catalase and neutral phosphatase in the replanted soil treated with XC1 fertilizer were significantly increased,which were 1.57,2.71,1.21 and 1.79 times higher than those of the control,respectively.The number of fungi in the soil were significantly reduced;and the number of bacteria and actinomycetes was increased;and the gene copy number of F.oxysporum treated with XC1 fertilizer was 76.4%lower than that of the control.This indicated that B.velezensis has obvious bacteriostatic effect,which can improve the soil environment,promote the growth of M.hupehensis Rehd.seedlings,and reduce the apple replant disease to a certain extent.