Identification, phylogenetic characterisation and proteolytic activity quantification of high biofilm-forming Pseudomonas fluorescens group bacterial strains isolated from cold raw milk

2020 ◽  
Vol 109 ◽  
pp. 104787
Author(s):  
Mehdi Zarei ◽  
Amin Yousefvand ◽  
Siavash Maktabi ◽  
Mahdi Pourmahdi Borujeni ◽  
Hooriyeh Mohammadpour
Keyword(s):  
Pseudomonas Fluorescens ◽  
Proteolytic Activity ◽  
Raw Milk ◽  
Bacterial Strains ◽  
Activity Quantification

scholarly journals Quantification of psychrotrophic bacteria and molecular identification of Pseudomonas fluorescens in refrigerated raw milk

2019 ◽  
Vol 86 ◽  
Author(s):  
Camila Lampugnani ◽  
Mykaella Zanatta Was ◽  
Maike Taís Maziero Montanhini ◽  
Luis Augusto Nero ◽  
Luciano dos Santos Bersot
Keyword(s):  
Pseudomonas Fluorescens ◽  
Proteolytic Activity ◽  
Molecular Identification ◽  
Raw Milk ◽  
Chain Reaction ◽  
Psychrotrophic Bacteria ◽  
Milk Samples ◽  
16S Gene ◽  
Polymerase Chain ◽  
Proteolytic Capacity

ABSTRACT In this study, we investigated the contamination of refrigerated raw milk produced in the western region of Paraná, southern Brazil, with psychrotrophic microorganisms, aiming to assay the proteolytic activity of the isolates and to identify Pseudomonas fluorescens, the main proteolytic species associated with the spoilage of milk products. Raw milk samples from 50 dairy farms were submitted to the counting of psychrotrophic microorganisms, being the microbiota characterized by its mesophilic behavior and proteolytic capacity, besides molecular identification of P. fluorescens. Of the samples evaluated, 94% had psychrotrophic counts ranging from 3 to 7.1 log CFU mL-1, and 48.5% of these showed mesophilic behavior. Of the isolates, 48.0% had proteolytic activity in at least one evaluated temperature (21 and 30°C), and 39.3% had proteolytic activity in both temperatures. Among the 61 isolates submitted to molecular identification by polymerase chain reaction (PCR), 86.8% contained the expression of the 16S gene characteristic for P. fluorescens. In this study, we demonstrated that P. fluorescens is the most prevalent psychrotrophic bacteria species in raw refrigerated milk and their proteolytic ability poses high risks to the dairy industry.

scholarly journals PROTEOLYTIC POTENTIAL OF PSEUDOMONAS FLUORESCENS ISOLATED FROM REFRIGERATED RAW MILK

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Cláudia Lúcia Oliveira Pinto1 ◽  
Solimar Gonçalves Machado ◽  
Rodrigo Rezende Cardoso ◽  
Rita Maria Alves ◽  
Maria Cristina Dantas Vanetti
Keyword(s):  
Pseudomonas Fluorescens ◽  
Proteolytic Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Heat Stability ◽  
Raw Milk ◽  
Activity Measurement ◽  
Sds Page ◽  
Milk Casein ◽  
Thermal Stability Of

The growth rate and the proteolytic activity of Pseudomonas fluorescens strains 07A and 041, isolated from cow’s milk, were evaluated at 2, 4, 7 and 10ºC. P. fluorescens promoted protein degradation during storage of milk samples as observed by Proteolytic activity measurement, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and heat stability of milk. Casein hydrolysis resulted in loss of thermal stability of milk and in formation of fragments of low and medium molecular mass. Temperatures up to 10°C did notguarantee raw milk quality when contamination by P. fluorescens was equal or higher than 106 cfu/mL.

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

2015 ◽  
Vol 46 (1) ◽  
pp. 207-217 ◽  
Author(s):  
Maurilio L. Martins ◽  
Uelinton M. Pinto ◽  
Katharina Riedel ◽  
Maria C.D. Vanetti
Keyword(s):  
Pseudomonas Fluorescens ◽  
Raw Milk

scholarly journals Presence of aprX gene in Pseudomonas spp. from refrigerated raw milk and their proteolytic ability

2020 ◽  
Vol 41 (4) ◽  
pp. 1421
Author(s):  
Rosana De Longhi ◽  
Samera Rafaela Bruzaroski ◽  
Josiane Ito Eleodoro ◽  
Regina Celia Poli-Frederico ◽  
Rafael Fagnani ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
High Probability ◽  
Raw Milk ◽  
Pseudomonas Spp

This study aimed to determine the frequency of Pseudomonas fluorescens, P. putida, and P. aeruginosa in refrigerated raw milk; their proteolytic potential; and your association with the aprX gene. Of the 173 isolates confirmed as belonging to Pseudomonas spp., 37% were P. fluorescens, 25.4% P. putida, and none belongs to P. aeruginosa. The aprX gene was distributed proportionally between P. putida (68%) and P. fluorescens (75%), but it was not associated with low or high proteolytic potential in both species. P. putida (16) and P. fluorescens (14) isolates with no aprX gene identified also had proteolytic potential. Considering the synthesis of proteases other than AprX by the isolates under study, we concluded that P. fluorescens and P. putida represented 62.4% of the Pseudomonas genus, with high probability of having the aprX gene and proteolytic potential. However, there was no association between the deteriorating potential with the presence of the aprX gene.

Effectiveness of 3 antagonistic bacterial isolates to control Rhizoctonia solani Kühn on lettuce and potato

2005 ◽  
Vol 51 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Rita Grosch ◽  
Franziska Faltin ◽  
Jana Lottmann ◽  
A Kofoet ◽  
Gabriele Berg
Keyword(s):  
Rhizoctonia Solani ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Dry Mass ◽  
Control Agent ◽  
Disease Suppression ◽  
Growth Chamber ◽  
Bacterial Strains ◽  
Serratia Plymuthica ◽  
Suppression Effect

Rhizoctonia solani causes yield losses in numerous economically important European crops. To develop a biocontrol strategy, 3 potato-associated ecto- and endophytically living bacterial strains Pseudomonas fluorescens B1, Pseudomonas fluorescens B2, and Serratia plymuthica B4 were evaluated against R. solani in potato and in lettuce. The disease-suppression effect of the 3 biocontrol agents (BCAs) was tested in a growth chamber and in the field. In growth chamber experiments, all 3 BCAs completely or significantly limited the dry mass (DM) losses on lettuce and the disease severity (DS) caused by R. solani on potato sprouts. Strain B1 showed the highest suppression effect (52% on average) on potato. Under field conditions, the DS on both crops, which were bacterized, decreased significantly, and the biomass losses on lettuce decreased significantly as well. The greatest disease-suppression effect on potato was achieved by strain B1 (37%), followed by B2 (33%) and then B4 (31%), whereas the marketable tuber yield increased up to 12% (B1), 6% (B2), and 17% (B4) compared with the pathogen control at higher disease pressure. Furthermore, in all experiments, B1 proved to be the most effective BCA against R. solani. Therefore, this BCA could be a candidate for developing a commercial product against Rhizoctonia diseases. To our knowledge, this is the first report on the high potential of endophytes to be used as a biological control agent against R. solani under field conditions.Key words: biocontrol, Rhizoctonia solani, field grown lettuce and potato, antagonistic bacteria, endophytes.

scholarly journals Antihypertensive Peptide Activity in Dutch-Type Cheese Models Prepared with Different Additional Strains of Lactobacillus Genus Bacteria

2019 ◽  
Vol 9 (8) ◽  
pp. 1674 ◽  
Author(s):  
Monika Garbowska ◽  
Antoni Pluta ◽  
Anna Berthold-Pluta
Keyword(s):  
Lactic Acid ◽  
Proteolytic Activity ◽  
Peptide Inhibitors ◽  
High Ability ◽  
Converting Enzyme ◽  
Bacterial Strains ◽  
Bacterial Cultures ◽  
Genus Lactobacillus ◽  
Ic50 Values ◽  
Cheese Model

The objective of this study was to determine the proteolytic activity of bacterial strains from the genus Lactobacillus and their capability in producing peptide inhibitors of angiotensin-converting enzyme (ACE) in cheese models prepared with their addition. After 5 weeks of ripening, all cheese models studied were characterized by a high ability of angiotensin convertase inhibition which exceeded 80%. The use of the adjunct bacterial cultures from the genus Lactobacillus contributed to lower IC50 values compared with the value determined for the control cheese model. The proteolytic activity of model cheeses varied in their increase through the period of ripening, with changes in values dependent on the adjunct lactic acid bacteria (LAB) strain used for cheesemaking. Starting from the first week of ripening, the lowest proteolytic activity was demonstrated for the control cheese models, whereas the highest activity throughout the ripening period was shown for the cheese models with the addition of Lb. rhamnosus 489.

Influence of NaCl and NaNO3 on Sinigrin Hydrolysis by Foodborne Bacteria

2011 ◽  
Vol 74 (12) ◽  
pp. 2162-2168 ◽  
Author(s):  
S. HERZALLAH ◽  
M. LARA LLEDÓ ◽  
R. HOLLEY
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Fluorescens ◽  
Starter Culture ◽  
Allyl Isothiocyanate ◽  
Escherichia Coli O157 ◽  
Bacterial Strains ◽  
Natural Antimicrobial ◽  
Staphylococcus Carnosus ◽  
Factors Influencing ◽  
Endogenous Plant

The glucosinolate sinigrin (SNG) is converted by endogenous plant myrosinase or by bacterial myrosinase-like activity to form the potent antimicrobial allyl isothiocyanate. In order to use SNG as a natural antimicrobial precursor in food, it became important to better understand the ability of bacteria to synthesize the enzyme(s) and understand factors influencing this synthesis at a constant SNG concentration. Eight spoilage, pathogenic, or starter culture bacteria were grown separately in medium containing individual or combined salts with SNG. SNG degradation by the bacteria and the formation of its major degradation product, allyl isothiocyanate, were followed for 12 days at 30 or 35°C. The bacterial strains varied in their ability to metabolize SNG, and this was enhanced by NaCl and/or NaNO3. SNG hydrolysis took place after 4 days, and the greatest amount occurred by day 12. At 12 days, Escherichia coli O157:H7 showed the greatest capacity to hydrolyze SNG (45.3% degradation), followed by Staphylococcus carnosus (44.57%), while Pseudomonas fluorescens was not active against SNG. The ability of tested strains to metabolize SNG, in decreasing order, was as follows: Escherichia coli O157:H7 > Staphylococcus carnosus > Staphylococcus aureus > Pediococcus pentosaceus > Salmonella Typhimurium > Listeria monocytogenes > Enterococcus faecalis > Pseudomonas fluorescens.

scholarly journals Complex regulation of AprA metalloprotease in Pseudomonas fluorescens M114: evidence for the involvement of iron, the ECF sigma factor, PbrA and pseudobactin M114 siderophore

Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Bláithín Maunsell ◽  
Claire Adams ◽  
Fergal O'Gara
Keyword(s):  
Pseudomonas Fluorescens ◽  
Proteolytic Activity ◽  
Yeast Extract ◽  
Sigma Factor ◽  
Skim Milk ◽  
Protease Production ◽  
Iron Starvation ◽  
Transcription Analysis ◽  
Skim Milk Agar ◽  
Complex Regulation

In the soil bacterium Pseudomonas fluorescens M114, extracellular proteolytic activity and fluorescent siderophore (pseudobactin M114) production were previously shown to be co-ordinately negatively regulated in response to environmental iron levels. An iron-starvation extracytoplasmic function sigma factor, PbrA, required for the transcription of siderophore biosynthetic genes, was also implicated in M114 protease regulation. The current study centred on the characterization and genetic regulation of the gene(s) responsible for protease production in M114. A serralysin-type metalloprotease gene, aprA, was identified and found to encode the major, if not only, extracellular protease produced by this strain. The expression of aprA and its protein product were found to be subject to complex regulation. Transcription analysis confirmed that PbrA was required for full aprA transcription under low iron conditions, while the ferric uptake regulator, Fur, was implicated in aprA repression under high iron conditions. Interestingly, the iron regulation of AprA was dependent on culture conditions, with PbrA-independent AprA-mediated proteolytic activity observed on skim milk agar supplemented with yeast extract, when supplied with iron or purified pseudobactin M114. These effects were not observed on skim milk agar without yeast extract. PbrA-independent aprA expression was also observed from a truncated transcriptional fusion when grown in sucrose asparagine tryptone broth supplied with iron or purified pseudobactin M114. Thus, experimental evidence suggested that iron mediated its effects via transcriptional activation by PbrA under low iron conditions, while an as-yet-unidentified sigma factor(s) may be required for the PbrA-independent aprA expression and AprA proteolytic activity induced by siderophore and iron.

scholarly journals Monitoring of psychrotrophic microorganisms in raw milk

2008 ◽  
Vol 56 (4) ◽  
pp. 21-28
Author(s):  
Radka Burdychová ◽  
Petra Hoferková
Keyword(s):  
Human Health ◽  
Raw Milk ◽  
Bacterial Strains ◽  
Lipolytic Enzymes ◽  
Bacterial Counts ◽  
Milk Products ◽  
Milk Samples

The group of psychrotrophic microorganisms belongs to the microorganisms representing a risk for human health as well as a risk of milk and milk products spoilage. Some genus are considered to be significant producers of proteolytic and lipolytic enzymes. In this work, we analysed raw milk samples (n = 109) originated from 26 different suppliers from the area of North and Middle Moravia. The screening was performed from March 2007 to February 2008. The total bacterial counts (TBC) ranged between 3.2 × 103 to 8.3 × 106 CFU/ml. The psychrotrophic bacterial counts (PBC) ranged between 1.0 × 103 to 8.2 × 106 CFU/ml. Total of 48.62 % and 48.62 % of samples exceeded the hygienic limit in raw milk for TBC and PBC, respectively. The correlation between TBC and PBC was highly significant (r = 0.87).Significantly higher (P < 0.05) numbers of psychrotrophic microorganisms were detected in summer months. The identification of isolates was carried out and all strains were sreened for ability to produce proteolytic and lipolytic enzymes. The most commonly identified genus in raw milk was of the genus Pseudomonas. The ability to produce proteases or lipases was found at 76 % identified bacterial strains.

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