The present disclosure describes novel bacterial strains which express a pyruvate decarboxylase gene and at least one alcohol dehydrogenase gene from a bacteria of the genus Zymomonas and also express a hemoglobin gene from a bacteria of the genus Vitreoscilla. The present disclosure further describes methods for producing fermentation products with a microorganism which expresses a pyruvate decarboxylase gene and at least one alcohol dehydrogenase gene from a bacteria of the genus Zymomonas and also express a hemoglobin gene from a bacteria of the genus Vitreoscilla. Further the present disclosure describes methods for increasing production of a fermentation product comprising genetically engineering a microorganism which expresses a xylose isomerase gene to also express a hemoglobin gene from a bacteria of the genus Vitreoscilla.