摘要
土壤邻苯二甲酸酯(PAE)污染对生态环境和农产品安全均构成威胁。为实现PAE污染土壤的生物修复,明确共代谢基质对微生物降解PAE的影响机制,从PAE污染的大蒜中筛选获得能降解PAE的内生菌。通过生理生化特征和16S rRNA基因测序对其种属进行了鉴定,并研究了内生菌对6种PAE的共代谢降解特性,优化了共代谢降解条件,初步探索了共代谢条件下内生菌对PAE的降解代谢途径。结果表明:从大蒜中共筛选出3株能降解PAE的内生菌DGB-1、DGB-3和DGB-8,经鉴定3者皆为巨大芽孢杆菌(Bacillus megaterium)。3株菌株均能以6种PAE为碳源生长,但处理3 d后PAE的降解率仅0.89%~10.40%,降解能力较弱。添加D-纤维二糖为共代谢基质后,3株菌株对6种PAE的降解率均显著提升,其中菌株DGB-1和DGB-3处理3 d后能完全降解20 mg/L质量浓度的邻苯二甲酸二丁酯(DBP)和邻苯二甲酸丁苄酯(BBP)。以DGB-1为供试菌株,发现吐温80添加量、碳源种类、碳源浓度和接菌量对6种PAE的降解率均有显著影响,最佳降解条件为吐温80添加量0.025%,碳源为D-纤维二糖、浓度为10 mmol/L,接种菌液OD_(600)为0.2。最佳降解条件下,当6种PAE质量浓度为50 mg/L时,邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、DBP、BBP、邻苯二甲酸二(2-乙基己)酯(DEHP)和邻苯二甲酸二辛酯(DnOP)在MSM培养基中的降解半衰期分别为9.01 d、2.27 d、2.13 d、1.99 d、7.84 d和6.72 d。菌株DGB-1不携带质粒,其PAE降解基因位于该菌染色体上;菌株DGB-1可通过水解作用完成对DBP、DEHP和DnOP的第一步降解,但水解作用均较弱;菌株DGB-1对6种PAE的降解代谢需要其细胞膜上的呼吸链系统参与,氧化还原反应增强可显著促进菌株DGB-1对6种PAE的降解。本研究为进一步利用内生菌进行PAE污染土壤的生物修复提供理论依据。
Soil phthalic acid esters(PAEs)pollution is a threat to the ecological environment and the safety of agricultural products.In order to realize the bioremediation of PAEs contaminated soil and clarify the influence mechanism of co-metabolic matrix on the degradation of PAEs by microorganisms,endophytic bacteria capable of degrading PAEs were screened from PAEs contaminated garlic.The strains were identified by physiological and biochemical characteristics and 16S rRNA gene sequencing,and the co-metabolic degradation characteristics of six PAEs by endophytes were studied.The co-metabolic degradation conditions were optimized,and the degradation metabolic pathway of PAEs by endophytes under co-metabolic condition was preliminarily explored.The results showed that three endophytic bacteria DGB-1,DGB-3 and DGB-8 capable of degrading PAEs were screened from garlic,and they were identified as Bacillus megaterium.Although three strains of bacteria demonstrated the ability to utilize six different types of PAEs as carbon sources for growth,their capacity for PAEs degradation was limited.After a three-day treatment,degradation rates ranged from 0.89%to 10.40%.After adding D-cellobiose as co-metabolism substrate,the degradation rates of six PAEs by the three strains were significantly improved.Among them,DGB-1 and DGB-3 strains could completely degrade 20 mg/L dibutyl phthalate(DBP)and butyl benzyl phthalate(BBP)after three days of treatment.Using DGB-1 as test strain,it was found that the addition amount of Tween 80,carbon source type,carbon source concentration and inoculation dose had significant effects on the degradation rates of six PAEs.The optimal degradation conditions were as follows:the addition amount of Tween 80 was 0.025%,the carbon source was D-cellobiose,the concentration was 10 mmol/L,and OD_(600)value of bacterial solution was 0.2.Under the optimal degradation conditions,when the initial concentrations of six PAEs were 50 mg/L,the degradation half-lives of dimethyl phthalate(DMP),diethyl phthalate(DEP),DBP
作者
肖霞霞
杨云
马丽雅
冯发运
葛静
李勇
王亚
余向阳
马桂珍
XIAO Xia-xia;YANG Yun;MA Li-ya;FENG Fa-yun;GE Jing;LI Yong;WANG Ya;YU Xiang-yang;MA Gui-zhen(School of Food Science and Engineering,Jiangsu Ocean University,Lianyungang 222005,China;Institute of Food Safety and Nutrition,Jiangsu Academy of Agricultural Sciences,Nanjing 210014,China;School of the Environment and Safety Engineering,Jiangsu University,Zhenjiang 212013,China)
出处
《江苏农业学报》
CSCD
北大核心
2023年第1期106-117,共12页
Jiangsu Journal of Agricultural Sciences
基金
国家自然科学基金面上项目(32272600)
江苏省农业科技自主创新基金项目[CX(20)1009]
江苏中晚熟大蒜产业集群建设项目(22912105)。
关键词
内生菌
共代谢
邻苯二甲酸酯
降解途径
endophytic bacteria
co-metabolism
phthalic acid esters
degradation pathways
