The aim of this study was to identify Pseudomonas spp. in raw milk the production of extracellular enzymes (e.g., peptidases and lipases). Keywords: Pseudomonas, hydrolases, protease, lipase, glycosidase The strain 1A4R was isolated from refrigerated raw milk in Plate Count Agar (PCA; Mast . Extracellular enzyme activities produced by Pseudomonas sp. during growth on. The LipM lipase had a maximum activity at 25 °C and a broad pH optimum ranging from to In Brazil, the practice of refrigerating raw milk at the dairy farm Many of these enzymes are produced by Pseudomonas fluorescens Genetic diversity and spoilage potentials among Pseudomonas spp.

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Peptidases secreted by Pseudomonas during cold storage are heat-stable extracellular peptidases that can retain their activity after pasteurization or ultrahigh temperature UHT treatment Marchand et al. These authors listed some important characteristics of the metalloproteases secreted by strains of P. Data represent the average of duplicate experiments.

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Extracellular protease activity of different Pseudomonas strains: HL helped in the research and writing. Table 4 Effect of inhibitors, denaturing and reducing agents on the activity of alkaline metalloprotease. MU-butyrate zymogram of milkk LipM. This study revealed a diverse Pseudomonas spp. Protease bands appear as clear zones on a blue background due to gelatin hydrolysis.

Trans Inst Chem Eng. National Center for Biotechnology InformationU. Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M Standard curve was generated using glycine Sigma—Aldrich. Unlike many proteolytic and lipolytic enzymes described in the literature Makhzoum et al. Rraw, other metal ions reduced the proteolytic activity Table 3.

Received Jul 10; Accepted Dec We evaluated the proteolytic activity of the isolates at all tested temperatures. There is a vast amount of scientific knowledge about the ability of psychrotrophic bacteria to produce spoilage enzymes, producttion no effective strategy has yet been presented to control this problem. LipM was also less heat stable than some lipases described by other authors Knaut, ; Cousin, ; Makhzoum et al. Purification and partial characterization of psychrotrophic Serratia marcescens lipase.


Phenotypic characterization of raw milk-associated psychrotrophic bacteria. For the isolation and detection of Pseudomonas spp. In the current work, all isolates belonging to Acinetoba showed high lipolytic activity and low proteolytic sp, which is in agreement with previous studies von Neubeck et al.

Thermostability of proteases and lipases from a number of species of psychotrophic bacteria of dairy origin. This process is of special economical importance since only trace levels of protease are required to cause gelation of UHT milk bg storage 5.

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enzymr The phenotypical characteristics indicate the isolate belongs to the genus Pseudomonas 11being mostly equivalent to Pseudomonas asplenii and Pseudomonas jenssenii The residual enzyme activities can cause coagulation and degradation of milk and dairy products over time.

Substrate solution was prepared with 1 mL of p NPP 0. Biochemical characteristics of LipM.

Psychrotrophic bacterial populations in Chinese raw dairy milk. Contrarily, low levels of lipase were produced on TSB and casein media Table 1indicating that the production of lipase is induced by lipids present in produxtion media. The frequencies of the Pseudomonas spp. In this work a protease and a lipase produced by P.

Specifically, Dogan and Boor 7 reported that of Pseudomonas spp. More isolates produced peptidases with an increase in temperature; however, different peptidases were active at different temperatures Supplementary Table S1. Age gelation of UHT milk. To our knowledge, few studies have reported any possible link between spoilage enzymes and bypseudoomnas formation by psychrotrophic bacteria.


The amplification of the apr X gene from Pseudomonas spp. However, isolates belonging to other predominant genera SphingobacteriumRahnellaButtiauxellaand Janthinobacterium lacked the ability to produce both proteases and lipases.

Materials and methods 2.

Hydrolytic potential of a psychrotrophic Pseudomonas isolated from refrigerated raw milk

Purification and characterization of a metalloprotease from Chryseobacterium indologenes Ix9a and determination of the amino acid specificity with electrospray mass spectrometry. Raw cow milk bacterial population shifts attributable to refrigeration. A commom type of protease produced by P. Amplification and sequencing of the protease and lipase genes by PCR The reaction consisted of 2. Spoilage of milk resulting from the contamination of dairy products with psychrotrophic microorganisms results in significant losses for the food industry and is a particular concern of the dairy industry Dogan and Boor, Tryptone soy broth TSB was also evaluated.

Pinto2 Katharina Riedel3 and Maria C. Towards the proteome of Burkholderia cenocepacia H The resulting cell pellets were finally resuspended in lysis buffer 8 M urea, 0. Phylogenetic affiliation of the pseudomonads based on 16S rRNA sequence.

prodiction Four-hundred and eighty strains previously isolated from Chinese raw milk samples were studied Yuan et al. These results confirm the spoilage potential of strain in milk due to, at least in part, these two enzymes.

The refrigeration of raw milk in the farm and dairy industries has improved the quality and shelf life of milk and dairy products.