Mass production of the entomopathogenic nematode, Steinernema carpocapsae CABA01, through the submerged monoxenic culture in two internal-loop airlift bioreactors with some geometric differences

The submerged monoxenic culture of the entomopathogenic nematode, Steinernema carpocapsae CABA01, was carried out in two internal-loop airlift reactors (R1 and R2) with some geometric differences. Two runs each reactor were carried out at operating conditions VL = 4.22 L, Q = 11.5 vvm, T = 22 C. The culture broth apparent viscosity changed from 2 to 12 mPa s determining global changes in both hydrodynamics (expressed as the dimensionless Reynolds number, Re) and oxygen transfer conditions (expressed as the kLa coefficient). Such changes were 170 < Re < 3080; 1.9 < kLa (10?2 s?1) < 3.5 for R1 experiments, and 400 < Re < 10,060; 1.9 < kLa (10?2 s?1) < 3.5, for R2 experiments. Infective juvenile stage (IJ) concentrations of 250,000/mL were achieved in R2 experiments whereas notably lower ones were obtained in R1 experiments (110,000 IJ/mL, approximately). The hydrodynamic conditions in both riser and downcomer sections of R2 experiments involved higher inertial forces than the corresponding ones to R1 runs, implying values of (ReR2/ReR1)riser from 2.3 to 3.3 and (ReR2/ReR1)downcomer from 1.8 to 2.5. These results suggest that higher inertial forces would promote the mating process among the vigorous adult nematodes of the first generation, probably due to encourage femalemale encounters in response to a better mixing of the culture broth. Further, the nematode reproduction appeared to be greatly influenced by the reactor geometry.