TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Microorganism: In the recombinant microorganism, the genetic modification is a modification of the himA gene selected from insertion, deletion, mutation, cosuppression, and antisense RNA expression, where the himA gene is made nonfunctional. An insertion is introduced into the himA gene by homologous recombination. The microorganism comprises heterologous genes encoding xylose isomerase, xylulokinase, transaldolase, and transketolase. The heterologous genes encoding xylose isomerase, xylulokinase, transaldolase and transketolase are from Xanthomonas, Klebsiella, Escherichia, Rhodobacter, Flavobacterium, Acetobacter, Gluconobacter, Rhizobium, Agrobacterium, Salmonella, and Pseudomonas, preferably Escherichia coli. The microorganism is identified as strain ZW801-4:: Delta himA or strain AcR#3. The microorganism has improved fermentation performance in the presence of acetate as compared to a microorganism with no genetic modification which reduces expression of the endogenous HimA protein. The microorganism produces at least 4% more ethanol in the presence of acetate than an isogenic strain without reduced expression of the endogenous HimA protein. Preparation (claimed): Generating the microorganism above comprises: (a) providing a recombinant Zymomonas strain capable of utilizing xylose to produce ethanol under suitable conditions where the genome of the strain expresses endogenous HimA protein; and (b) modifying the genome of the strain where the modifying reduces expression of the endogenous HimA protein. The recombinant Zymomonas strain of (a) is ATCC31821/pZB5, Zymomonas mobilis 8b, ZW658, ZM4(pZB5), ZW800, ZW801-4, ZW801-6, and Z. mobilis CP4:pZB5. EXAMPLE - ZW801-4 was derived from ZW658 (ATCC # PTA-7858) through an intermediate strain, ZW800. The latter strain was constructed by double-crossover insertion from a suicide plasmid of a spectinomycin resistance cassette (Spec-cassette), flanked by wild type loxP sites, into the gene encoding glucose-fructose oxidoreductase (GFOR). The resulting GFOR knockout mutant was shown to have reduced production of xylitol, a detrimental by-product of xylose metabolism, and better production of ethanol during mixed sugar fermentation with glucose and xylose. ZW800 was then converted to ZW801-4 through Cre-mediated excision of the Spec-cassette. Elimination of the selectable marker left a single wild type loxP site in the middle of the GFOR open reading frame, which resulted in an in-frame stop codon that prematurely truncates translation of the protein.