Novel microbial platform for degradation of hazardous organic contaminants and production of sustainable bioplastics

Abstract

Improper disposal of 1,4-dioxane and the chlorinated organic solvents trichloroethylene (TCE) and tetrachloroethylene (PCE) has resulted in widespread contamination of soil and groundwater. In the present study, a novel microbially-driven Fenton reaction system was designed to generate hydroxyl (HO) radicals for simultaneous degradation of source zone levels of single, binary, and ternary mixtures of TCE, PCE, and 1,4-dioxane. The new Fenton reaction system was driven by the Fe(III)-reducing facultative anaerobe Shewanella oneidensis amended with lactate, Fe(III), and contaminant mixtures and exposed to alternating anaerobic and aerobic conditions. The novel microbially-driven Fenton reaction system successfully degraded TCE, PCE, and 1,4-dioxane either as single contaminants or as binary and ternary mixtures. Degradation of lignocellulosic biomass was also demonstrated through the novel microbially driven fenton reaction by S. oneidensis. In this study, we have developed a new method that combines both pretreatment and saccharification of cellulose and xylan in a microbially driven fenton reaction. The combined pretreatment and saccharification method for cellulose and xylan developed did not involve the addition of acid, alkali compounds or the use of hydrolyzing enzymes thus being an economically feasible process to directly produce simple fermentable sugars from cellulose and xylan. Microbial Fe(III) reduction is a dominant anaerobic respiratory process in soil and sediments, which suggests that the microbially driven fenton reaction may play an important role in the degradation of decaying plant and woody materials in the natural environment. The expansion of metabolic capability to convert D-xylose to a useful product such as PHB can be beneficial in biotechnological applications to couple multiple carbon sources such as glucose, glycerol and D-xylose by S.oneidensis to improve efficiency of electricity generation, biofuel production and bioremediation of toxic contaminants.