Presence of a Na+/H+antiporter inMethanobacterium thermoautotrophicumand its role in Na+dependent methanogenesis

✍ Scribed by Peter Schönheit; Dieter B. Beimborn

• Publisher: Springer
• Year: 1985
• Tongue: English
• Weight: 868 KB
• Volume: 142
• Category: Article
• ISSN: 0302-8933
• DOI: 10.1007/bf00491903

✦ Synopsis

Methane formation from H2/COz by methanogenic bacteria is dependent on Na + ions. In this communication it is shown with Methanobacterium thermoautotrophicum that a Na+/H + antiporter plays a role in methane formation from H2 and CO2 and in the regulation of the ApH. This is based on the following findings:

(i) Li + ions, an alternative substrate of Na+/H + antiporters, could replace Na + in stimulating methanogenesis from H 2 and C02.

(ii) Harmaline, amiloride, and NH~, which are inhibitors of Na +/H + antiporters, inhibited methanogenesis; inhibition was competitive to Na + or Li +.

(iii) Addition of Na + or Li + rather than of other cations to cell suspensions resulted in an acidification of the suspension medium. The rate and extent of acidification was affected by those inhibitors, which inhibited methanogenesis competitively to Na + or Li.

(iv) During methane formation from H2 and C02 the generation of a ApH (inside alkaline) was dependent on the presence of Na + or Li +. However, methanogenesis was also dependent on Na + or Li + under conditions where ApH was zero.

(v) ATP synthesis driven by an electrogenic potassium efflux was significantly enhanced in the presence of Na + or Li +. Na + or Li + were shown to prevent acidification of the cytoplasm under these conditions.