Diverse Bacillus strains are known as producers
of polyhydroxyalkanoates (PHAs) under nutrient-limiting
conditions. However, these limiting conditions have the
same nutritional characteristics that stimulate spore generation
in Gram-positive microorganisms. In the present
work, a new isolated Bacillus megaterium strain was
characterized based on 16S rRNA gene sequences (1,411
bp) and studied in terms of its ability for producing polyhydroxybutyrate
(PHB) by implementing different fermentation
configurations on formulated media. The isolated
strain was able to produce PHB up to 59 and 60% of its dry
cell weight during bioreactor experiments employing glucose
and glycerol as carbon source, respectively. The
produced biopolymer was characterized and identified by
using carbon-13 nuclear magnetic resonance (13C-NMR)
and Fourier transform infrared (FTIR) techniques. In spite
of the sporulation phenomenon existing in Bacillus strains,
obtained results demonstrate that the new isolated strain
has the potential of accumulating high levels of intracellular
PHB. Supported by these experimental results and by those
reported by other authors, the last section of this paper
gives an outlook of future research topics on PHB and
polyhydroxyalkanoate (PHA) copolymers production by
Gram-positive bacteria. The importance of combining bioprocessing/biorefinering
concepts with bioreactor optimization
approaches is stressed and analyzed based on current
PHAs research trends.