Production of poly-3-hydroxyalkanoates from CO and H[sub 2] by a novel photosynthetic bacterium
- National Renewable Energy Lab., Golden, CO (United States)
A novel process is described to efficiently photoconvert low-grade organic materials such as waste biomass into natural biological plastics. When heterogeneous forms of dry biomass are thermally gasified, relatively homogeneous synthesis gas mixtures composed primarily of carbon monoxide and hydrogen are produced. Unique strains of photosynthetic bacteria (Rhodobacter sp.) were isolated that nearly quantitatively photo-assimilate the carbon monoxide and hydrogen components of synthesis gas into new cell mass. Under unbalanced culture conditions when cellular growth is limited by shortages of nitrogen, calcium, magnesium, iron, or essential vitamins, up to 28% of the new cell mass is found as granules of poly-3-hydroxyalkanoate (PHA), a high-molecular-weight thermoplastic that can be solvent-extracted. The dominant monomeric unit of PHAs is 3-hydroxybutyrate (3HB), which is polymerized into the homopolymeric poly-3-hydroxybutyrate (PHB). PHB is marketed as a biodegradable plastic with physical properties similar to polystyrene. When a green alga was cocultured with the photosynthetic bacterium in light-dark (day-night) cycles, the bacteria synthesized a polymer of poly-3-hydroxybutyrate-3-hydroxy-valerate (PHB-V) with a composition of 70% PHB and 30% 3-hydroxyvalerate (3HV) to an extent of 18% of the new cell mass. PHB-V is commercially marketed as Biopol and has physical properties similar to polypropylene or polyethylene. The results demonstrate that a strain of photosynthetic bacteria capable of photoassimilating synthesis gas or producer gas is a potential candidate for large-scale production of biological polyesters. 23 refs., 3 figs., 2 tabs.
- OSTI ID:
- 6778301
- Journal Information:
- Applied Biochemistry and Biotechnology; (United States), Vol. 45-46; ISSN 0273-2289
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BIOMASS
WASTE MANAGEMENT
PHOTOSYNTHETIC BACTERIA
BIOLOGICAL PATHWAYS
POLYESTERS
BIOSYNTHESIS
SYNTHESIS GAS
BIOCONVERSION
CARBON MONOXIDE
HYDROGEN
BACTERIA
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
ELEMENTS
ENERGY SOURCES
ESTERS
FLUIDS
GASES
MANAGEMENT
MICROORGANISMS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXIDES
OXYGEN COMPOUNDS
POLYMERS
RENEWABLE ENERGY SOURCES
SYNTHESIS
099000* - Biomass Fuels- Products & By-Products- (1990-)
550700 - Microbiology