Biotechnological Coproduction of Compatible Solutes and Polyhydroxyalkanoates using the Genus Halomonas

An increased usage of poly-beta-hydroxyalkanoates (PHA), for instance as bulk biodegradable and biocompatible plastics, will require a cheaper production and downstream processing. If the synthesis of this intracellular biopolyester could be combined with the production of another valuable intracellular product, the economic balance of the process could be improved. It was found that the moderately halophilic bacterium Halomonas elongata simultaneously synthesizes PHA and a protector molecule, called ectoine. Whereas the synthesis of PHA is a response to the shortage of nutrients, the production of ectoine counteracts osmotic imbalances. This behavior is In so far surprising as the conditions of a bi-factorial stress initiate the fast simultaneous synthesis of ectoine and PHA. In the presence of 100 g/L NaCl, Halomonas elongata accumulated up to 50% w/w PHA and up to 14% ectoine within 2-3 days under so far non-optimized conditions. Furthermore, it was found that other Halomonas species (e.g. Halomonas halodenitrificans and own isolates of Halomonas halodeneurihalina and Halomonas salina) were able to produce both ectoine and PHA.