Characterisation of the thermostable protease AprX in strains of Pseudomonas fluorescens and impact on the shelf-life of dairy products: preliminary results


Submitted: 19 July 2016
Accepted: 19 November 2016
Published: 6 December 2016
Abstract Views: 1776
PDF: 903
HTML: 927
Publisher's note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

Authors

  • Nadia Andrea Andreani Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
  • Lisa Carraro Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
  • Luca Fasolato Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
  • Stefania Balzan Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
  • Rosaria Lucchini Institute for Experimental Veterinary Medicine of Venezie, Legnaro (PD), Italy.
  • Enrico Novelli Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
  • Barbara Cardazzo Department of Comparative Biomedicine and Food Science, University of Padua, Legnaro (PD), Italy.
Bacterial proteases are involved in food spoilage and shelf-life reduction. Among the bacterial proteases, a predominant role in spoilage of dairy products seems to be played by the thermostable metallo-protease AprX, which is produced by various strains of Pseudomonas fluorescens. Differences in AprX enzyme activity among different strains were highlighted, but the most proteolytic strains were not identified. In this study, the presence of the aprX gene was evaluated in 69 strains isolated from food matrices and 18 reference strains belonging to the P. fluorescens group, which had been previously typed by the multi locus sequence typing method. Subsequently, a subset of reference strains was inoculated in ultra-high temperature milk, and the expression of the aprX gene was evaluated at 22 and 6°C. On the same milk samples, the proteolytic activity was then evaluated through Azocasein and trinitrobenzenesulfonic acid solution assays. Finally, to assess the applicability of the former assay directly on dairy products the proteolityc activity was tested on industrial ricotta samples using the Azocasein assay. These results demonstrate the spread of aprX gene in most strains tested and the applicability of Azocasein assay to monitor the proteolytic activity in dairy products.

1.
Andreani NA, Carraro L, Fasolato L, Balzan S, Lucchini R, Novelli E, Cardazzo B. Characterisation of the thermostable protease AprX in strains of Pseudomonas fluorescens and impact on the shelf-life of dairy products: preliminary results. Ital J Food Safety [Internet]. 2016 Dec. 6 [cited 2024 Jun. 13];5(4). Available from: https://www.pagepressjournals.org/ijfs/article/view/6175

Downloads

Download data is not yet available.

Citations