Culture dependent analysis of bacterial activity, biofilm-formation and oxidative stress of seawater with the contamination of microplastics under climate change consideration.

Temperature changes due to climate change and microplastic contamination are worldwide concerns, creating various problems in the marine environment. Therefore, this study was carried out to discover the impact of different temperatures of seawater exposed to different types of plastic materials on culture dependent bacterial responses and oxidative characteristics. Seawater was exposed to microplastics obtained from various plastic materials at different temperature (-18, +4, +20, and +35 °C) for seven days. Then microplastics were removed from the suspension and microplastic-exposed seawater samples were analyzed for bacterial activity, biofilm formation and oxidative characteristics (antioxidant, catalase, glutathione, and superoxide dismutase) using Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus. The results showed that the activity and biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus were affected through oxidative stress by catalase, glutathione, and superoxide dismutase due to the microplastic deformation by temperature changes. This study confirms that temperature changes as a result of climate change might influence microplastic degradation and their contamination impact in seawater in terms of bacterial metabolic and oxidation reactions.

Oxidative stress, biofilm-formation and activity responses of P. aeruginosa to microplastic-treated sediments: Effect of temperature and sediment type.

Climate change and plastic pollution are the big environmental problems that the environment and humanity have faced in the past and will face in many decades to come. Sediments are affected by many pollutants and conditions, and the behaviors of microorganisms in environment may be influenced due to changes in sediments. Therefore, the current study aimed to explore the differential effects of various microplastics and temperature on different sediments through the metabolic and oxidative responses of gram-negative Pseudomonas aeruginosa. The sediments collected from various fields including beaches, deep-sea discharge, and marine industrial areas. Each sediment was extracted and then treated with various microplastics under different temperature (-18, +4, +20 and 35 °C) for seven days. Then microplastics were removed from the suspension and microplastic-exposed sediment samples were incubated with Pseudomonas aeruginosa to test bacterial activity, biofilm, and oxidative characteristics. The results showed that both the activity and the biofilm formation of Pseudomonas aeruginosa increased with the temperature of microplastic treatment in the experimental setups at the rates between an average of 2-39 % and 5-27 %, respectively. The highest levels of bacterial activity and biofilm formation were mainly observed in the beach area (average rate +25 %) and marine industrial (average rate +19 %) sediments with microplastic contamination, respectively. Moreover, oxidative characteristics significantly linked the bacterial activities and biofilm formation. The oxidative indicators of Pseudomonas aeruginosa showed that catalase and glutathione reductase were more influenced by microplastic contamination of various sediments than superoxide dismutase activities. For instance, catalase and glutathione reductase activities were changed between -37 and +169 % and +137 to +144 %, respectively; however, the superoxide dismutase increased at a rate between +1 and + 21 %. This study confirmed that global warming as a consequence of climate change might influence the effect of microplastic on sediments regarding bacterial biochemical responses and oxidation characteristics.

A characterization and an exposure risk assessment of microplastics in settled house floor dust in Istanbul, Turkey.

The presence of microplastics in the indoor environment presents growing environmental and human health risks because of their physicochemical and toxic characteristics. Therefore, we aimed to isolate, identify, and characterize plastic debris in settled house floor dusts. This study is a rare study which assess the risks of plastic debris in settled house dust through multiple approaches including the estimated daily intake, pollution loading index, and polymer hazard index. The results indicated that polyethylene and polypropylene were the predominate polymer type of plastic debris in settled house dust with various shapes and colors. The risk assessment results also indicated the serious impact of microplastics in terms of extremely dangerous contamination as well as the fact that they present a polymer hazard. Results indicated that humans have a higher risk of exposure to microplastics via ingestion rather than inhalation. In addition, infants had a higher risk of potential intake compared to other age groups.