Single cell proteins (SCP) have emerged as an alternative protein source to partially alleviate the current problem of food scarcity. However, there is a need for the production of SCP from renewable and pathogen-free sources, such as gaseous streams. This study evaluated, for the first time, the use of enriched phototrophic purple bacteria (PPB) consortia for the production of SCP using H2 and CO2. The influence of pH (6-8.5), temperature (15-50 ºC) and light intensity (0-50 W m-2) on the growth kinetics and biomass yields was investigated. Optimal conditions were found at a pH of 7, temperature of 25 ºC and light intensities over 30 W•m-2. High biomass yields (~ 1 g CODbiomass⸱g-1 CODconsumed) and protein yields of ~4 g protein⸱g-1 H2 were achieved, regardless of the environmental conditions. The biomass had high protein contents (51-64 %w/w), potentially suitable as SCP. The biomass yields are amongst the highest ones reported from gaseous streams.