Published in Scientific Bulletin. Series F. Biotechnologies, Vol. XXI
Written by Caterina TOMULESCU, Mişu MOSCOVICI, Bujor ALBU, Roxana STOICA, Claudia SEVCENCO, Delia JITEA, Radu TAMAIAN, Adrian VAMANU

Microbial enzymes are known to be superior to enzymes obtained from other organisms, particularly for applications in industries on commercial scales. The species of the genus Bacillus are known to be producers of enzymes of industrial interest. Among them, amylolytic enzymes have got great biotechnological applications and economic exploitations. Amylases are known to be produced by a variety of bacteria and fungi and their applications at industrial level have stimulated interest to explore their amylolytic activity in several microbes to be used as bioresources. A newly soil-isolate, identified as a Bacillus mycoides strain, was tested for its ability to produce extracellular amylase in liquid media, using multiple carbon sources and starchy substrates. Chip electrophoresis was used to obtain the electrophoretic profile of proteins derived from the bacterial isolate and a molecular weight of 60 kDa, characteristic for amylase produced by Bacillus genus, was obtained in two experimental media. Bioprocess optimization was designed using L9 and L16 Taguchi orthogonal arrays and analyzed by ANOVA statistical methods. A maximum enzymatic activity (10.44 U/ml) was determined when malt extract and ammonium sulphate, as starchy substrate and nitrogen source, were used. Optimum growth conditions were identified to be 32°C, 220 rpm and 48 hrs fermentation time, while the inoculation volume was 2%. A positive effect for amylase production was observed for citric acid and CaCl₂ interaction in the culture media.

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