Fig. 3From: Petroleum hydrocarbon rich oil refinery sludge of North-East India harbours anaerobic, fermentative, sulfate-reducing, syntrophic and methanogenic microbial populationsComposition of three microbial communities at phylum (a) and class (b) levels. Phyla with cumulative abundance ≥0.5% (across the three samples) were considered. Class level distribution was plotted for three major phyla Proteobacteia, Chlroflexi and FirmicutesBack to article page