Isolation, characterization, and optimization of extracellular laccase-producing bacteria from dye-contaminated...

Textile industries are important in both the global economy and our daily lives. They are, however, simultaneously becoming one of the main sources of environmental pollution in the world. It needs a greater amount of water for wet textile operations such as dyeing, and as a result, produces significant dosages of wastewater. Textile wastewater is highly colorful and contains dyes that are highly harmful to living creatures, and is discharged to the environment every day. The objective of the present study was to isolate and characterize extracellular laccase-producing bacteria from textile dye-contaminated wastewater to decolorize the dye. Samples were collected from the dye-contaminated wastewater sample site, including dye centers (DC), dye printing (DP), dye mixers (DM), and dye drains (DD). To isolate extracellular laccase producing bacteria from dye contaminated wastewater sample, 1 ml of sample was taken and serially diluted in physiological saline solution. Then, 0.1 ml from each diluted test tube was spread over nutrient agar and incubated. Then, the colonies were sub-cultured. Ten bacterial isolates were identify and designated as DMC1, DMC2, DMC3, DMG3, DMW1, DMY, DDY, DPG, DPC, and DCC. These bacterial isolates were tested for laccase production, and only four of them (DMC2, DMC3, DMG3, and DMW1) gave a positive result. Using morphological and biochemical characters, the four isolate were identified as a presumptive Bacillus species. Laccase production by isolates was optimized, and Maximum laccase production and dye decolonization were achieved at pH 7, a temperature of 42°C, and a dye concentration of 0.05 g per 50 mL of culture mediumTherefore, the enzyme produced, using the potential strain is capable of decolorizing textile dyes (black, yellow, and red). As a result, crude laccase enzyme from these bacterial isolates could be employed since a viable alternative to the physical and chemical processes of textile dye, as they have a high potential for decolorizing the dyes in this study. Scale up the production of laccase enzyme at certain industrial level is significant. Laccase enzyme should be purified whenever possible. Furthermore, molecular identification can be used to correctly identify up to strain level. The information gathered in this study could be used as a baseline for treating dye-polluted and contaminated environments.