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.

Author: Felkree Moogumuro
Country: Philippines
Language: English (Spanish)
Genre: Sex
Published (Last): 8 September 2006
Pages: 120
PDF File Size: 1.9 Mb
ePub File Size: 2.25 Mb
ISBN: 520-9-53867-313-5
Downloads: 26380
Price: Free* [*Free Regsitration Required]
Uploader: Gardall

Although LipM exhibits the conserved serine lipase catalytic domain, it presented somewhat lower similarity, as compared to AprX alignment, to the sequences described in the data base Figure 6. Lipolytic and proteolytic activity of Pseudomonas spp. Purification and partial characterization of psychrotrophic Serratia marcescens lipase. In the standard curve, relating glycine concentration to absorbance in the TNBS assay, the R 2 value was bypseudoomonas than 0.

Aliquots 1 mL of selected dilutions were placed onto Pseudomonas agar Oxoid Ltd. Regulation of the aprX-lipA operon of Pseudomonas fluorescens B The plasmids were subsequently transformed into the expression strain E. Food spoilage – interactions between food spoilage bacteria.

Hydrolytic potential of a psychrotrophic Pseudomonas isolated from refrigerated raw milk

In total Pseudomonas isolates were confirmed. The amount of P. This could be attributed due to differences in the enzymes structures or to differences in experimental procedures, as the above mentioned studies have used purified enzymes from culture supernatants and we have purified those from overexpressing E.


Then the proteolytic activity was determined according to the protocol described by Caldera et al. This article does not contain any studies with human or animal subjects performed by any of the authors. DaroitRenata V. Comparison of identification systems for psychrotrophic bacteria isolated from raw bovine milk. The amplification of the apr X gene from Pseudomonas spp.

LBSA1 isolated from raw milk produced only one extracellular protease. Production of glycosidases by psychrotrophic bacteria. As reported by Decimo et al. Received Aug 8; Accepted Jun 6. The work highlights the importance of studies of this kind with P. Quantitative assessment of total lipolytic activity Strains that showed positive lipase production on screening medium were selected to quantify the total lipolytic activity. However, other metal ions reduced the proteolytic activity Table 3.

Find articles by Maria C.

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

Support Center Support Center. These results are in agreement with the findings of Liao and McCallus who observed that P. Log of percentage residual activity Bypaeudomonas was plotted against heating time and expressed as the thermo-stability.

An increase in enzyme inactivation correlated well with temperature and heating time. Many studies have determined the heat stability of proteases, but the heat stability of lipases is less well known. Cultivable microbial communities in raw cow milk and potential transfers from stables of sixteen French farms. Molecular typing of industrial strains of Pseudomonas spp.


Pseudomonas has been identified as predominant milk-associated psychrotrophic bacteria, making it one of the most important bacterial groups in the dairy industry Wiedmann et al. The proteolytic activity of the predominant psychrotrophic bacteria is shown in Fig. Temperature optimum of purified LipM; B: In the current study, the 14 Pseudomonas species are divided into 4 different groups, according to Anzai et al.


Proteolytic activity was investigated on azocasein, according to Ljpase et al. As different bacterial strains yield different levels of enzymes with different stabilities, the identification of spoilage bacteria is important 3.

Most approaches currently available are time consuming, do not have good sensitivity or have detection limits that are too high. In the current work, all isolates belonging to Acinetoba showed high lipolytic activity and low proteolytic activity, which is in agreement with previous studies von Neubeck et al.

Rheinheimera chironomi showed the lowest protease activity followed by A. This is a pertinent observation as it confirms the ability of Pseudomonas species to produce proteolytic enzymes under psychrotrophic conditions. Gelatin zymogram of Pseudomonas sp.

There was a problem providing the content you requested

Diagnosing the cause of proteolysis in UHT milk. Abstract The storage and transportation of raw milk at low temperatures promote the growth of psychrotrophic bacteria and the production of thermo-stable enzymes, which pose great threats to the quality and shelf-life of dairy products. However, it is not clear if these proteolysis bands corresponded to different monomeric producion or to aggregates or multimers