EFFICIENT HYDROGEN PHOTOPRODUCTION BY SYNCHRONOUSLY GROWN CELLS OF A MARINE CYANOBACTERIUM, SYNECHOCOCCUS SP MIAMI BG-043511, UNDER HIGH CELL-DENSITY CONDITIONS
S. Kumazawa et A. Mitsui, EFFICIENT HYDROGEN PHOTOPRODUCTION BY SYNCHRONOUSLY GROWN CELLS OF A MARINE CYANOBACTERIUM, SYNECHOCOCCUS SP MIAMI BG-043511, UNDER HIGH CELL-DENSITY CONDITIONS, Biotechnology and bioengineering, 44(7), 1994, pp. 854-858
The capability of hydrogen photoproduction under high cell density con
ditions was examined using synchronously grown cells of nitrogen-fixin
g Synechococcus sp. Miami BG 043511. Optimum hydrogen yield was obtain
ed when vessels (25 mL) contained 0.2 to 0.3 mg chlorophyll a in 3-mL
cell suspension. During a 24-h incubation period, an initial phase of
hydrogen and carbon dioxide production and a subsequent phase of carbo
n dioxide uptake and oxygen production were observed; hence, hydrogen
and oxygen accumulated as major products after 24 h. After the initial
24-h incubation, as high as 7.4 and 3.7 mL (at standard condition) of
hydrogen and oxygen, respectively, accumulated in vessels with 22-mL
gas phase. This indicated that the pressure in the flask increased to
1.5 atmosphere. Energy conversion efficiency based on photosynthetical
ly active radiation (25 W/m(2)) was about 2.6%. However, increased pre
ssure somehow reduced the duration of hydrogen production. Duration of
hydrogen and oxygen production was prolonged by periodical (24-h inte
rval) gas replacement during incubation. (C) 1994 John Wiley & Sons, I
nc.