ISSN:
1433-4909
Keywords:
Key words Psychrophilic bacterium
;
Vibrio
;
NH4+ transport system
;
14CH3NH3+ uptake
;
Nitrogen source for growth
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract NH4 + transport system of a psychrophilic marine bacterium Vibrio sp. strain ABE-1 (Vibrio ABE-1) was examined by measuring the uptake of [14C]methylammonium ion (14CH3NH3 +) into the intact cells. 14CH3NH3 + uptake was detected in cells grown in medium containing glutamate as the sole nitrogen source, but not in those grown in medium containing NH4Cl instead of glutamate. Vibrio ABE-1 did not utilize CH3NH3 + as a carbon or nitrogen source. NH4Cl and nonradiolabeled CH3NH3 + completely inhibited 14CH3NH3 + uptake. These results indicate that 14CH3NH3 + uptake in this bacterium is mediated via an NH4 + transport system and not by a specific carrier for CH3NH3 +. The respiratory substrate succinate was required to drive 14CH3NH3 + uptake and the uptake was completely inhibited by KCN, indicating that the uptake was energy dependent. The electrochemical potentials of H+ and/or Na+ across membranes were suggested to be the driving forces for the transport system because the ionophores carbonylcyanide m-chlorophenylhydrazone and monensin strongly inhibited uptake activities at pH 6.5 and 8.5, respectively. Furthermore, KCl activated 14CH3NH3 + uptake. The 14CH3NH3 + uptake activity of Vibrio ABE-1 was markedly high at temperatures between 0° and 15°C, and the apparent K m value for CH3NH3 + of the uptake did not change significantly over the temperature range from 0° to 25°C. Thus, the NH4 + transport system of this bacterium was highly active at low temperatures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007920050103
Permalink
