Molecular and microscopic analyses of PHB-producing bacteria associated with plants

By applying both cultivation-independent as well as cultivation-dependent methods the results clearly demonstrate that plants are colonised by numerous bacteria which are potentially able to accumulate polyhydroxybutyrates as energy and carbon source. Particularly the rhizosphere, which is in contrast to the endosphere characterised by temporal and spatial changes in nutrient availability, appears to be a good source for the isolation of PHB producers for biotechnological applications. For the screening procedure two techniques were applied. On the one hand, the cultivation of the bacterial isolates under nutrient limitation resulted in the selection of few PHB positive strains. In contrast, using PCR analysis a higher number of investigated bacteria were shown to carry genes for enzymes involved in PHB biosynthesis. For a comprehensive study of the population of PHB producing bacteria in any habitat a combined strategy was approved.