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Submerged monoxenic culture of the entomopathogenic nematode Steinernema carpocapsae in an internal‐loop airlift bioreactor using two configurations of the inner tube
Author(s) -
ChavarríaHernández Norberto,
SanjuanGalindo René,
RodríguezPastrana BlancaRosa,
MedinaTorres Luis,
RodríguezHernández AdrianaInés
Publication year - 2007
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.21356
Subject(s) - airlift , fermentation , bioreactor , entomopathogenic nematode , nematode , biology , botany , zoology , food science , chromatography , chemistry , ecology
This article reports the submerged culture of the entomopathogenic nematode Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila , within an internal‐loop airlift bioreactor. Two configurations of the inner cylinder were tested: a standard draft tube (SDT) and a static mixer (SM), as well as two production media: MP1 (500 mL/L whey, among other ingredients) and MP2 (82 mL/L agave‐juice from Agave spp., among other ingredients). Three fermentations were carried out: F1 → SDT‐MP1, F2 → SM‐MP1 and F3 → SM‐MP2. The operating conditions were expressed on the basis of dimensionless Reynolds number (Re) and volumetric oxygen transfer coefficient ( k L a), both of them determined on riser and downcomer sections within the bioreactor. The experiments began with fewer than 1,000 infective juvenile nematode stages (IJ) per mL and at t = 20 d, they achieved (nematodes/mL‐%IJ) 222,000‐87%, 62,200‐23% and 114,600‐80%, within F1, F2 and F3 experiments, respectively. Nonetheless, the achieved maximum nematode biomass concentrations (g/L) were F1 → 408, F2 → 557 and F3 → 613, and occurred at t = 16, 10 and 12 d, respectively. The fermentation operating conditions involved 0.042 (−) < Re < 647 (−) and 2.8× 10 −4 s −1 < k L a < 0.0447 s −1 , as functions of 0.004 m/s < superficial gas velocity (within the riser) < 0.079 m/s, 0.001 m/s < mean downcomer velocity < 0.014 m/s, and culture broth rheological properties which evolved from nearly the Newtonian behaviour to the pseudoplastic one. The maximum IJ concentration was achieved within F1 experiment (193,406 IJ/mL). Also, fermentation conditions involving higher riser‐Re and lower downcomer‐Re as well as higher nutriment concentrations in culture medium, promote higher nematode biomass concentrations but lower %IJ, maybe as a result of better conditions for the nematode population development. Biotechnol. Bioeng. 2007; 98: 167–176. © 2007 Wiley Periodicals, Inc.