Isolation and characterisation of a heat-resistant peptidase from Pseudomonas panacis withstanding general UHT processes |
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| Affiliation: | 1. Department of Microbiology, Federal University of Viçosa, Viçosa, MG 36.570-900, Brazil;2. CAPES Foundation, Ministry of Education of Brazil, Brasília, DF 70.040-020, Brazil;3. Institute for Agricultural and Fisheries Research (ILVO), Technology and Food Science Unit, Brusselsesteenweg 370, B-9090 Melle, Belgium;4. Department of Pathology, Bacteriology and Poultry Diseases, Ghent University (UGent), Salisburylaan 133, B-9820 Merelbeke, Belgium;5. Laboratory for Protein Biochemistry and Biomolecular Engineering, Department of Biochemistry and Microbiology, Ghent University (UGent), KL Ledeganckstraat 35, B-9000 Gent, Belgium |
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| Abstract: | A secreted peptidase from Pseudomonas panacis was identified and purified. Genome sequencing of the producer strain allowed identification of the peptidase as AprA based on a comparison to peptide sequences of mass spectra obtained from the purified enzyme. The amino acid sequence of the 49.4 kDa peptidase was 98% similar to the metallopeptidase AprX from a Pseudomonas fluorescens strain. The peptidase showed maximum activity at pH 8 and 40 °C and withstood general ultra-high temperature (UHT) processing (138 °C for 18 s) in skim milk, with 88.0 ± 7.7% of the initial enzyme activity remaining after heating. The peptidase showed considerable enzyme activity under storage conditions of UHT milk. The potential for spoilage of milk might during storage was verified by adding very low enzyme activities to UHT-treated milk. The addition of 1 pkat mL?1 peptidase activity resulted in a destabilisation of the milk during four weeks storage. |
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