Microbes Isolated from Landfill Soil Utilize Polyethylene Terephthalate (PET) as Their Sole Source of Carbon: An Unexplored Possibility of Bioremediation in Bangladesh

Abstract

Plastic products are so extensively used that they continue to strain the already overburdened waste management system and, inevitably, the global climate. Biodegradation is a sustainable remedy. Here, we report a few microorganisms isolated from landfill soil near Dhaka that thrive especially on polyethylene terephthalate (PET) polymers. Soil samples were subjected to three enrichment cycles that contained no carbon except PET. Pure isolates were recovered and incubated on minimal agar containing PET as the sole carbon. A morphological examination was carried out. Potential PET-degrading enzyme sequences from the isolates and other microalgae were analyzed for homology using BLASTP and TBLASTN, and multiple sequence alignment (MSA) was performed to assess conserved domains. Six isolates were obtained. Two isolates grew around the PET film but did not grow sufficiently in other areas of the minimal agar. Two other isolates with greenish pigmentation flourished around the PET film as well as on other areas of the agar. One of the green cells resembled Aphanocapsa, with irregular shapes and occasionally brown dense bodies, while the others looked round like Microcystis. Homology analysis revealed the hypothetical PETases in green cells contained the highly conserved catalytic triad (Ser-His-Asp) at the active site, as always found in alpha-beta hydrolase fold containing enzymes. Microbes isolated from two landfill sites in the vicinity of Dhaka have been adapted to utilize PET as a carbon source. In the future, sequencing and further characterization would be necessary to validate the findings. Microalgal systems demand increased focus, given their potential to offer valuable resources for bioremediation.