REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa (UNL), 2829-516 Caparica, Portugal.
Water Res. 2010 Sep;44(17):4980-91. doi: 10.1016/j.watres.2010.08.006. Epub 2010 Aug 14.
Propanil (3,4-dichloropropionanilide) is a widely used herbicide, applied worldwide in rice paddies. Propanil is primarily transformed in nature to 3,4-dichloroaniline (DCA), which is more slowly biodegradable. Both compounds have adverse health and ecotoxicity effects. This work investigated the microbial ecology and kinetics of propanil-degrading enrichments obtained from soil in a sequencing batch reactor (SBR) operated with different feeding strategies, aiming at the enhanced biological removal of propanil and DCA from contaminated waters. During SBR operation with a dump feeding strategy, a high propanil concentration led to DCA accumulation, which was only fully degraded after 5 days, likely due to DCA inhibition. For this reason, the operational mode was changed to fed-batch operation with lower initial propanil concentrations, which resulted in faster propanil and DCA biodegradation. Thus a fed-batch operation seems more appropriate for the acclimatisation of an effective propanil- and DCA-degrading population. The changes in performance were accompanied by a shift in the microbial population structure, as determined by DGGE of the 16S rRNA gene, particularly after a feed of DCA as the sole carbon source. Isolates obtained from the acclimatised population included members of the genera Enterococcus and Rhodococcus, as well as Brevundimonas, which displayed >90% propanil biodegradation efficiency.
丙草胺（3,4-二氯丙酰替苯胺）是一种广泛使用的除草剂，在全世界的稻田中都有应用。丙草胺在自然界中主要转化为 3,4-二氯苯胺（DCA），后者的生物降解速度较慢。这两种化合物都对健康和生态毒性有不良影响。本研究采用序批式反应器（SBR），通过改变不同的进料策略，调查了从土壤中获得的丙草胺降解富集物的微生物生态学和动力学，旨在增强从受污染水中去除丙草胺和 DCA 的生物去除能力。在采用批量进料策略的 SBR 运行中，高浓度的丙草胺会导致 DCA 的积累，只有在 5 天后才会完全降解，这可能是由于 DCA 的抑制作用。出于这个原因，操作模式更改为进料分批操作，并降低初始丙草胺浓度，这导致更快的丙草胺和 DCA 生物降解。因此，进料分批操作似乎更适合于驯化有效降解丙草胺和 DCA 的种群。性能的变化伴随着微生物种群结构的变化，这是通过 16S rRNA 基因的 DGGE 确定的，特别是在以 DCA 作为唯一碳源进行进料后。从驯化种群中获得的分离物包括肠球菌属和红球菌属以及短小芽孢杆菌属的成员，它们对丙草胺的生物降解效率>90%。
