HYDROGEN FORMATION BY CYANOBACTERIA CULTURES SELECTED FOR NITROGEN-FIXATION

Seventy-one cyanobacteria containing cultures were enriched from various soil and water locations either under aerobic and/or anaerobic conditions on agar medium selective for nitrogen fixation. Kept under argon containing 1% CO2 for 24 and 48 h most of these cultures evolved hydrogen at very variable rates up to 116 μl per mg chlorophyll and hour as a mean value over a time period of 24h. Several samples evolved hydrogen more efficiently compared with known hydrogen producing pure strains from culture collections. Thirty-one of the investigated cultures showed a hydrogen formation higher than 10 μl per mg chlorophyll and hour measured over 24 or 48 h. Among these all the morphological forms of cyanobacteria i.e. unicellular and filamentous with or without heterocysts are found. Hence, selecting for nitrogen fixing cyanobacteria seems to be a practical method to find efficient hydrogen producers. © 1979 Springer-Verlag.