Fig. 8From: Petroleum hydrocarbon rich oil refinery sludge of North-East India harbours anaerobic, fermentative, sulfate-reducing, syntrophic and methanogenic microbial populationsArchaeal distribution and phylogenetic tree of archaeal 16S rRNA gene sequences retrieved from the samples. Distribution of archaebacterial taxa in GR1, GR3 and DB2 (a) using clone library analysis. Phylogentic tree was constructed using the neighbour joining method incorporating Jukes-Cantor distance corrections (b). Sequence of Anabaena circinalis was used as the out-group. One thousand bootstrap analyses were conducted and bootstrap values > 50% were indicated at the nodes. Scale bar = 0.05 change per nucleotide positionBack to article page