Wickerhamomyces anomalus killer strains are important for fighting pathogenic yeasts and for controlling harmful yeasts and bacteria in the food industry. Targeted disruption of key genes in β-glucan synthesis of a sensitive Saccharomyces cerevisiae strain conferred resistance to the toxins of W. anomalus strains BS91, BCA15 and BCU24 isolated from olive brine. Competitive inhibition of the killing activities by laminarin and pustulan refer to β-1,3- and β-1,6-glucans as the main primary toxin targets. The extracellular exoglucanase-encoding genes WaEXG1 and WaEXG2 from the three strains were sequenced and were found to display noticeable similarities to those from known potent W. anomalus killer strains. Accession Nos for WaEXG1 genes for the strains in brackets are JQ734563 (BS91), JQ734564 (BCA15) and JQ734565 (BCU24); for WaEXG2 genes JQ734566 (BS91), JQ734567 (BCA15) and JQ734568 (BCU24), respectively. Copyright © 2012 John Wiley & Sons, Ltd.