Purple non-sulphur photosynthetic bacteria in brewery wastewater during anaerobic digestion

ABSTRACT: Anaerobic digestion of brewery wastewater (BWW), under batch and constant light conditions, provided 70 mL of biogas with 80% CH4 and a COD removal of 64%, corresponding to a yield of 372 m3 biogas/kg COD removed. Additionally, a reddish pigmentation has developed throughout the process due to the growth of purple nonsulphur bacteria (PNSB). Based on morphological, physiological and cultural properties two strains of PNSB belonging to the genus Rhodobacter were isolated. The comparison of the nucleotide sequences of the 16S rRNA genes of the strains with the international databases (NCBI GenBank) made it possible to establish their taxonomical status as Rhodobacter capsulatus and R. azotoformans species.N/