Project title: Bioplastics interactions with microbial communities along the fresh and saltwater interface
Summary: The biggest advantage of plastics, being durable, is also their biggest problem. With improper waste disposal it builds up in the environment as their durability outweighs their intended service life. To address this problem, bioplastics emerged. Given that their production has been increasing exponentially, 1.2 million tonnes manufactured in 2020, it is expected that their input into aquatic environments augments too. To date, very little is known about their impact on the environment. Studies on their biodegradability have almost solely been led under controlled laboratory conditions. Whether biodegradable bioplastics might actually biodegrade in the natural environment remains enigmatic. Furthermore, studies have shown how microbial communities associated with plastics may have biogeochemical activities that differ from their surrounding ecosystem. Biofouling may also affect their density and buoyancy, and therefore their transport into the environment. Additionally, the plastisphere might be composed of pathogens or harmful algal blooms using plastics as a vector. Hence, investigating microbial communities associated with these new bioplastics is a key issue to assessing their fate and ecological impact. Whilst plastics accumulation is well documented, knowledge about their interaction with microorganisms is scanty, with even smaller attention being devoted to biodegradable bioplastics.
The aim of this PhD research is to look at the interactions between microbial communities and biodegradable bioplastics in comparison with conventional plastics in aeras of intense pollutant accumulation and physicochemical changes: estuaries. Particularly, the biofilms’ diversity, abundance, dynamic and metabolic activity associated with bioplastics will be revealed along salinity gradients, and oxygenated levels. Those goals will be reached with field sampling, long term in situ and mesocosms experiments and with methods such as 16S rRNA gene sequencing, gas chromatography, scanning electron microscopy and metagenomic/transcriptomic analyses.