CONSTRUCTION AND GROWTH KINETICS OF A BIOLUMINESCENT METHIONINE AUXOTROPH ESCHERICHIA COLI STRAIN FOR POTENTIAL USE IN A METHIONINE BIOASSAY

Autor: C.A. Froelich, I.B. Zabala Díaz, S.C. Ricke
Rok vydání: 2002
Předmět:
Zdroj: Journal of Rapid Methods and Automation in Microbiology. 10:69-82
ISSN: 1745-4581
1060-3999
DOI: 10.1111/j.1745-4581.2002.tb00013.x
Popis: Methionine is one of the essential and first limiting amino acids in animal nutrition. In this study, an Escherichia coli methionine auxotroph bacterial strain that exhibits a linear growth response to methionine concentrations was transformed with a plasmid containing genes encoding ampicillin resistance and bioluminescence in order to develop a microbiological technique for methionine quantitation. Transformants were selected based on antibiotic resistance and plasmid containing candidates were confirmed by restriction enzyme digestion and gel electrophoresis. To confirm the bioluminescent phenotype, video imaging of the strain using long exposure photography yielded colonies exhibiting bioluminescence. The strain was also tested in the presence of ampicillin supplemented media with increasing methionine concentrations and growth response (measured as optical density, OD), growth rates and methionine affinities were compared before and after transformation. Although the transformed E. coli methionine auxotroph exhibited somewhat different growth kinetic responses than the nontransformed strain, the standard curves used for estimating methionine concentrations were not different. Based on the results in this study the transformed bioluminescent strain could be used as an OD-based assay if bioluminescence equipment and materials are not available.
Databáze: OpenAIRE
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