An insight into insect cell metabolism through selective nutrient manipulation

Nutritional information of insect cell cultures, required for designing str ategies to increase protein productivity, is still limited. In this work, n utrient feeding or removal was used to determine the role of selected nutri ents and their interactions in insect cell metabolism before viral infectio n. Glucose, glutamine, tyrosine, and methionine were consumed at the highes t rates in batch and fed-batch cultures, and thus were selected to be manip ulated. Glucose and glutamine could be replaced by other carbon sources or amino acids, respectively. However, growth was reduced when such alternativ e sources were utilized, revealing the distinctive role of glucose and glut amine. Glucose and glutamine consumption rates were regulated by their own concentration, although glutamine concentration did not affect glucose cons umption rate or vice versa. Excessive glucose or glutamine supply caused en ergy and carbon wastes, as observed by reduced cell yields and accumulation of by-products, such as alanine. Nevertheless, growth inhibition was atten uated by simultaneous excess of both nutrients, probably because cells had both carbon and ammonia available to deal with toxic by-products in the for m of alanine. Other amino acids, such as tyrosine and methionine, were also relevant for maintaining prolonged viability. The importance of an adequat e nutrient supply was demonstrated; particularly, the need to maintain gluc ose and glutamine concentrations just above their critical values. (C) 1999 Elsevier Science B.V. All rights reserved.