A proteomic, reverse-genetic and sequencing approach to reveal genes and enzymes for LAS-surfactant degradation in bacterial communities

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The complete biodegradation of industrial chemicals can impose great challenges to environmental microbial communities. One prominent example is the mineralization of xenobiotic laundry surfactant LAS (linear alkylbenzene sulfonate; sec. 4-sulfophenyl alkane). Commercial LAS is a complex mixture of isomers, and its mineralization is accomplished by heterotrophic bacterial communities (LAS-community) in two tiers: bacteria in the first tier utilize the LAS-alkyl chains for growth and convert LAS to short-chain SPCs (sulfophenyl carboxylates); bacteria in the second tier mineralize these SPCs. To date, the complete LAS and SPC pathways and the genes and enzymes involved remain unknown, as well as the phylogenetic composition of the LAS-community, e.g. in sewage treatment plants. Now, a three-member, genome-sequenced ‘model LAS-community’ is available, Parvibaculum lavamentivorans DS-1 (first tier) with Comamonas testosteroni KF-1 and Delftia acidovorans SPH-1 (second tier). This allows for renewed attack on understanding LAS- and SPC-degradation, through a proteomic and reverse-genetic approach. The exploration is expected to deliver insight into the evolution of these important, novel degradation pathways, and, e.g., discover novel P450 monooxygenases and Baeyer-Villiger-type monooxygenases. However, the ‘model LAS-community’ mineralizes only a subset of the many SPCs generated from commercial LAS. Hence, the environmental community needed to catalyze the complete degradation of commercial LAS is expected to be much more complex, but this has never been demonstrated. Therefore, also the environmental LAS-community will be explored, firstly, for its phylogenetic complexity, and secondly, for the abundance and diversity of key genes for LAS- and SPC-degradation, through a massively-parallel sequencing approach.