Exploring putative plastic degrading microorganisms within the hot springs of Aotearoa–New Zealand

Abstract

Plastics are valued globally for their light weight, malleability, and durability. However, plastic’s long-lasting nature is proving to have unforeseen ramifications. Hence, mitigating this ever-amassing plastic problem has become one of the largest environmental issues in the public and scientific eye. Plastic biodegradation by microorganisms is a prominent field in the search for tangible solutions. Several microorganisms have been reported to break down polymer plastics. However, their efficiency and applicability are frequently overstated. Geothermal hot springs have been suggested as a potential source for plastic degrading microorganisms, since their thermophilic communities and thermostable enzymes could be useful in industrial applications. This project investigates Aotearoa–New Zealand hot springs across a temperature spectrum to evaluate their potential for containing plastic degrading microorganisms. The microbial communities of Te Manaroa Spring, Waikite Valley were compared with a long-term incubation experiment of buried plastic inside hot spring sediment. Select taxa (including Pseudomonas spp. and archaea) dominated across plastic types after a year of growth. Culture-based methods were used to screen for plastic degrading bacterial and fungal isolates, resulting in modified laboratory techniques for isolating plastic degrading thermophiles. Whole-genome sequencing and screening of bacterial isolates with PlasticDB revealed high levels of plastic degrading genes, even in isolates with no culture-based evidence of plastic degradation. Finally, metagenomic data from a previous study in the wider Tāupo Volcanic Zone (TVZ) revealed similar trends of putative plastic degraders across the temperature spectrum, which bodes well for future exploration in hot springs for thermophilic plastic degraders and thermostable enzymes. It is the goal of this research to contribute to the wider, rapidly expanding knowledge base of plastic degrading microorganisms as we strive for an unpolluted world.