AimsIn this paper, we introduce a new Burkholderia contaminans capable of producing a newly characterized polymer. Methods and ResultsCG-MS and magnetic nuclear resonance H-1 and C-13 were used to determine the constitution of polymers produced in glucose, glucose with casein, sucrose and sucrose with casein. Three pairs of primers were used to find the polyhydroxyalkanoates (PHA) synthase class and sequence. The synthesized polymers were composed by short-chain length PHA (scl-PHA), especially polyhydroxybutyrate (PHB), and medium chain length PHA (mcl-PHA), especially polyhydroxydodecanoate (PHDd), and their concentration, constitution and molecular weight depend on carbon source used. The bacterium showed only class I synthase which could not explain the mcl-PHA production. ConclusionsBurkholderia contaminans has a class I PHA synthase and produces PHB combined to PHDd when cultivated in sucrose or glucose, and PHDd concentration is affected when casein is used. Significance and Impact of the StudyPHA are natural polymers produced by a wide range of bacteria. The presence of PHDd monomers confers to the polymer elastomeric properties. Previously, PHDd was only obtained when bacteria were cultivated in related carbon source. In this work, B. contaminansIPT553 produced PHB with PHDd using simple and low-cost carbon sources that can make possible the cheaper production of a more flexible biopolymer with crystallinity and elasticity different from the more common PHAs.