The molecular properties and the regulation of the carriers involved in the sodium cycle of extremely alkaliphilic bacteria are the focus of the research planned. Transposon mutagenesis will be used to identify genes of Bacillus firmus OF4 that encode the Na+/H+ antiporter or its regulatory genes. This approach, coupled with analysis of gene sequences, should provide a key initial step in the definition of these antiporters characteristic of extreme alkaliphiles and permit rigorous testing of hypotheses about the functioning of such antiporters. Bacteria which thrive under alkaliphilic conditions carry out a cycling of sodium using proton pumps. The molecular properties of, and the regulation of, the carriers involved in the unusal, membrane-related events of these bacteria will be studied and should lead to a more complete understanding of the functioning of these carriers in extreme alkaliphiles.
