Monoxenic liquid culture of the entomopathogenic nematode Steinernema carpocapsae using a culture medium containing whey: Kinetics and modeling

The submerged culture of the entomopathogenic nematode Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila, was carried out in orbitally agitated bottles using a culture medium containing whey (in grams per litre: 500 whey, 20 yeast extract, 10 dried egg yolk-food grade, 3 sodium chloride, 37 corn oil-food grade). Maximum total viable nematode concentrations of 198,333 ml−1 were achieved within fermentations of 24 days with 64% of the nematode population within the infective juvenile stage (IJ) (126,666 ml−1) at the end. The kinetics of the bioprocess was well modelled using the four-parameter Sigmoidal model and the corresponding maximum specific rates of nematode production (0.47 day−1), carbohydrates consumption (0.0008 gcarbohydrates gnematodes−1 day−1) and nitrogen consumption (4.44 gnitrogen gnematodes−1 day−1) are first proposed. Besides, X. nematophila appears to have the capacity of lactose hydrolysis.