This study reports on the evaluation of biodegradation and biosorption mechanism of indigenous bacteria on azo dye decolorization. The bacterial strains were screened for their ability in decolorizing of selected toxic azo dyes in aqueous solution. Lysinibacillus fusiformis W1B6 showed the highest decolorizing of about 96% of methyl red within 2 h, with the specific growth rate of 0.273/h. The optimum decolorization under aerobic condition was achieved at pH 7.5, 30 ± 2°C, inoculum 10% (v/v), and initial dye concentration of 100 mg/L. Spectrum analysis confirmed biodegradation as the principal mechanism of decolorization, although biosorption also occurred. Extracellular and intracellular azoreductase, laccase, and lignin peroxidase plays a role in the oxidoreductive mechanism of decolorization. The absorption isotherms fitted with the Langmuir equation and the reaction kinetics of methyl red decolorization followed a pseudo first-order.

中文翻译：

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Lysinibacillus fusiformis W1B6 对选定偶氮染料的脱色：生物降解优化、等温线和动力学研究生物吸附机制

本研究报告了土著细菌对偶氮染料脱色的生物降解和生物吸附机制的评价。筛选细菌菌株对水溶液中选定的有毒偶氮染料脱色的能力。Lysinibacillus fusiformis W1B6在2 h内对甲基红的脱色率最高，约为96%，比增长率为0.273/h。pH 7.5、30±2°C、接种量10% (v/v)、初始染料浓度100 mg/L时，在好氧条件下达到最佳脱色效果。光谱分析证实生物降解是脱色的主要机制，尽管也发生了生物吸附。细胞外和细胞内偶氮还原酶、漆酶和木质素过氧化物酶在脱色的氧化还原机制中起作用。