Bioprocessing & Biotechniques Properties of the Entomoparasitic Nematodes (Heterorhabditis bacteriophora) Liquid Culture using a Helicoidal Ribbon Agitator as Rheometric System (original) (raw)

2015

Abstract

ABSTRACT The rheological parameters: flow behaviour index n, flow consistency index K and effective viscosity ηe were estimated for the entomoparasitic nematodes Heterorhabditis bacteriophora liquid broth at different culture maturation times. The nematode or nematodes were cultivated during 20 days in a bioreactor, and the growth media inside the bioreactor was enriched with protein and fat sources. Rheological parameters for the heterogeneous suspension were estimated with mixer principles employing a helical ribbon agitator fixed to a rheometer. As the culture matured, n decreased from 0.8 to 0.2 (and nd K increased up to 1200 mPa • sn; ηe showed a non-Newtonian (n<1) behaviour, ηe reached peak values of 0.32 Pa • s for a rotational speed of 0.5 revolutions per second (rps) and 0.048 Pa • s for 2.5 rps. Rheological properties reported here could be more reliable as compared to those reported for non-homogeneous liquid fermentations where estimations were performed with conventional geometries (i.e. concentric cylinders) which are appropriate for homogeneous systems but not for non-homogeneous ones.

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