Lists
Lists
Prebble, John Nower (1958) Studies on the physiology of pigment production by Corynebacterium fascians (Tilford) Dowson. Doctoral thesis, Sir John Cass College.
The effect on carotenogenesis in Corynebacterium fascians (Tilford) Dowson, of a number of substrates has been studied: these included ammonium chloride, a number of carboxylic acids, amino acids, and carbohydrates. Observations of growth (dry weight), pigment (measured spectrophotometrically) and the pH of the medium were made on each culture.
In submerged liquid culture, both growth and pigmentation were poor, but the latter was much higher on a surface culture.
On a simple agar medium most of the pigment synthesis occurred at the end of the growth of the culture and was apparently independent of pH between 4.2 and 7.8. An adequate sugar concentration was necessary for optimum pigment production and sugars differed in their powers to promote carotenogenesis; more pigment was synthesised on glucose than on mannitol.
The addition of a number of substances to the medium stimulated pigment synthesis; these included glycerol, succinate, fumarate, lactate, valine, leucine, isoleucine and glycine. Of the amino acids, only glycine promoted carotenogenesis during the logarithmic phase of growth.
From a factorial experiment in which the concentrations of mannitol and valine were varied, it was concluded that a metabolic balance existed between growth and carotenogenesis.
In the absence of asparagine, increases in the concentration of ammonium chloride decreased pigment synthesis: in the presence of asparagine there was no affect. Increases in asparagine concentration at first promoted pigment synthesis and then reduced it.
Autolysis was found to occur in the cultures immediately after growth had ceased and this resulted in considerable irregularities in the data, and hence in the interpretation of effects of substances on the pigment/dry weight ratio. The inclusion in the medium of acetate and succinate was found to increase autolysis, while valine, leucine, alanine, lactate and probably asparagine decreased it to varying degrees.
 |
View Item |