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Milk-deteriorating exoenzymes from Pseudomonas fluorescens 041 isolated from refrigerated raw milk.

Authors
  • Martins, Maurilio L1
  • Pinto, Uelinton M2
  • Riedel, Katharina3
  • Vanetti, Maria C D4
  • 1 Departamento de Ciência e Tecnologia de Alimentos, Instituto Federal do Sudeste de Minas Gerais, Rio Pomba, MG, Brazil. , (Brazil)
  • 2 Departamento de Ciência de Alimentos, Universidade Federal de Ouro Preto, Ouro Preto, MG, Brazil. , (Brazil)
  • 3 Institute of Microbiology, Ernst-Moritz-Arndt University of Greifswald, Germany. , (Germany)
  • 4 Departamento de Microbiologia, Universidade Federal deViçosa, Viçosa, MG, Brazil. , (Brazil)
Type
Published Article
Journal
Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]
Publication Date
Mar 01, 2015
Volume
46
Issue
1
Pages
207–217
Identifiers
DOI: 10.1590/S1517-838246120130859
PMID: 26221110
Source
Medline
Keywords
License
Unknown

Abstract

The practice of refrigerating raw milk at the farm has provided a selective advantage for psychrotrophic bacteria that produce heat-stable proteases and lipases causing severe quality problems to the dairy industry. In this work, a protease (AprX) and a lipase (LipM) produced by Pseudomonas fluorescens 041, a highly proteolytic and lipolytic strain isolated from raw milk obtained from a Brazilian farm, have been purified and characterized. Both enzymes were purified as recombinant proteins from Escherichia coli . The AprX metalloprotease exhibited activity in a broad temperature range, including refrigeration, with a maximum activity at 37 °C. It was active in a pH range of 4.0 to 9.0. This protease had maximum activity with the substrates casein and gelatin in the presence of Ca (+2) . The LipM lipase had a maximum activity at 25 °C and a broad pH optimum ranging from 7.0 to 10. It exhibited the highest activity, in the presence of Ca (+2) , on substrates with long-chain fatty acid residues. These results confirm the spoilage potential of strain 041 in milk due to, at least in part, these two enzymes. The work highlights the importance of studies of this kind with strains isolated in Brazil, which has a recent history on the implementation of the cold chain at the dairy farm.

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