Batch and fed-batch growth of Pichia pastoris under increased air pressure

Abstract

Pichia pastoris CBS 2612 behavior under air pressures of 1, 3 and 5 bar in culture media of glycerol (pure and crude) and methanol was studied. Generally, the increase in oxygen transfer rate due to the increase of total pressure improved cellular growth for all carbon sources and for batch and fed-batch processes with different feeding rate strategies. In batch cultures, 1.4-, 1.2-, and 1.5-fold improvement in biomass production was obtained with the increase of air pressure up to 5 bar, using methanol, pure glycerol, and crude glycerol, respectively. The increase of air pressure to 5 bar using exponential feeding rate led to 1.4-fold improvement in biomass yield per glycerol mass consumed, for crude and pure glycerol. The current low cost of crude glycerol from the biodiesel production together with the present results shows the possibility of improving cell mass production of P. pastoris using increased air pressure.

Enhanced heterologous protein production in Pichia pastoris under increased air pressure

“… The values of OTR max were obtained from Lopes et al for the same hyperbaric bioreactor used in this work.…”

“…The OTR from the gas phase into the medium is controlled by the oxygen solubility and the volumetric oxygen mass transfer coefficient ( K L a). The oxygen solubility in the liquid medium can be raised by increasing the total air pressure in the cultivation system, since this parameter is affected by the oxygen partial pressure and, consequently, by the total pressure …”

“…Published works have reported the use of increased air pressure as a way of improving OTR that can be applied to the cultivation of yeast species such as Yarrowia lipolytica , Saccharomyces cerevisiae , Kluyveromyces marxianus , Candida utilis, and non‐recombinant P. pastoris . However, the effect of increased air and oxygen pressure is strongly dependent of the species and strains as described elsewhere …”

Over‐pressurized bioreactors: Application to microbial cell cultures

“…Lopes et al observed a 2.3‐fold increase of OTR in a bioreactor without mechanical agitation by shifting the total air pressure from 2 to 8 bar. In addition, in a mechanical stirred bioreactor, a threefold improvement in OTR by increasing air pressure from 1 to 5 bar was reported …”

“…Several other yeast species different from S. cerevisiae , such as Kluyveromyces marxianus , Candida utilis , and Pichia pastoris , were cultured under increased air pressure and it was proved possible to overcome the oxygen limitation and to improve cellular growth. The ethanol production was considerably reduced in K. marxianus (“Kluyver‐negative”) batch cultures under 6 bar of air pressure, and in C. utilis fed‐batch process at 12 bar of air pressure .…”