A New Raw-Starch-Digesting alpha-Amylase: Production Under Solid-State Fermentation on Crude Millet and Biochemical Characterization

A new Bacillus strain degrading starch, named Bacillus sp. UEB-S, was isolated from a southern Tunisian area. Amylase production using solid-state fermentation on millet, an inexpensive and available agro-resource, was investigated. Response surface methodology was applied to establish the relationship between enzyme production and four variables: inoculum size, moisture-to-millet ratio, temperature, and fermentation duration. The maximum enzyme activity recovered was 680 U/g of dry substrate when using 1.38 x 10(9) CFU/g as inoculation level, 5.6:1 (mug) as moisture ratio (86%), for 4 days of cultivation at 37 degrees C, which was in perfect agreement with the predicted model value. Amylase was purified by Q-Sepharose anion-exchange and Sephacryl S-200 gel filtration chromatography with a 14-fold increase in specific activity. Its molecular mass was estimated at 130 kDa. The enzyme showed maximal activity at pH 5 and 70 degrees C, and efficiently hydrolyzed starch to yield glucose and maltose as end products. The enzyme proved its efficiency for digesting raw cereal below gelatinization temperature and, hence, its potentiality to be used in industrial processes

Evaluation of dough rheological properties and bread texture of pearl millet-wheat flour mix

This study was undertaken with the objective of formulating composite bread using pearl millet (Pennisetum glaucum) and wheat (Triticum aestivum) flours . Rheological and bread making properties of composite flours were evaluated. Mixolab results revealed torque increased and dough stability time decreased upon incorporation of pearl millet flour in wheat flour. The incorporation of millet flour at optimum level (5 %) led to an increase of the dough strength (W) and the elasticity-to-extensibility ratio (P/L) by 31 % and 65 % respectively. The bread texture and volume were also improved. These findings indicated the potentiality of using millet flour in bread making

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 x 10(9) CFU/g as inoculation level and 6.16:1 (mL/g) as moisture ratio, for 4.6 days of cultivation at 35 degrees 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. (C) 2012 Elsevier B.V. All rights reserved