Distribution of human fecal marker GB-124 bacteriophages in urban sewage and reclaimed water of São Paulo city, Brazil

Abstract

Bacteriophages infecting Bacteroides fragilis GB-124 have been described as potential markers of human fecal contamination in water sources. The aim of this study was to evaluate the occurrence of GB-124 phages in raw sewage, secondary effluents and reclaimed water of the São Paulo city using a low-cost microbial source tracking method. Samples were collected monthly from April 2015 to March 2016 in four municipal wastewater treatment plants that operate with activated sludge processes followed by different tertiary treatments (sand-anthracite filtration, membrane bioreactor/reverse osmosis) and final chlorination. GB-124 phages were detected in 100% of the raw sewage samples, with viral loads varying from 7.5 × 10 to 1.32 × 10 PFU/L. Virus removal efficiency in activated sludge processes ranged from 1.89 to 2.31 log. Frequencies of phage detection were lower in reclaimed water samples (0-22.2%). The results indicated that GB-124 phage could be a complementary low-cost viral marker for the detection of human fecal pollution in waters impacted with urban sewage in this region. However, the datasets of tertiary effluents resulted in several samples with concentrations below the detection limit (DL ≤1 PFU/mL) suggesting the need to obtain analytical methods with lower DL for greater accuracy of negative results.

Antibiotic Resistance Characterization of Environmental E. coli Isolated from River Mula-Mutha, Pune District, India

“…Residual antibiotics in wastewater as pollutants can exert selective pressure and contribute to the increase in antibiotic-resistant bacteria [ 23 ]. Sewage from hospitals and the community, agricultural effluent and aquaculture wastewater are also important sources of resistant bacteria polluting the water sources [ 23 , 24 , 25 ].…”

Evaluation of Low-Cost Phage-Based Microbial Source Tracking Tools for Elucidating Human Fecal Contamination Pathways in Kolkata, India

“…The overall goal of this study was to establish low-cost, geographically suitable tools to identify potential pathways of exposure to human fecal contamination that could serve as transmission routes of typhoid fever in Kolkata. Whilst phages against Bacteroides strain GB-124 had previously been successfully detected in municipal sewage (untreated and treated) from England, Cuba, Ireland, France, Portugal, Denmark, Brazil, Spain, Italy, United States, and Uganda ( Ebdon et al, 2007 , 2012 ; Vijayavel et al, 2010 ; McMinn et al, 2014 ; Dias et al, 2015 , 2018 ; Purnell et al, 2016 ; Prado et al, 2018 ), the suitability of phages infecting GB-124 as indicators of human fecal contamination in India had not been characterized. The consistent detection of phages of GB-124 in sewage and a wide range of fecally contaminated environmental matrices, and its absence from pooled cattle, chicken, goat and dog feces suggest its potential as a culture-based indicator of human fecal contamination in Kolkata.…”

“…However, research has also shown that phages that are capable of lysing a specific host strain of Bacteroides in one part of the world, are not necessarily detected in samples of similar origin (or at similar levels) in other parts of the world ( Kator and Rhodes, 1992 ; Chung et al, 1998 ; Puig et al, 1999 ; Payan et al, 2005 ; Blanch et al, 2006 ), suggesting that different host strains may be needed for meaningful MST studies in different catchments or geographic regions. However, phages infecting certain B. fragilis strains (e.g., GB-124) have been shown to be restricted to human hosts ( Ogilvie et al, 2012 , 2018 ) and have been previously reported in Europe and North and South America as a potentially low-cost human fecal indicator ( Payan et al, 2005 ; Ebdon et al, 2007 , 2012 ; McMinn et al, 2014 , 2017 ; Prado et al, 2018 ). Geographic variations in the efficacy of MST markers have been reported in the extant literature ( Ebdon and Taylor, 2006 ; Harwood et al, 2013 ) due to potential differences in host genetics, antibiotic usage, immunological factors and dietary differences.…”

Genome Characterization of a Novel Wastewater Bacteroides fragilis Bacteriophage (vB_BfrS_23) and its Host GB124

“…The exact origin of B. fragilis strain GB124 is unknown. It was isolated from untreated wastewater from a treatment plant in South East England and wastewater and impacted surface waters in the United Kingdom, United States, Brazil, and India (Payan et al, 2005;Prado et al, 2018;Wadhwa et al, 2018). Coupled with previously reported existence of a clear human gutassociated eco-genomic signature within the Bacteroides phage genomes (Ogilvie et al, 2012(Ogilvie et al, , 2013(Ogilvie et al, , 2018, it is assumed to be a human gut commensal.…”