Complementation of Lecithinase Activities by Closely Related Pseudomonads: Its Taxonomic Implication

Bates, J; Liu, Pinghui V.

doi:10.1128/jb.86.3.585-592.1963

Cited by 12 publications

(4 citation statements)

References 19 publications

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“…The production of extracellular phospholipases (lecithinases) was determined on Plate Count Agar (Oxoid) supplemented with 10% egg yolk emulsion (Biolife), as described by Dogan and Boor (). Colonies surrounded by an opaque ring were deemed to evince lecithinase activity (Bates and Liu ).…”

Section: Methodsmentioning

confidence: 99%

Characterization of Gram‐Negative Psychrotrophic Bacteria isolated from Italian Bulk Tank Milk

Decimo¹,

Morandi²,

Silvetti³

et al. 2014

Journal of Food Science

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Eighty psychrotrophic bacterial strains, isolated from different northwest Italian bulk tank milks destined for Grana Padano cheese production, were identified by 16S rRNA gene amplification and partial sequence analysis of the rpoB gene. Pseudomonas spp. were the most commonly occurring contaminants, P. fluorescens being the predominant isolated species, along with Enterobacteriaceae, primarily Serratia marcescens. RAPD-PCR was used to study genetic variability and distinguish closely related strains; a high degree of genetic heterogeneity among the strains was highlighted. All the strains were characterized for their ability to produce proteases, lipases and lecithinases at different temperatures (7, 22, and 30 °C). Forty-one of the psychrotrophic strains were positive for all the enzymatic activities. The highest number of positive strains for all the incubation temperatures was found for lipolytic activity (59), followed by proteolytic (31) and lecithinase (28) activities, and the enzymatic traits varied among the Pseudomonas and Enterobacteriaceae strains. The proteolytic psychrotrophic strains were screened for the presence of the aprX gene, coding for a heat-resistant metalloprotease in Pseudomonas spp. The aprX gene was detected in 19 of 63 Pseudomonas strains, and was widespread in the P. fluorescens strains (14/19). PRATICAL APPLICATION: The study provides new data on the enzymatic activity of Gram-negative psychrotrophic bacteria, useful in developing strategies to control the proteo-lipolytic spoilage of raw and processed milk that causes gelation, off-flavors, and loss of sensory quality and shelf life.

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Section: Methodsmentioning

confidence: 99%

Characterization of Gram‐Negative Psychrotrophic Bacteria isolated from Italian Bulk Tank Milk

Decimo¹,

Morandi²,

Silvetti³

et al. 2014

Journal of Food Science

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“…The production capacity of proteases, lipases, and lecithinases was evaluated according to the methodology proposed by Dogan & Boor (2003) and Bates & Liu (1963). For the proteases production analysis, the isolates were inoculated in Skim Milk Agar and incubated at 7 °C for 10 days.…”

Section: Extracellular Enzymes: Evaluation Of Production Capacitymentioning

confidence: 99%

Psychrotrophic bacteria in Brazilian organic dairy products: identification, production of deteriorating enzymes and biofilm formation

et al. 2021

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The psychrotrophic bacteria count and the profile of Gram-negative bacteria present in commercial Brazilian organic dairy products (27 samples, pasteurized whole milk, Minas Frescal cheese, and yoghurt, equally distributed) as well as the biofilmproducing capacity and the production of deteriorating enzymes were investigated. Most of the samples (59%) presented psychrotrophic bacteria counts higher than 4 log CFU/g, indicating problems in the microbiological quality of the products. The identification of Gram-negative bacteria revealed the presence of micro-organisms that can be potentially harmful (39.4% Acinetobacter baumanii/calcoaceticus, 23.2% Burkoderia pseudomallei, 10.1% Halfnia alvei) and/or deteriorating microorganisms (6.1% Pseudomonas aeruginosa) with the capacity of producing proteases (36.4%), lecithinases (41.4%), and lipases (4%). Roughly, 68.7% of micro-organisms were non-producers of biofilms, 28.3% were medium biofilm producers, and 3.0% were high biofilm producers. The findings suggest there are problems related to the good practices of obtaining organic milk and in the manufacture of dairy products.

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“…Assessment of the production of lecithinase was performed on plate count agar (Merck KGaA) containing 10% egg yolk emulsion (Oxoid Ltd.). After incubation at 37°C for 72 h, plates were observed the presence of colonies surrounded by opaque zones (Bates and Liu, 1963).…”

Section: Screening Of Extracellular Enzyme Producing Pseudomonas Sppmentioning

confidence: 99%

Spoilage potentials and antimicrobial resistance of Pseudomonas spp. isolated from cheeses

Arslan

Eyi

Özdemir

2011

Journal of Dairy Science

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Pseudomonas spp. are aerobic, gram-negative bacteria that are recognized as major food spoilage microorganisms. A total of 32 (22.9%) Pseudomonas spp. from 140 homemade white cheese samples collected from the open-air public bazaar were isolated and characterized. The aim of the present study was to investigate the biochemical characteristics, the production of extracellular enzymes, slime and β-lactamase, and antimicrobial susceptibility of Pseudomonas spp. isolated from cheeses. The identified isolates including Pseudomonas pseudoalcaligenes, Pseudomonas alcaligenes, Pseudomonas aeruginosa, Pseudomonas fluorescens biovar V, and P. pseudoalcaligenes ssp. citrulli were found to produce extracellular enzymes, respectively: protease and lecithinase production (100%), and lipase activity (85.7, 42.9, 100, and 100%, and nonlipolytic, respectively). The isolates did not produce slime and had no detectable β-lactamase activity. The antimicrobial susceptibility of the isolates was tested using the disk diffusion method. Pseudomonas spp. had the highest resistance to penicillin G (100%), then sulphamethoxazole/trimethoprim (28.1%). However, all Pseudomonas spp. isolates were 100% susceptible to ceftazidime, ciprofloxacin, amikacin, gentamicin, and imipenem. Multidrug-resistance patterns were not observed among these isolates. In this study, Pseudomonas spp., exhibiting spoilage features, were isolated mainly from cheeses. Isolation of this organism from processed milk highlights the need to improve the hygienic practices. All of the stages in the milk processing chain during manufacturing have to be under control to achieve the quality and safety of dairy products.

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Complementation of Lecithinase Activities by Closely Related Pseudomonads: Its Taxonomic Implication

Cited by 12 publications

References 19 publications

Characterization of Gram‐Negative Psychrotrophic Bacteria isolated from Italian Bulk Tank Milk

Characterization of Gram‐Negative Psychrotrophic Bacteria isolated from Italian Bulk Tank Milk

Psychrotrophic bacteria in Brazilian organic dairy products: identification, production of deteriorating enzymes and biofilm formation

Spoilage potentials and antimicrobial resistance of Pseudomonas spp. isolated from cheeses

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