Biodegradation of weathered polystyrene films in seawater microcosms

Abstract

A microcosm experiment was conducted at two phases in order to investigate the ability of indigenous consortia alone or bioaugmented to degrade weathered polystyrene (PS) films under simulated marine conditions. Viable populations were developed on PS surfaces in a time dependent way towards convergent biofilm communities, enriched with hydrocarbon and xenobiotics degradation genes. Members of Alphaproteobacteria and Gammaproteobacteria were highly enriched in the acclimated plastic associated assemblages while the abundance of plastic associated genera was significantly increased in the acclimated indigenous communities. Both tailored consortia efficiently reduced the weight of PS films. Concerning the molecular weight distribution, a decrease in the number-average molecular weight of films subjected to microbial treatment was observed. Moreover, alteration in the intensity of functional groups was noticed with Fourier transform infrared spectrophotometry (FTIR) along with signs of bio-erosion on the PS surface. The results suggest that acclimated marine populations are capable of degrading weathered PS pieces.

Rapid Physicochemical Changes in Microplastic Induced by Biofilm Formation

“…Such a band is particularly prominent in our PS Water spectra but also visible in the Biofilm samples of PS and PP. In addition to this band, Syranidou et al (2017) observed a broad band between 1,500 and 1,350 cm −1 for one of the weathered PS samples, which was absent in our samples. Taken together, our results indicate surface modifications of the PP and PS Biofilm samples that differ from those observed for the respective Water samples.…”

“…The reported maximum was at 1,735 or 1,712 cm −1 , which is different from the band positions observed in our study, which might be related to differences in both biotic and abiotic conditions. In fact, exposure to polymerdegrading microbes reduced at least some of the spectral changes caused by polymer degradation in PP (Auta et al, 2018) and PS (Syranidou et al, 2017). Moreover, in the latter study a broad band in the 1,200-900 cm −1 spectral range for one the of the weathered PS samples was reported.…”

“…Likewise, the carboxylic acid species absorbing near 1,710 cm-1 (Adams, 1970;Geuskens and Kabamba, 1982;Lacoste et al, 1993) was not detected. Degradation-induced changes near 3,400, 1,730, and 1,640 cm −1 have been reported for PP (Adams, 1970;Geuskens and Kabamba, 1982;Lacoste et al, 1993;Philippart et al, 1999;Cooper and Corcoran, 2010;Xiong et al, 2017;Auta et al, 2018) and PS (Syranidou et al, 2017) but one should keep in mind that spectral pattern and, therefore, the degradation products are condition-dependent. Isotactic PP that was exposed at different geographic locations showed vinyl bands near 1,630 cm −1 , carbonyl bands with maxima between 1,730 and 1,720 cm −1 , and a shoulder at higher wavenumbers (Xiong et al, 2017).…”

Ability of Trichoderma hamatum Isolated from Plastics-Polluted Environments to Attack Petroleum-Based, Synthetic Polymer Films

“…PS was highly resistant to biodegradation by T. hamatum, the degradation rate after two months being only 0.9% (w/w) ( Table 3). The extremely low degradability of PS is in agreement with the reports of other authors [41].…”

“…PS was highly resistant to biodegradation by T. hama being only 0.9% (w/w) ( Table 3). The extremely low de reports of other authors [41].…”