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Use of response surface methodology to optimize protease synthesis by a novel strain of Bacillus sp. isolated from Portuguese sheep wool

Publication . Queiroga, A.C.; Pintado, M.E.; Malcata, F.X.

Aims: To investigate the influence of yeast extract, peptone, temperature and pH upon protease productivity by Bacillus sp. HTS102 – a novel wild strain isolated from wool of a Portuguese sheep breed (Merino). Methods and Results: A 24 full factorial, central composite design together with response surface methodology was used to carry out the experiments and analyse the results, respectively. Among the individual parameters tested, temperature and peptone concentration produced significant effects upon protease productivity. A high correlation coefficient (R2 = 0Æ994, P < 0Æ01) indicated that the empiric second-order polynomial model postulated was adequate to predict said productivity, with the optimum loci characterized by: temperature of 43 C, peptone content of 1Æ4 g l)1, pH of 5Æ1 and yeast extract concentration of 10Æ0 g l)1. Conclusions: Protease synthesis depends chiefly on temperature and peptone level. The maximum protease activity was more than twice that obtained with the basal medium, so the experimental design and analysis undertaken were effective towards process optimization. Significance and Impact of the Study: Rational choice of processing conditions for maximum protease productivity will be relevant if an economically feasible fermentation process based on Bacillus sp. HTS102 is intended.

2012Journal article

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Search for novel proteolytic enzymes aimed at textile and agro-industrial applications: an overview of current and novel approaches

Publication . Queiroga, A. Catarina; Pintado, Manuela E.; Malcata, F. Xavier

The types and sources of proteolytic enzymes, enzyme assays, strategies for fermentation yield improvement, and novel proteases and their applications in industrial sectors are widely covered in this review. We give a special focus on alkaline proteases for the textile and detergent industries, as well as for the degradation of keratin-rich wastes.

2012Journal article

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