CHARACTERIZATION OF POLYHYDROXYALKANOATES (PHA) PRODUCED BY ISOLATED NOVOSPHINGOBIUM SP. THA_AIK7 USING CRUDE GLYCEROL: EFFECT OF INITIAL PH AND TEMPERATURE

Impact of the initial pH of medium and incubation temperature on Polyhydroxyalkanoates (PHA) production and polymer characterization from Novosphingobium sp. THA_AIK7 isolate were investigated in batch culture of mineral salts medium supplemented with 2% (w/v) crude glycerol. It was found that an initial pH of 7 and temperature of 30 degree C was an appropriate condition for polymer production. An initial pH of 7 showed a higher PHA production than an initial pH of 6 of about 17-20% at both 30 C and 35 degree C. Molecular weight of polymer, interestingly, was strongly affected by the initial pH of culture medium. The polymer produced using a medium with an initial pH of 6 had a number average molecular weight (Mn) about 18-30% higher than and weight average molecular weight (Mw) about 33-35% greater than those of an initial pH of 7. However, both Mn and Mw of polymer were extremely low which may be caused from the effect of sodium hypochlorite used in an extraction method. Thermal property and polymer structure were less affected from different initial pH and incubation temperature. The polymers produced from various conditions were reported as PHB homopolymer.