The iol cluster (consisting of genes involved in myo-inositol utilization) was investigated in Lactobacillus casei strains isolated from koumiss. Ten strains were tested for the presence of iol cluster by PCR screening; three strains encoded this cluster. Full-sequencing procedure was conducted; the iol cluster was identical to that of L. casei BL23 (GenBank access. no. FM177140) except for an upstream transposase. The iol cluster is not a common feature for L. casei strains isolated from koumiss.