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Bacterial contamination inethanol production industries can cause product yield losses and pose risks ofprocess failures worldwide. To address such problem in Thailand a commercial plantfor ethanol production using cane molasses as raw material was surveyed for contaminationof lactic acid bacteria, the major group of contaminants. Molasses samples werecollected from yeast propagation and fermentation tanks, as well as from transferlines. Concentrated molasses, buffer and nitrogen supplements were alsocollected from storage vessels.  Lacticacid bacteria were enumerated by spread plating on MRS agar supplemented with100 ppm cycloheximide.  The resultsshowed that all samples except concentrated molasses were contaminated withlactic acid bacteria ranging from 7.07 to 7.89 log cfu/ml.  Five bacterial isolates were identified usingAPI 50CH biochemical identification schemes as Lactobacillus plantarum, L.brevis, L. rhamnosus, L. buchneri and Pediococcus damnosus.  These lactic acid bacteria were then testedfor susceptibility against 0.1-12.8 ppm Kamoran®, an ionophore antibiotic used to control bacterialcontamination in this ethanol plant. Then, L. plantarum showing strongKamoran® resistance when testing in MRS broth was chosen forfurther study in molasses medium.  It wasdemonstrated that when applying 25.6 ppm Kamoran® for 18 hrs the numbers of this bacterial straindecreased from an initial amount of about 6 log cfu/ml by only 1.83  log cfu/ml. These results indicate bacterial contamination in ethanol industry ofThailand and point to needs for more efficient measures for dealing with suchproblems.