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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Both enzymes were overexpressed in Escherichia colipurified to homogeneity by affinity chromatography and biochemically characterized in order to evaluate their role in the spoilage of milk components.

Identification of proteins by mass spectrometry P. Data represent the average of duplicate experiments. This will be taken into consideration in the future research. Subsequently, protease production was investigated in submerged cultivations. Isolation and characterization of a protease from Pseudomonas fluorescens RO 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.

Aliquots 1 mL of selected dilutions liipase placed onto Pseudomonas agar Oxoid Ltd. They are present in different environments and are frequently linked to food spoilage, especially, that of raw milk Quigley et al.

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

The complex microbiota of raw milk. Standard curve was generated using glycine Sigma—Aldrich. Psychrotrophic spoilage of raw milk at different temperatures of storage. During storage, the microbiota shifts toward psychrotrophic microorganisms, which can reduce the quality of raw milk Lafarge et al. The phenotypical characteristics indicate the isolate belongs to the genus Pseudomonas 11being mostly equivalent oroduction Pseudomonas asplenii and Pseudomonas bypseudominas Growth of Pseudomonas weihenstephanensisPseudomonas proteolytica and Pseudomonas sp.


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Thus, the population of psychrotrophic bacteria plays a key role in the determination of the quality of dairy products. Extracellular protease bypseuvomonas of different Pseudomonas strains: Milk is a good medium for lipase production, since the synthesis of such enzymes can be stimulated by lipids, such as milkfat 3.

Introduction Raw milk serves as an ideal medium for the growth of bacteria due to its high nutritional value Champagne et al.

Proteinases of psychrotrophic bacteria: The 14 different Pseudomonas species Table 1 were mainly based on the rpo B gene sequence data, since universal 16S rRNA gene sequences are less discriminative Caldera et al. National Center for Biotechnology InformationU. Amplification of enzyem gene and preparation for cloning in pQEXa.

Moreover, strain exhibited a higher capacity to hydrolyze milk than P. This article does not contain any studies with human or animal subjects performed by any of the authors.

Native proteolytic enzyme levels in raw milk were determined from the absorption ratios. The aprX gene of P. A simple procedure using trinitrobenzenesulphonic acid for monitoring proteolysis in cheese. Briefly, all raw milk samples were diluted fold in 0. Enzymes from isolates of Pseudomonas fluorescens involved in food spoilage. Amplification and sequencing of the protease and lipase genes by PCR The enayme consisted of 2.

Find articles by Katharina Riedel. Adequate addition of CO 2 to raw milk has been shown to reduce proteolysis and lipolysis by limiting prodution growth and the production of microbial proteases Ma et al. Increasing global demand for dairy products requires dairy manufacturers to produce products with high quality and prolonged shelf-life. Partial purification and characterization of the organic solvent-tolerant lipase produced by Pseudomonas fluorescens RB isolated from milk. The production of extracellular hydrolases by a psychrotrophic bacterium isolated from refrigerated raw milk, and identified as a Pseudomonas sp.


In some countries, the majority of raw milk is not processed after milking until delivery to a dairy, which productjon last up to 3 or 4 days. Spoilage patterns of skim and whole milks.

National Center for Biotechnology InformationU. Three independent replicate measurements were performed.

The inactivation of enzymes fits first-order kinetics, and kinetic parameters indicate that while a higher temperature and longer heat treatment period may result in a higher reduction of enzymatic activity, the destruction and inactivation of milk constituents will be increased. A commom type of protease produced by P. Thus, better knowledge of their heat stability is needed. This process is of special economical importance since only trace levels of protease are required to cause gelation of UHT milk during storage 5.

No directly correlations were observed between Pseudomonas groups and the degree of proteolysis Supplementary Table S1. Species of YersiniaPseudomonasSerratiaand Chryseobacterium showed high proteolytic activity. This approach would reduce the time for detecting these bacteria in raw milk giving flexibility for the dairy manager to choose the best use for a particular milk batch during processing.

Hydrolytic potential of a psychrotrophic Pseudomonas isolated from refrigerated raw milk

Keratinolytic bacteria isolated from feather waste. Interestingly, in this study enzym was verified that aprX encodes for the major, if not the only extracellular protease produced by P.

Detection of the apr gene in proteolytic psychrotrophic bacteria isolated from refrigerated raw milk. These extracellular enzymes might play an important role in the shelf-life of milk and dairy products, since the hydrolysis of glycoconjugates may render the non-carbohydrate portion of a molecule accessible to specific hydrolases 6 However, other metal ions reduced the proteolytic activity Table 3.