Influence of operational conditions on the performance of biogas bioconversion into ectoines in pilot bubble column bioreactors

The application of biogas as a low-priced substrate for the production of ectoines constitutes an opportunity to decrease their production costs and to enhance the viability of anaerobic digestion. The influence of operational conditions on CH4-biogas biodegradation and on ectoines production yields was assessed in continuous pilot bubble column bioreactors. The rise in biomass concentration from 1 to 3 g L-1 resulted in a decrease in the specific ectoine content from 42 +/- 8 to 30 +/- 4 mgectoine gVSS (-1) . The concentration of Cu2+ and Mg2+ did not impact process performance, while the use of ammonium as N source resulted in low CH4 biodegradation and ectoine yields (13 +/- 7 mgectoine gVSS(-1) ). The increase in CH4 content from 4.5 to 9 %v.v(-1) enhanced CH4 removal efficiency. Process operation at NaCl concentrations of 3 %w.w(-1) instead of 6 %w.w(-1) decreased the ectoine yield to 17 mgectoine gVSS(-1) . Finally, Methylomicrobium buryatense was identified as the dominant species.