Optimization studies on laccase activities of bacteria isolated from paper and textile industry factories treatment sludge

The aim of this study is to determine the laccase enzyme activities of bacteria which isolated from wastewater and treatment sludges of different paper and textile factories and to reach maximum enzyme activity with minimum cost and energy with optimization studies. In this purpose, 78 isolates isolated from 5 different textile and paper factory wastewater and biological treatment sludge from 3 different cities in our country were screened for the presence of laccase enzymes and the 8 isolates with the highest activity were determined. Of these 8 strains, whose laccase activity was determined by spectrophotometric methods, 2 isolates with the highest activity were selected for further studies. After various tests to determine the morphology of the selected isolates, molecularbased techniques were applied and one of the isolates was identified as Proteus mirabilis with 99.71% similarity and the other as Bacillus atrophaues with 99.71% similarity in the NCBI database. In order to increase the laccase enzyme activities of the isolates, carbon source (Glucose, Fructose, Sodium Acetate, CMC, Xylose), nitrogen source (KNO3, Yeast Extract, Pepton From Soybean, Bacteriological Peptone), CuSO4 concentration (0.5mM, 1mM, 1.5mM), pH (5, 6, 7, 8, 9, 10, 11), temperature (17°C, 27°C, 37°C, 47°C), incubation time (12, 24, 36, 48, 60, 72, 96th hours), inoculum amount (0.5%, 1%, 1.5%, 2%), medium and culture conditions were optimized, and according to the results obtained, Response Surface Method, which is a statistical optimization method, was performed in 6 different variables and 3 in each variable level has been applied. According to the data obtained from the response surface method, when the pH is 7.77, the temperature is 30.030C, 0.5% CuSO4, the inoculum amount is 1.5%, the fructose amount is 5 g for 1000 ml medium, the yeast extract amount is 0.82 g for 1000 ml medium taken, it can obtain maximum laccase enzyme activity from Proteus mirabilis and when pH 8, temperature 35.28 0C, 1.5% CuSO4, inoculum amount 0.5%, fructose amount 3.7 g for 1000 ml medium, yeast extract amount 1.08 g for 1000 ml medium taken it can obtain maximum laccase enzyme activity from Bacillus atrophaeus.