Optimization of temperature and light intensity for improved photofermentative hydrogen production using Rhodobacter capsulatus DSM 1710

Photofermentative hydrogen production is influenced by several parameters, including feed composition, pH levels, temperature and light intensity. In this study, experimental results obtained from batch cultures of Rhodobacter capsulatus DSM 1710 were analyzed to locate the maximum levels for the rate and yield of hydrogen production with respect to temperature and light intensity. For this purpose, a 3k general full factorial design was employed, using temperatures of 20, 30 and 38 °C and light intensities of 100, 200 and 340 W/m2. ANOVA results confirmed that these two parameters significantly affect hydrogen production. Surface and contour plots of the regression models revealed a maximum hydrogen production rate of 0.566 mmol H2/L/h at 27.5 °C and 287 W/m2 and a maximum hydrogen yield of 0.326 mol H2/mol substrate at 26.8 °C and 285 W/m2. Validation experiments at the calculated optima supported these findings.