Effect of biomass adaptation to the degradation of anionic surfactants in laundry wastewater using EGSB reactors

AbstractTwo expanded granular sludge bed reactors were operated. RAB (adapted biomass) was operated in two stages: Stage I, with standard LAS (13.2mgL−1); and Stage II, in which the standard LAS was replaced by diluted laundry wastewater according to the LAS concentration (11.2mgL−1). RNAB (not adapted biomass) had a single stage, using direct wastewater (11.5mgL−1). Thus, the strategy of biomass adaptation did not lead to an increase of surfactant removal in wastewater (RAB-Stage II: 77%; RNAB-Stage I: 78%). By means of denaturing gradient gel electrophoresis, an 80% similarity was verified in the phases with laundry wastewater (sludge bed) despite the different reactor starting strategies. By pyrosequencing, many reads were related to genera of degraders of aromatic compounds and sulfate reducers (Syntrophorhabdus and Desulfobulbus). The insignificant difference in LAS removal between the two strategies was most likely due to the great microbial richness of the inoculum

Anaerobic reactor applied to laundry wastewater treatment : unveiling the microbial community by gene and genome-centric approaches

Gene and genome-centric approaches were applied to investigate the microbial taxonomic and metabolic diversity profiles from a lab-scale anaerobic reactor applied to laundry wastewater treatment with increasing concentrations of linear alkylbenzene sulfonate (LAS). Therefore, metagenomic analysis was carried out with reactor samples collected under three conditions, (i) Stage I, the reactor was fed with synthetic medium, (ii) Stage II, synthetic medium was replaced by diluted laundry wastewater with specific LAS loading rates (SLLRs) of 1.0 ± 0.3 mgLASgTVS−1d−1 and (iii) Stage III, SLLRs increased to 2.7 ± 0.7 mgLASgTVS−1d−1. Shotgun metagenomic sequencing was performed on an Illumina HiSeq 2 × 150 bp platform. Gene-centric analysis of each step of the metabolic pathway (fumarate addition, β-oxidation, ring cleavage and desulfonation) for anaerobic aromatic degradation showed eight over-representative genera (Achromobacter, Pelodictyon, Pseudomonas, Psychrobacter, Rhodococcus, Stenotrophomonas, Sulfurovum and Syntrophobacter), suggesting a microbial core with an important role in LAS biodegradation. Some of these genera were also recovered through a differential binning method, representing fifteen bacterial and one archaeal metagenome-assembled genomes (MAGs). Biodegradation pathway reconstruction of LAS using six MAGs unveiled the syntrophism for complete degradation of the LAS molecule. Only the MAGs with taxonomic annotation for Syntrophobacter showed genetic potential for fumarate addition, whereas in the ring cleavage, there was a predominance of genes in MAGs with taxonomic annotation for Pseudomonas fragi and Rhodococcus. This work represents the first report of genome-centric approach to study biological reactors applied in anionic surfactant degradation, contributing with detailed metabolic information of the key microbial actors in LAS degradation and opening perspectives for future biotechnological strategies aiming at bioaugmentation and/or biostimulation of indigenous microbial populations149COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP0012014/16426–0; 2015/06246–