A visual method for rapid screening of xylose-fermenting ethanolic strains of Klebsiella pneumoniae.

A simple and rapid screening method for selecting hyper-ethanolic strains of Klebsiella pneumoniae is described. The method involves a novel biological screening marker, namely, the yeast Candida ethanothermophilum. The screening marker was seeded on an agar plate to the surface of which agar blocks, each containing a colony of K. pneumoniae, were subsequently fixed. This seeded plate lacked sources of carbon and energy. Ethanol formed in the agar blocks by the K. pneumoniae colonies diffused into the seeded medium and served as a carbon and energy source for the ethanotrophic yeasts. Colonies of yeasts appeared around the agar blocks in regions of ethanolic diffusion. Hyper-ethanolic strains of K. pneumoniae were thus selected on the basis of the number of colonies of the screening marker that appeared around the blocks containing the ethanolic colonies of K. pneumoniae.