DECOLORIZATION AND DETOXIFICATION OF CATIONIC BLUE 41 BY HALOTOLERANT STRAINSS. NAMWONG AND S. TANASUPAWAT
Thirty-three salt-tolerant bacteria were tested for azo dye decolorization of cationic blue (CB41). Strains C15-2 and SR5-3aw were the most efficient strains for dye removal in saline conditions. They were able to grow in a wide range of NaCl concentration (0-30%, w/v; optimally in the absence of NaCl). On the basis of the phenotypic characterization and 16S rRNA gene sequence similarities (97.0-99.9%), these strains were identified as Staphylococcus sp. strains C15-2 and Staphylococcus sp. strain SR5-3aw. Their Decolorization capability was linearly correlated to the concentration of NaCl up to 15%, w/v, while at high concentration of NaCl (250%, w/v), the decolorization rate was inversely linear. Meanwhile, the relationship between the specific decolorization rate of two Staphylococcus species with the CB41 concentration can be explained by Michaelis-Menten kinetics [Maximal velocity (Vmax) = 1.86-2.86 mg/h, Michaelis constant (Km) = 28.1-47.6 mg/ L]. The decolorization products were analyzed by Fourier transform infrared spectroscopy (FTIR), and the results represented the biotransformation of CB41 to other metabolite compounds, which were less phytotoxic than the undecolorized dye. According to rapid dye decolorization under saline conditions, these halotolerant bacteria can facilitate the improvement of biological wastewater treatment with economically and environmentally friendly processes.
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