Evaluation Of Jatropha Oil For The Production Of Polysydroxyalkanoates (PHAs) By Cupriavidus Necator H16
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Date
2011-05
Authors
Ng, Ko Sin
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Publisher
Universiti Sains Malaysia
Abstract
Jatropha oil, a non-edible vegetable oil, could serve as an alternative substrate to food grade oils for polyhydroxyalkanoates (PHAs) production. Jatropha oil contains oleic acid (42%), linoleic acid (35%) and palmitic acid (17%) as the major fatty acid constituents. Cupriavidus necator H16 accumulated 87 wt% of poly(3-hydroxybutyrate) [P(3HB)] from 13.1 g/L of cell dry weight (CDW) when 12.5 g/L of jatropha oil and 0.54 g/L of urea were used. Lipase activity was detected in the initial stages of P(3HB) production, when 1 g/L of jatropha oil was added to the preculture medium. However, the addition of oil in preculture did not affect final CDW and P(3HB) accumulation. Copolymers of poly(3-hydroxbutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] with different molar fractions of 3HV (4 – 41 mol%) were produced when sodium valerate or sodium propionate were used as precursors. The amount of 3HV units incorporated in the polymer was proportional to the concentration of precursors. However, higher composition of 3HV units (41 mol%) and CDW (6.7 g/L) were produced from sodium valerate compared to sodium propionate. The thermal properties of P(3HB) homopolymer and P(3HB-co-3HV) copolymer were determined by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). The molecular weights of the polymers were determined by Gas Permeation Chromatography (GPC). The results revealed that the PHAs produced from jatropha oil were essentially the same as that produced from other more established carbon sources such as sugars and plant oils. This study has demonstrated that jatropha oil is a potential renewable carbon source for the production of PHA.
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Keywords
Jatropha oil, a non-edible vegetable oil , food grade oils for polyhydroxyalkanoates