A new strain of PSB, Z08 (Rhodobacter sphaeroides) extracted from local soil was used. Yeast (Candida tropicalis) was obtained from China General Microbiological Culture Collection Center. Activated sludge was obtained from a local wastewater treatment plant. Z08 was cultured in a thermostat shaker (120 rpm, 26–30 _C) using improved RCVBN medium (with 100 mg/L yeast extract) for 48 h. Yeast was cultured in a thermostat shaker (120 rpm, 26–30 _C) in malt extract medium for 12 h.