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Appl Environ Microbiol. 1967 May; 15(3): 537-542
Copyright © 1967 American Society for Microbiology. All Rights Reserved.

Influence of Cations on Spheroplasts of Marine Bacteria Functioning as Osmometers

Department of Bacteriology, University of Georgia, Athens, Georgia 30601

ABSTRACT

Penetration of substrates into marine bacteria as influenced by cations has been demonstrated by the effects of increased osmotic pressure in spheroplasts of these cells. Spheroplasts of Pseudomonas natriegens, stabilized with lactose, underwent a metabolic swelling in the presence of a substrate to which they had been induced. Maximal and persistent swelling was achieved only by addition of catabolizable substrate and both Na⁺ and K⁺. Addition, along with substrate, of Na⁺ alone or K⁺ alone did not stimulate swelling; no metabolic swelling occurred in the presence of a sugar to which the cells had not been induced. Confirmation of rapid uptake by induced cells of the inducer sugar, L-arabinose, but not the D-isomer, was obtained with ¹⁴C-labeled substrate. Addition of NaN₃ completely inhibited swelling, and 2, 4-dinitrophenol and ouabain each suppressed it by 50%, indicating requirement for energy metabolism and involvement of an adenosine triphosphatase in the penetration phenomena of these cells.