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Microbial status of irrigation water for vegetables as affected by cultural practices

agronomic aspects

Alam, Mehboob (2014). Microbial status of irrigation water for vegetables as affected by cultural practices. Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2013:97
ISBN 978-91-576-7932-1
eISBN 978-91-576-7933-8
[Doctoral thesis]

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Human pathogens present in irrigation water can be transmitted to plants. Consumption of fruits and vegetables irrigated with pathogen-contaminated water can cause illness in humans. Leafy vegetables that are consumed fresh are particularly prone to cause such illnesses. Understanding the microbiota of irrigation water and its decontamination and introducing some preventative pre-harvest cultural practices can help procure hygienically safe horticultural produce.

Variations were found in water indicator organisms, including heterotrophic plate counts, total coliforms, thermotolerant coliforms, Escherichia coli and faecal enterococci, at five different sampling sites in an irrigation water distribution system (IWDS) on a commercial vegetable-growing farm. 454-pyrosequencing data showed that the IWDS bacterial community was dominated by Bacteriodetes and Proteobacteria, with classes within these phyla, including Flavobacteriia, Sphingobacteriia, α-, β- and γ-Proteobacteria, being found at all five sampling sites. The genera Arcicella, Flavobacterium, Limnohabitans, Sejongia, Fluviicola, Escherichia, Clostridium and Legionella were present at various sites. Indicator organisms and the pathogen Salmonella in the IWDS were significantly reduced by photocatalytic treatment in most cases.

Pre-harvest cultural practices to reduce pathogen load, including cessation of irrigation with contaminated water three days before harvest and decreasing the water regime of the growing medium for leafy vegetables, were assessed. The results showed that an attenuated gfp-tagged E. coli O157:H7 decreased with increasing time to harvest after cessation of irrigation, but were present in the plant phyllosphere three days after cessation, irrespective of dose applied. Similarly, both attenuated gfp-tagged E. coli O157:H7 and an attenuated strain of L. monocytogenes persisted in vegetables grown at a reduced water regime in the growing medium. Total microbiota and Enterobacteriaceae remained unchanged on plants after cessation of irrigation with contaminated water and on plants grown on different water regimes. Use of contaminated irrigation water for leafy vegetable production should thus be avoided. Photocatalytic treatment can be used to decontaminate irrigation water.

Authors/Creators:Alam, Mehboob
Title:Microbial status of irrigation water for vegetables as affected by cultural practices
Subtitle:agronomic aspects
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2014
Number of Pages:67
I.Alsanius, B.W., Alam, M. , Ahlström , C., Sylla, J., Rosberg, A - K., Olsson, C., Mogren, L., Ahrné, S., Molin, G. & Jensén, P. Microbial community structure of the free water phase in a field irrigation system . (provisionally accepted for publication in Science of the Total Environment ).
II.Alam, M. , Ahlström , C., Rosberg, A - K., Mogren, L., Ahrné, S., Molin, G., Jensén, P. & Alsanius, B .W. Impact of photocatalysis on microbial decontamination of irrigation water. (manuscript).
III.Alam, M. , Ahlström , C., Burleigh, S., Olsson, C., Ahrné, S., El - Mo gy, M., Molin, G. , Jensén, P., Hultberg, M. & Alsanius, B. W. ( 2014 ). Prevalence of Escherichia coli O157:H7 on spinach and rocket as affected by inoculum and time to harvest . Scientia Horticulturae 165, 235-241.
IV.Alam, M. , Mogren, L., Ahrné, S., Molin , G., Jensén, P., Boqvist, S., Vågsholm, I. & Alsanius, B .W . Do es grow ing medi um water regime affect Escherichia coli O157:H7 and Listeria monocytogenes occurrenc e on lea fy vegetables ? (manuscript).
Place of Publication:Alnarp
Publisher:Dept. of Biosystems and Technology, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-576-7932-1
ISBN for electronic version:978-91-576-7933-8
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F06 Irrigation
Q Food science > Q03 Food contamination and toxicology
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Agricultural Science
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Horticulture
(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 405 Other Agricultural Sciences > Agricultural Occupational Health and Safety
Agrovoc terms:irrigation water, microbial properties, pathogens, escherichia coli, listeria monocytogenes, leaf vegetables, spinacia oleracea, spinach, eruca sativa, crop management, irrigation, biocatalysts, human diseases, food hygiene
Keywords:decontamination, food safety, human pathogens, irrigation water hygiene, pre-harvest cultural practices, rocket, spinach, Swiss chard
Permanent URL:
ID Code:10986
Faculty:LTJ - Faculty of Landscape Planning, Horticulture and Agricultural Science (until 2013)
Department:(LTJ, LTV) > Department of Biosystems and Technology (from 130101)
External funders:FORMAS
Deposited By: Mr Mehboob Alam
Deposited On:24 Jan 2014 15:10
Metadata Last Modified:13 Dec 2014 23:50

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