Biodiversity of Microorganisms Colonizing the Surface of Polystyrene Samples Exposed to Different Aqueous Environments

Tatyana Tourova,Denis Grouzdev,Anatoly Laptev,Tamara Nazina,Eugeni Kurshev,Diyana Sokolova

doi:10.3390/su12093624

Abstract

The contamination of marine and freshwater ecosystems with the items from thermoplastics, including polystyrene (PS), necessitates the search for efficient microbial degraders of these polymers. In the present study, the composition of prokaryotes in biofilms formed on PS samples incubated in seawater and the industrial water of a petrochemical plant were investigated. Using a high-throughput sequencing of the V3–V4 region of the 16S rRNA gene, the predominance of Alphaproteobacteria (Blastomonas), Bacteroidetes (Chryseolinea), and Gammaproteobacteria (Arenimonas and Pseudomonas) in the biofilms on PS samples exposed to industrial water was revealed. Alphaproteobacteria (Erythrobacter) predominated on seawater-incubated PS samples. The local degradation of the PS samples was confirmed by scanning microscopy. The PS-colonizing microbial communities in industrial water differed significantly from the PS communities in seawater. Both communities have a high potential ability to carry out the carbohydrates and amino acids metabolism, but the potential for xenobiotic degradation, including styrene degradation, was relatively higher in the biofilms in industrial water. Bacteria of the genera Erythrobacter, Maribacter, and Mycobacterium were potential styrene-degraders in seawater, and Pseudomonas and Arenimonas in industrial water. Our results suggest that marine and industrial waters contain microbial populations potentially capable of degrading PS, and these populations may be used for the isolation of efficient PS degraders.

Highlights

Polystyrene (PS) is a high-molecular-mass synthetic glassy polymer with a linear structure, which is produced industrially by styrene radical polymerization
The chemical oxygen demand (COD) of industrial water decreased in the course of incubation from 103 to 72 mg O2/dm3, which indicated a gradual removal of harmful contaminants from the recycling water during this period
Members of Alphaproteobacteria, Gammaproteobacteria, and Bacteroidetes predominated in biofilms on PS in both aquatic habitats, while Planctomycetes were better represented in seawater

Summary

Introduction

Polystyrene (PS) is a high-molecular-mass synthetic glassy polymer with a linear structure, which is produced industrially by styrene radical polymerization. Out of 61.8 Mt of plastics produced in Europe in 2018, PS production accounted for ~18 Mt [1]. The large scale of PS production and its resistance to biodegradation results in the contamination of freshwater and marine ecosystems with this plastic [2,3,4,5]. In 2015, the global plastic pollution of the oceans was estimated to weigh between. 93,000 and 236,000 metric tons [3] These results are larger than the global estimates by Eriksen et al [4] but account for ~1% of the plastic input to the ocean, which weighed 4.8–12.7 million metric tons in 2010 alone, according to Jambeck et al [5]. A potential environmental risk of contamination of marine and freshwater ecosystems with plastics has been reported [6]

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