Valorization of glycerol through the production of biopolymers:
The PHB case using Bacillus megaterium
Javier M. Naranjo, John A. Posada, Juan C. Higuita, Carlos A. Cardona
Instituto de Biotecnología y Agroindustria, Universidad Nacional de
Colombia sede Manizales,
Betreuer: Benjamen Stenger
Ammar Abdulmughni
Overview
 Introduction
Polyhydroxyakanoate (PHA):
Structure, Biosynthesis
Production
 Aim of this subject
 Results
 Summary
Polyhydroxyakanoate (PHA)
 PHAs are linear polyesters

Many prokaryotes can synthesize and store PHAs in form of granules
(up to 80 % of total bacterial weight)

PHAs have similar mechanical properties to conventional plastics
 They are generally biodegradable
Polyhydroxyakanoate (PHA)
 The biosynthesis of PHA :
certain deficiency conditions and
excess supply of carbon sources
 The most common/produced form of PHA is polyhydroxybutyrate,
PHB
 Like polypropylene or polyethylene.
PHB
Biosynthesis of PHB
PHB Production
 Production costs are heigh:
 PHB accumulate intercellularly:
- Use of a solvent
- thermal treatment of biomass, enzymatic digestion and washing with an
surfactant
a self-disruptive strain.
The lysis system of Bacillus amyloliquefaciens
phage was inserted into shuttle vector
The expression of a target gene is inhibited by
glucose
 When the glucose concentration approached
zero, self-disruption is induced
PHB Production
 Production costs are heigh:
carbon sources
The carbon source could account for 25–45% of the total production
costs
Cheaper carbon sources
PHB Production
 Agroindustrial wastes are attractive candidates as substrates:
 low prices and heigh availability
 solving an environmental problem
 A variety of microorganisms are able to produce PHB from diverse
agroindustrial wastes:
 Methylobacterium rhodesianum (Borman et al., 1999)
 Cupriavidus necator (Cavalheiro et al., 2009)
 E. coli CT1061 (Nikel et al., 2008)
Glycerol is carbon source
 Crude glycerol is a co-product in the production of biodiesel
 Glycerol is an important industrial feedstock :
- food, drugs, cosmetics, pharmaceuticals, textile and tobacco industries

Glycerol can be used as carbon source in microbiological processes

Polyhydroxyakanoate (PHA) production is an interesting biological
transformation of glycerol.
PHB Production
 Currently, PHB is produced at an industrial scale using Gram negative
bacteria
 lipopolysaccharides (LPS) which co-purify with the PHAs and
induce a strong immunogenic reaction (Valappil et al., 2007)
Bacillus megaterium
Aim
 Techno-economic analysis of PHB production:
- Glycerol transformation into PHB (using Bacillus megaterium)
- Glycerol or Glucose as substrate
- Productivity at different conditions
Results

Different initial concentration of glycerol
Biomass
PHB Production
The fermentation conditions:
temperature 30 °C, air flow 12 l/min and uncontrolled pH
Results

Different temperatures of fermentation
Biomass
PHB Production
The fermentation conditions:
initial glycerol concentration of 20 g/l, air flow 12 l/min, and uncontrolled pH
Results

PHB production using glucose or glycerol
Very Similar yields
Results
 Batch cultivation:
The fermentations to produce PHB were carried out for 42 h in a 3.7 l
Lab Fermen
Results
 Economic analysis:
 The current sale prices are between 3.1 and 4.4 USD/kg
Summary
 PHAs are linear polyesters and can be synthesized and itnracellularly
stored by many prokaryotes.
 The most produced form of PHA is PHB
 PHAs have similar mechanical properties to conventional plastics


Production costs are heigh
PHB Production using B. megaterium, and glycerol as carbon source
 The results confirm the ability of B. megaterium to use glycerol as the
only carbon source.
References

Valorization of glycerol through the production of biopolymers: The PHB case using Bacillus
megaterium, Javier M. Naranjo, John A. Posada, Juan C. Higuita, Carlos A. Cardona, Bioresource
Technology 133 (2013) 38–44.

Polyhydroxybutyrate synthesis on biodiesel wastewater using mixed microbial consortia, Zachary T.
Dobroth a, Shengjun Hub, Erik R. Coats a, Armando G. McDonaldBioresource Technology 102
(2011) 3352–3359

Large-scale production and efficient recovery of PHB with desirable material properties, from the
newly characterised Bacillus cereus SPV, Valappil SP, Misra SK, Boccaccini AR, Keshavarz T, Bucke
C, Roy I., J Biotechnol. 2007 Nov 1;132(3):251-8

Construction of self-disruptive Bacillus megaterium in response to substrate exhaustion for
polyhydroxybutyrate production. Hori K, Kaneko M,TanjiY, Xing XH, Unno H. Graduate School
of Bioscience and Biotechnology, 4259 Nagatsuta-cho, Midori-ku,Yokohama 226-8501, Japan.
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