Development of a rapid qPCR method to quantify lactic acid bacteria in cold-smoked salmon

2021 ◽  
pp. 109504
Author(s):  
Marc Jérôme ◽  
Delphine Passerini ◽  
Frédérique Gigout ◽  
Laetitia Marchand ◽  
Françoise Leroi ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Smoked Salmon ◽  
Qpcr Method

Modeling and Predicting the Growth of Lactic Acid Bacteria in Lightly Preserved Seafood and Their Inhibiting Effect on Listeria monocytogenes

2007 ◽  
Vol 70 (11) ◽  
pp. 2485-2497 ◽  
Author(s):  
OLE MEJLHOLM ◽  
PAW DALGAARD
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Chemical Characterization ◽  
Effect Of Temperature ◽  
Inhibiting Effect ◽  
Smoked Salmon ◽  
Boundary Model ◽  
Parameter Values ◽  
Separate Product

A cardinal parameter model was developed to predict the effect of diacetate, lactate, CO2, smoke components (phenol), pH, NaCl, temperature, and the interactions between all parameters on the growth of lactic acid bacteria (LAB) in lightly preserved seafood. A product-oriented approach based on careful chemical characterization and growth of bacteria in ready-to-eat seafoods was used to develop this new LAB growth model. Initially, cardinal parameter values for the inhibiting effect of diacetate, lactate, CO2, pH, and NaCl–water activity were determined experimentally for a mixture of LAB isolates or were obtained from the literature. Next, these values and a cardinal parameter model were used to model the effect of temperature (Tmin) and smoke components (Pmax). The cardinal parameter model was fitted to data for growth of LAB (μmax values) in lightly preserved seafood including cold-smoked and marinated products with different concentrations of naturally occurring and added organic acids. Separate product validation studies of the LAB model resulted in average bias and accuracy factor values of 1.2 and 1.5, respectively, for growth of LAB (μmax values) in lightly preserved seafood. Interaction between LAB and Listeria monocytogenes was predicted by combining the developed LAB model and an existing growth and growth boundary model for the pathogen (O. Mejlholm and P. Dalgaard, J. Food Prot. 70:70–84). The performance of the existing L. monocytogenes model was improved by taking into account the effect of microbial interaction with LAB. The observed and predicted maximum population densities of L. monocytogenes in inoculated lightly preserved seafoods were 4.7 and 4.1 log CFU g−1, respectively, whereas for naturally contaminated vacuum-packed cold-smoked salmon the corresponding values were 0.7 and 0.6 log CFU g−1 when a relative lag time of 4.5 was used for the pathogen.

Effect of the lactic acid bacteria on the control of listerial activity and shelf life of smoked salmon scraps

2011 ◽  
Vol 46 (10) ◽  
pp. 2042-2051 ◽  
Author(s):  
Cristian Bernardi ◽  
Barbara Ripamonti ◽  
Simone Stella ◽  
Erica Tirloni ◽  
Carla Bersani ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Shelf Life ◽  
Smoked Salmon

scholarly journals A Novel qPCR Method for the Detection of Lactic Acid Bacteria in Fermented Milk

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3066
Author(s):  
Xiankang Fan ◽  
Xiefei Li ◽  
Tao Zhang ◽  
Jue Xu ◽  
Zihang Shi ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Fermented Milk ◽  
Confocal Laser ◽  
Quantitative Detection ◽  
Rrna Gene ◽  
Detection Range ◽  
Qualitative And Quantitative ◽  
Tuf Gene ◽  
Qpcr Method

The number of live lactic acid bacteria (LAB) is an important quality indicator for yogurt, the quantitative testing of LAB has become an important task in the evaluation of product quality and function. By analyzing and comparing the performance of 16S rRNA gene and tuf gene used in absolute quantification, the tuf gene with copy number 1 was selected as the target gene of six LAB. By drawing a standard curve to achieve qualitative and quantitative detection of six strains of LAB, the detection range was found to be 1 × 103–1 × 108 copies/µL. The traditional plate colony count and Flow Cytometry (FCM) were compared with the method of qPCR, which was used in this experiment. Meanwhile, the confocal laser microscope combined with STYO 9 and propidium iodide dyes was used to determine that the content of viable bacteria in the yogurt was more than 90%, which proved that the detection result using qPCR method was closer to the true level of LAB in yogurt. Compared with the existing methods, the method in this study allowed the qualitative and quantitative detection of the six kinds of LAB in yogurt, and the distribution of live and dead bacteria in yogurt could be calculated.

Could Modifications of Processing Parameters Enhance the Growth and Selection of Lactic Acid Bacteria in Cold-Smoked Salmon To Improve Preservation by Natural Means?

2007 ◽  
Vol 70 (7) ◽  
pp. 1607-1614 ◽  
Author(s):  
ELISABETTA TOMÉ ◽  
PAUL A. GIBBS ◽  
PAULA C. TEIXEIRA
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Salt Content ◽  
Storage Period ◽  
Processing Parameters ◽  
Viable Count ◽  
Smoked Salmon ◽  
Microbiological Analyses ◽  
Natural Means ◽  
Selection Of

Several smoking conditions were examined with the objective of enhancing the numbers of lactic acid bacteria (LAB) by natural means in vacuum-packaged cold-smoked salmon during 21 days of storage at 5°C. Three combinations of salting, drying, and smoking were used: (i) dry salting × time of salting (2 or 6 h); (ii) wet salting (6 h) × dry salting (6 h) × with or without sugar; and (iii) wet salting (6 h) × dry salting (6 h) × different times of smoking (2 or 6 h of drying and 2 or 6 h of smoking). Two batches were processed for each set of conditions. Determinations of pH and salt content in the water phase were carried out for products in each treatment. Microbiological analyses (total viable count, total LAB, Lactobacillus spp., and Enterobacteriaceae) also were conducted at the beginning of storage (t0) and after 21 days of refrigerated storage (t1). There were differential increases in total LAB and lactobacilli during the storage period according to the treatment performed. The most effective treatment to enhance LAB growth was6hof dry salting with sugar, 6 h of drying, and 2 h of smoking. These salting-drying-smoking conditions also selected the LAB as the dominant flora at the end of the storage period. The LAB promoted by these processing parameters seem to be potentially useful protective cultures because of their anti-Listeria activity. From the results of this research, we conclude that it is possible to enhance the growth of LAB in general and that of inhibitory strains in particular by suitable choices of processing parameters.

Psychrotrophic Lactic Acid Bacteria Used To Improve the Safety and Quality of Vacuum-Packaged Cooked and Peeled Tropical Shrimp and Cold-Smoked Salmon

2009 ◽  
Vol 72 (2) ◽  
pp. 365-374 ◽  
Author(s):  
S. MATAMOROS ◽  
F. LEROI ◽  
M. CARDINAL ◽  
F. GIGOUT ◽  
F. KASBI CHADLI ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Listeria Monocytogenes ◽  
Lactic Acid Bacteria ◽  
Shelf Life ◽  
Pathogenic Bacteria ◽  
Smoked Salmon ◽  
Seafood Products ◽  
Challenge Tests ◽  
Leuconostoc Gelidum

Previously isolated lactic acid bacteria (LAB) from seafood products have been investigated for their capacity to increase the sensory shelf life of vacuum-packaged shrimp and cold-smoked salmon and to inhibit the growth of three pathogenic bacteria. Two different manufactured batches of cooked, peeled, and vacuum-packaged shrimp were inoculated with seven LAB strains separately at an initial level of 5 log CFU g−1, and the spoilage was estimated by sensory analysis after 7 and 28 days of storage at 8°C. Two Leuconostoc gelidum strains greatly extended the shelf life of both batches, two Lactococcus piscium strains had a moderate effect, two bacteria were spoilers (Lactobacillus fuchuensis and Carnobacterium alterfunditum), and the last one (another Leuconostoc gelidum strain) showed highly variable results depending on the batch considered. The four strains showing the best results (two Leuconostoc gelidum and two Lactococcus piscium strains) were selected for the same experiment in cold-smoked salmon. In this product, Lactococcus piscium strains showed better inhibiting capacities, improving the sensory quality significantly at 14 and 28 days of storage. Finally, the inhibiting capacities of two strains (one Leuconostoc gelidum strain and one Lactococcus piscium strain) were tested against three pathogenic bacteria (Vibrio cholerae, Listeria monocytogenes, and Staphylococcus aureus) by challenge tests in shrimp. LAB and pathogenic bacteria were coinoculated in vacuum-packaged shrimp and enumerated during 5 weeks. Lactococcus piscium strain EU2241 was able to reduce significantly the number of Listeria monocytogenes and S. aureus organisms in the product by 2 log throughout the study for Listeria monocytogenes and up to 4 weeks for S. aureus.

scholarly journals Diversity and Antimicrobial Activity towards Listeria spp. and Escherichia coli among Lactic Acid Bacteria Isolated from Ready-to-Eat Seafood

Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 271
Author(s):  
Jelena Stupar ◽  
Ingunn Grimsbo Holøymoen ◽  
Sunniva Hoel ◽  
Jørgen Lerfall ◽  
Turid Rustad ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Antimicrobial Effect ◽  
Food Preservation ◽  
Rrna Gene ◽  
E Coli ◽  
Preservation Technology ◽  
Smoked Salmon

Biopreservation is a food preservation technology using microorganisms and/or their inherent antimicrobial metabolites to inhibit undesirable microorganisms. The aim of the present study was to explore the diversity and antimicrobial activity of lactic acid bacteria (LAB) strains (n = 99) isolated from ready-to-eat (RTE) seafood (cold-smoked salmon (CSS), gravlax, and sushi) towards two strains of Listeria monocytogenes (CCUG 15527, F11), Listeria innocua (CCUG 15531) and Escherichia coli (CCUG 38079). The LAB strains were assigned to five different genera (Carnobacterium spp., Lactobacillus spp., Leuconostoc spp., Weissella spp., and Enterococcus sp.) by sequencing a 1150 bp stretch of the 16S rRNA gene. A significant association between the seafood source and the distribution of LAB genera was found (p < 0.001), of which Leuconostoc spp. were most prevalent in sushi and Carnobacterium sp. and Lactobacillus sp. were most frequently isolated from CSS and gravlax. Antimicrobial activity among the LAB was significantly affected by LAB genera (F= 117.91, p < 0.001, one-way ANOVA), product of origin (F = 3.47, p < 0.05), and target (F = 4.64, p = 0.003). LAB isolated from sushi demonstrated a significantly higher antimicrobial effect than LAB from CSS and gravlax (p < 0.05). In general, a significantly higher antimicrobial activity was found towards Listeria spp. than E. coli (p < 0.05). However, Leuconostoc spp. demonstrated similar antimicrobial effects towards E. coli and Listeria spp., except for L. monocytogenes F11 being more sensitive (p < 0.05). This study suggested that seafood-derived LAB strains could be selected for technological application in RTE seafood systems.

Effect of Salt and Smoke on the Microbiological Quality of Cold-Smoked Salmon during Storage at 5°C as Estimated by the Factorial Design Method

2000 ◽  
Vol 63 (4) ◽  
pp. 502-508 ◽  
Author(s):  
F. LEROI ◽  
J. J. JOFFRAUD ◽  
F. CHEVALIER
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Design Method ◽  
Microbiological Quality ◽  
Viable Count ◽  
Minimum Concentration ◽  
Salt Level ◽  
Smoked Salmon ◽  
Two Factors ◽  
Natural Flora

The simultaneous effect of salt and smoke on the natural flora of cold-smoked salmon was studied during 5 weeks of vacuum storage at 5°C. The quadratic polynomial, as a function of factors, was used to express total viable count (TVC), total lactic acid bacteria, lactobacilli numerated on Rogosa agar, H2S-producing bacteria, and yeasts at different sampling times. TVC and total lactic acid bacteria were mainly inhibited by the salt concentration (5% wt/wt) in the meat and to a lesser extent by the phenol content. Inhibition was linearly proportional to salt and smoke content (the higher the concentration, the greater the inhibition). No synergistic effect on inhibition was observed between the two factors. In our working conditions, the TVC French standard (&lt;106 CFU g−1) was maintained during 4 weeks of storage at 5°C, with a minimum concentration of 2.4% (wt/wt) of salt in meat and smoking treatment corresponding to 0.6 mg 100 g−1 of phenol. When the salt level was higher than 3%, the TVC standard was maintained, regardless of phenol level. A negative interaction between the two factors was found for H2S-producing bacteria and a positive one for yeasts.

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