PHB Production in Biofermentors Assisted through Biosensor Applications

Poly-hydroxy-alcanoates (PHAs) are biodegradable and biocompatible polymers synthesized and accumulated in intracellular compartments in several bacterial species. Polyhydroxyalcanoates (PHAs) are synthesized by numerous prokaryotes, such as Cupriavidus necator (Ralstonia eutropha), Pseudomonas spp., Comamonas spp., in response to stress conditions, i.e., under high carbon and low nitrogen (24:1 ratio). PHA can be synthesized using recombinant microorganisms (provided with the operon phbA/phbB/phbC), escaping the constrains of nutrient request, except addition of high amount of sugar (glucose, lactose, fructose). Recombinant E. coli systems were studied to produce PHB using metabolic engineering. In biofermentors, the critical points are the excess of fermentable sugars and the ratio of nutrients versus cell optical density. In order to allow production in biofermentors in automated system, sensors are envisaged to evaluate critical parameters such as sugar consumption, bacteria concentration and level of synthesis of PHA. The need of fermentors and operation control has compelled for application of three biosensing units, one linked to a Nanodrop to evaluate OD, one linked to an enzymatic reaction chamber to measure sugars consumed by enzyme linked sugar biosensing tools, and one for sampling the bacteria, Nile Blue staining, and fluorescence intensity reads. These detectors will make possible to exploit the full potential of bioreactors optimizing the time of use and maximizing the number of bacteria synthesizing PHA