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J Bacteriol. 1967 May; 93(5): 1499-1508
Copyright © 1967 American Society for Microbiology. All Rights Reserved.

Oligopeptide Uptake by Bacteroides ruminicola¹

^a Dairy Cattle Research Branch, Animal Husbandry Research Division, Agricultural Research Service, U.S. Department of Agriculture, Beltsville, Maryland 20705
Department of Chemistry, University of Maryland, College Park, Maryland 20740
^c Dairy Science Department, University of Illinois, Urbana, Illinois 61803

ABSTRACT

Bacteroides ruminicola did not take up ¹⁴C from exogenous ¹⁴C-labeled L-proline or ¹⁴C-labeled L-glutamic acid and took up very little ¹⁴C from exogenous ¹⁴C-labeled L-valine. Growing cultures of B. ruminicola rapidly took up ¹⁴C from ¹⁴C-proline-labeled peptides of molecular weights up to 2,000 and incorporated it into trichloroacetic acid-insoluble cell material. Uptake and incorporation did not occur at 0 C and were reduced or eliminated in glucose-starved cells, depending upon the length of time the cells were starved. The initial rate of uptake of peptides seemed to exhibit saturation kinetics, but it was impossible to establish this conclusively. The initial uptake of ¹⁴C from peptides was not affected by chloramphenicol but the incorporation of it into trichloroacetic acid-insoluble cell material was virtually eliminated. Only moderate amounts of trichloroacetic acid-extractable, labeled material were present in cells during peptide uptake, whether or not chloramphenicol was present. ¹⁴C-proline was rapidly released from labeled peptides during uptake, whether or not chloramphenicol was present. The amount of ¹⁴C fixed into trichloroacetic acid-insoluble cell material was directly related to the size of peptides originally supplied in the medium. It is concluded that B. ruminicola possesses a general system for the uptake of peptides, that peptides are rapidly hydrolyzed during or after uptake, and that oligopeptides function only to supply amino acids in a form available to the organism.

¹ Work reported is part of a dissertation submitted by K. A. Pittman to the faculty of the Graduate School of the University of Maryland in partial fulfillment of the requirements for the Ph.D. degree. A preliminary report of this work was presented at the Annual Meeting of the American Society for Microbiology, Atlantic City, April 1965.