Abstract:

with the increase of ginseng planting years， the accumulation of autotoxic substances in the soil results in the occurrence of continuous cropping obstacles， which significantly impeding the robust advancement of ginseng cultivation. The biodegradation of autotoxic compounds in the soil is as an effective strategy to mitigate the continuous cropping obstacles. The bacteria degrading phenolic acid autotoxic substances were isolated and identified from the ginseng rhizosphere soil. Using 16S rRNA gene sequencing along with physiological and biochemical experiments， the degradation strains were classified and identified. The degradation rate was assessed through UV spectrophotometry， while the culture conditions were refined through a single-factor experiment. The biocontrol of degradation strains on ginseng seeds with phenolic acid stress was investigated. The results showed that 10 strains of bacteria capable of degrading autotoxic substances were isolated from the inter-root soil of ginseng， predominantly belonging to the genus Pseudomonas. Preliminary degradation experiments indicated that strain S1 exhibited the highest degradation rate on salicylic acid， reaching 65.32%， and was identified as Burkholderia. The results of single-factor experiment indicated that the degradation rate of strain S1 was 88.58% with calcium nitrate as the nitrogen source， cultivation temperature of 30 ℃， and 500 mg·L^-1 autotoxic substances， which was higher than before optimization. Strain S1 could alleviate the inhibitory impact of salicylic acid on the growth of ginseng seeds， achieving a growth promotion efficiency of 12.56%. In conclusion， the Burkholderia S1 strainisolated from soil exhibited a commendable biocontrol effect， which had promising application value for mitigating continuous cropping obstacles.

Key words: bacteria degrading phenolic acid, autotoxic substance, ginseng, continuous cropping obstacles, condition optimization

摘要：

随着人参种植年限的增加，土壤中自毒物质的积累会导致连作障碍的发生，极大地影响人参种植业的健康发展。生物降解土壤中自毒物质是缓解连作障碍的有效途径。以酚酸类自毒物质为筛选指标，从人参根际土壤中分离、筛选酚酸类自毒物质降解细菌，结合16S rRNA基因测序及生理生化试验对降解菌株进行分类鉴定，采用紫外分光光度法测定其降解能力，并进一步采用单因素试验对其培养条件进行优化，利用降解菌对酚酸胁迫下的人参种子进行生防研究。结果表明，从人参根际土壤中分离出10株自毒物质降解菌，以假单胞菌属（Pseudomonas）为主。初步降解试验显示菌株S1对水杨酸的降解率最高，达65.32%，经鉴定该菌株为伯克霍尔德属（Burkholderia）细菌。单因素试验结果表明，以硝酸钙作为氮源，培养温度30 ℃，500 mg·L^-1自毒物质下，菌株S1的降解率达88.58%，较优化前明显提升。生防试验结果表明，菌株S1可缓解水杨酸对人参种子生长的抑制作用，促生效率达12.56%。综上所述，从土壤中分离出可降解水杨酸的伯克霍尔德属菌株S1具有较好的生防效果，对于解决连作障碍问题具有潜在生防应用价值。

关键词: 酚酸降解菌, 自毒物质, 人参, 连作障碍, 条件优化