Bioconversion of glycerol to poly(HB-co-HV) copolymer in an inexpensive medium by a Bacillus megaterium strain isolated from marine sediments

Abstract

A Bacillus megaterium strain, as an alternative to produce biopolymers from an industrial waste in a low cost medium, is studied. A culture medium composed by salt solution, trace elements, glycerol and urea was used. The growth of B. megaterium BBST4 and the production of PHA achieved by different concentrations of glycerol and urea, were analyzed at various C/N ratios. The effect of temperature, the incubation time and the addition of yeast extract, on the growth, PHA production and sporulation, were determined. The strain showed better growth and PHA production (30% w/w) after 48h of incubation at 30°C in a SWG medium with 3% of glycerol, 0.08% of urea, and 0.005% of yeast extract. Under these conditions no sporulating cells were observed. The obtained PHA was characterized by FTIR, NMR, DSC, SEC and GC-MS. It was determined that the biopolymer produced by B. megaterium BBST4 is a copolymer, composed of 3-hydroxybutyrate (92.2mol%) and 3-hydroxyvalerate (7.8mol%). This copolymer offer industrial and biomedical applications.