Fig. 6

Impact of the dissolved oxygen level on the fermentation of sunflower seed milk by a co-culture of P. freudenreichii NCC 1177 and B. amyloliquefaciens NCC 156. Impact of oxygen supply on vitamin B₁₂ production (A), growth (B), vitamin B₁₂ production per cell (C), and the production of vitamins B₁, B₂, B₃, B_6, and B₇ during fermentation (D). Prior to fermentation, the milk was processed by ultra-high temperature treatment. The different aeration regimes from low to high (shown from left to right) were created by incubation in non-baffled flasks at 80 rpm, baffled flasks at 80 rpm, non-baffled flasks at 130 rpm, baffled flasks at 130 rpm, non-baffled flasks at 180 rpm and baffled flasks at 180 rpm. The inoculum ratio between strains NCC 1177 and NCC 156 was 1000:1. Fermentation was carried out at 30 °C for 72 h, including an initial 48 h anaerobic phase, followed by a 24 h aerobic phase. n = 3