Paslawski Janice C, Headley John V, Hill Gordon A, Nemati Mehdi
Division of Environmental Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
Biodegradation. 2009 Feb;20(1):125-33. doi: 10.1007/s10532-008-9206-2. Epub 2008 Jul 17.
Naphthenic acids are a complex mixture of organic compounds which naturally occur in crude oil. Low molecular weight components of the naphthenic acids are known to be toxic in aquatic environments and there is a need to better understand the factors controlling the kinetics of their biodegradation. In this study, a relatively low molecular weight naphthenic acid compound (trans-isomer of 4-methyl-1-cyclohexane carboxylic acid) and a microbial culture developed in our laboratory were used to study the biodegradation of this naphthenic acid and to evaluate the kinetics of the process in batch cultures. The initial concentration of trans-4-methyl-1-cyclohexane carboxylic acid (50-750 mg l(-1)) did not affect the maximum specific growth rate of the bacteria at 23 degrees C (0.52 day(-1)) to the maximum biodegradable concentration (750 mg l(-1)). The maximum yield observed at this temperature and at a neutral pH was 0.21 mg of biomass per milligram of substrate. Batch experiments indicated that biodegradation can be achieved at low temperatures; however, the biodegradation rate at room temperature (23 degrees C) and neutral pH was 5 times faster than that observed at 4 degrees C. Biodegradation at various pH conditions indicated a maximum specific growth rate of 1.69 day(-1) and yield (0.41 mg mg(-1)) at a pH of 10.
环烷酸是天然存在于原油中的有机化合物的复杂混合物。已知环烷酸的低分子量成分在水生环境中具有毒性，因此有必要更好地了解控制其生物降解动力学的因素。在本研究中，使用一种相对低分子量的环烷酸化合物（4-甲基-1-环己烷羧酸的反式异构体）和我们实验室培养的微生物，来研究这种环烷酸的生物降解，并评估分批培养过程的动力学。反式-4-甲基-1-环己烷羧酸的初始浓度（50-750 mg l(-1)）在23℃时对细菌的最大比生长速率（0.52 day(-1)）至最大可生物降解浓度（750 mg l(-1)）没有影响。在此温度和中性pH条件下观察到的最大产率为每毫克底物0.21毫克生物量。分批实验表明，低温下也可实现生物降解；然而，室温（23℃）和中性pH条件下的生物降解速率比4℃时快5倍。在不同pH条件下的生物降解表明，在pH为10时最大比生长速率为1.69 day(-1)，产率为（0.41 mg mg(-1)）。
