IDENTIFICATION OF 29 COMPLETE BACTERIAL GENOMES FROM TWO SMALL DAIRY INDUSTRY WASTEWATER STABILIZATION PONDS

IRAZOQUI JM; AMADIO, ARIEL F.

San Miguel de Tucumán

Congreso; XII Congreso Argentino de Microbiología General; 2017

SAMIGE

Stabilization ponds are the most common treatment technology in developing countries due to their low operation and maintenance costs. Normally, they are organized in several serial ponds that combine anaerobic and facultative processes. The microbial community composition in two stabilization ponds systems of dairy industries was analyzed using whole genome shotgun sequencing. Samples were collected from six full-scale stabilization ponds belonging to two small dairy industries (CYC and AUR) located in the center of Santa Fe in Argentina. CYC treatment consisted in four serial ponds, while AUR have two serial stabilization ponds. For this work, we carried out a contig binning strategy aiming to reconstruct complete genomes from the metagenomic reads. First, reads were assembled using IDBA_UD and bins were constructed using MaxBin2. The quality of the binning was evaluated using CheckM, which uses collocated sets of genes that are ubiquitous and single-copy within a phylogenetic lineage. Later, these bins were manually corrected, removing contigs with marker genes corresponding to distant lineages and all reads mapping to each bin were re-assembled in order to produce a better assembly with less contamination . The bins were taxonomical classified using marker genes from CheckM and annotated using the RAST annotation server. Last, to give extra support to the classification, the bins were placed in a phylogenetic tree and the predicted gene composition was compared to its nearest neighbor. In total, we found 29 complete bins (>90% of the markers present) with low contamination (<5% of duplicated markers), 20 from CYC samples and nine from AUR. Based on the markers found and the placement in the phylogenetic tree, 11 of CYC bins classified as Firmicutes, mainly Clostridiales. The rest corresponded to Proteobacteria (four), Bacteroidetes (four) and Spirochaetes. Among the AUR bins, four Proteobacterias, two Verrucomicrobias, two Actinobacteria and one Synergistetes were identified. All bins shared a high percentage of the genes with their closest neighbor in the same lineage, which supports the assignation proposed. The bins AUR008, AUR009, CYC015 and CYC067 had a larger proportion of unique genes, which suggest that these bins could represent more distant organisms. The reconstruction of complete genomes from metagenomic data is not only key to obtain information about uncultured microorganisms, but also to understand the process of substrate processing in systems like stabilization ponds, and represents a new way to identify genes of biotechnological