28
Tecnología y Ciencias del Agua
, vol. VIII, núm. 3, mayo-junio de 2017, pp. 27-37
Aburto-Medina
et al
.
, Prevalence of
Enterobacteriaceae
and contaminants survey in sediments of the Atoyac River
•
ISSN 2007-2422
Introduction
The Atoyac River originates in the Calpulalpan
sierra in the state of Tlaxcala and along its
course, through the state, it is fed by the Za-
huapan River forming the Alto Atoyac sub-basin
with an area of 2013 km
2
(Carrera-Villacrés,
2007). The Atoyac River later finds its way into
the state of Puebla and runs through its capital
city before ending up on the Valsequillo dam.
However, these rivers receive urban, industrial
and agricultural effluents from the towns and
industrial activities along with their course. The
industrial activities are quite varied and they
include the food, textile, chemical, petrochemi-
cal, pharmaceutical, metallurgic, electric, and
automobile industries, among others (Sandoval-
Villasana, Pulido-Flores, Monks, Gordillo-
Martínez, & Villegas-Villareal, 2009). Aprevious
study has assessed the quality of waters, sedi-
ments, and the genotoxic potential in the hydro-
logical Atoyac-Zahuapan river system and the
Avila Camacho dam (Mangas
et al
., 2005). The
genotoxic potential of sediments and superficial
water of this system has been confirmed with
the plant
Vicia faba
(Villalobos-Pietrini, Flores,
& Gómez, 1994; Juárez-Santacruz
et al
., 2012).
Chromosomal aberrations and centromeric
alterations were found in root tip cells of this
plant after being exposed to the Atoyac River
waters (ob. cit.) while the micronuclei frequency
was increased after exposure to the river sedi-
ments in a recent study (Juárez-Santacruz
et
al
., 2012). Moreover, metals such as lead and
arsenic have been detected in the Alto Atoyac
sub-basin and their concentrations were above
the Mexican and international permissible
limits (García-Nieto
et al
., 2011). Other studies
have also revealed the number and location of
effluents in the Atoyac River (Saldaña & Gómez,
2006; Sandoval-Villasana
et al
., 2009) and have
established them as the main source of con-
tamination. Furthermore, concentrations of Mn
and Fe in waters of the Valsequillo dam were
also above the permissible limits (Díaz, Bonilla,
Tornero, Cabrera, & Corona, 2005). These waters
are used for irrigation of nearby crops such as
maize and alfalfa and their soils also have Pb
concentrations above the norm (Larenas-Bazán,
2010). The most recent study on these river
sediments and waters reported severe pollution
that includes hydrocarbons, metals, POPs, en-
docrine disruptors and potentially carcinogenic
compounds (Greenpeace, 2014). Therefore, this
study aims to elucidate the microbial diversity
in a river area where it has received all the major
domestic and industrial effluents prior to the
water storage in the Valsequillo dam. The iden-
tification of the microbial diversity will provide
a clearer idea of their catabolic potential in those
sediments.
Materials and methods
A list of the different methods used in this study
is included in table 1.
Table 1. List of methods used in this study.
Method
Objective
References
Clone libraries
Identification of the bacterial population (Aburto
et al
., 2009)
Shiga toxins by PCR
Detection of pathogens
(Fagan, Hornitzky, Bettelheim, &
Djordjevic, 1999)
Coliforms enumeration
Fecal and total coliforms as indicators of
water quality
(NMX-AA-42-1987)
Biochemical Oxygen Demand (BOD)
Water quality
(NOM-003-Semarnat-1997)
X-Ray fluorescence Analyzer (FPXRF)
Identification of heavy metals
(USEPA, 2007a)
Analytical chemistry (GC-MS)
Toxic compounds elucidation
(USEPA, 2007b), (USEPA, 2007c)
