Effect of oxygen supply on biomass, organic acids and vitamin B-12 production by Propionibacterium shermanii

Propionibacterium shermanii CDB 10015 was able to grow at different volumet ric oxygen transfer coefficients (K(L)a) of 10, 22, 53 h(-1). These results demonstrate that this bacterium, known as anaerobic, is able to grow well under aerobic conditions. The cell biomass increased from 7.9 in anaerobic conditions to 18.3 g/l at K(L)a 53 h(-1), increasing also the cell yield fr om 0.3 to 0.7 g/g. The organic acid production pattern also changed with ae ration. The acetic: propionic acid ratio increased from 0.38 in anaerobiosi s to 6.25 at K(L)a 53 h(-1). The vitamin B-12 production decreased from 3.1 mg/l in anaerobiosis to 0.5 mg/l at: K(L)a 53 h(-1).