Abstract

To elucidate respective effects of sodium and chloride ion on filament formation inZymomonas mobilis 232B culture induced by NaCl, the morphological changes of cell grown in medium containing 0.2 M (NH₄)₂SO₄, Na⁺(as Na₂SO₄) and Cl^-(as NH₄Cl) were observed using a scanning electronic nicroscope (SEM). The occurrence of filament formation began as early as 4 h after exposuring to NaCl and Cl^- and the length was approximate 10 to 15 μm after exposuring for 20 h, which was 3 to 5 fold longer compared to normal cell, while Na⁺ and (NH₄)₂SO₄ treated cells kept normal morphology, indicating that filament formation in NaCl-inhibited Z. mobilis cultures is attributable to chloride ion. In the presence of 0.2 M chloride ion, increase in cell number stop almost immediately, whereas cells continued to elongate slowly, suggesting that chloride ion has a direct inhibitory effect on cell division.

Key words: Zymomonas mobilis, chloride ion, filament formation, cell division.