Sulfonamides-induced oxidative stress in freshwater microalga Chlorella vulgaris: Evaluation of growth, photosynthesis, antioxidants, ultrastructure, and nucleic acids

Abstract

Sulfadiazine (SD), sulfamerazine (SM1), and sulfamethazine (SM2) are widely used and disorderly discharged into surface water, causing contamination of lakes and rivers. However, microalgae are regard as a potential resource to alleviate and degrade antibiotic pollution. the physiological changes of Chlorella vulgaris in the presence of three sulfonamides (SAs) with varying numbers of-cH 3 groups and its SA-removal efficiency were investigated following a 7-day exposure experiment. Our results showed that the growth inhibitory effect of SD (7.9-22.6%), SM1 (7.2-45.9%), and SM2 (10.3-44%) resulted in increased proteins and decreased soluble sugars. oxidative stress caused an increase in superoxide dismutase and glutathione reductase levels but decreased catalase level. the antioxidant responses were insufficient to cope-up with reactive oxygen species (hydrogen peroxide and superoxide anion) levels and prevent oxidative damage (malondialdehyde level). the ultrastructure and DnA of SAtreated algal cells were affected, as evident from the considerable changes in the cell wall, chloroplast, and mitochondrion, and DnA migration. C. vulgaris-mediated was able to remove up to 29% of SD, 16% of SM1, and 15% of SM2. Our results suggest that certain concentrations of specific antibiotics may induce algal growth, and algal-mediated biodegradation process can accelerate the removal of antibiotic contamination. The increase in the use of antibiotics in human and veterinary medicine has raised concerns about their environmental accumulation 1. The accumulation of sulfonamides (SAs), the antibacterial agents that inhibit dihydrofolic acid synthesis, is of particular interest 2. Although the recorded environmental levels of SAs are usually within the microgram per litre range, this concentration may increase bacterial resistance and magnify toxicity via bioaccumulation in food chains 3. Considering the non-degradability of SAs, modern sewage treatment plants may be insufficient to completely remove these agents 4 , resulting in their continuous presence in aquatic environment 5. Thus, there is an urgent need to develop effective methods for SA-removal. Freshwater algae form the most abundant biomass source in aquatic environments and are known to survive under extremely hostile environments 6,7. Several studies have reported the ability of algae to effectively remove persistent organic pollutants such as pesticides 8 , phenols 9,10 , and estrogen 11,12 , and algae can uptake organic pollutants as carbon sources for their growth 7. Thus, algae are considered as a potential resource to alleviate and

The Potential of Chaetoceros muelleri in Bioremediation of Antibiotics: Performance and Optimization

“…The results specified that the protein remained moderately stable. Increasing the protein content of diatoms at low antibiotic concentrations was justified by Chen et al [54]. This increase was related to the increase in enzyme synthesis or other energy-producing fractions.…”

“…In high antibiotic concentrations, the decrease in chlorophyll and carotenoid contents was justified with the reactive oxygen species (ROS)-mediated damage to the photosystem and chlorophyll biosynthesis in microalgae. Chlorophyll of cells may be used as a protective method to reduce the accumulated ROS in chloroplasts [54].…”

The Toxic Effects of Antibiotics on Freshwater and Marine Photosynthetic Microorganisms: State of the Art

“…The toxic effects of sixteen antibiotic classes including aminoglycosides, beta-lactams, tetracyclines, and quinolones presented as median effective concentrations (EC 50 ) are based mainly on biomass endpoints, including growth inhibition and cell density. The most studied antibiotic group based on the number of records regarding EC 50 values is quinolones with 78 records, followed by tetracyclines (55 records), macrolides (58), sulphonamides (44), amphenicols (27), diaminopyrimidine and beta-lactams (26 and 27), lincosamides (15), aminoglycosides (9), quinoxalines and nitroimidazoles (3), pleuromutilins and cephalosporins (2), rifamycins (1), and oxazolidinones (1). The most studied antibiotic is oxytetracycline with 29 records on the median effective toxicity towards green algae (four), cyanobacteria (nine), and diatom (one), respectively (followed by trimethoprim (26 records), erythromycin (21), and enrofloxacin, tylosin and sulfamethoxazole (15)).…”

“…Many studies have demonstrated the reduced photosynthetic efficiency and pigment content as a result of antibiotic exposure [ 42 , 43 ]. Previous research showed that some antibiotics inhibit chlorophyll synthesis by interfering with gene expression of the chloroplast, thus disrupting the physiological process of photochemical reactions [ 44 ]. The variations in chlorophyll a fluorescence kinetics defined as O, J, I, and P steps of redox states of photosystems PSI and PSII are directly related to the efficiency of electron transfer.…”

Toxicological Effects of Microplastics and Sulfadiazine on the Microalgae Chlamydomonas reinhardtii

“…Furthermore, oxidative stress increases the activity of SOD and glutathione reductase, while decreases the activity of catalase. This made the antioxidant response inadequate to cope with the rising ROS and prevent oxidative damage ( Chen et al, 2020a ). Studies have shown that the co-occurrence of MPs and antibiotics decreases microbial activity and diversity in natural environments such as soil and nitrifying sludge, resulting in combined pollution ( Wang et al, 2020a , b ).…”