Acclimation of microbial consortia on acidogenic effluents for enhanced production of polyhyrtoxyalkanoates.

The aim of the present study was to develop efficient MMCs via their acclimation to a mixture of volatile fatty acids, sugars, and lactate i.e. the acidogenic effluents of a hydrogen-generating bioreactor processing food wastes. Acclimation was conducted under sequential carbon (C) and nitrogen (N) limitation in draw fill reactors with organic loading 3 g/L (in terms of the chemical oxygen demand (COD)) in the C phase and ammonium chloride as N source in the N phase. Two DFRs were operated simultaneously with different carbon-to-nitrogen ratios (C/N) i.e. 10 g COD/g N-NH4+ and 50 g COD/g N-NH4+ and differences in the operational efficiency and microbial structure were assessed. Subsequently, batch experiments were conducted with both of the acclimated MMCs and with different initial substrate concentrations (6 -24 g COD/L) and different C/N ratios (50-200 g COD/g N-NH4+). It was shown that the feeding strategy during acclimation resulted in the domination of different microbial genera of Betaproteobacteria and affected greatly the yields and production rates of PHAs at batch mode, with the highest obtained yield exceeding 0.7 g PHAs/ g microbial biomass.