Optimization of spray-drying conditions for obtaining Bacillus sp. SMIA-2 protease powder

Microbial proteases, especially from Bacillus spp., have enormously been exploited for a broad variety of applications such as for physiological processes, food and feedstuff, detergents, as well as in the pharmaceutical and leather. In this work, proteases produced by the thermophilic Bacillus sp. SMIA-2 submerged cultures were spray-dried in an attempt to improve its stability for applications in industry. The enzymatic extract was dried using drying adjuvants, and optimal conditions for preserving enzymatic activity were studied following a statistical experimental design. The spray process factors studied were the drier air inlet temperature and the adjuvants concentrations. The responses analyzed were the enzymatic activity and mass recovered of the powder after spray drying. Additionally, the stability of the powder was assessed during 180 days at room temperature. The results revealed that satisfactory levels of enzymatic activity were obtained when 0.5% (w/v) carboxymethylcellulose and 1.0% (w/v) maltodextrin were incorporated to enzymes solutions and the spray drier inlet temperature was 110 oC. Furthermore, this dried protease extracts showed potential for future commercial applications because of their stability at room temperature for 180 days.