Abstract: A combination of a cell adhesion factor and a positively-charged molecule are bound to the surface of a cell culture support of a bioreactor to improve cell attachment and stabilize cell growth. The positively charged molecule is preferably polylysine, chitosan, poly(ethyleneimine) or acrylics polymerized from acrylamide or methacrylamide and incorporating positively-charged groups in the form of primary, secondary or tertiary amines, or quaternary salts. The cell adhesion factor is preferably fibronectin, laminin, collagen, vitronectin or tenascin, or fragments or analogs having a cell binding domain thereof. The positively-charged molecule and the cell adhesion factor can be covalently bound to the supporting surface. In another embodiment, the positively-charged molecule and the cell adhesion factor are covalently bound to one another and either the positively-charged molecule or the cell adhesion factor is covalently bound to the supporting surface.

Abstract: Targeted gene insertion methodology can increase the production of an antimicrobial metabolite and comprises the steps of:a) identifying the gene in unaltered chromosomal DNA which encodes an enzyme that catalyzes the rate controlling step in a biosynthetic pathway in the production of increased concentration of a precursor to a core molecule which leads to the antimicrobial metabolite; andb) inserting into unaltered chromasomal DNA a genetic delivery vehicle (such as a vector, phage, or virus) which carries a gene which encodes the enzyme that catalyzes the rate controlling step in the biosynthesis in the production of a core molecule which is a precursor to the antimicrobial metabolite into unaltered chromosomal DNA, said delivery vehicle being compatible with said unaltered chromosomal DNA, the delivery vehicle being generated byinserting at least one exact or modified copy of the gene determining the rate controlling step into the compatible delivery vehicle, andinserting the delivery vehicle containing t

Abstract: A method of inducing aggregate formation of animal cells is carried out by forming a nutrient medium suspension of animal cells and introducing itno the suspension microspheres of a derivatized diameter of not more than about 60 .mu.m, when measured in a suitable buffer saline or cell culture media.