Fig. 1.

Proposed phosphate uptake and release by Beggiatoa. a, b Under oxic conditions and exposure to low sulfide concentrations, phosphate is taken up by Beggiatoa and accumulated as polyphosphate. The phosphate concentration in the medium decreases. c, d When the conditions change to anoxia and exposure to sulfide increases, the Beggiatoa decompose polyphosphate and release phosphate. This leads to an increase in phosphate in the medium. Reprinted by permission from Macmillan Publishers Ltd: ISME J [89], copyright 2011