Rubrivivax gelatinosus previously isolated from poultry slaughterhouse wastewater and characterized by morphological and biochemical tests was used in this experiment. The cells were maintained in Pfennig medium containing (per liter): 0.5 g KH2PO4; 0.4 g MgSO4.7 H2O; 0.4 g NaCl; 0.4 g NHCl; 0.05 g CaCl2.2H2O; 1.0 g sodium acetate, 0.2 g yeast extract; 0.005 g ferric citrate; 10.0 mL trace elements solution (FeSO4.7H2O 200 mg; ZnSO4.7H2O 10 mg; MnCl2.4H2O 3 mg; H3BO3 30 mg; CoCl2.6H2O 20 mg; CuCl2.2H2O 1 mg; NiCl2.6H2O 2 mg; Na2MoO4. 2H2O 3 mg); 20.0 g bacteriological agar; 10.0 ml biotin sol. (0.0015% ) and 10.0 ml thiamine-HCl sol. (0.005%). The pH was adjusted to 7.0 before autoclaving at 121oC for 15 min.

For the initial inoculum preparation, cells were grown in Pfennig liquid medium with the same pH and composition described above but bacteriological agar, under anaerobiosis (fully filled screw-crap tubes), 32 ± 2°C and 1,400 ± 200 lux for approximately 3 days, until a slight red color arose.

For the final inoculum, an aliquot from initial inoculum was transferred at 1% (v/v) to the same medium and incubation was carried out under the same conditions described before, until optical density at 600 nm reached 0.5 (Ponsano et al., 2003a).