Description of bacterial microbiota in biosolids generated in the San Fernando wastewater treatment plant. Itagüí, Colombia

Objective To describe bacterial microbiota in the biosolids generated in one of the largest wastewater treatment plants of Colombia. Materials and Methods Using NGS technology, 16S rRNA Gene Amplicon libraries were amplified and sequenced. The Roche 454 FLX Titanium platform was used, while the V1-V3 and V6-V9 hypervariable regions were amplified and analyzed independently. Amplicon processing and bacterial classification were performed using the AmpliconNoise pipeline and the RDP Classifier tool. Results The analysis showed that the most dominant Phyla in the biosolids were Chloroflexi, Proteobacteria, Bacteroidetes, Actinobacteria and Firmicutes. The most dominant genera were Pseudomonas, Dysgonomonas and Proteiniphilum; however, the dominant group according in the V1-V3 variable region was Anaerolineaceae, which does not conform to the species described for this family. Pathogenic bacteria such as Salmonella and E. coli/Shigella were not detected in the studied biosolid sample. Conclusions In the biosolids samples analyzed, environmental bacteria involved in organic matter stabilization processes during secondary biological treatments and anaerobic digestion were predominant. One of the dominant species in this sludge is a novel species of the Anaerolineaceae group. At the time of the study, it was found that the anaerobic digester system was able to maintain pathogenic bacteria at very low concentrations.