Quantification of the proteolytic and lipolytic activity of microorganisms isolated from raw milk

Baur, Claudia; Krewinkel, Manuel; Kranz, Bertolt; Neubeck, Mario von; Wenning, Mareike; Scherer, Siegfried; Stoeckel, Marina; Hinrichs, Jörg; Stressler, Timo; Fischer, Lutz

doi:10.1016/j.idairyj.2015.04.005

Cited by 74 publications

(63 citation statements)

References 49 publications

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“…Among indoor teat samples, soil-type Proteobacteria, such as Variovorax and Devosia, were more abundant in INP teats than in IP teats. Variovorax has previously been found in hay (2), and Devosia has previously been found in raw milk (28). It was surprising that teat prep increased the numbers of total bacteria in both indoor and outdoor milk.…”

Section: Discussionmentioning

confidence: 91%

Impacts of Seasonal Housing and Teat Preparation on Raw Milk Microbiota: a High-Throughput Sequencing Study

Doyle

Gleeson

O’Toole

et al. 2017

Appl Environ Microbiol

134

121

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In pasture-based systems, changes in dairy herd habitat due to seasonality results in the exposure of animals to different environmental niches. These niches contain distinct microbial communities that may be transferred to raw milk, with potentially important food quality and safety implications for milk producers. It is postulated that the extent to which these microorganisms are transferred could be limited by the inclusion of a teat preparation step prior to milking. High-throughput sequencing on a variety of microbial niches on farms was used to study the patterns of microbial movement through the dairy production chain and, in the process, to investigate the impact of seasonal housing and the inclusion/exclusion of a teat preparation regime on the raw milk microbiota from the same herd over two sampling periods, i.e., indoor and outdoor. Beta diversity and network analyses showed that environmental and milk microbiotas separated depending on whether they were sourced from an indoor or outdoor environment. Within these respective habitats, similarities between the milk microbiota and that of teat swab samples and, to a lesser extent, fecal samples were apparent. Indeed, SourceTracker identified the teat surface as the most significant source of contamination, with herd feces being the next most prevalent source of contamination. In milk from cows grazing outdoors, teat prep significantly increased the numbers of total bacteria present. In summary, sequence-based microbiota analysis identified possible sources of raw milk contamination and highlighted the influence of environment and farm management practices on the raw milk microbiota. IMPORTANCEThe composition of the raw milk microbiota is an important consideration from both a spoilage perspective and a food safety perspective and has implications for milk targeted for direct consumption and for downstream processing. Factors that influence contamination have been examined previously, primarily through the use of culture-based techniques. We describe here the extensive application of high-throughput DNA sequencing technologies to study the relationship between the milk production environment and the raw milk microbiota. The results show that the environment in which the herd was kept was the primary driver of the composition of the milk microbiota composition.KEYWORDS farm practices, food chain, food safety, metagenomics, microbial source tracking, raw milk microbiota T he impact of the dairy farm environment on the microbial composition of raw milk and raw milk products has been appreciated for some time (1). There are numerous niches that collectively constitute the dairy farm environment, and these harbor a vast array of microbes. The transfer of microbes from the farm environment to raw milk can be influenced be a number of factors, including farmer hygiene, husbandry practices,

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Section: Discussionmentioning

confidence: 91%

Impacts of Seasonal Housing and Teat Preparation on Raw Milk Microbiota: a High-Throughput Sequencing Study

Doyle

Gleeson

O’Toole

et al. 2017

Appl Environ Microbiol

134

121

View full text Add to dashboard Cite

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“…High protease and lipase activities were detected in the supernatant of species belonging to the genus Pseudomonas , especially P. fluorescens (Baur et al . ).…”

Section: Resultsmentioning

confidence: 97%

Spoilage potential characterization ofShewanellaandPseudomonasisolated from spoiled large yellow croaker (Pseudosciaena crocea)

Zhu

et al. 2016

Lett Appl Microbiol

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Members of the bacterial genera Shewanella and Pseudomonas are widely known to be responsible for the specific spoilers in iced fish. Ten strains isolated from spoiled large yellow croaker (Pseudosciaena crocea) were identified as Shewanella baltica and Pseudomonas spp. S. baltica was demonstrated as the predominant spoiler in the refrigerated P. crocea due to its high metabolic activities. This work has generated baseline information for a better understanding of the role of various spoilage bacteria in chilled marine fish and for the control of contamination and growth of main spoilage bacteria to extend the shelf life of marine fish.

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“…Due to substrate specificity, lipolytic enzymes are classified according to the chain length of the hydrolyzed acylglycerols into esterases (EC 3.1.1.1) and lipases (EC 3.1.1.3). Esterases are defined as enzymes that hydrolyze short‐chain acylglycerols ( C ≤ 10), whereas lipases hydrolyze long‐chain acylglycerols ( C > 10) (Baur et al., ). Tributyrin (C4) is used as a substrate for the majority of screening tests for lipolytic activity.…”

Section: Resultsmentioning

confidence: 99%

Potential characterization of yeasts isolated from Kazak artisanal cheese to produce flavoring compounds

et al. 2017

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Cheese is a typical handcrafted fermented food in Kazak minority from the Uighur Autonomy Region in China and Central Asia. Among the microbial community that is responsible for Kazak cheese fermentation, yeasts play important role in flavor formation during ripening. To develop ripening cultures, we isolated 123 yeasts from 25 cheese products in Kazak, and identified 87 isolates by the D1/D2 domain of the large subunit rRNA gene sequence. Pichia kudriavzevii was the dominant yeast in Kazak cheese, followed by Kluyveromyces marxianus and Kluyveromyces lactis. Of these, the ability to exhibit enzyme of dominant isolates and contribution to the typical flavor of cheeses was assessed. Enzyme producing yeast strains were inoculated in Hazak cheese‐like medium and volatile compounds were identified by head space solid phase micro extraction coupled to gas chromatography and mass spectroscopy. Pichia kudriavzevii N‐X displayed the strongest extracellular proteolytic and activity on skim milk agar and produced a range of aroma compounds (ethanol, ethyl acetate, 3‐methylbutanol, and acetic acid) for Kazak cheese flavor, could be explored as ripening cultures in commercial production of Kazak cheeses.

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Quantification of the proteolytic and lipolytic activity of microorganisms isolated from raw milk

Cited by 74 publications

References 49 publications

Impacts of Seasonal Housing and Teat Preparation on Raw Milk Microbiota: a High-Throughput Sequencing Study

Impacts of Seasonal Housing and Teat Preparation on Raw Milk Microbiota: a High-Throughput Sequencing Study

Spoilage potential characterization ofShewanellaandPseudomonasisolated from spoiled large yellow croaker (Pseudosciaena crocea)

Potential characterization of yeasts isolated from Kazak artisanal cheese to produce flavoring compounds

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