乙酸丁酯降解菌的分离鉴定及降解特性

Isolation and identification of a bacterial strain capable of degrading butyl acetate

摘要:

【背景】酯类是工业生产废气中常见组分之一。利用微生物降解含酯类废气具有研究价值和应用前景。【目的】从浙江某污水处理厂活性污泥中驯化分离出一株能以乙酸丁酯为唯一碳源生长的降解菌，研究其降解乙酸丁酯的特性及降解途径。【方法】对分离纯化的降解菌进行形态学、生理生化及分子生物学鉴定以确定种属，采用单因素变量法分析菌株降解乙酸丁酯的特性，并对降解中间产物进行检测和分析。【结果】经生理生化和16S rRNA基因鉴定为莫德斯托斯不动杆菌(Acinetobacter modestus)，命名为HYY-1。菌株HYY-1在碱性(pH 8.0−10.0)条件下对乙酸丁酯有较好的降解效果。在乙酸丁酯浓度为264.75−1 059.00 mg/L时降解率较高，在120 h内对最高浓度乙酸丁酯的降解率可达100%。菌株HYY-1的初始接种浓度对降解效率影响不大，120 h内不同接种浓度下的降解效率均能达到100%。菌株HYY-1降解乙酸丁酯的中间产物为正丁醇和乙酸，最终降解为CO₂、细菌生物量等，在不同初始乙酸丁酯浓度下降解产物比例有所不同。【结论】菌株HYY-1具有高效降解乙酸丁酯的能力，推测可能的降解机制为经酯键水解酶部分转化为正丁醇和乙酸，最终完全矿化为CO₂和细菌生物量。本研究为进一步解析乙酸丁酯生物降解机理和探索乙酸丁酯污染环境的生物修复路径提供了理论支持。

关键词:乙酸丁酯降解菌;分离鉴定;降解特性;碳平衡;降解途径

Abstract:

[Background] Esters are one of the common components in industrial waste gas. Using microorganisms for the degradation of esters has a promising application prospect and thus deserves research. [Objective] To study the degradation characteristics and pathway of a butyl acetate-degrading strain isolated from the activated sludge of a sewage treatment plant in Zhejiang Province. [Methods] This strain was identified based on the physiological, biochemical, and 16S rRNA gene sequence. The single factor experiments were carried out to analyze the degradation characteristics of the strain for butyl acetate, and the degradation intermediates were detected. [Results] The strain was identified as Acinetobacter modestus HYY-1. It demonstrated strong degradation effect on butyl acetate under alkaline conditions (pH 8.0–10.0). The strain showed high degradation efficiency for butyl acetate at 264.75–1 059.00 mg/L, which nearly reached 100% within 120 h in the case of the highest butyl acetate concentration. The initial inoculation concentration of the strain had little effect on the degradation efficiency, which reached 100% within 120 h in the case of different initial inoculation concentrations. The main intermediates in the degradation of butyl acetate by this strain were n-butanol and acetic acid, and the final products were CO₂ and bacteria biomass. The proportions of the products varied under different initial butyl acetate concentrations. [Conclusion] Strain HYY-1 has the ability to efficiently degrade butyl acetate. Specifically, the strain may degrade butyl acetate by ester bond hydrolases into n-butanol and acetic acid, which were ultimately mineralized into CO₂ and bacteria biomass. This study provides theoretical support for deciphering the biodegradation mechanism of butyl acetate and exploring the bioremediation path of butyl acetate-contaminated environment.

Key words:butyl acetate-degrading strain;isolation and identification;degradation characteristics;carbon balance;degradation pathway