the unique diazotrophic and phototrophic capabilities of purple phototrophic bacteria could provide a sustainable alternative to the current fossil-based food production systems. We show here that mixed purple non-sulphur bacteria cultures can fix at extremely high N and COD yields (average values of 0.99±0.03 and 0.89±0.02 gbiomass ·gremoved-1 ), and with high crude protein contents (up to 58%). While the photoautotrophic rates (fed with H 2 and CO 2) were relatively low (0.85±0.29 g COD substrate ·g COD biomass-1 ·d -1 ), the values obtained during photoheterotrophic growth (fed with volatile fatty acids) were surprisingly high, averaging 6.4±0.5 g COD substrate ·g COD biomass-1 ·d -1 ). The latter are around three times higher than common rates reported for non-diazotrophic photoheterotrophic growth. These promising results suggest that specialised cultures of these bacteria could be effectively applied to fix nitrogen while converting reduced carbon (e.g. mixed fermentation effluents) into microbial protein.