Lactobacillus fermentum bacteria with antifungal activity

Abstract

The present invention relates to a bacterium of the species Lactobacillus fermentum having the ability to inhibit the growth of the fungus Penicillium solitum deposited under the accession No.: DSM32093 or the growth of the fungus Penicillium brevicompactum deposited under the accession No.: DSM32094 by at least 50%. The inhibitory activity can be determined in an assay comprising: (1) preparing a fermented milk product by: (a) inoculating a milk with the Lactobacillus fermentum in a concentration of at least 107 CFU / g and with a starter culture, (b) fermenting until a p H of 4.6 is reached, and (c) solidifying the fermented milk by the addition of agar; (2) generating at least one spot of the P. solitum or the P. brevicompactum on the agar solidified fermented milk with a concentration of 500 spores / spot and incubating the 1 same for 7 days at 25° C.; (3) determining the percent inhibition by determining the largest diameter of the colony formed by growth of the P. solitum or P. brevicompactum and expressing the diameter as percent of the largest diameter formed under the same conditions but in the absence of the Lactobacillus fermentum strain. The invention further relates to compositions comprising the bacterium, methods for producing fermented milk products using the bacterium and the products thus obtained.

Description

FIELD OF THE INVENTION[0001]The present invention relates to Lactobacillus fermentum bacteria with antifungal activity, compositions comprising the bacteria, in particular adjunct cultures comprising the bacteria, methods of producing a fermented milk product using the bacteria or the cultures and the fermented milk products thus obtained, including food, feed and pharmaceutical products.BACKGROUND OF THE INVENTION[0002]Lactic acid bacteria (LAB) have been used in decades for increasing the shelf life of food products. During fermentation LAB produce lactic acid as well as other organic acids which cause a reduction of pH of the fermented product. Products having an acidic pH do not support further growth of most microorganisms, including pathogenic and spoilage bacteria. However, growth of yeasts and moulds is not affected by low pH and often cause spoilage of fermented dairy products.[0003]In addition to the production of organic acids some LAB also produce metabolites with antimi...

AI Technical Summary

Benefits of technology

The present invention relates to Lactobacillus fermentum strains that have beneficial effects on fermented milk products. These strains increase the pH of the product during storage after fermentation, which helps to prevent the product from becoming too acidic. This is particularly useful in fermentation processes that use starter cultures that can cause post-acidification. The strains also reduce the post-acidification effect caused by other bacteria, such as antifungal bacteria. The strains can be derived from deposited strains or can be developed through genetic modification. Overall, the invention provides a way to improve the quality and stability of fermented milk products.

Problems solved by technology

Products having an acidic pH do not support further growth of most microorganisms, including pathogenic and spoilage bacteria.

However, growth of yeasts and moulds is not affected by low pH and often cause spoilage of fermented dairy products.

Developing cultures with antifungal effects represents a big challenge, as it requires the identification of cultures that provide significant antifungal effect in real food applications.

A problem that has been identified in the commercial products is the extent of post acidification, i.e. continuation of acidification by the culture after the product has reached the desired pH.

This represents a problem in particular at elevated storage temperatures, during holding of the fermented product in fermentation tanks before product cooling or during maturation steps.

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