Acetic acid production of Vibrio halioticoli from alginate:: a possible role for establishment of abalone-V-halioticoli association

Acetic acid, which is converted from cellulose by means of the metabolism of their gut microbes, is an important oxidizable energy source and precursors of anabolism in ruminant animals and xylophagus insects. However, acetic acid production from algal polysaccharides by means of the metabolism of gut microbes of marine herbivorous invertebrates is not well studied. Abundance of Vibrio halioticoli, which is a dominant alginolytic gut microbe of abalone Haliotis discus hannai, in the gut of various marine herbivorous invertebrates and major fermentation products from alginate of these strains were investigated in this study. V halioticoli strains were detected from the gut of three species of the Japanese abalone, Haliotis discus discus, Haliotis diversicolor aquatilis, and Haliotis diversicolor diversicolor, and a South African abalone, Haliotis midae, with a range of 40-65% amongst these microflora. The bacterium was also found in the gut of a turban shell, Turbo cornutus, of which occupation rate was 16%. Furthermore, acetic acid and formic acid were detected as major fermentation products of alginate in these V halioticoli strains. It is suggested that the abundant populations of V halioticoli in the gut of Haliotis abalone may have a great role for converting alginate to acetic acid. (C) 2003 Elsevier Science B.V. All rights reserved.