Survival of Escherichia coli O157:H7 in Soils from Jiangsu Province, China

Taoxiang Zhang,Jianming Xu,Haizhen Wang,Jun Lou,Jianjun Wu,Laosheng Wu,Philip C Brookes,Dongsheng Zhou

doi:10.1371/journal.pone.0081178

Abstract

Escherichia coli O157:H7 (E. coli O157:H7) is recognized as a hazardous microorganism in the environment and for public health. The E. coli O157:H7 survival dynamics were investigated in 12 representative soils from Jiangsu Province, where the largest E. coli O157:H7 infection in China occurred. It was observed that E. coli O157:H7 declined rapidly in acidic soils (pH, 4.57 – 5.14) but slowly in neutral soils (pH, 6.51 – 7.39). The survival dynamics were well described by the Weibull model, with the calculated td value (survival time of the culturable E. coli O157:H7 needed to reach the detection limit of 100 CFU g−1) from 4.57 days in an acidic soil (pH, 4.57) to 34.34 days in a neutral soil (pH, 6.77). Stepwise multiple regression analysis indicated that soil pH and soil organic carbon favored E. coli O157:H7 survival, while a high initial ratio of Gram-negative bacteria phospholipid fatty acids (PLFAs) to Gram-positive bacteria PLFAs, and high content of exchangeable potassium inhibited E. coli O157:H7 survival. Principal component analysis clearly showed that the survival profiles in soils with high pH were different from those with low pH.

Highlights

Applications of animal manure as fertilizers or soil amendments to agricultural soils are routine, world-wide
The results suggested that soil pH and G2/G+ were the most important factors determining the survival of E. coli O157:H7 in the test soils (Table 3)
E. coli O157:H7 could survive for 32.7961.16 days in neutral soils, and only 6.561.34 days in acidic soils

Summary

Introduction

Applications of animal manure as fertilizers or soil amendments to agricultural soils are routine, world-wide. In the UK, the annual amount of animal manure applied to land was recently estimated at 4.36105 tons dry weight [1]. Escherichia coli O157:H7 (E. coli O157:H7), which can cause severe hemorrhagic colitis and haemolytic uraemia in humans, can persist in soil for days to more than 1 year following manure application to land [3]. Increasing evidence shows that soil and animal manures are the main transport agents of E. coli O157:H7 to contaminate fresh vegetables, fruits and drinking water [1], [5], [6]. It is important to understand the nature of E. coli O157:H7 survival and its infective risk in soil or soil-related (manure) environments

Objectives

Methods

Conclusion