Antimicrobial Properties of Different Hop (<i>Humulus lupulus</i>) Genotypes
Zala Kolenc,
Tomaž Langerholc,
Gregor Hostnik,
Miha Ocvirk,
Sara Štumpf,
Maša Pintarič,
Iztok Jože Košir,
Andreja Čerenak,
Alenka Garmut,
Urban Bren
Affiliations
Zala Kolenc
Laboratory of Physical Chemistry and Chemical Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova Ulica 17, SI-2000 Maribor, Slovenia
Tomaž Langerholc
Department of Microbiology, Biochemistry, Molecular Biology and Biotechnology, Faculty of Agriculture and Life Sciences, University of Maribor, Pivola 10, 2311 Hoče, Slovenia
Gregor Hostnik
Laboratory of Physical Chemistry and Chemical Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova Ulica 17, SI-2000 Maribor, Slovenia
Miha Ocvirk
Department for Agrochemistry and Brewing, Slovenian Institute of Hop Research and Brewing, Cesta Žalskega Tabora 2, SI-3310 Žalec, Slovenia
Sara Štumpf
Laboratory of Physical Chemistry and Chemical Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova Ulica 17, SI-2000 Maribor, Slovenia
Maša Pintarič
Department of Microbiology, Biochemistry, Molecular Biology and Biotechnology, Faculty of Agriculture and Life Sciences, University of Maribor, Pivola 10, 2311 Hoče, Slovenia
Iztok Jože Košir
Department for Agrochemistry and Brewing, Slovenian Institute of Hop Research and Brewing, Cesta Žalskega Tabora 2, SI-3310 Žalec, Slovenia
Andreja Čerenak
Department for Plants, Soil and the Environment, Slovenian Institute of Hop Research and Brewing, Cesta Žalskega Tabora 2, SI-3310 Žalec, Slovenia
Alenka Garmut
Department of Microbiology, Biochemistry, Molecular Biology and Biotechnology, Faculty of Agriculture and Life Sciences, University of Maribor, Pivola 10, 2311 Hoče, Slovenia
Urban Bren
Laboratory of Physical Chemistry and Chemical Thermodynamics, Faculty of Chemistry and Chemical Technology, University of Maribor, Smetanova Ulica 17, SI-2000 Maribor, Slovenia
The antimicrobial activity of hop extracts obtained from different hop genotypes were investigated against Staphylococcus aureus and Lactobacillus acidophilus. In this study the pure xanthohumol, purified β-acids rich fraction, as well as α-acids with β-acids rich fraction were used to test antimicrobial activity against Staphylococcus aureus and Lactobacillus acidophilus; whereby, the antimicrobial activity of different hop extracts against Lactobacillus acidophilus was studied for the first time. Microbial susceptibility to purified hydroacetonic extracts from different hop varieties was investigated by the broth microdilution assay to determine the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The hop hydroacetonic extracts were more effective against Staphylococcus aureus than against Lactobacillus acidophilus. Strong inverse correlations of MIC and MBC values were obtained with xanthohumol, cohumulone, n+adhumulone, colupulone and n+adlupulone contents, suggesting that the identified chemical hop compounds are directly responsible for antimicrobial effects. Moreover, the effect of the growth medium strength on the MIC values of hop extracts against Staphylococcus aureus was systematically investigated for the first time. The current study also reveals the effect of different hop extracts on Staphylococcus aureus, which responds to their presence by lag phase extension and generation time prolongation.
