The Effect of the 2015 Earthquake on the Bacterial Community Compositions in Water in Nepal.

Sital Uprety,Pei-Ying Hong,Antarpreet Jutla,Rameswor Adhikari,Nora Sadik,Bipin Dangol,Joanna L Shisler,Patrick Degnan,Thanh H Nguyen

doi:10.3389/fmicb.2017.02380

Abstract

We conducted a study to examine the effect of seasonal variations and the disruptive effects of the 2015 Nepal earthquake on microbial communities associated with drinking water sources. We first characterized the microbial communities of water samples in two Nepali regions (Kathmandu and Jhapa) to understand the stability of microbial communities in water samples collected in 2014. We analyzed additional water samples from the same sources collected from May to August 2015, allowing the comparison of samples from dry-to-dry season and from dry-to-monsoon seasons. Emphasis was placed on microbes responsible for maintaining the geobiochemical characteristics of water (e.g., ammonia-oxidizing and nitrite-oxidizing bacteria and archaea and sulfate-reducing bacteria) and opportunistic pathogens often found in water (Acinetobacter). When examining samples from Jhapa, we identified that most geobiochemical microbe populations remained similar. When examining samples from Kathmandu, the abundance of microbial genera responsible for maintaining the geobiochemical characteristics of water increased immediately after the earthquake and decreased 8 months later (December 2015). In addition, microbial source tracking was used to monitor human fecal contamination and revealed deteriorated water quality in some specific sampling sites in Kathmandu post-earthquake. This study highlights a disruption of the environmental microbiome after an earthquake and the restoration of these microbial communities as a function of time and sanitation practices.

Highlights

Safe drinking water requires that the microbial community remains stable to minimize the risk of pathogen propagation and release (Rittmann, 1984; Hu et al, 1999; Prest et al, 2016)
There are only a few studies examining the microbial community in water in Nepal, and these studies show the presence of multiple pathogens and multi-drug resistance species of bacteria (Pokhrel and Viraraghavan, 2004; Tanaka et al, 2012)
Instead of analyzing the changes in the microbial community of water longitudinally to determine the direct impact of an earthquake, most studies tend to examine the indirect impact at a given time due to earthquakes or earthquake-triggered tsunamis

Summary

Introduction

Safe drinking water requires that the microbial community remains stable to minimize the risk of pathogen propagation and release (Rittmann, 1984; Hu et al, 1999; Prest et al, 2016). It has been appreciated that environmental conditions that favor an increased load of pathogens in water are crucial factors contributing to outbreaks of waterborne diseases, as was the case for Haiti in 2010 (Lobitz et al, 2000; Jutla et al, 2013). It is not known how the dynamics of water microbial communities change after a catastrophic earthquake that destroys sanitation and water infrastructure

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