Effect of tetrahydroiso-alpha-acids on the growth of beer-spoiling and –nonspoiling bacteria
| Authors | |
|---|---|
| Year of publication | 2010 |
| Type | Article in Periodical |
| Magazine / Source | Kvasný Průmysl |
| MU Faculty or unit | |
| Citation | |
| Field | Microbiology, virology |
| Keywords | beer spoilage, resistance to hop bitter compounds, Lactobacillus brevis, tetrahydroiso-alpha-acids, growth parameters, stress |
| Description | We studied the effects of hop analogue compounds tetrahydroiso-alpha-acids (Tetra) on the growth and growth parameters of 23 Lactobacillus brevis strains isolated from several Czech lager breweries. Forcing test was used to divide the isolates into two groups, beer-spoilage strains (10 isolates) and non-spoilers (13 isolates). The growth of L. brevis in MRS-broth containing varying concentrations of Tetra was investigated using Bioscreen C. The measured growth curves were used to calculate the basic growth parameters. All 23 isolates were able to grow in the presence of tetrahydroiso-alpha-acids, albeit to a varying extent. Tetra affected the growth and multiplication of all L. brevis strains regardless of their beer-spoilage ability. Increasing concentrations of Tetra led to a decrease in cell suspension optical density (O.D.) and in the specific growth rate, and extension of lag phase. The results and their statistic analysis revealed no relationship between the beer-spoilage ability and hop-resistance. The degree of resistance to the antibacterial activity of Tetra was strongly affected by the initial pH of culture medium, but there was no correlation between the pH-induced change in the level of resistance and the beer spoilage ability of any L. brevis strain. |
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