Suitability of different Escherichia coli enumeration techniques to assess the microbial quality of different irrigation water sources

2016 ◽  
Vol 58 ◽  
pp. 29-35 ◽  
Author(s):  
P. Truchado ◽  
F. Lopez-Galvez ◽  
M.I. Gil ◽  
F. Pedrero-Salcedo ◽  
J.J. Alarcón ◽  
...  
Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1708
Author(s):  
Matthew Stocker ◽  
Dong Jeon ◽  
Ekaterina Sokolova ◽  
Hoonsoo Lee ◽  
Moon Kim ◽  
...  

Evaluating the microbial quality of irrigation water is essential for the prevention of foodborne illnesses. Generic Escherichia coli (E. coli) is used as an indicator organism to estimate the microbial quality of irrigation water. Monitoring E. coli concentrations in irrigation water sources is commonly performed using water samples taken from a single depth. Vertical gradients of E. coli concentrations are typically not measured or are ignored; however, E. coli concentrations in water bodies can be expected to have horizontal and vertical gradients. The objective of this work was to research 3D distributions of E. coli concentrations in an irrigation pond in Maryland and to estimate the dynamics of E. coli concentrations at the water intake during the irrigation event using hydrodynamic modeling in silico. The study pond is about 22 m wide and 200 m long, with an average depth of 1.5 m. Three transects sampled at 50-cm depth intervals, along with intensive nearshore sampling, were used to develop the initial concentration distribution for the application of the environmental fluid dynamic code (EFDC) model. An eight-hour irrigation event was simulated using on-site data on the wind speed and direction. Substantial vertical and horizontal variations in E. coli concentrations translated into temporally varying concentrations at the intake. Additional simulations showed that the E. coli concentrations at the intake reflect the 3D distribution of E. coli in the limited pond section close to the intake. The 3D sampling revealed E. coli concentration hot spots at different depths across the pond. Measured and simulated 3D E. coli concentrations provide improved insights into the expected microbial water quality of irrigation water compared with 1D or 2D representations of the spatial variability of the indicator concentration.


Author(s):  
Željka Rudić ◽  
Igor Kljujev ◽  
Bojana Vujović ◽  
Mile Božić ◽  
Vera Raičević

1994 ◽  
Vol 57 (5) ◽  
pp. 431-435 ◽  
Author(s):  
MOHAMMED I. YAMANI ◽  
BASIM A. AL-DABABSEH

Sixty samples of fresh hoummos (chickpea dip) from 15 restaurants were examined in winter and summer to find out numbers and types of microorganisms present. Five reference samples, produced by the investigators under hygienic conditions, were examined for comparison. The microbial load of commercial hoummos was high, and spherical lactic acid bacteria (LAB) belonging to Lactococcus, Enterococcus and Leuconostoc were the predominant microorganisms. The means of the aerobic plate count (APC) and the counts of LAB and coliforms (1.9 × 108, 1.6 × 108 and 2.9 × 105/g, respectively) in summer samples were significantly higher (p < 0.05) than the averages of the same counts in winter samples (2.7 × 107, 1.6 × 107 and 2.2 × 103/g). The average summer and winter yeast counts were 4.2 × 104 and 1.5 × 104g, respectively. In reference samples of hoummos, APC and LAB counts were < 103/g, while the coliform and yeast counts were < 10/g and 102/g, respectively, indicating lack of hygienic practices during the production of commercial hoummos. Salmonella was not detected in any sample, and Escherichia coli and Staphylococcus aureus counts of all samples were < 10/g. The relatively low pH of hoummos (the average pH of all samples was 5.1) and the rapid growth of LAB, possibly accompanied by production of inhibitory substances, may explain the predominance of these bacteria, and could have contributed to the absence of the pathogens examined.


2009 ◽  
Vol 106 (2) ◽  
pp. 442-454 ◽  
Author(s):  
B. Fremaux ◽  
T. Boa ◽  
A. Chaykowski ◽  
S. Kasichayanula ◽  
J. Gritzfeld ◽  
...  

2013 ◽  
Vol 76 (6) ◽  
pp. 959-966 ◽  
Author(s):  
GAYEON WON ◽  
PAMELA J. SCHLEGEL ◽  
JENNIFER M. SCHROCK ◽  
JEFFREY T. LeJEUNE

Irrigation water is considered a potential source of preharvest pathogen contamination of vegetables. Hence, several organizations have recommended microbiological standards for water used to irrigate edible plants. The purpose of this study was to determine the strength of association between microbial quality indicators (coliforms and Escherichia coli) in irrigation water and on irrigated vegetables. Data analyzed included original results from a cross-sectional study conducted in the Midwestern United States during summer 2009 and information presented in two previously published studies performed in France and Portugal to investigate microbial quality of irrigation water and watered produce. In the cross-sectional study, repetitive PCR (rep-PCR) was used to characterize genetic relatedness of E. coli isolates from water and vegetables. No significant correlations were found between fecal indicators on leafy greens (lettuce and parsley, n = 91) or fruit (tomatoes and green peppers, n = 22) and those found in irrigation water used in the cross-sectional study (P > 0.40) or in the previously published data sets (data set 1: lettuce and waste irrigation water, n = 15, P > 0.40; data set 2: lettuce and irrigation water, n = 32, P = 0.06). Rep-PCR banding patterns of E. coli strains were all distinguishable among the pairs of E. coli isolates recovered from produce and irrigation water on the same farm. From the available data, the concentration of indicator organisms based on a single measure of irrigation water quality was not associated with the presence of these indicators on produce. In the absence of additional information, the use of a single microbial water quality parameter as an indicator of produce safety is of limited value for predicting the safety of the produce.


2014 ◽  
Vol 12 (2) ◽  
pp. 231-236
Author(s):  
R Khaton ◽  
MA Hasnat ◽  
S Rahman ◽  
MM Rahman

The aim of the present study was to determine the microbial quality of freshly drawn cow’s milk belonging to the arsenic affected and non-affected areas. In the present work 25 milk sample were collected from five different arsenic affected and non-affected areas. The analysis comprised enumeration of total viable count (TVC), total coliform count (TCC) and total staphylococcal count (TSC) for the determination of sanitary quality. The highest total viable count, total coliform count and total staphylococcus count were log 5.894 ± 0.221, log 2.832± 0.129 and log 2.898 ± 0.162 respectively. Staphylococcus spp, Escherichia coli, Pseudomonas spp and Bacillus spp were isolated from the milk samples. Among them Escherichia coli were isolated from the maximum milk samples. It is found that the level of microbial quality in terms of TVC, TCC and TSC were high in arsenic affected areas than arsenic non-affected area. It also found that TVC and TCC were positively correlated with each other. This survey indicates that most of the raw milk samples were not satisfactory in course of public health standard as some pathogenic bacteria were detected from these samples and it is necessary to improve the hygienic practices required for the handling and processing of milk.DOI: http://dx.doi.org/10.3329/bjvm.v12i2.21297 Bangl. J. Vet. Med. (2014). 12 (2): 231-236 


2020 ◽  
Vol 86 (20) ◽  
Author(s):  
Sultana Solaiman ◽  
Sarah M. Allard ◽  
Mary Theresa Callahan ◽  
Chengsheng Jiang ◽  
Eric Handy ◽  
...  

ABSTRACT As climate change continues to stress freshwater resources, we have a pressing need to identify alternative (nontraditional) sources of microbially safe water for irrigation of fresh produce. This study is part of the center CONSERVE, which aims to facilitate the adoption of adequate agricultural water sources. A 26-month longitudinal study was conducted at 11 sites to assess the prevalence of bacteria indicating water quality, fecal contamination, and crop contamination risk (Escherichia coli, total coliforms [TC], Enterococcus, and Aeromonas). Sites included nontidal freshwater rivers/creeks (NF), a tidal brackish river (TB), irrigation ponds (PW), and reclaimed water sites (RW). Water samples were filtered for bacterial quantification. E. coli, TC, enterococci (∼86%, 98%, and 90% positive, respectively; n = 333), and Aeromonas (∼98% positive; n = 133) were widespread in water samples tested. Highest E. coli counts were in rivers, TC counts in TB, and enterococci in rivers and ponds (P < 0.001 in all cases) compared to other water types. Aeromonas counts were consistent across sites. Seasonal dynamics were detected in NF and PW samples only. E. coli counts were higher in the vegetable crop-growing (May-October) than nongrowing (November-April) season in all water types (P < 0.05). Only one RW and both PW sites met the U.S. Food Safety Modernization Act water standards. However, implementation of recommended mitigation measures of allowing time for microbial die-off between irrigation and harvest would bring all other sites into compliance within 2 days. This study provides comprehensive microbial data on alternative irrigation water and serves as an important resource for food safety planning and policy setting. IMPORTANCE Increasing demands for fresh fruit and vegetables, a variable climate affecting agricultural water availability, and microbial food safety goals are pressing the need to identify new, safe, alternative sources of irrigation water. Our study generated microbial data collected over a 2-year period from potential sources of irrigation (rivers, ponds, and reclaimed water sites). Pond water was found to comply with Food Safety Modernization Act (FSMA) microbial standards for irrigation of fruit and vegetables. Bacterial counts in reclaimed water, a resource that is not universally allowed on fresh produce in the United States, generally met microbial standards or needed minimal mitigation. We detected the most seasonality and the highest microbial loads in river water, which emerged as the water type that would require the most mitigation to be compliant with established FSMA standards. This data set represents one of the most comprehensive, longitudinal analyses of alternative irrigation water sources in the United States.


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