While several research groups are utilizing purified enzymes to break down postconsumer PET to the monomers TPA and ethylene glycol to produce new PET products, here, we present a group of five soil bacteria in culture that are able to partially degrade this polymer. To date, mixed Pseudomonas spp. and Bacillus spp. biodegradation of PET has not been described, and this work highlights the possibility of using bacterial consortia to biodegrade or potentially to biorecycle PET plastic waste.

Bioaugmentation is a possible remediation strategy for the massive amounts of plastic waste in our oceans and landfills. For this study, soil samples were collected from petroleum polluted locations in the Houston, Texas area to isolate microorganisms capable of plastic degradation.Bacteria were propagated and screened for lipase activity, which has been associated with the bacterial degradation of some plastics to date. We identified three lipase-positive Pseudomonas species, and Bacillus cereus as part of two consortia, which we predict enhances biofilm formation and plastic degradation. Lipase-positive consortia bacteria were incubated alongside blank and E.coli controls with UV-irradiated polyethylene terephthalate (PET), high-density polyethylene (HDPE), or low-density polyethylene (LDPE) as sole sources of carbon. Surface degradation of PET plastic was quantified by changes in molecular vibrations by infrared spectroscopy. The bacteria formed biofilms on PET, observed by scanning electron microscopy, and induced molecular changes on the plastic surface, indicating the initial stages of plastic degradation. We also found molecular evidence that one of the Pseudomonas isolates degrades LDPE. To date, lipase positive Pseudomonas spp. degradation of PET has not been well described, and this work highlights the potential for using consortia of common soil bacteria to degrade plastic waste.

Aims:  To investigate the morphological and chemical changes in attached cells of Pseudomonas aeruginosa (ATCC 14886) at different stages of biofilm development on two different types of substrata. Methods and Results:  The development of primary biofilm on aluminium plates representing metals and on CaF2 discs representing dielectric materials was monitored by FTIR microscopy, ESEM, EDAX and protein analysis by SDS‐PAGE. A unique cellular feature similar in morphology to pili was observed on the surface of P. aeruginosa adhering on aluminium but not on CaF2. Results derived from FTIR analysis confirm on both substrata the successive importance of polysaccharides and proteins during the biofilm development. These results also revealed that the increase of the ratio of carboxylates to amide I was higher with the aluminium plates than with the CaF2 discs. The number of cells adhered and the amount of oxygen incorporated in adhered cells on the latter materials were, respectively, less and almost nil in comparison with the former. Protein analysis of the lysates of cells by SDS‐PAGE revealed that expression of one protein with a molecular weight of 45 kDa, was greatly enhanced in attached cells on both substrata. However, expression of another protein with molecular weight of 35 kDa was up‐regulated only in cells adhering on CaF2 but not in those on aluminium. Conclusion:  Depending on the nature of the surface, new proteinaceous complexes and cellular features were formed in the attachment process of P. aeruginosa. Significance and Impact of the Study:  The pattern of P. aeruginosa cells adhering onto CaF2 discs and aluminium plates is different. Formation of biofilm is more difficult on CaF2 than on aluminium.