Evaluation of olive mill wastewater as culture medium to produce lipolytic enzymes by Bacillus aryabhattai BA03

Abstract

Lipases are widely used enzymes in several industries such as chemistry, food, feed, paper, pharmaceutical and environmental. However, the industrial production of microbial lipases is related to high production costs due to the price of carbon and nitrogen sources necessary for the cultivation of microorganisms. In this study, olive mill wastewater (OMWW) was postulated as a low-cost substrate to produce lipases by Bacillus aryabhattai BA03. Thus, the influence of the pH (6, 7 and 8), the temperature (20, 27 and 37 °C), and the concentration of OMWW (undiluted, 25% or 50% (v/v) diluted) were analyzed. Furthermore, the effect of sterilization on the culture media was also evaluated in order to reduce the final cost of the process. Results showed that the use of non-sterilized or sterilized media formulated with 25% of OMWW leads to double (11.54 ± 0.09 U·mL−1) or triple (16.61 ± 0.40 U·mL−1) activity of the enzyme respectively, compared to the synthetic medium (5.86 ± 0.25 U·mL−1). However, the highest activity (28.34 ± 1.15 U·mL−1) was found at pH 8, 27 °C and 50% (w/w) of OMWW under non-sterile conditions. Therefore, it is possible to use non-sterile culture media formulated with OMWW to grow the strain and produce lipases, concomitantly with the reduction in sugars and phenols content of the final effluent.