A
kinetic study of polyhydroxybutyrate production on nitrogen limited medium
using Bacillus subtilis MTCC 9763 through a
two
stage cultivation strategy
R. Muralidharan
and K.V. Radha*
Department of Chemical
Engineering, A.C. College of Technology, Anna University, Chennai-600 025,
India
*Corresponding
Author?s Email : radhavel@yahoo.com
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Publication Data
Paper received:
10 June 2013
Revised received:
29 December 2013
Re-revised received:
21 April 2014
Accepted:
29 April 2014
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Abstract
In
this study, a two-stage cultivation strategy was adopted for the production
of Poly-β-hydroxy butyrate (PHB), using Bacillus subtilis MTCC
9763. The culture conditions for PHB production by Bacillus subtilis
MTCC 9763 were optimized with different carbon, nitrogen sources,
temperature, pH and incubation time. Glucose showed a maximum of 73 mg l-1
(12.56%) yield out of the carbon sources used, whereas peptone gave 81 mg l-1
PHB (14.72%) for nitrogen source. The optimized condition observed for PHB
production was 42 hr of incubation time with a temperature of 37?C and pH 7.
A two stage cultivation strategy was approached. Nitrogen source was limited
in the production medium with various concentrations (25%, 50%, 75% and 100%)
for enhanced production of PHB. Product yield was doubled when the nitrogen
concentration was completely limited as compared with 75% of limitation with
an yield of 93 mg l-1 (20.26%).? PHB was characterized using Infra
Red spectroscopy. A kinetic model that describes microbial growth, cell
concentration and biopolymer production was used to predict the performance
of batch fermentation of Bacillus subtilis MTCC 9763. The experimental
data was also fitted with the logistic equation that could provide adequate
description for PHB synthesis. The present investigation revealed that
industrial effluents could also be used for effective production of PHB so as
to greatly reduce the risk of production cost.
Key
words
Industrial
effluents, Kinetic model, Logistic equation, Poly-β-hydroxybutyrate,
Sodium hypochlorite
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Copyright
? 2015 Triveni Enterprises. All rights reserved. No part of the Journal can
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regarding the authenticity of the data, and the acceptability of the
conclusions enforced or derived, rest completely with the author(s).
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