甲硫醚降解菌JLM-8的分离鉴定与降解条件优化

从制药厂的活性污泥中分离到一株能以唯一碳源和硫源降解甲硫醚的菌株JLM-8,经过生理生化测试与16S rDNA系统发育树分析鉴定为嗜麦芽寡养单胞菌(Stenotrophomonas maltophilia)。通过测定菌株的生长量、甲硫醚的降解率,利用响应面法优化最佳降解条件,并测定了该菌降解甲硫醚的动力学参数。结果表明:当接种量为25 mg·L^-1时,通过响应面法优化的最佳降解条件为温度31.3℃、pH 7.5,初始甲硫醚浓度50 mg·L^-1时最大预测降解率为98.2%,实验验证降解率为97.9%。菌株降解动力学参数最大比降解速率、半饱和系数、抑制系数分别为2.37 h^-1、143.55 mg·L^-1、51.35 mg·L^-1,临界抑制浓度为78.46 mg·L^-1。

Isolation and characterization of a novel dimethyl sulfide degrading strain Stenotrophomonasmaltophilia JLM-8

Dimethyl sulfide (DMS) is one of the most important volatile organic sulfur compounds. Due to its malodorous smell and the extremely low odor threshold, DMS has become a critical issue in wastewater collection and treatment systems. In this study, a novel strain JLM-8, with capability of degrading DMS as sole carbon and sulfur source, was isolated from the active sludge of a pharmaceutical plant. Based on the morphological, physiological and biochemical properties as well as its 16S rDNA gene sequence analysis, the strain JLM-8 was identified as a member of Stenotrophomonas maltophilia. The strain could degrade approximately 100% of 50 mg·L^-1 DMS within 8 hours at pH 7 and 30℃. Response surface methodology (RSM) analysis showed that the optimum conditions for degradation were at pH 7.5 and 31.3℃, using an inoculum amount of 25 mg·L^-1. Under these conditions, approximately 97.9% of DMS was degraded. The kinetic parameters q_max, K_s, and K_i were established to be 2.37 h^-1, 143.55 mg·L^-1, 51.35 mg·L^-1, respectively. The critical inhibitor concentration was determined to be 78.46 mg·L^-1. Research on the characterization of DMS degradable bacteria can provide a new theoretical and technical fundamental basis for bioremediation of DMS-contaminated environments.