IMMOBILIZED AEROBIC 1,2-DCA DECHLORINATING CONSORTIA FOR ENHANCED BIOREMEDIATION

The immobilization of biodegrading microorganisms is a promising bioremediation approach known to enhance the clean-up of water contaminated by organic pollutants. 1,2-dichloroethane (1,2-DCA) is a toxic groundwater contaminant that can be biodegraded by specialized bacteria under aerobic and anaerobic conditions. The main catabolic pathways include the aerobic hydrolytic dechlorination, mediated by the key enzyme DhlA, carried by some Xanthobacteriaceae members. In this work we evaluated the dechlorinating potential of newly isolated aerobic 1,2-DCA-degrading consortia to be exploited in bioremediation strategies based on degrading biofilms immobilized on biodegradable scaffolds. The consortia were isolated from 1,2-DCA contaminated groundwater through enrichment cultures on mineral medium amended with 1,2-DCA as sole carbon source. Their degradation abilities were monitored by Cl- release assay and Gas Chromatography-Mass Spectrometry (GC-MS). The consortia were PCR-screened for the dhlA gene and characterized by Whole Genome Sequencing (WGS). The formation of a 1,2-DCA-degrading biofilm on biodegradable biopolymeric polylactic acid (PLA) electrospun scaffolds was assessed by Scanning Electron Microscopy and GC-MS monitoring. Four out of six stable 1,2-DCA-dechlorinating consortia, consisting of known aerobic 1,2 DCA-degrading genera (Ancylobacter, Starkeya, Xanthobacter) and others with unclear role, were immobilized on PLA scaffolds. The consortia-scaffold systems could degrade 1,2-DCA and maintain this ability after transfer into a fresh contaminated medium. A dhlA gene fragment identical to that of other known aerobic 1,2-DCA-degraders and other genes involved in the hydrolytic 1,2-DCA degradative pathway were found in all consortia. Successful immobilization on biopolymeric supports and 1,2-DCA degradation suggest the potential application of the consortia-scaffold systems as bioremediation devices.