Effect of toluene concentration and hydrogen peroxide on Pseudomonas plecoglossicida cometabolizing mixture of cis-DCE and TCE in soil slurry

Abstract

An indigenous Pseudomonas sp., isolated from the regional contaminated soil and identified as P. plecoglossicida, was evaluated for its aerobic cometabolic removal of cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE) using toluene as growth substrate in a laboratory-scale soil slurry. The aerobic simultaneous bioremoval of the cis-DCE/TCE/toluene mixture was studied under different conditions. Results showed that an increase in toluene concentration level from 300 to 900 mg/kg prolonged the lag phase for the bacterial growth, while the bioremoval extent for cis-DCE, TCE, and toluene declined as the initial toluene concentration increased. In addition, the cometabolic bioremoval of cis-DCE and TCE was inhibited by the presence of hydrogen peroxide as the additional oxygen source, while the bioremoval of toluene (900 mg/kg) was enhanced after 9 days of incubation. The subsequent addition of toluene did not improve the cometabolic bioremoval of cis-DCE and TCE. The obtained results would help to enhance the applicability of bioremediation technology to the mixed waste contaminated sites.

Recent advances and trends of trichloroethylene biodegradation: A critical review

“…Most Pseudomonas sp. strains exhibit strong resistance to organic solvents, and some of them can aerobically co-metabolize TCE in the presence of toluene and phenol ( Winter et al, 1989 ; Landa et al, 1994 ; Sun and Wood, 1996 ; Applegate et al, 1997 ; Ryoo et al, 2001 ; Chen et al, 2007 ; Chee, 2011 ; Abu Hamed et al, 2013 ; Li et al, 2014 , 2015 ). Moreover, other strains from Mycobacterium ( Wackett et al, 1989 ; Vanderberg et al, 1995 ), Burkholderia ( Mars et al, 1996 ; Chee, 2011 ), Comamonas ( Futamata et al, 2001 ; Zalesak et al, 2017 ), Methylosinus ( Tsien et al, 1989 ), Methylomonas ( Hanada et al, 1998 ), Alcaligenes ( Harker and Kim, 1990 ), Xanthobacter ( Reij et al, 1995 ), and Cupriavidus ( Chang et al, 2021 ) were also effective TCE co-metabolizing bacteria ( Table 4 ).…”

Acetylene Tunes Microbial Growth During Aerobic Cometabolism of Trichloroethene

“…Several strategies tested to minimize bioclogging during in situ TCE aerobic cometabolism include: (i) decreasing the pulse frequency of the metabolic organic substrate (e.g., toluene, propane), (ii) alternating delivery of the metabolic organic substrate and O 2 , or (iii) adding the chemical oxidant, hydrogen peroxide. , Additionally, when surfactants are added to facilitate TCE dissolution into the aqueous phase, biomass aggregation and distribution may also be decreased to some extent. − While these strategies diminish the likelihood of bioclogging in some cases, neither strategy can reliably preclude bioclogging. ,,,, Here, we propose that acetylene (C 2 H 2 ), a gaseous alkyne, can serve as a tuning agent of heterotrophic biomass overgrowth in TCE cometabolizing microbial communities. Acetylene is a mono/dioxygenase-specific inhibitor, which covalently binds to the active sites of an oxygenase, temporarily preventing the degradation of the metabolic substrate (e.g., propane) and cometabolic contaminant (e.g., TCE). − Acetylene has been shown to inactivate oxygenases of alkanotrophs and ammonia-oxidizing bacteria capable of cometabolizing TCE, chloroform, dichloroethene, vinyl chloride, 1,2,3-trichloropropane, methyl tert -butyl ether, toluene, and 1,2-dibromoethane. ,− To overcome inhibition by acetylene and resume metabolic and cometabolic activity, microorganisms are required to produce additional new acetylene-unaffected copies of the oxygenase enzymes. ,,, …”

“… 34 − 36 While these strategies diminish the likelihood of bioclogging in some cases, neither strategy can reliably preclude bioclogging. 23 , 26 , 28 , 37 , 38 Here, we propose that acetylene (C 2 H 2 ), a gaseous alkyne, can serve as a tuning agent of heterotrophic biomass overgrowth in TCE cometabolizing microbial communities. Acetylene is a mono/dioxygenase-specific inhibitor, which covalently binds to the active sites of an oxygenase, temporarily preventing the degradation of the metabolic substrate (e.g., propane) and cometabolic contaminant (e.g., TCE).…”