Thermostability of peptidases secreted by microorganisms associated with raw milk

Glück, Claudia; Rentschler, Eva; Krewinkel, Manuel; Merz, Michael; Neubeck, Mario von; Wenning, Mareike; Scherer, Siegfried; Stoeckel, Marina; Hinrichs, Jörg; Stressler, Timo; Fischer, Lutz

doi:10.1016/j.idairyj.2016.01.025

Cited by 41 publications

(72 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The microbiota of raw milk is various due the possibility of contamination from cowshed, bedding material, the seasonal feed, the teat purity and the dairy equipment (GLÜCK et al, 2016). First step was determined the microbial population including psychrophilic, mesophilic and thermophilic microorganisms in raw cow milk by plate counting on selected media (MRS and MPA) (data not shown).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Natural Microflora of Raw Cow Milk and their Enzymatic Spoilage Potential

Pukančíková¹,

Lipničanová²,

Kačániová³

et al. 2016

Nova Biotechnologica Et Chimica

View full text Add to dashboard Cite

The aim of this work was to identify the main microbiota in raw cow milk from dairy farm of Slovakia and to describe the selected microorganisms responsible for thermostable protease and lipase production which can affected the quality of dairy products. The main bacterial classes identifying by MALDI-TOF MS were Gammaproteobacteria (62 %), Actinobacteria (19 %) and Bacilli (12 %). The dominant microbial genus of raw cow milk was Pseudomonas. From milk bacteria, the strain Lactococcus lactis and from the family Enterobacteriaceae, namely Enterococcus faecalis, Hafnia alvei, Citrobacter braakii and Raoultella ornithinolytica were observed in raw milk. The spoilage of milk products is caused by thermostable enzymes with lipolytic and proteolytic activity. Qualitative proteolytic and lipolytic activities were performed on skin milk agar and olive oil, respectively. From 16 identified microorganisms, only 8 strains (P. fragii, P. gessardii, P. lundesis, H. alvei, C. braakii, R. ornithinolytica, Kocuria rhizophila and Candida inconspicua) showed protease activity. Quantitative protease and lipase activities were determined by casein and olive oil, respectively. The highest both activities were measured for the genus Pseudomonas. While lipases produced by all isolated microbial species lose enzymatic activity at 77 °C for 30 – 40 min, almost proteases showed comparable activities during whole pasteurization experiment at selected experimental conditions (70 °C, 40 min).

show abstract

Section: Resultsmentioning

confidence: 99%

“…The ability of enzyme production by microbiota from milk was determined previously by several authors (HANTSIS-ZACHAROV et al, 2007;TEH et al, 2011;GLÜCK et al, 2016). In total, 17 isolates were obtained from raw caw milk.…”

Section: Identification Of Proteolytic and Lipolytic Isolatesmentioning

confidence: 99%

Natural Microflora of Raw Cow Milk and their Enzymatic Spoilage Potential

Pukančíková¹,

Lipničanová²,

Kačániová³

et al. 2016

Nova Biotechnologica Et Chimica

View full text Add to dashboard Cite

show abstract

“…Many proteases produced by strains of P. fluorescens are heat-resistant and retain activity even after UHT treatment. This residual activity can cause changes in the physicochemical properties of the casein micelles and lead to destabilization and gelation of UHT milk during storage (GLÜCK et al, 2016;VITHANAGE et al, 2016). Thus, adoption of appropriate practices for obtaining milk is necessary to minimize contamination of the raw material by psychrotrophic microorganisms.…”

Section: Resultsmentioning

confidence: 99%

“…Besides compromising the integrity of the milk constituents, the microbial proteases and lipases are thermostable and can remain active even after the elimination of the vegetative microorganisms by heat treatments applied by the dairy industry (GLÜCK et al, 2016;VITHANAGE et al, 2016). The activities of proteases and lipases that resist the heat treatments may cause changes in quality and shelf life as well as compromise functional properties and cause flavor defects of milk products during storage (CHEN et al, 2003;MACHADO et al, 2017).…”

Section: Abstract: Contamination; Proteolysis; Refrigerationmentioning

confidence: 99%

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

et al. 2019

View full text Add to dashboard Cite

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.

show abstract

“…On top of that, the high content of glycine close to the Ca 2+ binding site would lead to a weak coordination of Ca 2+ and thus increase local flexibility (Davail, Feller, Narinx, & Gerday, ). The flexible structure enables reversible unfolding during heat treatments at higher temperatures, such as UHT processing, thus probably causing its thermostability (Adams et al., ; Glück et al., ), as further discussed in section Thermal Stability of AprX in Milk. The flexible structure also allows AprX to pass easily through the cell wall during its secretion (Pollock & Richmond, ).…”

Section: Biological Properties Of Protease Aprxmentioning

confidence: 99%

The Extracellular Protease AprX from Pseudomonas and its Spoilage Potential for UHT Milk: A Review

Zhang

Bijl

Svensson

et al. 2019

Comp Rev Food Sci Food Safe

View full text Add to dashboard Cite

The negative effects of proteases produced by psychrotrophic bacteria on dairy products, especially ultra‐high‐temperature (UHT) milk, are drawing increasing attention worldwide. These proteases are especially problematic, because it is difficult to control psychrotrophic bacteria during cold storage and to inactivate their heat‐resistant proteases during dairy processing. The predominant psychrotrophic species with spoilage potential in raw milk, Pseudomonas, can produce a thermostable extracellular protease, AprX. A comprehensive understanding of AprX on the aspects of its biological properties, regulation, proteolytic potential, and its impact on UHT milk can contribute to finding effective approaches to minimize, detect, and inactivate AprX. AprX also deserves attention as a representative of all extracellular metalloproteases produced by psychrotrophic bacteria in milk. The progress of current research on AprX is summarized in this review, including a view on the gap in current understanding of this enzyme. Reducing the production and activity of AprX has considerable potential for alleviating the problems that arise from the instability of UHT milk during shelf‐life.

show abstract

Thermostability of peptidases secreted by microorganisms associated with raw milk

Cited by 41 publications

References 53 publications

Natural Microflora of Raw Cow Milk and their Enzymatic Spoilage Potential

Natural Microflora of Raw Cow Milk and their Enzymatic Spoilage Potential

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

The Extracellular Protease AprX from Pseudomonas and its Spoilage Potential for UHT Milk: A Review

Contact Info

Product

Resources

About