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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