Biodiversity of Bacteriocin-Producing Lactic Acid Bacteria from Mexican Regional Cheeses and their Contribution to Milk Fermentation

Abstract

The aim of this work was to examine the biodiversity of bacteriocin-producing lactic acid bacteria from homemade cheeses produced in Veracruz (México) and assess their contribution as adjunct cultures in dairy products. Ninety-three presumptive bacteriocinogenic strains were detected by direct antagonism assays and twenty-nine out of them were active against Enterococcus faecalis NRRL-B537, Listeria innocua 062 AST, or Listeria monocytogenes ATCC19115 by the well diffusion test using cell-free supernatants, adjusted to pH 6.0 to exclude inhibition by organic acids. Positive isolates were identified by partial sequencing of the 16s rDNA as Pediococcus acidilactici (4 isolates), Enterococcus faecium (17 isolates), Lactobacillus plantarum (6 isolates) and Lactobacillus fermentum (2 isolates). RAPD-PCR discriminated 7 groups with a 50% similarity and revealed the presence of the same isolates. The coding genes for the synthesis of plantaricin EF, plantaricin JK, plantaricin N, plantaricin NC8 and the inducing peptide plantaricin A were detected by PCR in L. plantarum. Similarly, enterocin P and pediocin PA-1 genes were amplified from Enterococcus and Pediococcus genomic DNA, respectively. Overall, co-culturing of bacteriocin producing Lactobacillus and Pediococcus strains with the dairy starter Lactococcus lactis IPLA947 did not interfere with milk acidification. Lactose consumption, acidification rate and production of lactic acid were unchanged. Nonetheless, higher levels of acetic acid, ethanol and succinic acid were detected depending on the strain. Our results demonstrate the diversity of bacteriocinogenic species in homemade Mexican cheeses which may be used as adjunct cultures to enhancing safety of this wellappreciated cheese while providing a richer range of metabolites.

Effect of lactic acid bacterial fermentation on amino acids and volatile compounds of pork trimming hydrolysate

“…These results agree with Portilla‐Vázquez et al . (2016), who found that Lactobacillus species could produce succinic acid from citric acid via the reductive pathway of the tricarboxylic acid (TCA) cycle, while acetic acid may be formed from citrate metabolism by citrate lyase. Fig.…”

Genetic identification of native lactic acid bacteria in raw cow’s milk and artisanal Poro cheese

“…Esta especie (Lb. fermentum) se ha reportado en el queso artesanal Kazak (Xinjiang, China) (Li et al, 2020), queso Oaxaca (Caro et al, 2013) y quesos frescos artesanales de Veracruz, México (Portilla-Vázquez et al, 2016). Otra BAL es Lb.…”

“…plantarum son productoras de bacteriocinas, actividad antagónica contra Entrb. faecalis, Listeria innocua o L. monocytogenes) (Portilla-Vázquez et al, 2016). Esta última, también ha registrado resistencia a los antibióticos y capacidad acidificante (Caro et al, 2013).…”

“…Estas BAL desarrollan metabolitos secundarios funcionales como: etanol, ácido acético y ácido succínico durante su actividad metabólica en el alimento. Por lo que, se sugieren como cultivos iniciadores en la elaboración de quesos artesanales (Portilla-Vázquez et al, 2016). El género Enterococcus se ha recuperado de queso elaborado con leche de vaca sin pasteurizar en Pico, Portugal (Domingos-Lopes et al, 2017), de leche y quesos en Minas Gerais, Brasil (Moraes et al, 2012) y Entrc.…”