一株草莓连作自毒障碍主要物质苯甲酸降解细菌的筛选及其降解效果研究

草莓连作障碍的主要原因是根系产生的自毒作用,苯甲酸是草莓连作障碍的主要自毒物质之一。为减少苯甲酸对草莓的危害,选用苯甲酸为唯一碳源的选择培养基,逐步提高苯甲酸浓度,以期筛选出草莓根际中降解苯甲酸的细菌,并通过紫外可见分光光度法测定其对苯甲酸的降解能力。随后,对筛选出的有效降解菌与3株草莓根腐病菌进行拮抗试验,同时对其显微形态特征和16S rDNA基因序列进行分析与分子鉴定。筛选出的菌株L501对苯甲酸的降解率为87.5%,表明其能有效减轻苯甲酸的自毒作用,同时L501对草莓根腐病菌有较强的拮抗作用。经鉴定,菌株L501为枯草芽孢杆菌Bacillus subtilis,具有解毒抗菌双重功能。

Study on screening degrading bacteria and its degradation effect on benzoic acid of autotoxic compounds in strawberry cropping obstacle

The main reasons of the barrier of strawberry planting were the autotoxic compounds from the soil of strawberry. In order to effectively reduce the harm of the autotoxicity of strawberry, the study was aimed to screen the bacteria with the capacity of degrading benzoic acid. The strains were isolated by using benzoic acid as the sole carbon source and gradually increasing benzoic acid to screen degrading bacteria of strawberry autotoxic compounds. The domestication method was adopted by the ultraviolet spectrophotometry. Antagonistic effects of the effective degradation strain on three strawberry root rot strains were determined. The bacteria were identified by the microbiology characteristics and the sequence analysis of 16S rDNA gene. The degradation rate was 87.5%, which indicated the stain L501 has high efficiency degradation to benzoic acid. Meanwhile, the stain L501 showed strong antagonistic effects against all tested three fungi of strawberry root rot. The stain L501 was identified as Bacillus subtilis, which had double function of degradation benzoic acid and antagonistic.