Proteolytic Microorganisms

Marcy, J. A.; Pruett, W. Payton

doi:10.2105/9780875531755ch16

Cited by 4 publications

(3 citation statements)

References 18 publications

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“…To determine spoilage potential, the isolates were evaluated with regard to their capacity to produce proteases in Standard Methods Caseinate Agar (Marcy and Pruett ) as well as lipases in tributyrin agar (Haas ). The inoculation of the isolates on the surface of the respective culture media was performed with the aid of a platinum needle.…”

Section: Methodsmentioning

confidence: 99%

Microbiological quality of Brazilian UHT milk: Identification and spoilage potential of spore‐forming bacteria

Pinto

Souza

Meloni

et al. 2017

Int J of Dairy Tech

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Counts of aerobic mesophilic micro-organisms and aerobic mesophilic spore-forming bacteria were determined in 91 ultra-high-temperature (UHT) commercial Brazilian samples. Forty-six sporeforming bacteria were identified and characterised in terms of their spoilage potential. Among the 20 brands evaluated, 45% had counts of aerobic mesophilic micro-organisms higher than 1.0 9 102 cfu/mL. The sporulated bacteria were identified as Bacillus subtilis/amyloliquefaciens, Bacillus licheniformis, Bacillus pumilus and Bacillus megaterium, and 31% and 33% showed proteolytic and lipolytic activity, respectively. Our findings indicate that there is a potential risk of UHT milk samples becoming spoiled during their commercial shelf life.

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Section: Methodsmentioning

confidence: 99%

Microbiological quality of Brazilian UHT milk: Identification and spoilage potential of spore‐forming bacteria

Pinto

Souza

Meloni

et al. 2017

Int J of Dairy Tech

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“…) as described by the manufacturer (bioMérieux, Marcy l'Etoile, France). Skim milk agar was used to assess the ability of the bacteria to hydrolyse casein (Marcy and Pruett ). The test was performed at both 30 and 37°C in aerobic and anaerobic conditions.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the microbial community in industrial rye sourdough upon continuous back-slopping propagation revealed Lactobacillus helveticus as the dominant species

Viiard

Mihhalevski

Rühka³

et al. 2012

J Appl Microbiol

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Aims: To assess the structure and stability of a dominant lactic acid bacteria (LAB) population during the propagation of rye sourdough in an industrial semi-fluid production over a period of 7 months. Methods and Results: The sourdough was started from a 6-year-old freezedried sourdough originating from the same bakery. A unique microbial consortium consisting mainly of bacteria belonging to species Lactobacillus helveticus, Lactobacillus panis and Lactobacillus pontis was identified based on culture-dependent (Rep-PCR) and culture-independent [denaturing gradient gel electrophoresis (DGGE)] methods. Three of the isolated Lact. helveticus strains showed remarkable adaptation to the sourdough conditions. They differed from the type strain by the ability to ferment compounds specific to plant material, like salicin, cellobiose and sucrose, but did not ferment lactose. Conclusion: We showed remarkable stability of a LAB consortium in rye sourdough started from lyophilized sourdough and propagated in a large bakery for 7 months. Lactobacillus helveticus was detected as the dominant species in the consortium and was shown to be metabolically adapted to the sourdough environment. Significance and Impact of the study: The use of an established and adapted microbial consortium as a starter is a good alternative to commercial starter strains.

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“…After taking the samples under refrigerated conditions, they were submitted to successive decimal dilutions and analyzed as follows: Standard Methods Caseinate Agar (SMCA -Himedia, Mumbai, India) to count and isolate proteolytic psychrotrophic bacteria (Marcy & Payton Pruett, 2001), PCA with the addition of 1% tributyrin to count and isolate lipolytic psychrotrophic bacteria, incubating at 6.5 ± 0.5 ºC for 10 days (Haas, 2001), and the base agar for Pseudomonas (20 g/L casein peptone, 10 g/L potassium sulfate, 1.4 g/L magnesium chloride, 13.6 g/L agar, 0.025 g/L Irgasan and 20 mL/L glycerol (Interlab, São Paulo, Brazil), supplemented with the following selective agents: 10 mg/L cetrimide, 10 mg/L fucidin and 50 mg/L cephalosporin (Merck®, Barueri, São Paulo, Brazil), to count and isolate bacteria of the genus Pseudomonas ssp., incubating at 22.0 ºC for 72 hours (Cousin & Bramley, 1981). After incubation, from two to three colonies were selected from the plates with the highest dilutions that presented casein clarification and/or precipitation halos on SMCA agar and clarification halos due to lipolysis on PCA agar with the addition of 1% tributyrin.…”

Section: Introductionmentioning

confidence: 99%

Identification of the contaminating psychrotrophic bacteria in refrigerated bulked raw milk and the assessment of their deteriorating potential

Condé

Pinto

Gandra

et al. 2022

Semina: Ciênc. Agrár.

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This work aimed to characterize, identify, and determine the deteriorating potential of the contaminating psychrotrophic bacteria in refrigerated raw milk. Samples were submitted to serial dilutions and plated in specific culture media to form a bacterial culture collection. The isolates were characterized for their morphology and biochemical characteristics. The deteriorating potential of the isolates was determined according to the proteolytic, lipolytic and lecithinase activities at 4.0 ºC, 6.5 ºC, and 25.0 ºC. The results obtained for deterioration potential were assessed by the multivariate statistical method and by the principal components analysis (PCA). A total of 159 isolates were characterized, and of these, 46 strongly proteolytic Gram-negative isolates were selected for identification using the API 20 NE kit. The predominant bacteria were Gram-negative and oxidase and catalase positive, with a predominance of bacteria of the genus Pseudomonas. Using PCA, it was shown that the bacteria with the greatest deterioration potential were lecithinase producers, and that, in the autumn, proteolytic bacteria predominated at 4.0 ºC. Of the 46 isolates identified, more than 80% belonged to the species Pseudomonas fluorescens. Thus, attention should be given to the importance of implementing microbial contamination prevention measures in the bulking process, since, even under refrigeration, psychrotrophic bacteria multiply and produce enzymes that deteriorate lipids and proteins, with consequent quality losses of the milk and its derivatives, yield losses in the production of dairy products, and economic losses.

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Proteolytic Microorganisms

Cited by 4 publications

References 18 publications

Microbiological quality of Brazilian UHT milk: Identification and spoilage potential of spore‐forming bacteria

Microbiological quality of Brazilian UHT milk: Identification and spoilage potential of spore‐forming bacteria

Evaluation of the microbial community in industrial rye sourdough upon continuous back-slopping propagation revealed Lactobacillus helveticus as the dominant species

Identification of the contaminating psychrotrophic bacteria in refrigerated bulked raw milk and the assessment of their deteriorating potential

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