Photoheterotrophy of photosynthetic bacteria ( Rhodopseudomonas palustris ) growing on oil palm and soybean cooking oils

Abstract

Abstract Cooking oil wastes are environmentally damaging and costly to deal with. Photoheterotrophic growth of Rhodopseudomonas palustris (photosynthetic bacteria) (CGA 009) was used to decompose different types of cooking oil (palm and soybean oils; cooked and uncooked palm oil) under anaerobic and microaerobic conditions. Photosynthesis was measured in R. palustris using PAM technology (Pulse Amplitude Modulation Fluorometry): Optimum irradiance ≈ 284 μ mol photon m−2 s−1 and maximum photosynthetic electron transport rate (ETR) ≈ 341 μ mol e − g−1 BChl a s−1. R. palustris grew photoheterotrophically on both cooking oils as the sole carbon source grown anaerobically and microaerobically in PM media with a NH3-nitrogen source. R. palustris grew well on used palm oil. R. palustris produces small volumes of hydrogen gas from biodegradation of oil but only under nitrogen fixing conditions (anaerobic: no ammonia or organic nitrogen). N-fixing cells grew very slowly. Cooking oil waste residues are also produced at the production stage (Palm Oil Milling Effluent, POME) and in recycling them for reuse or to produce biodiesel. Hence, biodegradation of cooking oil wastes is an important issue at the production, domestic consumption and recycling stages of their use. A two-stage digestion using an anaerobic yeast first stage, followed by a R. palustris digestion was feasible. Two Line Capsule: The photosynthetic bacterium R. palustris grows photoheterotrophically on Palm Oil and Soybean Oil. Photosynthetic rates were measured using PAM technology.