Sunday, July 24, 2011
Grand Ballroom, 5th fl (Sheraton New Orleans)
Biodiesel-contaminated wastewater was used to screen for PHA-producing bacteria by using crude glycerol as the sole carbon source. A gram-negative THA_AIK7 isolate was chosen as a potential PHA producer. The 16s rRNA phylogeny indicated that THA_AIK7 isolate is a member of Novosphingobium genus which is supported by a bootstrap percentage of 100% with Novosphingobium capsulatum. The 1,487 bp of 16S rRNA gene sequence of THA_AIK7 isolate has been deposited in the GenBank database under the accession number HM031593. Transmission electron micrograph results exhibited the PHA granules accumulated inside the bacterial cell. PHA polymer production in mineral salt media supplemented with 2% (w/v) of crude glycerol at initial pH 7 was extracted by the sodium hypochlorite method. Polymer film spectrographs from Nuclear magnetic resonance (NMR) displayed a pattern of signal virtually identical to spectra of commercial PHB. Thermal analysis by Differential scanning calorimeter (DSC) showed a melting temperature (Tm) at 179oC. Molecular weight analysis by Gel permeation chromatography (GPC) showed two main peaks of 133,000 and 700 g/mol with Mw value of 23,800 and Mn value of 755. Endotoxin-free of PHA polymer was preliminarily assessed by a negative result of the gel-clot formation, Pyrotell® Single test vial (STV), at sensitivity of 0.25 EU/ml. To our knowledge, this is the first certified test of endotoxin-free PHA naturally produced from gram-negative bacteria which could be used for biomedical application.