Biodegradation of hexachlorobenzene by a constructed microbial consortium

Abstract

A consortium comprised of an engineered Escherichia coli DH5α and a natural pentachlorophenol (PCP) degrader, Sphingobium chlorophenolicum ATCC 39723, was assembled for degradation of hexachlorobenzene (HCB), a persistent organic pollutant. The engineered E. coli strain, harbouring a gene cassette (camA (+) camB (+) camC) that encodes the F87W/Y96F/L244A/V247L mutant of cytochrome P-450cam (CYP101), oxidised HCB to PCP. The resulting PCP was then further completely degraded by ATCC 39723. The results showed that almost 40 % of 4 μM HCB was degraded by the consortium at a rate of 0.033 nmol/mg (dry weight)/h over 24 h, accompanied by transient accumulation and immediate consumption of the intermediate PCP, detected by gas chromatography. In contrast, in the consortium comprised of Pseudomonas putida PaW340 harbouring camA (+) camB (+) camC and ATCC 39723, PCP accumulated in PaW340 cells but could not be further degraded, which may be due to a permeability barrier of Pseudomonas PaW340 for PCP transportation. The strategy of bacterial co-culture may provide an alternative approach for the bioremediation of HCB contamination.

Novel Biochar-Plant Tandem Approach for Remediating Hexachlorobenzene Contaminated Soils: Proof-of-Concept and New Insight into the Rhizosphere

“…Under aerobic conditions, HCB could be degraded into pentachlorophenol, tetrachlorohydroquinone, and 2,6-dichlorohydroquinone by certain microbes. 30,31 Although previous studies reported that soil amendment with biochar could enhance the degradation of organic contaminants (e.g., PAHs and benzonitrile), it was ascribed to the nutritional stimulation of microbes by the biochar. 32,33 Far more research has concluded that biochar mainly inhibits the dissipation of organic contaminants in soil due to its strong sorption ability.…”

“…The dissipation of HCB in the control treatment during preplanting incubation might be partly ascribed to the degradation of HCB by soil microbes, as well as to the volatilization of HCB since it was newly spiked into the soil and incubated in an unsealed pot. Under aerobic conditions, HCB could be degraded into pentachlorophenol, tetrachlorohydroquinone, and 2,6-dichlorohydroquinone by certain microbes. , Although previous studies reported that soil amendment with biochar could enhance the degradation of organic contaminants (e.g., PAHs and benzonitrile), it was ascribed to the nutritional stimulation of microbes by the biochar. , Far more research has concluded that biochar mainly inhibits the dissipation of organic contaminants in soil due to its strong sorption ability …”

Engineering bacteria for biogenic synthesis of chalcogenide nanomaterials

“…We used a co‐culture approach to synthesize arsenic sulfide nanomaterials: an E. coli strain expressing arsenate reductases from ANA‐3 and another E. coli strain expressing thiosulfate reductase from Salmonella enterica were used. Similar to our approach, reseachers used an engineered E. coli strain and Sphingobium chlorphenolicum for the bioremediation of hexachlorobenzene (Yan et al ., ). A shift towards division of labour and the implementation of co‐cultures for bioprocessing has been explored in recent publications using synthetic microbial communities (Kim et al ., ; Lindemann et al ., ).…”

An intelligent synthetic bacterium with sound-integrated ability for chronological toxicant detection, degradation, and lethality

“…Regarding degradation, analysis of the catabolic pathways in natural strains facilitates the migration of functional genes to artificial cells that do not possess efficient or complete degradation abilities ( 5, 7 ). For example, an artificial consortium of three E. coli BL21(DE3) strains with synergistic functional modules was designed to completely degrade phenanthrene ( 8 ), and the pathway of engineered E. coli DH5α was linked with a natural pentachlorophenol degrader to mineralize hexachlorobenzene ( 9 ). Additionally, restraining their proliferation is one of the primary challenges for genetically modified microorganisms.…”