This family consists of several fatty acid cis/trans isomerase proteins which appear to be found exclusively in bacteria of the orders Vibrionales and Pseudomonadales. Cis/trans isomerase (CTI) catalyzes the cis-trans isomerisation of esterified fatty acids in phospholipids, mainly cis-oleic acid (C(16:1,9)) and cis-vaccenic acid (C(18:1,11)), in response to solvents. The CTI protein has been shown to be involved in solvent resistance in Pseudomonas putida.