Mutualistic Cross Feeding Mediated by Metabolic Intermediates and Siderophores Enhances Dibenzo--dioxin Removal.

Microbial interactions, such as cross-feeding and competition, are crucial in the bioremediation of recalcitrant organic pollution. However, information regarding the metabolic interactions and associated mechanisms during bioremediation remains scarce. This study used a bottom-up approach to illustrate how mutually beneficial cross-feeding relationships form and influence the degradation of recalcitrant organic pollutants. The synthetic bacterial consortium is comprised of a competent bacterial degrader, sp. strain p52, and a nondegrader, sp. BD6 that facilitates dibenzo--dioxin degradation. Strain p52 releases metabolic intermediates, such as catechol, during dibenzo--dioxin degradation, supporting the growth of strain BD6. Not only is strain BD6 able to compete with strain p52 for cytotoxic catechol consumption, but it is also able to secrete types of siderophores for increasing iron bioavailability that were beneficial to strain p52. The microbial consortium regulates the transcriptional activities of genes involved in dibenzo--dioxin catabolism and siderophore synthesis and transport in strains p52 and BD6, conferring a survival advantage. Thus, based on an externalized metabolic intermediate and shared siderophores, a mutualistic metabolic cross-feeding relationship is established between strains p52 and BD6. This study provides insights into the specific mechanisms underlying microbial mutualistic metabolic cross-feeding and the role of siderophores in microbial interactions.