Microbiological water quality monitoring of four ponds from Lagoa do Sino Farm located in São Paulo State, Brazil

Patrícia Alexandre Evangelista,Mayara Andrade Martins De Souza,Iuri Emanuel De Paula Ferreira,Natan De Jesus Pimentel-Filho

doi:10.4025/actascibiolsci.v43i1.52901

Patrícia Alexandre Evangelista, Mayara Andrade Martins De Souza + Show 2 more

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https://doi.org/10.4025/actascibiolsci.v43i1.52901

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Abstract

This study aimed to evaluate the microbiological quality of the water of four ponds used for irrigation on the Lagoa do Sino Farm, as well as to perform the genotypic characterization of virulence factors in Escherichia coli isolates. Sampling was conducted for 11 months, between 2015 and 2016. Samples were analyzed for the presence of thermotolerant coliforms, E. coli and heterotrophs. DNA was extracted from E. coli isolates, followed by genotypic characterization by polymerase chain reaction. Agricultural activities and pesticides used in the sampling period were documented in order to assess possible relationships between agricultural activities and microbiological water quality. The absence of suitable riparian vegetation around all the ponds was observed, benefiting the entry of organic matter and contaminants in the water body. A high index of thermotolerant coliforms in some months indicated the possibility of the transmission of pathogenic microorganisms in these ponds. The values found in some months were above the regulatory limits for water potability and water intended for irrigation. The agrochemicals used in the period seem to influence the results obtained. All 17 E. coli isolates showed at least one of the virulence genes estA, stx1, stx2, and aatA, indicating enterotoxigenic, enterohaemorrhagic or enteroaggregative nature. The presence of E. coli in the waters may be associated with the presence of animals. The water samples analyzed are not suitable for irrigation of vegetables that are consumed raw and/or low lying fruits ingested without skin removal. It is essential to broaden the control of the use of chemicals, as well as the preservation of riparian vegetation to improve the quality of water used in the farm's agricultural activities.

Highlights

Water is a fundamental resource for life
The occurrence of thermotolerant coliforms and, the presence of E. coli in this sample location was verified in October and November 2015 and February 2016, especially the latter, with high detection (930 NMP. (100 mL)-1) (Figure 2)
Water used for irrigation of arboreal, cereals and forages is classified as class 3, with a limit of 4,000 thermotolerant coliforms per 100 mL of water (Brasil, 2005)

Summary

Introduction

Water is a fundamental resource for life. This resource is used in different ways to meet human needs including domestic, leisure and recreation and economic needs such as electricity generation, wastewater reception, waterway transportation, industrial use, fishing and aquaculture. Agriculture, especially large-scale agriculture, uses products aiming to increase production, often resulting in improper soil treatment. This in turn is exposed to rainwater resulting in surface runoff. There is an increase of edaphic material to water sources in the proximity, carrying organic and inorganic matter and chemical compounds responsible for surface water contamination due to erosive processes as well as pollutant leaching due to unsustainable management (Steffen, Steffen, & Antoniolli, 2011). It is noteworthy that water contamination is aggravated by the destruction of riparian vegetation (Jarek, Souza, Favaretto, & Ruaro, 2016)

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