This invention pertains to a method for increasing the ratio of the pHBA ester glucoside to total pHBA glucose conjugates in pHBA-producing microorganisms and green plant cells using nucleic acid fragments encoding plant glucosyltransferases that exhibit catalytic activity with p-hydroxybenzoic acid (pHBA) as a substrate and only attach glucose to the aromatic carboxyl group of pHBA, to form the pHBA glucose ester.