Microbial solubilisation of Cd from apatite during aerobic cellulose biodegradation

Synthetic model sediments were used to investigate the processes of biologi cal Cd solubilisation, during cellulose biodegradation in batch experiments under aerobic conditions. The model sediments consisted of a mixture of qu artz sand, Cd-substituted or non-substituted hydroxyapatite and cellulose. The culture medium was inoculated with a mixed microflora and incubated und er controlled conditions. After 53 days, cellulose biodegradation reached h igh rates for both sediments (34 to 37% of initial carbon content) in the p resence of microorganisms. Simultaneously, Cd release was significant and r eached 34% of initial Cd. Solubilisation of Cd and Ca was correlated with a pH decrease from 6.7 to 4.5, and was thus a consequence of proton release in the solution. The use of model sediments allows assessment of biological weathering processes, particularly the influence of heterotrophic microorg anisms in mineral solubilisation, and their involvement in the dispersion o f trace elements in soils and sediments.