Hydrogen production by marine photosynthetic bacteria: Effect of environmental factors and substrate specificity on the growth of a hydrogen-producing marine photosynthetic bacterium, Chromatium sp. Miami PBS 1071

Abstract The growth potential of the marine Chromatium sp. Miami PBS 1071, a strain of photosynthetic bacteria exhibiting high hydrogen-production capabilities, was studied. This strain, isolated by our laboratory from the subtropical marine environment, grows well at high light intensities (light saturation: 140 μEinstein m −2 s −1 ), high temperatures (optimum: 34°C), salinities normally found in marine environments (optimum: 30‰) and slightly basic pHs (optimum: 7.4–8.1). This strain grows in sulfide concentrations of 0.5–2.5 mM, and oxygen less than 4%. The growth rate in terms of doubling time was 1.75 h, which is one of the fastest rates observed for marine photosynthetic bacteria. Thus, the strain would be well suited for application to a saltwater-based tropical or subtropical outdoor mass-culturing system linked to bio-solar hydrogen-production technologies. This strain cannot utilize carbohydrates for growth but can employ various other carbon and nitrogen compounds. Besides the subject of utilization, the contribution of this work to the study of primary productivity and ecology in tropical and subtropical marine environments is discussed.