PHASE-SEPARATION WITHIN ARTIFICIAL GRANULES FROM A BLEND OF POLYHYDROXYBUTYRATE AND POLYHYDROXYOCTANOATE - BIOLOGICAL IMPLICATIONS

A recently developed in vitro o procedure for preparing artificial gra nules of microbial polyesters has been applied to a blend of poly(3-hy droxybutyrate) (PHB) and poly(3-hydroxyoctanoate) (PHO). Density gradi ent analysis showed that these granules formed a single, uniform popul ation; n.m.r. showed that the polymers retained their amorphous elasto meric state; and thermal analysis indicated that the polymers formed s eparate phases within these granules. These results contrast strongly with the observation that a recombinant bacterial strain simultaneousl y expressing PHB and PHO stores the two polymers in separate cellular granules. The implications of the in vitro findings for granule format ion in vivo are discussed.