Metabolic Mechanism of Sulfadimethoxine Biodegradation by sp. L38 and MASCC-0025.

Antibiotic resistance is one of the most important environmental challenges. Microalgae has been considered as a promising green media for environmental purification. In this work, sulfadimethoxine (SDM) biodegradation potential of sp. L38 and MASCC-0025 is investigated. Experimental results indicated that the tested freshwater and marine microalgae strains presented stress response to SDM addition. For sp. L38, it has a good adaptability to SDM condition antioxidant enzyme secretion (SOD, MDA, and CAT up to 23.27 U/mg, 21.99 μmol/g, and 0.31 nmol/min/mg) with removal rate around 88%. MASCC-0025 exhibited 100% removal of 0.5 mg/L SDM. With increasing salinity (adding a certain amount of NaCl) of cultivation media, the removal rate of SDM by microalgae increased. Although its adaptive process was slower than sp. L38, the salinity advantage would facilitate enzyme accumulation. It indicated that microalgae could be used to remove SDM from freshwater and marine environment suitable microalgae strain screening.