Abstract: The invention relates to a process of manufacturing D(-)-3-hydroxybutyric acid by breeding microorganisms capable of producing said acid in a nutrient medium containing certain specific carbon source; bacterial strains especially suitable in carrying out the process; an application of the process for obtaining such microorganisms; and uses of thus produced acid.

Abstract: The invention relates to a method of obtaining selected bacterial strains which can convert an assimilable carbon source selected from carbohydrates, methanol, ethanol, glycerin, carbon dioxide and spent lyes from caprolactam synthesis into poly-(D-3-hydroxybutyric acid), selected bacterial strains obtained thereby and their use in producing poly-(D-3-hydroxybutyric acid).

Abstract: The use of cyclic carbonic acid esters of the formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4, which may be the same or different, are hydrogen or alkyl with 1 to 6 C-atoms, as a solvent for racemic or optically active poly-(.beta.-hydroxybutyric acid).The preferred embodiment uses hot (120.degree. to 150.degree. C) ethylene carbonate or 1,2-propylene carbonate to extract poly-(.beta.-hydroxybutyric acid) from moist or dry fermentation masses. These solvents have the advantage that the extracted poly-(.beta.-hydroxybutyric acid) is precipitated in good yield from them on cooling. In addition they may be recycled without the need for a solvent regeneration step. These cyclic carbonic acid esters may also be used as the solvent in the processing of poly-(.beta.-hydroxybutyric acid) by e.g. wet spinning.