The bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria was analysed. The vegetable samples were collected during October 2013 and September 2014 in Aliero town in a period of three months across the two seasons (i.e., the dry and rainy seasons). After the analysis, the following bacterial spp were isolated from the vegetable crops irrigated with domestic wastewater water; Salmonella spp (14.0%), Pseudomonas aeruginosa (13.2%), Klebsiella spp (16.0%), Shigella spp (19.2%), Escherichia coli (41.6%), Citrobacter spp (25.2%), Proteus spp (15.6%) and Campylobacter spp (6.8%). The bacterial spp isolated from vegetables irrigated with tube well water was Staphylococcus aureus (26.8%), Escherichia coli (14.0%), Pseudomonas aeruginosa (8.8%), Diplococcus spp (12.0%) and Corynebacteria spp (1.2%). Escherichia coli and Citrobacter spp were recorded to have the highest number of occurrence in vegetables irrigated with domestic wastewater, with the percentage of 41.6% and 22.2% respectively. While Staphylococcus aureus and Escherichia coli have the highest occurrence of 26.8% and 14.0% respectively in vegetables irrigated with tube well water. This study highlights the health risk associated with the consumption of these vegetables particularly those consumed raw.

1. Studies on the Bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria
WJM
Studies on the Bacteriological quality of vegetable crops
irrigated with domestic wastewater in Aliero, Kebbi
State, Nigeria
1Manga Sule Sahabi, 1Sule Zeporah, 1Abubakar Adamu Samira, 2Kalgo Zaharaddin Muhammad,
2Bazata Abbas Yusuf and 1Keta Jibrin Naka
1Department of Biological Sciences, Kebbi State University of Science and Technology, Aliero, Kebbi State, Nigeria
2Department of Microbiology, Federal University Birnin Kebbi, Kebbi State, Nigeria.
The bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi
State, Nigeria was analysed. The vegetable samples were collected during October 2013 and
September 2014 in Aliero town in a period of three months across the two seasons (i.e., the dry
and rainy seasons). After the analysis, the following bacterial spp were isolated from the
vegetable crops irrigated with domestic wastewater water; Salmonella spp (14.0%), Pseudomonas
aeruginosa (13.2%), Klebsiella spp (16.0%), Shigella spp (19.2%), Escherichia coli (41.6%),
Citrobacter spp (25.2%), Proteus spp (15.6%) and Campylobacter spp (6.8%). The bacterial spp
isolated from vegetables irrigated with tube well water was Staphylococcus aureus (26.8%),
Escherichia coli (14.0%), Pseudomonas aeruginosa (8.8%), Diplococcus spp (12.0%) and
Corynebacteria spp (1.2%). Escherichia coli and Citrobacter spp were recorded to have the
highest number of occurrence in vegetables irrigated with domestic wastewater, with the
percentage of 41.6% and 22.2% respectively. While Staphylococcus aureus and Escherichia coli
have the highest occurrence of 26.8% and 14.0% respectively in vegetables irrigated with tube
well water. This study highlights the health risk associated with the consumption of these
vegetables particularly those consumed raw.
Key words: Vegetable, crops, domestic, wastewater, tube well, Aliero.
INTRODUCTION
Water is essential for life and for maintaining our health
and dignity. Sanitation problems in the country are equally
enormous, no aspect of environmental sanitation is
properly managed. Poor access to basic sanitary facilities
is a big issue. Water is a vital resource, but good quality
water is very limited in most countries, particularly in
developing countries like Nigeria. The alarming increase in
global population has not only increased the demand for
freshwater but also increased the volume of wastewater
generated. The increasing water need has resulted in the
emergence of the application of domestic wastewater for
agriculture purposes. The reuse of wastewater for
agriculture is encouraged, for the fact that the wastewater
has a positive impact on soil characteristics, crop
production, and water management (FAO, 2013).
The quality of life depends on the quality and quantity of
water available since the quality of water and health are
interrelated. Moreover, it is very disheartening to note that
health hazards associated with direct wastewater use are
enormous.
*Corresponding author: Kalgo Zaharaddin Muhammad,
Department of Microbiology, Federal University Birnin
Kebbi, Kebbi State, Nigeria. Tel: +2348031367195 Email:
zaharaddin28@gmail.com
World Journal of Microbiology
Vol. 4(2), pp. 100-104, June, 2017. © www.premierpublishers.org. ISSN: 2141-5032
Research Article

2. Studies on the Bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria
Kalgo et al. 101
The quality of life depends on the quality and quantity of
water available since the quality of water and health are
interrelated. Moreover, it is very disheartening to note that
health hazards associated with direct wastewater use are
enormous. It is very necessary to consider the existing
municipal wastewater disposal infrastructure, wastewater
irrigation, quality of water used, the health implications and
the institutional awareness level of wastewater related
issues (Rutkosky et al., 2006).
Access to clean water for vegetable farm irrigation is a
major challenge, urban and peri-urban vegetable farmers
have no other choice than to use water from these highly
polluted sources (Girmaye et al., 2014). The continued use
of untreated wastewater and manure fertilizers for the
production of vegetables is on the high side in developing
countries and is a major contributing factor to
contamination that causes numerous food borne disease
outbreaks (Johannessen et al., 2002; Adeoluwa and Cofie,
2012). The pathogens are transmitted to the public through
consumption of irrigated produce, especially crops eaten
raw (Blumenthal et al., 2000).
In arid and semi-arid regions, wastewater is considered a
valuable source of irrigation water and a fertilizing material
(Al-Rashed and Sherif, 2000). The use of this waste in
agriculture is seen as an important issue for both soil
conservation and residual disposal. In fact, most sewage
wastes contain valuable nutrients that improve soil fertility
and crop production (Ahmad et al., 2006). Earlier studies
have shown that the effect of an industrial effluent varies
from crop to crop (Kaushik et al., 2005; Tarchitsky et al.,
1999). Therefore, inappropriate handling and
management of waste reuse for irrigation can create
serious environmental and health hazards (Angelakis,
1999).
Several studies throughout the world demonstrated a very
close relation between the consumption of fruits and
vegetables irrigated with raw wastewater and many food-
borne diseases like gastroenteritis, cholera, chemical
toxicity (Sou et al., 2011). Vibrio cholorae, the etiologic
agent of cholera is consumed from contaminated water,
foods, including vegetables and seafood with water
playing a central role in its transmission (Adesina et al.,
2013; Madoraba and Moba, 2010). Faecal coliforms are
the indicator bacteria most commonly used in discussions
of wastewater reuse (Blumenthal et al., 2000). They are
broadly equivalent to thermo tolerant coliforms. The
preferred grouping would be thermo tolerant
“coliforms/Escherichia coli” which would eventually allow
E. coli to be used as the preferred and exclusively faecal
indicator bacterium. Hence are considered an indicator of
microbial pollution (Edberg, 2000 and Halablab et al.,
2010).
Considering the paucity of data on the bacteriological
quality of vegetable crops irrigated with domestic
wastewater and tube well water in this environment, This
study was designed to investigate the bacteriological
quality of vegetable crops irrigated with domestic
wastewater and tube well water in Aliero, Kebbi State,
Nigeria, due to fact that Aliero is a local government in
Kebbi state known for its high yield of vegetable and fruits
produce, which are consumed in all parts of the state and
some part of the country. The increase in use of
wastewater to compensate water shortage and the
outbreak of diseases in this environment prompted the
study. This study would help in reducing the burden of
enteric diseases in a populace.
MATERIALS AND METHODS
Sample collection
This research was carried out in Aliero town, Aliero Local
Government area, Kebbi state. The samples were
collected across the two seasons (i.e. the dry and rainy
season). Samples were collected for the period of three
months in each season to be able to compare the
bacteriological quality of irrigated crops and that of tube
well water. Wastewater samples were collected by
immersing the sterilized 100ml bottles to the depth of about
30cm. When water filled the bottles, the caps were
carefully replaced. The samples were taken to the
Microbiology Laboratory of Kebbi State University of
Science and Technology, Aliero for microbiological
analysis within 2 to 3 hours of collection (Klansmewyer et
al., 2004). Soil samples were collected with the aid of soil
auger in clean and sterile polythene bags and taken to the
Laboratory for bacteriological analysis as described by
Oyeleke (2000). Vegetable crops (onions, spinach and
lettuce) were collected from the irrigated farm land in clean
and sterile polythene bags. The samples were processed
by washing with sterilized distilled water which was then
used for serial dilution before inoculating them on the
surface of various agar plates (5% sheep blood, chocolate,
Mac Conkey, Salmonella Shigella (SS) and Skirrows
media).
Isolation of Bacteria
Different colonies were observed from various culture
plates after 24-48 hours, distinct colonies were then
selected and further sub-cultured on nutrient agar using
streak plate technique. The pure cultures were inoculated
into sterile nutrient agar slants and incubated at 37oC for
24 hours. The slants were kept in the refrigerators for
further analysis.
Characterization and identification of bacteria
The bacterial isolates were characterized and identified
based on colonial morphology, cultural characteristics and
biochemical tests as described by Fawole and Oso 1998;

3. Studies on the Bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria
World J. Microbiol. 102
Table 1: Mean bacterial count of various sample (cfu/g) on Total Plate Count Agar
Samples Irrigated with domestic sewage Irrigated with tube well water
Onions 2.5x106b
2.0 x104d
Spinach 7.6 x106a
3.1 x105c
Lettuce 6.8 x106a
2.9 x105c
Soil 2.3 x106b
2.4 x105c
Sewage/Water 9.0 x106a
1.2 x102e
Values having the same superscripts are not significantly different
Table 2: Occurrence of bacteria in vegetable irrigated with domestic sewage
Bacteria Onions Spinach Lettuce Soil Sewage % Occurrence
Salmonella spp 4 6 8 - 17 14.0
P. aeruginosa - 2 - 18 13 13.2
Klebsiella spp - 5 7 15 13 16.0
Shigella spp 2 11 15 9 11 19.2
E. coli 8 15 19 25 37 41.6
Citrobacter spp 7 5 11 15 25 25.2
Proteus spp 5 9 3 7 15 15.6
Campylobacter spp - - 1 5 11 6.8
Table 3: Percentage occurrence of bacteria in vegetable irrigated with tube well water (upland)
Bacteria Onions Spinach Lettuce Soil Sewage % Occurrence
S. aureus 6 16 13 30 2 26.8
Streptococcus spp 5 7 - 9 - 8.4
E. coli 3 9 5 15 3 14.0
P. aeruginosa - 2 - 20 - 8.8
Diplococcus spp - - 1 3 - 1.2
Corynobacteria spp - - 1 2 - 1.2
Cowan 1974, Cruikshank, 1973; Cheesbrough, 1998. The
colonial morphology of the isolates was examined and
characteristic colonies were identified and compared with
those of known taxa as described previously Klansmewyer
et al., (2004). The bacteria identified were further
confirmed using series of biochemical tests (Klansmewyer
et al., 2004).
Statistical analysis
Analysis of variance was used to analysed the result
obtained.
RESULTS
Table 1 represents the mean bacterial count of the
vegetable crops analysed. There was significant difference
between the mean bacterial count of vegetables irrigated
with the domestic sewage compared to the ones irrigated
with the tube well water(p≤0.05). The bacteria identified
from the samples analysed are presented in Table 2 and
Table 3. The following bacterial spp were isolated from the
vegetable crops irrigated with domestic sewage;
Salmonella spp (14.0%), Pseudomonas aeruginosa
(13.2%), Klebsiella spp (16.0%), Shigella spp (19.2%),
Escherichia coli (41.6%), Citrobacter spp (25.2%), Proteus
spp (15.6%) and Campylobacter spp (6.8%). The bacterial
spp isolated from vegetables irrigated with tube well water
was Staphylococcus aureus (26.8%), Escherichia coli
(14.0%), Pseudomonas aeruginosa (8.8%), Diplococcus
spp (12.0%) and Corynebacteria spp (1.2%).
DISCUSSION
The present study indicated that the vegetable crops
irrigated with domestic sewage are more contaminated
with bacteria than the ones irrigated with tube well water
as shown in Table 1 (p≤0.05). This could not be connected
with the high bacterial load observed from the domestic
sewage used in the irrigation of the vegetable crops.
Comparing the types of bacteria identified from the two
types of irrigated crops, it was observed that almost all the
bacteria identified from the vegetable crops irrigated with
domestic sewage are enteric bacteria (Table 2), while the
other set, had only a few enteric bacteria (Table 3). Many
researchers have reported that vegetables are one of the
major reservoir of enteric bacteria that may be transmitted
from humans through faeces in the domestic sewage.
There are health implications in using domestic sewage for
irrigation because the pathogenic bacteria in the
vegetables may consequently find their way to the
consumers through the crops, which could result in many
diseases outbreak (Blumenthal et al., 2000; Johannessen
et al., 2002; Adeoluwa and Cofie, 2012).
An epidemiologic study in Nigeria revealed that, Vibrio

4. Studies on the Bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria
Kalgo et al. 103
cholerae, the aetiologic agent of cholera is consumed from
contaminated water, foods including vegetables and
seafood with water playing a central role in its transmission
(Adesina et al., 2013; Madoraba and Moba, 2010).
Adesina et al., (2013) also reported that in the last quarter
of 2009, more than 260 people died of cholera in the
northern part of the country. This contradict the finding of
this study, where Vibrio cholarae were not part of the
organisms recovered, these differences may be attributed
to differences in the geographical location.
Previous study reported high prevalence of enteric
bacteria among children living in the areas where
wastewater irrigated vegetables are cultivated compared
with those from an area that did not practice sewage
irrigation (Fattal et al., 1986b). It was also reported that
enteric bacteria are the most frequently isolated bacteria
from vegetables. Spread of cholera case was stopped
when irrigation of vegetables was forbidden by authorities
in Santiago (Weinberger and Keller, 2005).
According to a report of incidence of food-borne diseases
caused by the consumption of vegetables and fruits, it was
found that a contributing factor of such disease incidence
was mostly vegetable consumption, particularly salads
which mainly were fresh vegetables that were touched by
food preparers. The concerned practitioners have to be
very meticulous about sanitation. Microorganisms that
were found to reside in ready-to-eat vegetables and fruits
are Escherichia coli, Listeria monocytogenes spp, Shigella
spp, Salmonella spp (Melloul et al., 2001).
Samuel et al. (2013) also identified the microbial quality of
fresh vegetables at the farm gate of the water works road
vegetable farm at Gumbihini, Tamale Metropolis, Ghana.
The vegetables examined includes lettuce, amarantus and
cabbages. and observed that all vegetables had high
levels of total and faecal coliform bacteria. Lettuce
generally recorded high levels of microbial contamination
because of the large surface area occupied by its leaves
(Singh and Singh, 2004), which is similar to the findings of
this study.
CONCLUSION
It was observed from this study that, almost all the bacteria
identified from the vegetable crops irrigated with domestic
waste water were enteric bacteria, while only few were
isolated from crops irrigated with tube well water. The
Presence of enteric bacteria such as Escherichia coli as
recorded in this study, is of public health concern and as
an indication of faecal contamination, therefore such
vegetables are not safe for consumption unless when
properly or thoroughly washed and cooked. On the other
hand, highest health risk is often associated with any crop
eaten uncooked such as fresh vegetables like: lettuce,
carrots and onions. This brings about the need to assess
the microbial quality of irrigation water and irrigated
vegetables in Nigeria is eminent, in order to propose
alternatives to prevent consumers from disease outbreaks.
ACKNOWLEDGMENT
My profound appreciations go to Tertiary Education Trust
Fund (TETFund) for sponsoring this research work,
without which this could have not been possible. I wish to
use this opportunity to express my gratitude to the
authority of Kebbi State University of Science and
Technology, Aliero for given me this privilege of forwarding
my request to the TETFund. I also want to thank the
reviewers of this article for their objective criticism to this
research work which improves its quality.
REFERENCES
Adeoluwa OO, Cofie O (2012). Urine as an alternative
fertilizer in agriculture: effects in amaranths (Amaranthus
caudatus) production in Nigeria. Renew. Agric. Food
Syst. 27(4):287-294.
AI-Rashed MF, Sherif MM (2000). Water resources in the
GCC Countries: An Overview. Water Resour. Mgt. 14(1):
59-73.
Ahmad B., Bakhsh K., Sarfraz H. (2006). Effect of sewage
water on spinach yield. International J. Of Agric.and
Biology. 2006; 8: 423-425
Angelakis AN (1999). Marecos-do-Monte, M.H.P.;
Bontoux, L; Asano, T. The status of wastewater reuse
practice in the Mediterranean Basin: need for guidelines.
Water Res. 33(10): 2201-2217.
Adesina SA, Adagbada OA, Nwaokorie OF, Niemogha M,
Coker AO (2013). Cholera epidemiology in Nigeria: an
overview. The Pan Afr. Med. J. 12:59.
Blumenthal U, Peasey A., Ruiz-Palacios G, Mara D
(2000). Guidelines for waste water reuse in agriculture
and aquaculture: recommended revisions based on new
research evidence.WEDC, Loughborough University,
UK, Pp:42
Cheesbrough M (1998). District Laboratory Practice in
Tropical Countries Part 2, Cambridge University Press,
Cambridge.
Cowan ST (1974). Identification of Medical Bacteria.
Cowan and steels Manual for the Identification of
Medical Bacteria, Cambridge University Press,
Cambridge
Cruikshank RD, Marmion JP, Swan RA (1973). Medical
Microbiology, Vol. 1 Church hills Livingstone Publishers,
Edinburg.
Edberg SCl (2000). Escherichia coli: the best biological
drinking water indicator for public health protection. J. of
Applied Microbiol. 88: 106S–116S.

5. Studies on the Bacteriological quality of vegetable crops irrigated with domestic wastewater in Aliero, Kebbi State, Nigeria
World J. Microbiol. 104
Fawole OM. and Oso AB (1998). Laboratory Manual of
Microbiology Lagos. Spectrum Books. Pp 77
FAO (2013). Health Risk Associated with Wastewater Use.
Food and Agricultural Organization.
Fattal B, Yekutiel P, Shuval HI (1986). Cholera outbreak in
Jerusalem 1970 revisited: The case for transmission by
wastewater irrigated vegetables. In: J.R. Goldsmith
(ed.) Environmental Epidemiology: Epidemiological
Investigation of Community Environmental Disease, pp.
49-59. CRC Press, Boca Raton.
Girmaye B, Ameha K, Sissay M (2014) Assessment of
bacteriological contaminants of some vegetables
irrigated with Awash River water in selected farms
around Adama town, Ethiopia. J. of Microbiol. and
Antimicrobials. 6(2): 37-42
Halablab MA, Sheet HI and Holail HM (2010).
Microbiological quality of raw vegetables grown in Bekaa
valley, Lebanon. American J. of Food Technol. 6:129-
139.
Johannessen GS, Loncarevic S, Kruse H (2002).
Bacteriological analysis of fresh produce in Norway. Int.
J. Food Microbiol. 77:199-204.
Kaushik P, Garg VK, Singh B (2005) Effect of textile
effluent on different cultivar of wheat. Biores. Technol.
96: 1189-1193.
Klansmewyer P, Fhimumy GN, McCloud TD, Shoemaker
RH (2004). A novel antimicrobial inlizinium alkaloid from
Aniba panurensis. J. of Natural Products. 67: 1732-
1735.
Madoroba E, Moba MNB (2010). Prevalence of Vibrio
choleraein rivers of Mpumalanga province, South Africa
as revealed by polyphasic characterisation. Afr. J. of
Biotechnology. 9(43): 7295-7301.
Melloul AA, Hassani L, Rafouk L (2001). Salmonella
contamination of vegetables irrigated with untreated
wastewater. World Jouranal of Microbiological
Biotechnology. 17:207-209
Oyeleke SB (2000). Observation of Sulphate Reducing
Bacteria Associated with Corrosion of Water Pipelines in
Minna. Journal of Applied Science and Education. 2 (1):
6-10.
Rutkosky T, Raschid-Sally L, Buechler S (2006).
Wastewater Irrigation in the Developing World- Two
Case Studies from the Kathmandu Valley in Nepal. Agric
Water Management. 88:83-91
Samuel JC, Mohammed CK, Joseph KK, Mark OA (2013).
Microbial Contamination in Vegetables at the Farm Gate
due to Irrigation with Wastewater in the Tamale
Metropolis of Northern. Pp.676 -682.
Sou M, Yacouba H and Mermoud A (2011). Fertilising
value and health risks assessment related to waste
water reuse in irrigation, case study in a Soudano-
Sahelian city. Ouagadougou. Journees Scientifiques du.
21E. 6: 4-8.
Tarchitsky J, Golobati Y, Keren R, Chen Y (1999).
Wastewater effect on Montmorillonite suspensions and
hydraulic properties of sandy soils. Soil Sci. Soc. Am. J.
63(3): 554-560.
Weinberger M, Keller N (2005). Recent trends in
epidemiology of non-typhoid Salmonella and
antimicrobial resistance: The Israeli experience and
worldwide review. Current Opinion Infectious Diseases.
18(6):513-521.
Accepted 19 May, 2017.
Citation: Sahabi MS, Zeporah S, Samira AA, Muhammad
KZ, Yusuf BA, Naka KJ. Studies on the Bacteriological
quality of crops irrigated with domestic wastewater in
Aliero, Kebbi State, Nigeria. World Journal of Microbiology,
4(2): 100-104.
Copyright: © 2017 Kalgo et al. This is an open-access
article distributed under the terms of the Creative
Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium,
provided the original author and source are cited.