Optimization studies on laccase activity of Proteus mirabilis isolated from treatment sludge of textile industry factories : Optimization of laccase activity of Proteus mirabilis.

ABSTRACT

Laccase is an exothermic enzyme with copper in its structure and has an important role in biodegradation by providing oxidation of phenolic compounds and aromatic amines and decomposing lignin. The aim of this study is to reach maximum laccase enzyme activity with minimum cost and energy through optimization studies of Proteusmirabilis isolated from treatment sludge of a textile factory. In order to increase the laccase enzyme activities of the isolates, medium and culture conditions were optimized with the study of carbon (Glucose, Fructose, Sodium Acetate, Carboxymethylcellulose, Xylose) and nitrogen sources (Potassium nitrate, Yeast Extract, Peptone From Soybean, Bacteriological Peptone), incubation time, pH, temperature and Copper(II) sulfate concentration then according to the results obtained. Response Surface Method (RSM) was performed on six different variables with three level. According to the data obtained from the RSM, the maximum laccase enzyme activity is reached at pH 7.77, temperature 30.03oC, 0.5 g/L CuSO4, 0.5 g/L fructose and 0.082 g/L yeast extract conditions. After all, the laccase activity increased 2.7 times. As a result, laccase activity of P. mirabilis can be increased by optimization studies. The information obtained as a result of the literature studies is that the laccase enzymes produced in laboratory and industrial scale are costly and their amounts are low. This study is important in terms of obtaining more laccase activity from P.mirabilis with less cost and energy.