Search

The effect of lactocin AL705, bacteriocin produced by Latilactobacillus (Lat.) curvatus CRL1579 against Listeria biofilms on stainless steel (SS) and polytetrafluoroethylene (PTFE) coupons at 10 °C was investigated. L. monocytogenes FBUNT showed the greatest adhesion on both surfaces associated to the hydrophobicity of cell surface. Partially purified bacteriocin (800 UA/mL) effectively inhibited L. monocytogenes preformed biofilm through displacement strategy, reducing the pathogen by 5.54 ± 0.26 and 4.74 ± 0.05 log cycles at 3 and 6 days, respectively. The bacteriocin-producer decreased the pathogen biofilm by ∼2.84 log cycles. Control and Bac - treated samples reached cell counts of 7.05 ± 0.18 and 6.79 ± 0.06 log CFU/cm 2 after 6 days of incubation. Confocal scanning laser microscopy (CLSM) allowed visualizing the inhibitory effect of lactocin AL705 on L. monocytogenes preformed biofilms under static and hydrodynamic flow conditions. A greater effect of the bacteriocin was found at 3 days independently of the surface matrix and pathogen growth conditions at 10 °C. As a more realistic approach, biofilm displacement strategy under continuous flow conditions showed a significant loss of biomass, mean thickness and substratum coverage of pathogen biofilm. These findings highlight the anti-biofilm capacity of lactocin AL705 and their potential application in food industries., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The effect of bioprotective extracts (BEs) from Lactobacillus acidophilus CRL641 (BE-1) and Latilactobacillus curvatus CRL705 (BE-2) against the exopolysaccharide producer Latilactobacillus sakei CRL1407 in vacuum-packaged meat discs at 4 °C was evaluated. Lat. sakei CRL1407 was able to grow in control samples from 2.80 to 7.77 log CFU/g after 38 days. BE-1 and BE-2 reduced bacterial growth by 2.11 and 1.35 log CFU/g, respectively, but their combination led to a greater growth reduction (3.31 log CFU/g). The antimicrobial activity was detected in treated samples with BE-1 and BE-1 + BE-2 until day 16, while with BE-2 only at the initial time. The pH values remained constant in the discs treated with the BEs combination, whereas the greatest drop in pH was observed in control samples. The minor lipid oxidation without perceptible color changes was detected in the presence of BE-1 and BE-1 + BE-2. The combination of BEs as biocontrol agent plus conventional preservation barriers could extend the fresh meat shelf-life without quality loss., (Copyright © 2021. Published by Elsevier Ltd.)

The effect of bioprotective extracts (BEs) from Latilactobacillus curvatus CRL705 and Lactobacillus acidophilus CRL641 against Latilactobacillus sakei CRL1407 was evaluated in a refrigerated meat model system under vacuum and aerobic conditions at 4 and 10 °C. As shown by culturing, the BE-1 from L. acidophilus completely inhibited the spoilage strain, while that from Lat. Curvatus CRL705 (BE-2) and its combination with BE-1 exerted a bacteriostatic effect. The antimicrobial activity and exopolysaccharide production correlated with the efficacy of inhibitory treatment while final pH decrease was higher in control samples. When flow cytometry was applied, a lack of correlation with plate counting was found; counts under the detection limit for BE-1 at 21 and 28 days at 4 and 10 °C represented between 64.15 and 73.70% of dead cells. Thus, the concurrence of lactic acid bacteria as biocontrol agents and the use of more accurate tools to prevent the growth of deteriorating species will contribute to the extension of fresh meat shelf-life without quality loss., (Copyright © 2021. Published by Elsevier Ltd.)

Diversity and dynamics of yeasts associated with the fermentation of Argentinian maize-based beverage chicha was investigated. Samples taken at different stages from two chicha productions were analyzed by culture-dependent and culture-independent methods. Five hundred and ninety six yeasts were isolated by classical microbiological methods and 16 species identified by RFLPs and sequencing of D1/D2 26S rRNA gene. Genetic typing of isolates from the dominant species, Saccharomyces cerevisiae, by PCR of delta elements revealed up to 42 different patterns. High-throughput sequencing (HTS) of D1/D2 26S rRNA gene amplicons from chicha samples detected more than one hundred yeast species and almost fifty filamentous fungi taxa. Analysis of the data revealed that yeasts dominated the fermentation, although, a significant percentage of filamentous fungi appeared in the first step of the process. Statistical analysis of results showed that very few taxa were represented by more than 1% of the reads per sample at any step of the process. S. cerevisiae represented more than 90% of the reads in the fermentative samples. Other yeast species dominated the pre-fermentative steps and abounded in fermented samples when S. cerevisiae was in percentages below 90%. Most yeasts species detected by pyrosequencing were not recovered by cultivation. In contrast, the cultivation-based methodology detected very few yeast taxa, and most of them corresponded with very few reads in the pyrosequencing analysis., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The typical Spanish dry-cured ham has a particular sensory quality that makes it a distinctive food, highly appreciated for consumers worldwide. Its particular physicochemical properties, such as high salt content and reduced water activity contribute to their shelf-stability. However, post-processing actions carried out for the commercialization of these products such as slicing may increase the risk of development of pathogenic microorganisms as Listeria monocytogenes. During ripening, muscle proteins are hydrolyzed by muscle peptidases releasing peptides and free amino acids. Some of these peptides have been described to exert biological activities such as antioxidant and ACE-inhibition. In this study, a peptidomic strategy using mass spectrometry techniques has been used to identify and sequence those naturally generated peptides showing antilisterial activity. One hundred and five peptides have been identified in active fractions and some synthesized and their MIC calculated. Ten peptides were able to inhibit the growth of L. monocytogenes, being the pentapeptide RHGYM the most effective showing a MIC value of 6.25 mM. This study proves for the first time the potential antimicrobial action against L. monocytogenes of certain naturally generated peptides obtained from Spanish dry-cured ham., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

In this study, proteolysis and low molecular weight (LMW) peptides (<3kDa) from commercial Argentinean fermented sausages were characterized by applying a peptidomic approach. Protein profiles and peptides obtained by Tricine-SDS-PAGE and RP-HPLC-MS, respectively, allowed distinguishing two different types of fermented sausages, although no specific biomarkers relating to commercial brands or quality were recognized. From electrophoresis, α-actin, myoglobin, creatine kinase M-type and L-lactate dehydrogenase were degraded at different intensities. In addition, a partial characterization of fermented sausage peptidome through the identification of 36 peptides, in the range of 1000-2100 Da, arising from sarcoplasmic (28) and myofibrillar (8) proteins was achieved. These peptides had been originated from α-actin, myoglobin, and creatine kinase M-type, but also from the hydrolysis of other proteins not previously reported. Although muscle enzymes exerted a major role on peptidogenesis, microbial contribution cannot be excluded as it was postulated herein. This work represents a first peptidomic approach for fermented sausages, thereby providing a baseline to define key peptides acting as potential biomarkers., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The ability of meat borne anti-Listeria Lactobacillus to form biofilms under different in vitro conditions and on abiotic surfaces was investigated. Biofilm formation by the adhesion to polystyrene microtiter plates was determined, this being higher for Lactobacillus curvatus CRL1532 and CRL705 and Lactobacillus sakei CRL1862. The physicochemical properties of the cell surface were relatively hydrophilic and acidic in character; L. sakei CRL1862 exhibiting the strongest autoaggregation. The adhesion of lactobacilli to stainless steel (SS) and polytetrafluoroethylene (PTFE) supports at 10°C was found to be maximal for L. sakei CRL1862 on SS after 6 days. When biofilm architecture was characterized by epifluorescence and SEM, L. sakei CRL1862 homogeneously covered the SS surface while cell clusters were observed on PTFE; the extracellular polymeric substance matrix adapted to the topography and hydrophilic/hydrophobic characteristics of each material. The feasibility of L. sakei CRL1862 to form biofilm on materials used in meat processing highlights its potential as a control strategy for Listeria monocytogenes biofilms., (© 2013. Published by Elsevier Ltd. All rights reserved.)

Angiotensin I converting enzyme (ACE) inhibitory activity of peptides derived from the hydrolysis of sarcoplasmic and myofibrillar porcine proteins by the action of Lactobacillus sakei CRL1862 and Lactobacillus curvatus CRL705 (whole cells+cell free extracts) was investigated at 30°C for 36 h. The protein hydrolysates were subjected to RP-HPLC in order to fractionate the extracts for further evaluation of ACE inhibitory activity. Bioactive fractions were only found from the hydrolysis of sarcoplasmic proteins by both assayed lactobacilli strains. Identification of peptides contained in the bioactive fractions was carried out by tandem mass spectrometry using a nanoLC-ESI-QTOF instrument and the mascot search engine. From the four most active fractions obtained, a total of eighteen and fifty peptides were characterized from L. sakei CRL1862 and L. curvatus CRL705 protein hydrolysates, respectively. The sequence FISNHAY was generated by the proteolytic activity of the two lactobacilli species. Sequence similarity analyses between the peptides identified in this study and those previously identified as ACE inhibitory peptides and detailed in the BIOPEP database were outlined. Results suggest that meat-borne Lactobacillus were able to generate peptides with ACE inhibitory activity, highlighting their potential to be used in the development of functional fermented products., Biological Significance: The results of this study would enable the obtention of porcine functional foods by applying lactic acid bacteria generating bioactive peptides. ACE inhibitory peptides obtained by the hydrolytic action of L. curvatus CRL705 and L. sakei CRL1862 on sarcoplasmic proteins were analyzed. Among them, the peptide FISNHAY exhibited the highest activity and its sequence has not yet been reported., (© 2013. Published by Elsevier B.V. All rights reserved.)

The microbial ecology of meat fermentation is a complex process in which lactic acid bacteria (LAB) and coagulase-negative cocci play a major role. The present work reviews the most significant developments in which LAB are the main characters acting both as starter cultures improving the sensorial quality and as biopreservative agents. New findings about the identification of low molecular weight peptides arisen from protein hydrolysis in dry fermented sausages and their relation with flavor is presented. Also, a brief description of a proteomic approach is detailed in order to exemplify its application as a tool in the search for improved LAB strains that will contribute to food quality and safety. Finally, the most important features of bacteriocinogenic LAB and its bacteriocins in bioprotection of meat and meat products are analyzed.

The acid-producing capacity and proteolytic activity of 13 strains of Lactobacillus plantarum and 5 strains of Lactobacillus casei isolated from dry sausages was determined at different temperatures and at different NaCl concentrations. Most strains exhibited a maximum acid-producing rate at 30°C. According to the acidification rate at this temperature, strains were divided into three rate groups: fast (I), medium (II) and slow (III), with titratable acidity values above 1.7, between 0.7 and 1.4, and below 0.7, respectively. The decrease in pH ranged between 3.1 and 3.95 according to the group to which the strains belonged. The addition of 3% NaCl produced a marked decrease in the rate of acidification for strains in group II, a slight decrease for those in group I and no effect for those in group III. The proteolytic activity of the strains under study reached a maximum at 40°C, with values between 5.2 and 10 mg% tyrosine released. At 30°C, and in the presence of 3% NaCl, the greatest activity (5.4 mg% tyrosine) was observed in L. plantarum GV 417 and the lowest (3.4 mg% tyrosine) in L. plantarum GV 420. A decrease of approximately 80% in proteolytic activity for all strains was observed in the presence of 5% NaCl.

Pure bacterial cultures were used in the production of Argentina salami, the most popular cured meat product in the country. Three selected groups of two strains each of Lactobacillus plantarum and Micrococcus varians were used as a starter cultures, with two different sugar concentrations. Apart from the use of these starter cultures, the salami was manufactured under the same conditions normally used in industrial production. When 0.6% sucrose was used, the levels of L. plantarum and M. varians were 10 8 and 10 7 CFU/g, respectively, on the second day of ripening. Similar levels of lactic acid bacteria were found in non-inoculated sausages at 2 d post-preparation. Under these conditions, coliforms decreased significantly. The final pH of the inoculated and uninoculated sausage were 5.0 and 5.2, respectively, after 7 d of ripening. When 0.9% glucose plus 0.6% sucrose was added, the level of lactic acid bacteria was 10 9 CFU/g on the second day, a value that remained constant in the inoculated sausages to the end of the ripening period. Staphylococci showed a marked decrease in population, while coliforms disappeared on the second or third day. The final pH of 4.40 or 4.55 was reached within 4 d. The product obtained under these conditions had a firm texture, a good slicing surface and pleasant flavor and aroma. The use of starter cultures in cured dry Argentine-style sausage shortened the ripening period from 14 to 7 d.