The effect of substrate and operational parameters on the abundance of sulphate-reducing bacteria in industrial anaerobic biogas digesters

► Abundance of sulphate-reducing bacteria was determined by qPCR targeting dsrB in biogas digesters. ► Sulphate-reducing bacteria were tolerant to most operational strategies used in industrial biogas plants. ► High concentrations of ammonia and ammonium lead to decreased abundance of sulphate-reducing bacteria. This study evaluated the effects of operational parameters and type of substrate on the abundance of sulphate-reducing bacteria in 25 industrial biogas digesters using qPCR targeting the functional dissimilatory sulphite reductase gene. The aim was to find clues for operational strategies minimizing the production of H2S. The results showed that the operation, considering strategies evaluated, only had scarce effect on the abundance, varying between 105 and 107 gene copies per ml. However, high ammonia levels and increasing concentration of sulphate resulted in significantly lower and higher levels of sulphate-reducing bacteria, respectively.