Culture Medium Optimization for Photosynthetic Bacteria

Abstract

Photosynthetic bacteria (PSB) have various applications but the culture cost is very expensive. To find an efficient and economic culture medium the effects of yeast extract, C/N ratio, and trace elements on the growth of PSB were studied. The results showed that the optimal condition for PSB growth was: yeast extract of 100mg/l, C/N of 12:1, and trace elements (in mol/L): Mn2 + (0.009), Fe3+ (0.0025), Co2+ (0.0024), Cu2 + (0.0024), and Zn2 + (0.0033). Trace element lack could affect the growth of PSB. The order was Mn2 +> Fe3 +> Co2+> Cu2 +> Zn2 +. The improved medium was named HCH, and the optimum medium components were (in g/l) DL-malic acid: (4), MgSO4: (0.12), (NH4)2 SO4: (1), CaCl2: (0.075), KH2PO4: (0.5), K2HPO4: (0.3), Na2EDTA: (0.02), yeast extract : (0.1), trace elements 1ml (in mol/l ): Fe3+: (0.0025), Mn2+: (0.009), Zn2+: (0.0033), Co2+: (0.0024), pH:6.8. Comparing with the traditional RCVBN medium, in HCH medium yield of PSB increased 1.2 times and the cost decreased 19.8 times.