Bacillus sphaericus AKU 229 was found to produce an acetaldehyde-tolerant and phosphorylated compound-tolerant phosphopentomutase useful for enzymatic 2'-deoxyribonucleoside production. The gene encoding the phosphopentomutase was cloned and expressed in Escherichia coli. The E. coli expressing B. sphaericus phosphopentomutase was an excellent catalyst as to production of 2'-deoxyribonucleoside in the presence of acetaldehyde and phosphorylated compounds such as fructose 1,6-diphosphate, and d-glyceraldehyde 3-phosphate, which are derived from glucose through glycolysis with yeast cells, and exist abundantly in the practical reaction mixture for enzymatic 2'-deoxyribonucleoside production.