Resumen

GARBOZA, Fátima et al. Use of alternative media based on casein hidrolyzates and Aspergillus niger extract and their effect over the genetic expression of an Escherichia coli strain. Rev. Soc. Ven. Microbiol. [online]. 2011, vol.31, n.2, pp.138-143. ISSN 1315-2556.

The search for alternative nutritional sources for mass microorganism cultures has been a common practice in the area of industrial microbiology. Nevertheless, it not possible to use these substitutes in all cases since the presence or absence of certain nutrients can condition cellular growth, as well as the expression of certain metabolites. In the present investigation several media were formulated based on casein hidrolyzate and Aspergillus niger mycelium extract to substitute the components of Luria-Bertani (LB) medium, for culturing a genetically improved Escherichia coli strain. The quality of the media was evaluated by following bacterial growth, comparing the kinetic parameters and analyzing the protein electrophoretic profile and total cell nucleic acids recovered from the cell packages of final cultures. It was found that the medium formulated with 75% casein hidrolyzate and 75% fungus extract favors cell growth and genetic expression in a similar fashion to LB medium. The cell protein profile varies significantly if a smaller proportion is used, indicating a limit in the reduction of nutritive components of the alternative medium

Palabras clave : casein; Aspergillus niger extract; Escherichia coli.