Degradation of starch-based bioplastic bags in the pelagic and benthic zones of the Gulf of Oman

Raeid M M Abed; Mahmood Al-Hinai; Yasmin Al-Balushi; Lorenz Haider; Thirumahal Muthukrishnan; Uwe Rinner

doi:10.1016/j.marpolbul.2023.115496

Degradation of starch-based bioplastic bags in the pelagic and benthic zones of the Gulf of Oman

Mar Pollut Bull. 2023 Oct:195:115496. doi: 10.1016/j.marpolbul.2023.115496. Epub 2023 Sep 12.

Authors

Raeid M M Abed¹, Mahmood Al-Hinai², Yasmin Al-Balushi², Lorenz Haider³, Thirumahal Muthukrishnan⁴, Uwe Rinner³

Affiliations

¹ Biology Department, College of Science, Sultan Qaboos University, P. O. Box: 36, PC 123 Al Khoud, Sultanate of Oman. Electronic address: rabed@squ.edu.om.
² Biology Department, College of Science, Sultan Qaboos University, P. O. Box: 36, PC 123 Al Khoud, Sultanate of Oman.
³ Institute of Applied Chemistry, IMC University of Applied Sciences Krems, Piaristengasse 1, 3500 Krems, Austria.
⁴ Department of Chemical Engineering and Applied Chemistry, University of Toronto, Ontario M5S 3E5, Canada.

PMID: 37703633
DOI: 10.1016/j.marpolbul.2023.115496

Abstract

The Gulf of Oman is becoming increasingly polluted with plastics, hence bioplastics have been considered 'a substitute', although their biodegradability in marine environments has not been well investigated. Most research has been performed on cellulose-based bioplastics, whereas starch-based bioplastics have proven to be a suitable, but less researched, alternative. This study is the first of its kind designed to investigate the degradability of two different types of starch-based bioplastic bags, available in the market and labeled as "biodegradable", in the pelagic and benthic zones of one of the warmest marine environment in the world. Fourier-Transform Infrared Spectroscopy (FTIR) showed a clear reduction in the presence of OH, CH, and CO in the bioplastic bags after 5 weeks of immersion. Thermo-Gravimetric Analysis (TGA) indicated degradation of glycerol, starch, and polyethylene. The biofouling bacterial communities on bioplastic surfaces showed distinct grouping based on the immersion zone. Candidaatus saccharibacteria, Verrucomicrobiae, Acidimicrobiia and Planctomycetia sequences were only detectable on bioplastics in the pelagic zone, whereas Actinomyces, Pseudomonas, Sphingobium and Acinetobacter related sequences were only found on bioplastics in the benthic layer. We conclude that starch-based bioplastics are more readily degradable in the Gulf of Oman than conventional plastics, hence could serve as a better environmentally friendly alternative.

Keywords: Biodegradation; Biofouling; MiSeq; Plastic pollution; Starch-based bioplastics.