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.

The biopreservation of foods using bacteriocinogenic lactic acid bacteria (LAB) isolated directly from foods is an innovative approach. The objectives of this study were to isolate and identify bacteriocinogenic LAB from various cheeses and yogurts and evaluate their antimicrobial effects on selected spoilage and pathogenic microorganisms in vitro as well as on a food commodity. LAB were isolated using MRS and M17 media. The agar diffusion bioassay was used to screen for bacteriocin or bacteriocin-like substances (BLS) producing LAB using Lactobacillus sakei and Listeria innocua as indicator organisms. Out of 138 LAB isolates, 28 were found to inhibit these bacteria and were identified as strains of Enterococcus faecium, Streptococcus thermophilu s, Lactobacillus casei and Lactobacillus sakei subsp. sakei using 16S rRNA gene sequencing. Eight isolates were tested for antimicrobial activity at 5°C and 20°C against L. innocua, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, Erwinia carotovora, and Leuconostoc mesenteroides subsp. mesenteroides using the agar diffusion bioassay, and also against Penicillium expansum, Botrytis cinerea and Monilinia frucitcola using the microdilution plate method. The effect of selected LAB strains on L. innocua inoculated onto fresh-cut onions was also investigated. Twenty percent of our isolates produced BLS inhibiting the growth of L. innocua and/or Lact. sakei. Organic acids and/or H₂O₂ produced by LAB and not the BLS had strong antimicrobial effects on all microorganisms tested with the exception of E. coli. Ent. faecium, Strep. thermophilus and Lact. casei effectively inhibited the growth of natural microflora and L. innocua inoculated onto fresh-cut onions. Bacteriocinogenic LAB present in cheeses and yogurts may have potential to be used as biopreservatives in foods.

ISHS XXVI International Horticultural Congress: Issues and Advances in Postharvest Horticulture OZONE AND 1-MCP TREATMENTS AFFECT THE QUALITY AND STORAGE LIFE OF FRESH CARROTS

Societal Impact Statement: Climate warming and demand for fuller‐bodied wines has resulted in increased grape sugar contents and, therefore, increased alcohol in wines. Concurrently, there are increased warnings about the health risks of alcohol, and consumers seek low‐alcohol options as part of a healthy lifestyle. High alcohol levels can also impact the flavor balance of wines, resulting in economic losses. However, exploration of native vineyard yeasts shows that fermentation with novel species can result in both alcohol reduction and improved wine flavor. Our findings show that native yeasts have the potential to bring the North American cool‐climate wine industry into a healthier future.Summary: There is recent interest in developing wines fermented with non‐traditional yeasts that reflect the microbial terroir of the grape‐growing region. These native yeasts inhabit grape skins and can produce wines with distinctive flavor profiles, and when used in concert with traditional wine yeast, the risk of incomplete fermentation is minimized. Non‐traditional yeasts can also produce wines with relatively low alcohol content, an attractive characteristic given the health and societal issues associated with overconsumption. Yeasts isolated from L'Acadie and Pinot Noir grapes grown at Nova Scotia vineyards were identified by DNA sequencing and characterized regarding fermentative properties. Promising isolates of Saccharomyces uvarum, Hanseniaspora uvarum, Wickerhamomyces anomalus, and Zygotorulaspora florentina were selected for mixed and sequential fermentations with Saccharomyces cerevisiae based on their ethanol and SO₂ tolerance, β‐glucosidase activity, and low H₂S production. The resulting wines were evaluated for sensory properties by 15 experienced panelists. Alcohol levels of many of the fermentations that included non‐traditional yeasts were significantly lower than those made with traditional yeast alone, while fructose was higher, and total phenolic contents were similar. Experienced panelists also found that these fermentations resulted in wines with novel fruit and floral attributes. Our results demonstrate that native yeasts from cool‐climate wine regions can be used in concert with traditional wine yeast to produce novel, lower alcohol wines with a low risk of fermentation failure. This unlocks the potential of naturally occurring yeasts from these vineyards to create wines with flavor profiles that reflect the local wine‐making regions.