The utilization of casein and amino acids by Streptococcus sanguis P4A7 in continuous culture

Abstract

Streptococcus sanguis P4A7 was grown in glucose limited conditions in continuous culture at pH 7.0 in a chemically defined medium containing either free amino acids or casein as the organic nitrogen source. Apart from aspartate and threonine, which were poorly utilized at the higher dilution rates, all amino acids in the free-amino-acid medium were utilized to various extents. At the higher dilution rates, aspartate actually increased in concentration, probably due to deamidation of asparagine. The amino acid most utilized at all dilution rates was arginine, with up to 99 % of the amino acid being consumed. Both casein and its α(s1)-casein fraction supported growth at a level only slightly l..