The inhibition of molds by sodium acetate in deMan Rogosa Sharpe (MRS) medium, along with the antifungal activity of Lactobacillus rhamnosus VT1, was studied by the slope agar plate method. MRS agar prepared with and without sodium acetate was used as the agar substrate. A total of 42 strains of Aspergillus, Penicillium, Fusarium, Alternaria, Cladosporium, and Rhizopus were used to compare sensitivities to the inhibitory activity of sodium acetate and L. rhamnosus VT1. It was found that sodium acetate in MRS medium affected the growth of 33 of the 42 mold strains tested to various degrees. The highest sensitivity to sodium acetate was shown by strains of Fusarium, followed by strains of Penicillium, Aspergillus, and Rhizopus. L. rhamnosus VT1 also inhibited mold growth. A significant finding was that sodium acetate and L. rhamnosus VT1 in combination exhibited a possible synergistic action. Thirty-nine of the 42 mold strains tested were completely inhibited by the presence of both antifungal agents. This finding confirms that sodium acetate, a basic component of commercial MRS medium, has strong antifungal properties, and this must be taken into consideration when evaluating the antifungal activity of Lactobacillus cultures grown in MRS broth.
Aims: To characterize and to purify a bacteriocin produced by Lactobacillus acidophilus strain with its activity restricted to Gram-positive bacteria. Methods and Results: Native acidocin CH5, a bacteriocin produced by L. acidophilus CH5 an isolate from a dairy starter culture forms in MRS (Oxoid, Basingstoke, UK) broth high-molecular weight aggregates which can dissociate into smaller units (retained by 5 kDa membrane) with higher activity. Acidocin CH5 was purified using combinations of chromatographic methods based on hydrophobic and cation exchange principles and the N-terminal region was sequenced. Conclusions: Based on our results it is evident that acidocin CH5 belongs, according to bacteriocin classification, to the class II bacteriocins with identical N-terminal amino acid sequence described in the literature previously. Significance and Impact of the Study: The study has provided further data on bacteriocin acidocin CH5 from class II with wide spectrum of antimicrobial activity atypical for bacteriocins produced by L. acidophilus sharing the same homology.
The possibility to control mould growth by Lactobacillus rhamnosus VT1 and Lactobacillus reuteri CCM 3625 in a milk environment was assessed using the milk agar plate method. Higher antifungal activity was exhibited by actively growing cells of both lactobacilli strains compared with the MRS broth supernatants of both bacterial strains containing metabolites with antifungal activity. The control of mould growth by Lactobacillus reuteri CCM 3625 was proved to be associated with the production of the mixture of lactic (0.9% w/w), acetic (0.2% w/w), and succinic (0.2% w/w) acids. The mechanism of mould growth control by Lactobacillus rhamnosus VT1 probably consists in the production of lactic acid (1.2% w/w) together with some other metabolite(s) of non-proteinaceous and non-saccharidic nature with antifungal activity.
Gas chromatography of brandies and whiskies shows that n-propanol, isobutanol, 2-methylbutan-1-01 and 3-methylbutan-1-01 comprise the major proportion of the higher alcohols. The furfural method for determining higher alcohols described in the Report of the Royal Commission on Whisky and Other Potable Spirits, 1909, gives results in excess of the sum of these alcohols determined by gas chromatography, but the method of the Association of Official Agricultural Chemists, which involves the use of p-dimethylaminobenzaldehyde, gives results that agree well with those obtained by gas chromatography.IN his evidence to the Royal Commission on Whisky and Other Potable Spirits 1908-1909, Dr. T. E. Thorpe, then Government Chemis.t, described a method for determining higher alcohols in potable spirits based on the colour formed by the action of furfural and sulphuric acid. The method had been developed under Dr. Bell, the previous Government Chemist, to meet the need for a rapid method suitable for examining samples submitted by H.M. Customs & Excise. Since that time, the met'hod has been further described by Simmondsl and Nicholls,2 and has gained a semi-official status in this country. Consistent results are not easily obtained without long practice, and discrepancies between results obtained in different laboratories prompted an investigation by Osborn and M ~t t , ~ who recommended several changes, the most important being the use of heat for developing the colour. When applied to samples of commercial spirits, this modification, however, was found by this
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