It was tested with a minimized screening assay if P. oleovorans is able to accumulate novel functionalized mcl-PHAs. Different carbon sources were added to cells which were pregrown C/N-limited with octanoic acid. Only some fatty acids which were known to yield PHA showed positive results. Cell growth and PHA accumulation was tested in batch culture with a range of carbon sources. P. oleovorans accumulated PHA with several fatty acids, plant oils and their hydrolyzation products. The length of the monomers in the PHA was dependent on the number of carbon atoms of the fatty acids supplied. The longest monomer had the same length as the growth substrate, but 3-hydroxy octanoic acid or 3-hydroxy nonanoic acid were always the most abundant monomers with a content of more than 50 mol% in the PHA. Although monomers with a chain length 2 or 4 carbon atoms shorter were detected, no chain elongation took place. Therefore P. oleovorans can only incorporate PHA compounds obtained directly from the substrate indicating that no metabolic link between the PHA accumulation pathway and the fatty acid neosynthesis exists. We produced two new PHAs with functionalized side chains in the continuous culture. The first is an amorphous polymer containing 35% of chlorinated monomers produced with mixtures of octanoic acid and 1-chlorooctane and the second was produced with 2-decanone and contained 10 mol% of 3-hydroxy-8-on nonanoic acid.