摘要
Biotransformation of 6:2 fluorotelomer sulfonate(6:2 FTS)by two species of white-rot fungi,Pleurotus ostreatus(P.ostreatus)and Trametopsis cervina(T.cervina),was investigated in a sulfurrich medium designed to stimulate production of lignin-degrading enzymes.Degradation of 6:2 FTS was observed by T.cervina over the study period of 30 d,but not by P.ostreatus.Biotransformation rates were comparable to those found in other studies investigating mixed culture degradation in nonsulfur limiting media,with approximately 50 mol%of applied 6:2 FTS removed after 30 d.Stable transformation products were short-chain perfluorocarboxylic acids(PFCAs),including PFHxA(2.27 mol%),PFPeA(0.24 mol%),and PFBA(0.28 mol%).The main intermediate products include 5:2 sFTOH(16.3 mol%)and 5:3 FTCA(2.99 mol%),while 6:2 FTCA,6:2 FTuCA,and 5:2 ketone were also identified at low levels.Approximately 60 mol%of detected products were assigned to the major pathway to 5:2 ketone,and 40 mol%were assigned to the minor pathway to 5:3 FTCA.The overall molar balance was found to decrease to 75 mol%by Day 30,however,was closed to near 95 mol%with a theoretical estimation for the volatile intermediates in the headspace,5:2 ketone and 5:2 sFTOH.The different capabilities of the two white-rot fungal species for 6:2 FTS biotransformation in sulfur-rich media suggest that the enzyme processes of T.cervina to de-sulfonate 6:2 FTS may be unrelated to sulfur metabolism.
基金
support by the Center for Air and Aquatic Resources Engineering and Sciences(CAARES)at Clarkson University and thank the employees at the Center of Forest Mycology Research(CFMR)in Madison,WI,for providing all cultures used in this research.
