Mechanism of Resistance of Lactic Acid Bacteria to<i>Trans</i>-Isohumulone

Abstract

AbstractResistance of beer-spoilage lactic acid bacteria to trans-isohumulone is not due to an ability of the organisms to convert the bitter acid to a less inhibitory substance. The bacteria are unable to grow in the absence of a transmembrane pH gradient after it has been dissipated by trans-isohumulone. There are no differences in the amounts of trans-isohumulone that bind to hop-sensitive and hop-resistant organisms. An inability of the antibacterial agent to reach its target is, therefore, unlikely to form the nature of resistance. Unlike sensitive organisms, resistant organisms maintain a transmembrane pH gradient and adenosine 5′-triphosphate pool in the presence of trans-isohumulone. These results suggest that hop resistance has its origins in the cell membranes of bacteria.KeywordsHopsLactobacillusPediococcusResistancetrans-Isohumulone