A laundry detergent compatible lichenase: Statistical optimization for production under solid state fermentation on crude millet

The optimization of lichenase production by Bacillus sp. UEB-S in solid state fermentation (SSF) with millet as solid support, was carried out using response surface methodology (RSM) based on Doehlert design.Four variables (inoculum volume, millet-to-moisture ratio temperature and duration of fermentation) were regarded as factors in the optimization process.The maximum enzyme activity predicted by the model was 684 ± 90 U/g of dry substrate when using 1.5 × 109 CFU/g as inoculation level and 6.16:1 (mL/g) as moisture ratio, for 4.6 days of cultivation at 35 °C. Using these conditions, 503 U/g of enzyme activity was experimentally obtained, which is in agreement with the predicted one (525 ± 76 U/g). The enzyme was stable toward non-ionic surfactants and oxidizing agents. In addition, it showed a good stability and compatibility with a wide range of commercial solid detergents suggesting that lichenase from UEB-S is a potential candidate in detergent formulation.

► We used statistical approach to optimize lichenase production.
► We tested solid state fermentation process on crude millet.
► We obtained useful amounts of lichenase.
► We showed the stability of lichenase with oxidizing agents.
► We tested the compatibility with commercial detergent.