Degradation of tetracycline, oxytetracycline & ampicillin by purified multiple copper oxidase like laccase from Stentrophomonas sp. YBX1

Multiple copper oxidase (MCO) like laccase is widely distributed in higher plant, fungi and bacteria. This study identified MCO like laccase producing bacterium isolated from a wastewater treatment plant based on 16S rRNA sequence analysis, and they were further confirmed by phylogenetic reconstruction. Biochemical and gene characterization of MCO like laccase from Stenotrophomonas sp. YBX1 is presented. Purification of MCO like laccase was carried out by ion exchange HQ Trap column and followed by gel filtration spheracryl S-100 column. The purified MCO like laccase from Stenotrophomonas sp. YBX1 shows a total activity of 1252 units and specific activity 391.2 U/mg and protein concentration 0.32 mg/mL. In SDS PAGE, the approximate molecular mass was found at 66 kDa and further confirmed from an MS spectrum of MALDI-TOF. The purified MCO like laccase is capable of degradation of antibiotics such as tetracycline completely, whereas oxytetracycline (78%) and ampicillin (62%) degraded within 96 min without any redox mediators at pH 5 and 30 ºC. Its degradation pathway was based on identification of metabolites by LC-MS spectrum. The enzymatic degradation may be used in advanced treatment of antibiotics containing wastewater.