Utilization of chymotrypsin as a sole carbon and (or) nitrogen source by Escherichia coli

Abstract

alpha-Chymotrypsin serves as a sole carbon source, sole nitrogen source, and as sole carbon plus nitrogen source for wild-type Escherichia coli in a totally defined medium. Hence, a mammalian host for E. coli may supply the necessary carbon and nitrogen nutrients for the microorganism. Growth is most rapid when chymotrypsin is a sole nitrogen source and least rapid with chymotrypsin as a carbon source. The approximate doubling times for E. coli utilizing chymotrypsin as a nitrogen source, carbon plus nitrogen source, and carbon source are 1.6, 4.6, and 11.3 h, respectively. The activity of the residual enzyme in the culture supernates falls off asymptotically over the source of time, as followed by cleavage of glutaryl-L-phenylalanine-p-nitroanilide. Chymotrypsin hydrolyzes succinyl-L-ala-L-ala-p-nitroanilide, the elastase substrate, to some extent. Peptidases do not appear to be secreted that hydrolyze such model substrates as benzoyl-DL-arginine-p-nitroanilide, the tryptic and cathepsin B substrate, L-leucine-p-nitroanilide, the leucine amino-peptidase substrate, or L-lysine-p-nitroanilide, the aminopeptidase B substrate. Growth of E. coli is generally directly related to the loss of chymotryptic activity in the medium. Hence, autolysis of chymotrypsin, i.e., self-degradation, is an important factor for the availability of degradation products of the enzyme to the bacterium for growth purposes. Accordingly, the degradation of a host protein by autolysis presents an opportunity for E. coli to survive during periods of host nutritional crisis by utilization of the degradation peptides that are produced during autolysis.

Lysine secretion by wild-type Corynebacterium glutamicum triggered by dipeptide uptake

“…2). Similar results were reported by Brecher et al (1992) concerning the growth of E. coli on degradation products of chymotrypsin, where the peptides support growth most effectively as the nitrogen source and less as the carbon source. Utilization of peptides by C. glutarnicum did occur even if lysine, which cannot be metabolized (Nakayama, 1985), was present in the peptide.…”

The potential for the control ofEscherichia coliO157 in farm animals

“…coli cannot use native proteins, Brecher et al (1992) showed that this species may use peptides as a C or N source under C-limited conditions. The rumen of animals in temperate climates is not usually N-limited and therefore, the addition of an N source to rumen fluid does not influence the growth of E. coli in rumen fluid (Duncan et al 1999a).…”