Biodegradation of tetracycline antibacterial using green algal species collectedfrom municipal and hospital effluents

In the present study biodegradation of oxytetracycline (OTC), doxycycline (DC), chlortetracycline (CTC) and tetracycline (TC) using algal species collected from municipal and hospital waste water was studied using microcosm experiments. Changes in antibiotic concentration were determined using reversed phase HPLC. The results show that algal species, Haematoloccus pluvialis, Chlorella sp,(hospital waste water) Selenastrum capricornutum and Pseudokirchnerilla subcapitata (municipal waste water) degrade tetracycline antibiotics. The order of degradation was DC > OTC > CTC > TC. Results are explained in terms of a two compartmental model consisting of free and adsorbed form with initial fast degradation rate constants ranging from 1.1 x 10-3 to 3.7 x 10-2 mg L-1 day-1. The corresponding slow degradation rate attributed to degradation of the bound form was not significantly different from zero, t-test p = 0.05 showing non degradability. TC results could not be explained using a two compartmental model. The results followed monophasic kinetics with slow degradation rates ranging from 1.3 x 10-4 to 9.0 x 10-3 mg L-1 day-1. H. pluvialis, S. capricornutum and P. subcapitata were better candidates than chlorella sp.