Non-ionic polysorbate surfactants: Alternative inducers of medium-chain-length poly(3-hydroxyalkanoates) (MCL-PHAs) for production of extracellular MCL-PHA depolymerases

The potential of non-ionic polysorbate surfactants as alternative inducers of medium-chain-length poly(3-hydroxyalkanoates) (MCL-PHAs) for the production of diverse bacterial MCL-PHA depolymerases was evaluated. When grown with corn oil as the sole carbon substrate, Pseudomonas alcaligenes LB19 preferentially produced lipolytic enzymes, but its MCL-PHA depolymerase was not induced by the substrate. However, the results of activity staining and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis clearly revealed that Tween 20 induced simultaneous production of lipolytic enzymes and the MCL-PHA depolymerase with the molecular mass (26.5 kDa) of P. alcaligenes LB19, which has been previously identified. Moreover, the co-production of two functionally distinct hydrolytic enzymes induced by Tween 20 was commonly observed in various Gram-positive and Gram-negative bacteria that were fed the substrate. Thus, it is expected that non-ionic polysorbate surfactants including Tween 20 can be widely exploited as promising universal substrates for the facile and efficient production of diverse MCL-PHA depolymerases.