H2 photoproduction by batch culture of Anabaena variabilis ATCC 29413 and its mutant PK84 in a photobioreactor
✍ Scribed by A. A. Tsygankov; V. B. Borodin; K. K. Rao; D. O. Hall
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 169 KB
- Volume
- 64
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
Hydrogen production by Anabaena variabilis ATCC 29413 and of its mutant PK84, grown in batch cultures, was studied in a photobioreactor. The highest volumetric H 2 production rates of native and mutant strains were found in cultures grown at gradually increased irradiation. The native strain evolved H 2 only under an argon atmosphere with the actual rate as high as the potential rate (measured in small vials under optimal conditions). In this case 61% of oxygenic photosynthesis was used for H 2 production. In contrast the mutant PK84 produced H 2 during growth under CO 2 -enriched air. Under these conditions at the maximum rate of H 2 production (10 mL h -1 L -1 ), 13% of oxygenic photosynthesis was used for H 2 production and the actual H 2 production was only 33% of the potential. Under an atmosphere of 98% argon + 2% CO 2 actual H 2 production by mutant PK84 was 85% of the potential rate and 66% of oxygenic photosynthesis was used for H 2 production. Hydrogen production under argon + CO 2 by the mutant was strictly light-dependent with saturation at about 300 µE m -2 s -1 . However, the rate of photosynthesis was not saturated at this irradiation. At limiting light intensities (below 250 µE m -2 s -1 ) 33-58% of photosynthesis was used for H 2 production. Hydrogen evolution by PK84 under air + 2% CO 2 was also stimulated by light; but was not saturated at 332 µE m -2 s -1 and did not cease completely in darkness. The rate of oxygen photoevolution was also not saturated. A mechanism for increasing cyanobacterial hydrogen production is proposed.