Influence of culture media, pH and temperature on growth and bacteriocin production of bacteriocinogenic lactic acid bacteria

Abstract

There has been continued interest in bacteriocins research from an applied perspective as bacteriocins have potential to be used as natural preservative. Four bacteriocinogenic lactic acid bacteria (LAB) strains of Lactobacillus curvatus (Arla-10), Enterococcus faecium (JFR-1), Lactobacillus paracasei subsp. paracasei (JFR-5) and Streptococcus thermophilus (TSB-8) were previously isolated and identified in our lab. The objective of this study was to determine the optimal growth conditions for both LAB growth and bacteriocins production. In this study, various growth conditions including culture media (MRS and BHI), initial pH of culture media (4.5, 5.5, 6.2, 7.4 and 8.5), and incubation temperatures (20, 37 and 44 °C) were investigated for LAB growth measured as optical density (OD), bacteriocin activity determined as arbitrary unit and viability of LAB expressed as log CFU ml−1. Growth curves of the bacteriocinogenic LAB were generated using a Bioscreen C. Our results indicated that Arla-10, JFR-1, and JFR-5 strains grew well on both MRS and BHI media at growth temperature tested whereas TSB-8 strain, unable to grow at 20 °C. LAB growth was significantly affected by the initial pH of culture media (p < 0.001) and the optimal pH was found ranging from 6.2 to 8.5. Bacteriocin activity was significantly different in MRS versus BHI (p < 0.001), and the optimal condition for LAB to produce bacteriocins was determined in MRS broth, pH 6.2 at 37 °C. This study provides useful information on potential application of bacteriocinogenic LAB in food fermentation processes.

Effect of growth media on natural starter culture composition and performance evaluated with a polyphasic approach

“…; Yang et al . ). At present, a few reports concerning the use of natural or synthetic media for the cultivation of complex natural starters are available in literature (Erkus et al .…”

“…The medium properties can influence bacterial growth, biomass and the production of metabolites (e.g. lactic acid, exopolysaccharides and bacteriocins), thus, stimulating species and strains differently, can change microbial composition and the balance of complex natural starters (Savoie et al 2007;Adebayo-Tayo and Onilude 2010;Marques Saccaro et al 2012;Basu et al 2015;Yang et al 2018). At present, a few reports concerning the use of natural or synthetic media for the cultivation of complex natural starters are available in literature (Erkus et al 2013;Frantzen et al 2016).…”

Influence of Storage Temperature and Packaging on Bacteria and Yeast Viability in a Plant-Based Fermented Food

“…Additionally, storage time and temperature can affect the bacterial survival [30,[38][39][40] thus the manipulation of environmental temperature could be useful for reducing the loss of viable bacteria. In general, high temperature importantly decreases microorganism's viability [41,42] while low temperature, like refrigeration, has been reported to be better for the survival of certain probiotics [43].…”

Films of Chitosan and Aloe vera for Maintaining the Viability and Antifungal Activity of Lactobacillus paracasei TEP6

“…The pH and lactose were not significant factors to maintain or increase the antifungal capacity of the films. In contrast, it has been reported that the gene expression of antimicrobial metabolites (mainly bacteriocins) is regulated by pH [26]. The pH values evaluated in the present study (4.5 and 5.5) are possibly not high enough to show an effect of pH on genetic regulation; the cited authors evaluated a wide pH range (4.5, 5.5, 6.2, 7.4 and 8.5) and reported that the optimal production of bacteriocins was at pH 6.2.…”

“…It has been reported that basic pH favors the accumulation of lactate, which can result in the loss of both membrane integrity and metabolic activity. The interaction between the pH and the chemical composition of the culture medium also seems to be important for cell viability, as others reported that survival is higher when LAB are cultivated at basic pH values (7.4 and 8.5) in MRS medium [26]; however, when the same cells were cultured in brain and heart infusion (BHI) broth, pH 5.5 was optimal to maintain cell viability.…”