Evolution of Culture Broth Rheological Properties during Propagation of the Entomopathogenic Nematode Steinernema carpocapsae,in Submerged Monoxenic Culture

摘要

This article presents the evolution of culture broth rheological properties during monoxenic cultures of Steinernema carpocapase in cylindrical bottles agitated orbitally.Rhelogical properties were evaluated in simple-shear flow conditions and were well-modeled by the Ostwald-de Eaele model.Rheological properties varied from slightly dialatent n=1.2 (-) to moderately pseudoplastic flow behavior n=0.6 (-),Nematode concentration oncreased from 750+-190 to 130 900 +- 6900 nematodes/mL,and the apparent viscosity (eta_a) evolved from 4.5+- 0.7 to 46.6 +- 3.2 mPa.s during the fermentations.Rheological behavior did not appear to be strongly influenced by nematode number and/or its stage of develpment;however,the release of substances from the decomposition of nematode cadavers appeared to be of great importance.Among the different developmetnal stages of the nematodes,only juveniles of the firdt stabvge (J1) were highly susceptible to the shearing conditions tested (SHEAR STRESS,tau-r theta,from 0.9 to 3.5 Pa during periods of 80-100 min) resulting in the viablity loss of 85% of J1 nematodes.