Veterinária
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11842
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Resultados da Pesquisa
Item Lactobacillus curvatus UFV-NPAC1 and other lactic acid bacteria isolated from calabresa, a fermented meat product, present high bacteriocinogenic activity against Listeria monocytogenes(BMC Microbiology, 2019) Castilho, Nathália Parma Augusto; Colombo, Monique; Oliveira, Leandro Licursi de; Todorov, Svetoslav Dimitrov; Nero, Luís AugustoBacteriocins produced by lactic acid bacteria (LAB) can be considered as viable alternatives for food safety and quality, once these peptides present antimicrobial activity against foodborne pathogens and spoilage bacteria. Fermented foods, such as artisanal sausages and cured meats, are relevant sources of LAB strains capable of producing novel bacteriocins, with particular interest by the food industry.Three LAB strains (firstly named as Lactobacillus curvatus 12, L. curvatus 36 and Weissella viridescens 23) were obtained from calabresa by presenting promising bacteriocinogenic activity, distinct genetic profiles (rep-PCR, RAPD, bacteriocin-related genes) and wide inhibitory spectrum. Among these strains, L. curvatus 12 presented higher bacteriocin production, reaching 25,000 AU/mL after incubation at 25, 30 and 37 °C and 6, 9 and 12 h. Partially purified bacteriocins from L. curvatus 12 kept their inhibitory activity after elution with isopropanol at 60% (v/v). Bacteriocins produced by this strain were purified by HPLC and sequenced, resulting in four peptides with 3102.79, 2631.40, 1967.06 and 2588.31 Da, without homology to known bacteriocins.LAB isolates obtained from calabresa presented high inhibitory activity. Among these isolates, bacteriocins produced by L. curvatus 12, now named as L. curvatus UFV-NPAC1, presented the highest inhibitory performance and the purification procedures revealed four peptides with sequences not described for bacteriocins to date.Item Molecular identification of naturally occurring bacteriocinogenic and bacteriocinogenic-like lactic acid bacteria in raw milk and soft cheese(Journal of Dairy Science, 2010-07) Ortolani, M. B. T.; Moraes, P. M.; Perin, L. M.; Viçosa, G. N.; Carvalho, K. G.; Silva Júnior, A.; Nero, L. A.Lactic acid bacteria (LAB) are currently used by food industries because of their ability to produce metabolites with antimicrobial activity against gram-positive pathogens and spoilage microorganisms. The objectives of this study were to identify naturally occurring bacteriocinogenic or bacteriocinogenic-like LAB in raw milk and soft cheese and to detect the presence of nisin-coding genes in cultures identified as Lactococcus lactis. Lactic acid bacteria cultures were isolated from 389 raw milk and soft cheese samples and were later characterized for the production of antimicrobial substances against Listeria monocytogenes. Of these, 58 (14.9%) LAB cultures were identified as antagonistic; the nature of this antagonistic activity was then characterized via enzymatic tests to confirm the proteinaceous nature of the antimicrobial substances. In addition, 20 of these antagonistic cultures were selected and submitted to genetic sequencing; they were identified as Lactobacillus plantarum (n = 2) and Lactococcus lactis ssp. lactis (n = 18). Nisin genes were identified by polymerase chain reaction in 7 of these cultures. The identified bacteriocinogenic and bacteriocinogenic-like cultures were highly variable concerning the production and activity of antimicrobial substances, even when they were genetically similar. The obtained results indicated the need for molecular and phenotypic methodologies to properly characterize bacteriocinogenic LAB, as well as the potential use of these cultures as tools to provide food safety.Item Characterization of bacteriocins produced by strains of Pediococcus pentosaceus isolated from Minas cheese(Annals of Microbiology, 2018-05-18) Nero, Luis Augusto; Gutiérrez-Cortés, Carolina; Suarez, Héctor; Buitrago, Gustavo; Todorov, Svetoslav DimitrovInterest in obtaining bacteriocin-producing strains of lactic acid bacteria (LAB) from different sources has been increasing in recent years due to their multiple applications in health and food industries. This study focused on the isolation and characterization of metabolically active populations of bacteriocinogenic LAB and the evaluation of their antimicrobial substances as well as of some nutritional requirements of them. One hundred and fifty colonies of LAB from artisanal cheeses produced in Minas Gerais state (Brazil) were isolated and screened for their antimicrobial activity. According to their activity against Listeria monocytogenes, ten strains were selected and subsequently identified using biochemical and molecular techniques including 16s rRNA amplification and sequencing as Enterococcus faecalis, Lactobacillus spp., and Pediococcus pentosaceus. Antimicrobial substances produced by four of the selected strains, P. pentosaceus 63, P. pentosaceus 145, P. pentosaceus 146, and P. pentosaceus 147, were biochemically characterized, and presented sensitivity to proteolytic enzymes (suggesting their proteinaceous nature) and to extreme pH. Antimicrobial activity showed stability after treatment with lipase, catalase, α-amylase, and chemicals. Growth kinetics of the P. pentosaceus selected showed maximal bacteriocin production at 37 °C during the end of the exponential growth phase (25,600 AU/mL) and stable production during 24 h of incubation. Dextrose, maltose, and a mixture of peptone, meat extract, and yeast extract increased bacteriocin production. This study demonstrated that dairy products provide a good alternative for obtaining LAB, with the ability to produce antimicrobial substances such as bacteriocins that have potential use as biopreservatives in food.Item In Vitro evaluation of bacteriocins activity against Listeria monocytogenes biofilm formation(Applied Biochemistry and Biotechnology, 2015-12-10) Camargo, Anderson Carlos; Paula, Otávio Almeida Lino de; Todorov, Svetoslav Dimitrov; Nero, Luís AugustoThe present study aimed to assess the activity of cell-free supernatant (CFS) containing bacteriocins on the formation and maintenance of biofilms developed by Listeria monocytogenes, and the associated effect of bacteriocins and ethylene-diamine-tetra-acetic acid (EDTA) on the formed biofilm. CFS from 9 lactic acid bacteria (LAB) strains was tested for inhibitory activity against 85 L. monocytogenes isolates and 21 LAB strains. Then, 12 L. monocytogenes strains were selected based on genetic profiles and sensitivity to CFS and were subjected to an in vitro assay to assess biofilm formation in microtiter plates, considering different culture media and incubation conditions. Based on these results, 6 L. monocytogenes strains were subjected to the same in vitro procedure to assess biofilm formation, being co-inoculated with CFS. In addition, these strains were subjected to the same in vitro procedure, modified by adding the CFS after biofilm formation. Relevant decrease in biofilm formation was observed in the first experiment, but CFS added after biofilm formation did not eliminate them. CFS from Lactobacillus curvatus ET31 were selected due to its anti-biofilm activity, being associated to EDTA at different concentrations and tested for biofilm control of three strains of L. monocytogenes, using the same in vitro procedure described previously. Concentrated bacteriocin presented poor performance in eliminating formed biofilms, and EDTA concentration presented no evident interference on biofilm elimination. Twelve selected L. monocytogenes strains were positive for investigated virulence makers and negative for luxS gene, recognized as being involved in biofilm formation. Selected L. monocytogenes strains were able to produce biofilms under different conditions. CFSs have the potential to prevent biofilm formation, but they were not able to destroy already formed biofilms. Nevertheless, low concentrations of CFS combined with EDTA caused a relevant reduction in already formed biofilms, but this association was not able to eliminate them. The activity of selected CFS was demonstrated against L. monocytogenes-formed biofilms, being more effective when associated to EDTA at different concentrations.Item Combined effect of bacteriocin produced by Lactobacillus plantarum ST8SH and vancomycin, propolis or EDTA for controlling biofilm development by Listeria monocytogenes(Revista Argentina de Microbiología, 2017-09-23) Todorov, Svetoslav D.; Paula, Otávio A.L.de; Camargo, Anderson C.; Lopes, Danilo A.; Nero, Luís A.The Listeria monocytogenes strains selected in the present study exhibited similar behavior in biofilm formation, independently of the tested conditions (bacteriocin from L. plantarum ST8SH, vancomycin, propolis (a natural antimicrobial product) and EDTA (chelating agent)), individual or in associations. The individual application of vancomycin had better inhibitory activity than that of propolis and EDTA; however, the association of the previously mentioned antimicrobial agents with bacteriocins resulted in better performance. However, when we compared the effects of vancomycin, propolis and EDTA, we could clearly observe that the combined application of bacteriocin and vancomycin was more effective than the combination of bacteriocin and propolis, and bacteriocin and EDTA. Considering the current need to reduce the use of antimicrobials and chemical substances in food processing, propolis can represent an alternative to improve the inhibitory effect of bacteriocins against L. monocytogenes biofilm formation, based on the obtained results. In general, high concentrations of bacteriocin produced by L. plantarum ST8SH were more effective in biofilm inhibition, and similar results were observed for vancomycin and propolis; however, all tested EDTA concentrations had similar effect on biofilm formation.