Toxicological Effects of Microplastics and Sulfadiazine on the Microalgae Chlamydomonas reinhardtii

Abstract

Despite the fact that microplastics (MPs) facilitate the adsorption of environmental organic pollutants and influence their toxicity for organisms, more study is needed on the combination of MPs and antibiotics pollutant effects. In this study, polystyrene MPs (1 and 5 μm) and sulfadiazine (SDZ) were examined separately and in combination on freshwater microalga, Chlamydomonas reinhardtii. The results suggest that both the MPs and SDZ alone and in combination inhibited the growth of microalgae with an increasing concentration of MPs and SDZ (5–200 mg l–1); however, the inhibition rate was reduced by combination. Upon exposure for 7 days, both the MPs and SDZ inhibited algal growth, reduced chlorophyll content, and enhanced superoxide dismutase (SOD) activities, whereas glutathione peroxidase (GSH-Px) activity was elevated only with the exposure of 1 μm MPs. Fluorescence microscopy and scanning electron microscopy also indicated that particle size contributed to the combined toxicity by aggregating MPs with periphery pollutants. Further, the amount of extracellular secretory protein increased in the presence of MPs and SDZ removal ratio decreased when MPs and SDZ coexisted, suggesting that MPs affected SDZ metabolism by microalgae. The particle size of microplastics affected the toxicity of MPs on microalgae and the combined effect of MPs and SDZ could be mitigated by MPs adsorption. These findings provide insight into microalgae responses to the combination of MPs and antibiotics in water ecosystems.

Effects of Polystyrene Microparticles on Growth and Physiological Metabolism of Microalgae Scendesmus obliquus

“…When faced with external stress, SOD is rapidly activated to mitigate the ROS as ROS accumulation. Low levels of ROS can regulate multiple physiological and biochemical reactions in cells; however, ROS is evidently toxic to organisms at high concentrations [34,46]. In this experiment, the SOD activity of microplastic-treated algal cells exhibited a pattern of initial increase followed by a subsequent decrease.…”

Impacts of Microplastics on Photosynthetic Efficiency and Pigment Composition in Chlorella pyrenoidosa

“…The dose-response analysis demonstrates a noticeable pattern in which higher concentrations of microplastics result in significant disruptions in photosynthetic efficiency (Tunali M et al, 2020), as indicated by the decreasing Fv/Fm ratios. This ratio is a crucial measure of the highest possible quantum efficiency of photosystem II (PSII), which is necessary for the light-dependent processes of photosynthesis (Li Z et al, 2022). A decrease in Fv/Fm indicates that microplastics may be causing physical harm to the photosynthetic equipment or triggering oxidative stress that hampers the functioning of PSII (Wu D, 2021).…”

“…PE microplastics commonly arise from the decomposition of items such as plastic bags, bottles, and films through physical, chemical, and photo-degradation mechanisms (Govindan N et al, 2021). Microplastics possess notable attributes of flexibility and durability, enabling them to endure in the environment for prolonged durations (Li Z et al, 2022). Conversely, microplastics from consumer items such as foam packing, cups, and food containers are the usual source of PS microplastics.…”

The Microalgae <em>Chlamydomonas </em>for Bioremediation and Bioproduct Production

“…Among these, Chlamydomonas has demonstrated high efficiency with the following compounds: Chlamydomonas sp. with 7-amino-cephalosporanic acid [84], C. mexicana with enrofloxacin [85], and C. reinhardtii with carbamazepine, ciprofloxacin, erythromycin, estrone, norfloxacin, ofloxacin, paracetamol, progesterone, roxithromycin, salicylic acid, sulfadiazine, sulfadimethoxine, sulfametoxydiazine, sulfamethazine, triclocarban, triclosan and trimethoprim [86], sulfadiazine [87] and ibuprofen [88]. C. reinhardtii has been found to biotransform antibiotics like azithromycin, erythromycin, and sulphapyridine [89].…”