Sucrose transport by the alkaliphilic, thermophilic Bacillus sp. strain TA2.A1 is dependent on a sodium gradient.
An alkaliphilic Bacillus designated strain TA2.A1, isolated from a thermal spring in Te Aroha, New Zealand, grew optimally at pH 9.2 and 70 degrees C. Sodium chloride (>5mM) was an obligate requirement for the growth of strain TA2.A1 on sucrose, and growth on sucrose was inhibited by monensin, an ionophore that collapses the sodium gradient (ApNa+) across the cell membrane. Sucrose transport by strain TA2.A1 was sodium dependent and was inhibited by monensin. The Kt for sucrose transport was 33 microM and the Eadie-Hofstee plot was linear, suggesting one high-affinity uptake system for sucrose. The affinity for sodium was low (0.5 mM), and the Hill plot had a slope of 1.6, suggesting that sodium binding was noncooperative and that the sucrose transporter had more than one binding site for sodium. Based on these results, Bacillus strain TA2.A1 uses a sodium gradient for sucrose uptake, in addition to the sodium-dependent glutamate uptake system reported previously.
Peddie
C J
CJ
Thermophile and Microbial Biochemistry and Biotechnology Unit, University of Waikato, Hamilton, New Zealand. sccjp@twp.ac.nz
Cook
G M
GM
Morgan
H W
HW
D001407:Bacillus / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001667:Binding, Competitive; D002455:Cell Division / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008985:Monensin / Q000494:pharmacology; D009004:Monosaccharide Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009520:New Zealand; D012964:Sodium / Q000378:metabolism* / Q000494:pharmacology; D013379:Substrate Specificity; D013395:Sucrose / Q000378:metabolism* / Q000494:pharmacology
D009004:Monosaccharide Transport Proteins; D013395:Sucrose; D008985:Monensin; D012964:Sodium