RESUMO
The globalization of trade and lifestyle ensure that the factors responsible for the emergence of diseases are more present than ever. Despite biotechnology advancements, meat-based foods are still under scrutiny because of the presence of pathogens, which causes a loss of consumer confidence and consequently a fall in demand. In this context, Lactic Acid Bacteria (LAB) as GRAS organisms offer an alternative for developing pathogen-free foods, particularly avoiding Listeria monocytogenes, with minimal processing and fewer additives while maintaining the foods' sensorial characteristics. The use of LAB strains, enabling us to produce antimicrobial peptides (bacteriocins) in addition to lactic acid, with an impact on quality and safety during fermentation, processing, and/or storage of meat and ready-to-eat (RTE) meat products, constitutes a promising tool. A number of bacteriocin-based strategies including the use of bioprotective cultures, purified and/or semi-purified bacteriocins as well as their inclusion in varied packaging materials under different storage conditions, have been investigated. The application of bacteriocins as part of hurdle technology using non-thermal technologies was explored for the preservation of RTE meat products. Likewise, considering that food contamination with L. monocytogenes is a consequence of the post-processing manipulation of RTE foods, the role of bacteriocinogenic LAB in the control of biofilms formed on industrial surfaces is also discussed.
RESUMO
Some lactic acid bacteria have the ability to form biofilms on food-industry surfaces and this property could be used to control food pathogens colonization. Lactobacillus sakei CR1862 was selected considering its bacteriocinogenic nature and ability to adhere to abiotic surfaces at low temperatures. In this study, the proteome of L. sakei CRL1862 grown either under biofilm on stainless steel surface and planktonic modes of growth at 10°C, was investigated. Using two-dimensional gel electrophoresis, 29 out of 43 statistically significant spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Ten proteins resulted up-regulated whereas 16 were down-regulated during biofilm formation. Differentially expressed proteins were found to belong to carbohydrate, nucleotide, aminoacid and lipid metabolisms as well as translation, peptide hydrolysis, cell envelope/cell wall biosynthesis, adaption to atypical conditions and protein secretion. Some proteins related to carbohydrate and nucleotide metabolisms, translation and peptide degradation were overexpressed whereas those associated to stress conditions were synthesized in lower amounts. It seems that conditions for biofilm development would not imply a stressful environment for L. sakei CRL1862 cells, directing its growth strategy towards glycolytic flux regulation and reinforcing protein synthesis. In addition, L. sakei CRL1862 showed to harbor nine out of ten assayed genes involved in biofilm formation and protein anchoring. By applying qRT-PCR analysis, four of these genes showed to be up regulated, srtA2 being the most remarkable. The results of this study contribute to the knowledge of the physiology of L. sakei CRL1862 growing in biofilm on a characteristic food contact surface. The use of this strain as green biocide preventing L. monocytogenes post-processing contamination on industrial surfaces may be considered.
Assuntos
Aderência Bacteriana/fisiologia , Biofilmes/crescimento & desenvolvimento , Latilactobacillus sakei/crescimento & desenvolvimento , Aço Inoxidável , Desinfetantes/farmacologia , Eletroforese em Gel Bidimensional , Indústria de Processamento de Alimentos , Perfilação da Expressão Gênica , Latilactobacillus sakei/genética , Latilactobacillus sakei/metabolismo , Listeria monocytogenes/crescimento & desenvolvimento , Proteoma/genética , Proteômica , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The effect of the bacteriocin-producing Lactobacillus sakei CRL1862 and its bacteriocin in the control of Listeria biofilm formation on industrial surfaces at 10°C was investigated. A screening among different Listeria species was performed allowing selecting L. monocytogenes FBUNT for its use as a biofilm producer on stainless steel (SS) and polytetrafluoroe-thylene (PTFE) surfaces. Three conditions were simulated to evaluate the ability of the bacteriocinogenic strain to displace, exclude and compete pathogen biofilm formation. Lactobacillus sakei CRL1862 effectively inhibited biofilm formation by L. monocytogenes FBUNT through the three assayed mechanisms, pathogen inhibition being more efficient on PTFE than on SS surface. Moreover, co-culture of L. monocytogenes FBUNT with the bacteriocin-producer displayed the highest efficacy reducing the pathogen by 5.54 ± 0.12 and 4.52 ± 0.01 on PTFE and SS, respectively. Industrially, the pre-treatment with L. sakei CRL1862 or its bacteriocin (exclusion) constitutes the most realistic way to prevent pathogen biofilm settlement. The use of bacteriocins and/or the bacteriocin-producer strain represents a safe and environmentally-friendly sanitation method to mitigate post-processing food contamination.
Assuntos
Antibiose , Bacteriocinas/biossíntese , Biofilmes/crescimento & desenvolvimento , Latilactobacillus sakei/fisiologia , Listeria monocytogenes/fisiologia , Técnicas de Cocultura , Contaminação de Alimentos/prevenção & controle , Listeria monocytogenes/patogenicidade , Politetrafluoretileno , Aço Inoxidável , Propriedades de SuperfícieRESUMO
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.