title: Aerobic and anaerobic microbial degradation of crude (4-methylcyclohexyl)methanol in river sediments.
abstract: Cyclohexane and some of its derivatives have been a major concern because of their significant adverse human health effects and widespread occurrence in the environment. The 2014 West Virginia chemical spill has raised public attention to (4-methylcyclohexyl)methanol (4-MCHM), one cyclohexane derivative, which is widely used in coal processing but largely ignored. In particular, the environmental fate of its primary components, cis- and trans-4-MCHM, remains largely unexplored. This study aimed to investigate the degradation kinetics and mineralization of cis- and trans-4-MCHM by sediment microorganisms under aerobic and anaerobic conditions. We found the removal of cis- and trans-4-MCHM was mainly attributed to biodegradation with little contribution from sorption. A nearly complete aerobic degradation of 4-MCHM occurred within 14 days, whereas the anaerobic degradation was reluctant with residual percentages of 62.6% of cis-4-MCHM and 85.0% of trans-4-MCHM after 16-day incubation. The cis-4-MCHM was degraded faster than the trans under both aerobic and anaerobic conditions, indicating an isomer-specific degradation could occur during the 4-MCHM degradation. Nitrate addition enhanced 4-MCHM mineralization by about 50% under both aerobic and anaerobic conditions. Both cis- and trans-4-MCHM fit well with the first-order kinetic model with respective degradation rates of 0.46-0.52 and 0.19-0.31 day(-)(1) under aerobic condition. Respective degradation rates of 0.041-0.095 and 0.013-0.052 day(-)(1) occurred under anaerobic condition. One bacterial strain capable of effectively degrading 4-MCHM isomers was isolated from river sediments and identified as Bacillus pumilus at the species level based on 16S rRNA gene sequence and 97% identity. Our findings will provide critical information for improving the prediction of the environmental fate of 4-MCHM and other cyclohexane derivatives with similar structure as well as enhancing the development of feasible treatment technologies to mitigate these compounds.
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Haidian District, Beijing 100871, China; Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States; Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, United States.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Haidian District, Beijing 100871, China; John and Willie Leone Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA 16802, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhi
authors.affiliation: College of Environmental Sciences and Engineering, Peking University, Haidian District, Beijing 100871, China. Electronic address: yshliu@pku.edu.cn.
authors.forename: Yangsheng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Smiley
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Gallagher
authors.affiliation: Department of Earth and Environmental Engineering, Columbia University, New York, NY 10027, United States.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States.
authors.forename: Andrea
authors.initials: A
authors.lastname: Dietrich
authors.affiliation: Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, United States. Electronic address: husen@vt.edu.
authors.forename: Husen
authors.initials: H
authors.lastname: Zhang
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D003510:Cyclohexanes / Q000032:analysis / Q000378:metabolism*; D045483:Rivers; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
chemical_list: D003510:Cyclohexanes; D014874:Water Pollutants, Chemical; C000607184:4-methylcyclohexanemethanol
keywords: 4-MCHM isomers; 4-MCHM-degrading bacteria; Crude (4-methylcyclohexyl)methanol; Degradation kinetics; Mineralization; West Virginia chemical spill