Development of a helical‐ribbon impeller bioreactor for high‐density plant cell suspension culture

Abstract

A double helical-ribbon impeller (HRI) bioreactor with a 11-L working volume was developed to grow high-density Catharanthus roseus cell suspensions. The rheological behavior of this suspension was found to be shear-thinning for concentrations higher than 12 to 15 g DW . L(-1). A granulated agar suspension of similar rheological properties was used as a model fluid for these suspensions. Mixing studies revealed that surface baffling and bottom profiling of the bioreactor and impeller speeds of 60 to 150 rpm ensured uniform mixing of suspensions. The HRI power requirement was found to increase significantly for agar suspensions higher than 13 g DW . L(-1), in conjunction with the effective viscosity increase. Oxygen transfer studies showed high apparent surface oxygen transfer coefficients (k(L)a approximately 4 to 45 h(-1)) from agar suspensions of 30 g DW . L(-1) to water and for mixing speeds ranging from 120 to 150 rpm. These high surface k(I)a values were ascribed to the flow pattern of this bioreactor configuration combined with surface bubble generation and entrainment in the liquid phase caused by the presence of the surface baffles. High-density C. roseus cell suspension cultures were successfully grown in this bioreactor without gas sparging. Up to 70% oxygen enrichment of the head space was required to ensure sufficient oxygen supply to the cultures so that dissolved oxygen concentration would remain above the critical level (> or =10% air saturation). The best mixing speed was 120 rpm. These cultures grew at the same rate ( approximately 0.4 d(-1)) and attained the same high biomass concentrations ( approximately 25 to 27 g DW . L(-1), 450 to 500 g filtered wet biomass . L(-1), and 92% to 100% settled wet biomass volume) as shake flask cultures. The scale-up potential of this bioreactor configuration is discussed.

Development of a small-scale bioreactor: Application to in vivo NMR measurement

“…However, this bioreactor is likely to generate a significant amount of foaming and cell entrainment with gas bubbles, which complicates long-term bioreactor operation. Moreover, mass transfer and mixing may be inadequate due to a high shear-thinning rheological behavior at high cell density (Jolicoeur et al, 1992). Membrane-based systems such as hollow fibers are interesting, but may reduce the working volume and create a high level of heterogeneity if placed within the magnetic field.…”

At‐line monitoring of bioreactor protein production by surface plasmon resonance

“…Culture parameters were as follow: agitation speed was maintained at 60 RPM by a double helical ribbon impeller having the same geometrical ratios as previously published (Jolicoeur et al, 1992). Dissolved oxygen was measured by a polarographic probe (InPro 6800, Mettler Toledo, Mississauga, ON, Canada) connected to a data acquisition and control system (Virgo, Longueil, QC, Canada) and maintained at 50 AE 5% from air saturation by continuous feed of an air/oxygen/5% CO 2 mixture in the headspace.…”

A high-rate perfusion bioreactor for plant cells

“…The bioreactor with an external loop used in the perfusion cultures is described in the next section. A 2.5-L working volume (3 L total volume) in-house bioreactor made of 316-L stainless steel (SS) parts and a glass vessel (12.5 Â 27 cm 2 , VWR, Montreal, Quebec, Canada; cat.#: 36390.086), and having the same geometrical ratios as Jolicoeur et al (1992) was used. A double-helical ribbon impeller (120 mm (height) Â 115 mm O.D., 22 mm width) was used.…”

“…The major constrains in the design of a cell/medium separator are the high-sedimented cell volume (SCV) reached in plant cell suspensions (up to $100%; Jolicoeur et al, 1992), cells shear sensitivity (Doran, 1999), and aggregates size distribution (Tanaka, 2000). The use of a grid showed to succeed retaining the cells and enabling continuous medium feed in flask cultures of Taxus cupidata at a maximum dilution rate of 1.0/day (nylon mesh, Seki et al, 1997) and of Eschscholtzia californica suspension cells at 4.9/day (stainless-steel mesh, Klvana et al, 2004).…”