Barley malt wort fermentation by exopolysaccharide-forming Weissella cibaria MG1 for the production of a novel beverage.

AIMS: The growing interest of governments and industry in developing healthy and natural alternative foods and beverages that will fulfil the consumer drive towards a healthy lifestyle and clean-label, natural diet has led to an increase in traditional lactic acid bacteria fermentation research. In particular, this research aims to address the organoleptic modulation of beverages using in situ-produced bacterial polysaccharides. METHODS AND RESULTS: Weissella cibaria MG1 is capable of producing exopolysaccharides (dextran) and oligosaccharides (glucooligosaccharides) during sucrose-supplemented barley-malt-derived wort fermentation. Up to 36·4 g l(-1) of dextran was produced in an optimized system, which improved the rheological profile of the resulting fermentate. Additionally, small amounts of organic acids were formed, and ethanol remained below 0·5% (v/v), the threshold volume for a potential health claim designation. CONCLUSIONS: The results suggest that the cereal fermentate produced by W. cibaria MG1 could be potentially used for the production of a range of novel, nutritious and functional beverages. SIGNIFICANCE AND IMPACT OF THE STUDY: Using conventional raw materials and traditional processes, novel LAB-fermented beverages can be produced representing an innovative mechanism towards fulfilling the aim to decrease government and personal costs as well as potentially ameliorating consumer lifestyle regarding dietary-related disease.

Inhibition of growth of Trichophyton tonsurans by Lactobacillus reuteri.

AIM: The aims of this study were to identify antifungal lactic acid bacteria (LAB) and characterize their activity against the dermatophyte Trichophyton tonsurans. METHODS AND RESULTS: A total of 165 different LAB were isolated and initially screened for anti-Penicillium expansum activity. Five strains, which exhibited strong inhibitory activity, were then tested against the dermatophyte T. tonsurans DSM12285, where they also caused inhibition as observed by large fungal clearing on agar surface. The strongest inhibition was seen with Lactobacillus reuteri R2. When freeze-dried cell-free supernatant powder from this strain was incorporated in culture medium at concentrations >1%, growth of fungal colony was inhibited. Conidia germination was also inhibited under these conditions as determined by microscopy. The anti-T. tonsurans activity of Lact. reuteri R2 was not affected neither by heat treatment nor by proteolytic treatment using pronase E and proteinase K, indicating that the responsible agent(s) were nonproteinaceous in nature. CONCLUSIONS: Lactobacillus reuteri R2 was identified as having strong inhibitory activity against the dermatophyte T. tonsurans DSMZ12285. SIGNIFICANCE AND IMPACT OF THE STUDY: LAB are naturally associated with many foods and are well recognized for their biopreservative properties. The use of these and/or their products may well provide alternative safe approaches for the inhibition of dermatophytic fungi.

The use of Lactobacillus brevis PS1 to in vitro inhibit the outgrowth of Fusarium culmorum and other common Fusarium species found on barley.

A total of 129 lactic acid bacteria (LAB) were screened for antifungal activity against common Fusarium spp. isolated from brewing barley. Four out of the five most inhibiting isolates were identified as Lactobacillus brevis, whereas one belonged to Weissella cibaria. L. brevis PS1, the isolate showing the largest inhibition spectrum, was selected and the influence of its freeze-dried cell-free supernatant (cfsP) on germination of macroconidia as well as mycelia growth was investigated using Fusarium culmorum as target organism.Addition of cfsP into the growth medium at concentrations > or = 2% altered the growth morphology of F.culmorum, whereas at concentrations > 5% the outgrowth of germ tubes from macroconidia was delayed and distorted. The presence of 10% cfsP completely inhibited the outgrowth of F. culmorum macroconidia. The activity of the compounds produced by L. brevis PS1 was higher at low pH values, i.e. pH < 5. Heating and/or proteolytic treatment reduced the inhibitory activity of cfsP, indicating that L. brevis produces organic acids and proteinaceous compounds which are active against Fusarium spp.