Wang Ying, Chen Hu, Xu Mengdi, Lü Yongkang
State Key Laboratory of Clean and Efficient Coal Utilization, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China.
College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China.
Sheng Wu Gong Cheng Xue Bao. 2023 Mar 25;39(3):1202-1216. doi: 10.13345/j.cjb.220822.
Biodegradation of pyridine pollutant by microorganisms is one of the economical and effective methods to solve the environmental pollution of pyridine under high salinity conditions. To this end, screening of microorganisms with pyridine degradation capability and high salinity tolerance is an important prerequisite. In this paper, a salt-resistant pyridine degradation bacterium was isolated from the activated sludge of Shanxi coking wastewater treatment plant, and identified as a bacterium belonging to on the basis of colony morphology and 16S rDNA gene phylogenetic analysis. Salt tolerance experiment showed that strain LV4 could grow and degrade pyridine with the initial concentration of 500 mg/L completely in 0%-6% saline environment. However, when the salinity was higher than 4%, strain LV4 grew slowly and the degradation time of pyridine by strain LV4 was significantly prolonged. Scanning electron microscopy showed that the cell division of strain LV4 became slower, and more granular extracellular polymeric substance (EPS) was induced to secrete in high salinity environment. When the salinity was not higher than 4%, strain LV4 responded to the high salinity environment mainly through increasing the protein content in EPS. The optimum conditions for pyridine degradation by strain LV4 at 4% salinity were 30 ℃, pH 7.0 and 120 r/min (DO 10.30 mg/L). Under these optimal conditions, strain LV4 could completely degrade pyridine with an initial concentration of 500 mg/L at a maximum rate of (29.10±0.18) mg/(L·h) after 12 h adaptation period, and the total organic carbon (TOC) removal efficiency reached 88.36%, indicating that stain LV4 has a good mineralization effect on pyridine. By analyzing the intermediate products in pyridine degradation process, it was speculated that strain LV4 achieved pyridine ring opening and degradation mainly through two metabolic pathways: pyridine-ring hydroxylation and pyridine-ring hydrogenation. The rapid degradation of pyridine by strain LV4 in high salinity environment indicates its application potential in the pollution control of high salinity pyridine environment.
微生物对吡啶污染物的生物降解是解决高盐度条件下吡啶环境污染的经济有效方法之一。为此，筛选具有吡啶降解能力和高盐耐受性的微生物是一个重要前提。本文从山西焦化废水处理厂的活性污泥中分离出一株耐盐吡啶降解菌，并根据菌落形态和16S rDNA基因系统发育分析将其鉴定为某属细菌。耐盐性实验表明，菌株LV4在0%-6%的盐环境中能够生长并完全降解初始浓度为500 mg/L的吡啶。然而，当盐度高于4%时，菌株LV4生长缓慢，其对吡啶的降解时间显著延长。扫描电子显微镜显示，在高盐环境中菌株LV4的细胞分裂变慢，诱导分泌更多颗粒状的胞外聚合物（EPS）。当盐度不高于4%时，菌株LV4主要通过增加EPS中的蛋白质含量来应对高盐环境。菌株LV4在4%盐度下吡啶降解的最佳条件为30℃、pH 7.0和120 r/min（溶解氧10.30 mg/L）。在这些最佳条件下，菌株LV4在12 h适应期后能够以最大速率(29.10±0.18) mg/(L·h)完全降解初始浓度为500 mg/L的吡啶，总有机碳（TOC）去除效率达到88.36%，表明菌株LV4对吡啶具有良好的矿化效果。通过分析吡啶降解过程中的中间产物，推测菌株LV4主要通过吡啶环羟基化和吡啶环氢化两条代谢途径实现吡啶的开环降解。菌株LV4在高盐环境中对吡啶的快速降解表明其在高盐吡啶环境污染控制中的应用潜力。
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