Optimization of co-cultivation conditions of chlamydomonas reinhardtii and Bradyrhizobium japonicum for hydrogen production

Chlamydomonas reinhardtii and Bradyrhizobium japonicum were co-cultivated under different ratios and light densities in order to determine the optimal culture condition and mechanism for hydrogen production. The results show that at 25℃, the optimal culture condition for hydrogen production of co-culture of B. japonicum and C. reinhardtii was under 200 μE/(m²·s) of light intensity and with the volume ratio at 1:80 of nearly saturated algal and bacterial cultures. Under such condition, the maximal hydrogen yield of co-culture system reached 272 μmol/(mg Chl), which is 17 times of the control group. The reasons for improvement of hydrogen yield are decrease of oxygon content, increase of hydrogenase activity and elevation of algal biomass of the co-culture.