一株可降解苹果废弃枝条的生防细菌鉴定

Identification of a Strain of Biocontrol Bacteria Capable of Degrading Abandoned Apple Branches

筛选对废弃苹果枝条具有降解作用的细菌,为农业废弃物的资源化利用奠定基础。首先利用稀释涂布法从采集的带菌苹果枝段中分离,再通过羧甲基刚果红培养基和复筛培养基挑选出产纤维素酶的菌株,利用发酵培养基验证筛选菌株的纤维素降解能力,进行腐烂病(Valsa mali)的对峙试验并测定其生防潜力,最后通过菌落形态、显微观察和gyrA序列的16SrDNA分析对细菌进行鉴定。从采集的苹果枝条中共分离出3株细菌,其中X-2菌株对苹果枝条具有降解作用,其最适生长pH为8,最适生长温度为30℃左右。菌株分泌产生的滤纸酶(FPAase)、β-葡萄糖苷酶和羧甲基纤维素酶(CMCase)活力分别高达(12.78±0.03)U/mL、(8.63±0.64)U/mL和(8.36±0.02)U/mL,枝条纤维素降解率高达12.36%±0.44%,经过16SrDNA序列测定和Blast同源序列检索,得出该生防菌株X-2为解淀粉芽孢杆菌(Bacillus am yloliquefaciens)。菌株X-2可以满足废弃苹果枝条的降解需求,其在碱性条件下生长良好,有望应用于碱性地区废弃枝条纤维素的降解。

To screen bacteria which can degradate waste apple branches will lay a foundation for resources utilization of agricultural wastes.Firstly,the dilution coating method was used to isolate bacteria from the collected apple branch segments with bacteria,then cellulase producing strains were selected by Carboxymethyl Congo red medium and re-screening medium,and cellulose degrading ability of the screened strains was verified by using fermentation medium.Stand off test for rot disease was conducted and its biological prevention potential was determined.Finally,the bacteria were identified by colony morphology,microscopic observation and 16S rDNA analysis of gyrA sequences.A total of three strains of bacteria were isolated from the collected apple branches,among which strain X-2 could degrade apple branches with an optimum growth pH of 8 and an optimum growth temperature of about 30℃.The enzymatic activities of Filter Paper Enzyme,β-glucosidase and Carboxymethyl Cellulase produced by the strain were as high as(12.78±0.03)U/mL,(8.63±0.64)U/mL and(8.36±0.02)U/mL,respectively,and the branch cellulose degradation rate was as high as 12.36%±0.44%.Strain X-2 was identified as Bacillus amyloliquefaciens.The strain X-2 can meet the degradation demand of waste apple branches and it grows well under alkaline condition,which is expected to be applied to degrade cellulose of waste branches in alkaline areas.