Reduce, reuse and recycle programs are important, but are not enough to address the massive plastic pollution problem facing our planet, and thus this research is focused on the biodegradation of plastics found in our environment. Toward creating a more circular plastic economy, investigators previously isolated a consortium of bacterial species, five in total, that degrade polyethylene terephthalate (PET), the material used to make plastic water bottles. Collectively, the consortium grew faster on, and produced more plastic-degrading enzyme activity than individual consortia or species alone. Researchers will determine the genetic and biochemical basis for these observations. The collaborative project will provide undergraduate and high school students research opportunities aimed at accomplishing the project?s goals. First generation and underrepresented minority students will be recruited for this exciting set of projects, with funding for summer research, and continued effort during the academic year. The genetic basis for bacterial degradation of PET also will be investigated in the laboratory portion of a general microbiology course, enriching the curriculum.
Synergistic degradation of PET plastic by soil bacteria is unexplored, but has the potential to aid in the removal of a portion of the estimated 6.3 billion metric tons that currently exist in our environment. Three Pseudomonas and two Bacillus spp. were isolated from petroleum polluted soils near Houston, TX, by screening for lipase activity, which has been associated with plastic degradation. The consortium of five bacterial species act synergistically, producing more lipase activity and degrading PET plastic faster than individual consortia or strains. Investigators will mine the genomes of the five bacteria to understand the metabolic pathways necessary for biodegradation of PET, aided by the KEGG pathways database, and will use NMR to identify byproducts, correlating these data with genetic information. Secreted enzymes will be identified using spectrometry techniques. Transposon mutagenesis, an unbiased approach will determine the genetic basis for expression and secretion of lipases, esterases, and biofilm formation necessary for PET degradation. Investigators will also dissect the genetic regulatory network, using RNA sequencing, of the consortium bacteria required for ester bond cleavage and the complete degradation of the monomers terephthalic acid and ethylene glycol, with the ultimate goal of reducing PET waste on land and in our oceans.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
