Ethylene glycol has the ability to act as a reactant when employed as a co-solvent for the enzymatic synthesis of ampicillin from (R)-phenylglycine methyl ester and 6-aminopenicillanic acid. The side reaction positively affects yield because its product, (R)-phenylglycine hydroxyethyl ester, is an intermediate for ampicillin synthesis. Biotechnol. Biotechnol. Bioeng. 2014;111: 1054-1058. (c) 2013 Wiley Periodicals, Inc.