Effect of Amino Acids on Steady-State Growth of a Group A Hemolytic Streptococcus1
AUTOR(ES)
Davies, Helen C.
RESUMO
Davies, Helen C. (University of Pennsylvania, Philadelphia), Fred Karush, and Joanne H. Rudd. Effect of amino acids on steady-state growth of a group A hemolytic streptococcus. J. Bacteriol. 89:421–427. 1965.—A study has been made of amino acid utilization by a strain of type 4, group A streptococcus growing under steady-state conditions in a continuous-culture device and supplied with a completely synthetic medium. At a fixed growth rate, corresponding to a generation of time of 84 min, and with the pH maintained constant at 7.4, the bacterial turbidity was made dependent on the concentration of one of the amino acids of the defined medium. Under these conditions, the extracellular concentration of the limiting amino acid is fixed by the preset growth rate. The steady-state concentration of each of 14 essential l-amino acids was measured by means of C14-labeled amino acids in such limited cultures. At approximately equal turbidities, these concentrations ranged from 1.6 × 10−6m for methionine to 4.3 × 10−4m for glutamic acid. The rates of utilization of the amino acids ranged from 26 mμmoles per mg (dry weight) of bacteria per hr for histidine to 310 mμmoles per mg (dry weight) of bacteria per hr for glutamic acid. The percentage of the limiting amino acid used varied from 95% for threonine and methionine to 43% for gluamic acid. The rate of utilization of the limiting amino acid at unit concentration (tmoles per gram per hour per m) differed by a factor of 27 between extremes. These observations reflect the variation in the capacity of this streptococcal cell to take up and use different amino acids.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=305524Documentos Relacionados
- Synthesis of M Protein by Group A Hemolytic Streptococci in Completely Synthetic Media During Steady-State Growth1
- Effect of some D-amino acids on the steady-state level of glutamine synthetase in Escherichia coli.
- GROWTH OF GROUP A HEMOLYTIC STREPTOCOCCUS IN THE STEADY STATE1
- Factors Necessary for Massive Growth of Group A Hemolytic Streptococcus1
- EXTRACELLULAR ANTIGENS IN STEADY-STATE CULTURES OF THE HEMOLYTIC STREPTOCOCCUS: PRODUCTION OF PROTEINASE AT LOW pH1