Figure 4

A novel strategy for reducing the risk of bacterial contaminations during bioethanol production. (A) The Ethanol strain used in this study excretes multiple amino acids via Qdr amino-acid exporters of the DHA1 family, thereby promoting proliferation of contaminating lactic acid bacteria. (B) Loss of Qdr transporters by means of homozygous mutations reduces amino acid excretion and cross-feeding of lactic acid bacteria, without altering ethanol production.