The increasing worldwide contamination of freshwater systems with thousands of emerging contaminants is one of the key environmental problems facing humanity. Levofloxacin (LEV), a fluoroquinolone antibiotic is causing serious aquatic pollution due to its ubiquitous distribution and ecotoxicological effects on aquatic microbiota and human beings. This study demonstrated the enhanced biodegradation of LEV by an acclimated, freshwater microalga, Chlorella vulgaris in the presence of elevated salinity. Among the six wild species (Chlamydomonas mexicana, Chlamydomonas pitschmannii, Chlorella vulgaris, Ourococcus multisporus, Micractinium resseri, Tribonema aequale), C. vulgaris showed the highest removal capacity (12%) of LEV at 1 mg L−1. The acclimated C. vulgaris, which was pre-exposed to 200 mg L−1 LEV for 11 days, exhibited enhanced removal of 1 mg LEV L−1 by 16% after 11 days of cultivation. The addition of 1% (w/v) sodium chloride into the media significantly improved removal of LEV by &gt;80% in the C. vulgaris culture. The bioaccumulation of LEV at day 11 in C. vulgaris cells without NaCl was 34 μg g−1, which was elevated to 101 μg g−1 LEV at 1% NaCl. The bioconcentration factor for LEV was 34 and 1,004 in 0 and 1% NaCl, respectively. The mass balance analysis of LEV showed that more than 90% of LEV was biodegraded by C. vulgaris at day 11 with the addition of 1% NaCl. These results demonstrated that the enhanced removal of LEV by salinity was mainly through bioaccumulation and subsequent intracellular biodegradation by C. vulgaris cells.

Biodegradation of fluoroquinolone antibiotic from aqueous media by an acclimated green microalgae Chlorella vulgaris

253rd National Meeting (2017)

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