scholarly journals Microbiological evaluation of constructed wetlands and solar disinfection in wastewater treatment and reuse

2020 ◽  
Vol 18 (6) ◽  
pp. 1146-1153
Author(s):  
Vinícius B. Santos ◽  
Beatriz S. Machado ◽  
Alexandre Atalla ◽  
Priscila S. Cavalheri ◽  
Fernando J. C. Magalhães Filho
Keyword(s):  
Constructed Wetlands ◽  
Limit Of Detection ◽  
Septic Tank ◽  
Salmonella Spp ◽  
Fecal Indicator ◽  
Total Coliforms ◽  
Solar Disinfection ◽  
E Coli ◽  
Significant Difference ◽  
Shigella Spp

Abstract The objective of this study was to evaluate the removal of fecal indicator bacteria and select bacterial pathogens (total coliforms, Escherichia coli, Shigella spp., Salmonella spp. and Pseudomonas aeruginosa) in vertical flow constructed wetlands (VF-CWs) with earthworms and solar disinfection (SODIS) as post-treatment of effluent from a septic tank. There was no significant difference between them in removing bacteria using a VF-CW with earthworms (VF-CW W/E) and without earthworms (VF-CW N/E). Both VF-CWs did not completely remove pathogens; however, with the SODIS technology receiving the effluent from VF-CW W/E, for E. coli, Shigella spp., Salmonella spp. and P. aeruginosa, the values were reduced below the limit of detection and 4.3 log unit average reduction for total coliforms, with 6 h in SODIS.

Bacteroidales as Indicators and Source Trackers of Fecal Contamination in Tomatoes and Strawberries

2018 ◽  
Vol 81 (9) ◽  
pp. 1439-1444 ◽  
Author(s):  
JOSE ANGEL MERINO-MASCORRO ◽  
LINDA G. HERNÁNDEZ-RANGEL ◽  
NORMA HEREDIA ◽  
SANTOS GARCÍA
Keyword(s):  
Limit Of Detection ◽  
Fecal Contamination ◽  
Fecal Indicator ◽  
Detection Range ◽  
Total Coliforms ◽  
E Coli ◽  
Gene Copies ◽  
Standard Procedures ◽  
Specific Sequences ◽  
Better Than

ABSTRACT Most methods that investigate fecal contamination of vegetables do not address the origin of contamination. Because host-specific sequences are conserved in their genomes, bacteria of the order Bacteroidales are regarded as alternative indicators for tracking sources of contamination of produce. The objective of this study was to determine the efficacy of host-specific Bacteroidales markers to identify sources of fecal contamination and to determine whether detection of Bacteroidales markers correlated with traditional fecal indicator bacteria (FIB) in strawberries and tomatoes. Tomato and strawberry samples were artificially contaminated with human and animal feces, which contained 6 to 7 log CFU Bacteroidales per 100 mL and 3 to 6 log CFU/100 mL of the bacterial indicators Escherichia coli, total coliforms, and Enterococcus. FIB were enumerated by standard procedures. Universal and host-specific Bacteroidales markers were detected and quantified by quantitative PCR, and the detection range was 1.35 to 10.35 logarithmic gene copies, which corresponds to a limit of detection of two Bacteroidales cells. Few correlations between levels of Bacteroidales and levels of FIB were observed. For most of the contaminated tomato and strawberry samples, Bacteroidales levels were higher than FIB levels, and detection of FIB was highly variable. Detection of Bacteroidales markers was similar to total coliforms when ≥0.1 mg of feces was inoculated. These indicators were better than E. coli and Enterococcus for detection of fecal contamination in produce. The host-associated Bacteroidales markers were detected at an inoculum of 1 mg of feces per produce item (except those from bovine feces in strawberry). All of the host-associated Bacteroidales markers were detected at an inoculum of 10 mg of feces per produce item. Thus, Bacteroidales markers are promising tools to identify sources of fecal contamination; however, more research is required for their potential use to reduce the risks of contamination of produce.

scholarly journals Microbiological Survey of Wheat Flour Sold at Retail in Canada, 2018-2019

2020 ◽  
Author(s):  
helen zhang ◽  
Etsuko Yamamoto ◽  
Johanna Murphy ◽  
Catherine Carrillo ◽  
Kate Hardie ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Wheat Flour ◽  
Virulence Genes ◽  
Limit Of Detection ◽  
Mitigation Strategies ◽  
Indicator Organisms ◽  
Salmonella Spp ◽  
Total Coliforms ◽  
E Coli ◽  
Two Samples

Following two O121 STEC outbreaks linked to wheat flour, this study was conducted to gain baseline information on the occurrence of bacterial pathogens and levels of indicator organisms in wheat flour in Canada. A total of 347 pre-packaged wheat flour samples were analyzed for Salmonella spp., Shiga Toxin-Producing Escherichia coli (STEC), Listeria monocytogenes ( L. monocytogenes ) , aerobic colony count (ACC), total coliforms, and generic Escherichia coli ( E. coli ) . Salmonella spp. and O157 STEC were not detected in any of the samples. L. monocytogenes was identified in two samples (0.6%) at levels below the limit of detection (<0.7 log CFU/g). Non-O157 STEC were isolated from six samples (1.7%) and were characterized for the presence of STEC virulence genes: stx 1, stx 2 and subtypes, eae , hlyA, and aggR . One O103:H25 STEC isolate carried virulence genes ( stx 1 a + eae ) that are known to be capable of causing diarrhea and/or bloody diarrhea in humans. Of the five remaining non-O157 STEC isolates, four carried single stx 2a or stx 2c genes and were considered to have the potential of causing diarrhea. The remaining non-O157 STEC isolate ( stx 2 ), while not a priority non-O157 STEC was not available for sequencing and thus its potential to cause illness is unknown. ACC, total coliforms, and generic E. coli were detected   in 98.8%, 72.6% and 0.6% of the flour samples. The mean counts of ACC were greater in whole-wheat flour as compared to the other flour types tested ( p <0.001). The results of this study suggest that the occurrence of O157 STEC and Salmonella  is low, but the occurrence of non-O157 STEC in wheat flour with the potential to cause human illness of diarrhea is relatively common. Therefore, the consumption of raw flour could increase the likelihood of STEC infections. Further research is merited for potential risk mitigation strategies within the food production system and with consumers.

scholarly journals Effects of Water Quality and Post-Harvest Handling on Microbiological Contamination of Lettuce at Urban and Peri-Urban Locations of Ouagadougou, Burkina Faso

Foods ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 206 ◽  
Author(s):  
Juliane Dao ◽  
Kathrin Stenchly ◽  
Oumar Traoré ◽  
Philip Amoah ◽  
Andreas Buerkert
Keyword(s):  
Water Quality ◽  
Irrigation Water ◽  
World Health ◽  
Vegetable Production ◽  
Salmonella Spp ◽  
Total Coliforms ◽  
E Coli ◽  
Post Harvest ◽  
Health Organization ◽  
Production Areas

Vegetable production in urban gardens of Ouagadougou contributes to food security, but water for irrigation is often of low quality. This is particularly acute if irrigation water is taken from wastewater polluted channels. This study aimed at (i) verifying to what degree irrigation water quality is correlated with contamination of lettuce with Escherichia coli, total coliforms, and Salmonella spp., and (ii) assessing effects of post-harvest handling on pathogen development during the trade chain. We tested pathogen removal efficiency on lettuce by applying post-harvest washing. Irrigation water of production areas in Ouagadougou (n = 10) showed a mean E. coli load of 2.1 × 105 CFU 100 mL−1. In 60% of the cases, irrigation water did not meet the standards of the World Health Organization (WHO) for safe irrigation water, and in 30% of the cases, irrigation water was contaminated with Salmonella spp. Loads of total coliforms on lettuce leaves ranged from 2.9 × 103 CFU g−1 to 1.3 × 106 CFU g−1, while E. coli averaged 1.1 × 102 CFU g−1. Results on post-harvest handling revealed that microbial loads increased along the trade chain. Overall, half of all lettuce samples (n = 60) were tested positively for Salmonella spp. The experiment showed that appropriate post-harvest handling could prevent the increase of total coliforms.

Microbial Quality, Safety, and Pathogen Detection by Using Quantitative PCR of Raw Salad Vegetables Sold in Dhanbad City, India

2016 ◽  
Vol 80 (1) ◽  
pp. 121-126 ◽  
Author(s):  
SUJEET K. MRITUNJAY ◽  
VIPIN KUMAR
Keyword(s):  
Food Safety ◽  
Quantitative Pcr ◽  
Indian Subcontinent ◽  
Microbiological Quality ◽  
Plate Count ◽  
Salmonella Spp ◽  
Total Coliforms ◽  
E Coli ◽  
Fresh Vegetables ◽  
Salad Vegetables

ABSTRACT Consumption of ready-to-eat fresh vegetables has increased worldwide, with a consequent increase in outbreaks caused by foodborne pathogens. In the Indian subcontinent, raw fresh vegetables are usually consumed without washing or other decontamination procedures, thereby leading to new food safety threats. In this study, the microbiological quality and pathogenic profile of raw salad vegetables was evaluated through standard protocols. In total, 480 samples (60 each of eight different salad vegetables) of cucumber, tomato, carrot, coriander, cabbage, beetroot, radish, and spinach were collected from different locations in Dhanbad, a city famous for its coal fields and often called the “Coal Capital of India.” The samples were analyzed for total plate count, total coliforms, Escherichia coli, E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. Incidences of pathogens were detected through quantitative PCR subsequent to isolation. Results showed that 46.7% (for total plate counts) and 30% (for total coliforms) of samples were unacceptable for consumption per the Food Safety and Standards Authority of India. Pathogenic microorganisms were detected in 3.7% of total samples. E. coli O157:H7 was detected in three samples of spinach (2) and beetroot (1); L. monocytogenes was detected in 14 samples of spinach (8), tomato (3), cucumber (2), and radish (1); and Salmonella spp. were detected in 16 samples of spinach (7), tomato (3), beetroot (2), cucumber (2), carrot (1), and radish (1). Pathogens were not detected in any of the cabbage and coriander samples.

Low Prevalence of Salmonella and Shiga Toxin–Producing Escherichia coli in Lymph Nodes of Australian Beef Cattle

2017 ◽  
Vol 80 (12) ◽  
pp. 2105-2111 ◽  
Author(s):  
Gavin Bailey ◽  
Long Huynh ◽  
Lachlan Govenlock ◽  
David Jordan ◽  
Ian Jenson
Keyword(s):  
Escherichia Coli ◽  
Lymph Nodes ◽  
Shiga Toxin ◽  
Limit Of Detection ◽  
Ground Beef ◽  
Plate Count ◽  
Salmonella Spp ◽  
Live Animal ◽  
E Coli ◽  
Low Prevalence

ABSTRACT Salmonella contamination of ground beef has been viewed as originating from the surface of carcasses. Recent studies have identified lymph nodes as a potential source of Salmonella contamination because these tissues play an active role in containment of pathogens in the live animal and because some lymph nodes are unavoidably present in manufacturing beef trimmings or primal cuts that may be incorporated into ground beef. A survey was conducted of the microbiological status of lymph nodes from Australian cattle at the time of slaughter to determine the prevalence of microbiological contamination. Sets of lymph nodes (n = 197), consisting of the superficial cervical (prescapular), prepectoral, axillary, presternal, popliteal, ischiatic, subiliac (precrural), coxalis, and iliofemoralis (deep inguinal), were collected from five geographically separated Australian abattoirs over a period of 14 months. Samples were tested for the presence of Salmonella spp. and Shiga toxin–producing Escherichia coli by BAX PCR assay. Aerobic plate count, E. coli, and coliforms were enumerated with a lower limit of detection of 80 CFU per node. The observed prevalence of Salmonella within peripheral lymph nodes was 0.48% (7 of 1,464). Two of the seven lymph nodes in which Salmonella organisms were detected came from the same animal. Grass-fed, grain-fed, and cull dairy cattle were all found to have detectable Salmonella in lymph nodes. All Salmonella detections occurred during cooler months of the year. No Shiga toxin–producing E. coli were detected. Aerobic microorganisms were detected above the limit of quantification in 3.2% of nodes (median count 2.24 log per node), and E. coli was detected in 0.8% of nodes (median count 3.05 log per node). The low prevalence of Salmonella and low concentration of aerobic microorganisms in Salmonella-positive lymph nodes of Australian cattle at the time of slaughter suggest that the likelihood of lymph nodes contributing significantly to the presence of Salmonella in ground beef is low.

scholarly journals Multiplex Detection of Salmonella spp., E. coli O157 and L. monocytogenes by qPCR Melt Curve Analysis in Spiked Infant Formula

2020 ◽  
Vol 8 (9) ◽  
pp. 1359
Author(s):  
Sarah Azinheiro ◽  
Joana Carvalho ◽  
Marta Prado ◽  
Alejandro Garrido-Maestu
Keyword(s):  
Food Industry ◽  
High Resolution Melting ◽  
Limit Of Detection ◽  
Food Poisoning ◽  
Relative Sensitivity ◽  
Multiplex Detection ◽  
Salmonella Spp ◽  
Melt Curve Analysis ◽  
E Coli ◽  
Reaction Inhibition

Food poisoning continue to be a threat in the food industry showing a need to improve the detection of the pathogen responsible for the hospitalization cases and death. DNA-based techniques represent a real advantage and allow the detection of several targets at the same time, reducing cost and time of analysis. The development of new methodology using SYBR Green qPCR for the detection of L. monocytogenes, Salmonella spp. and E. coli O157 simultaneously was developed and a non-competitive internal amplification control (NC-IAC) was implemented to detect reaction inhibition. The formulation and supplementation of the enrichment medium was also optimized to allow the growth of all pathogens. The limit of detection (LoD) 95% obtained was <1 CFU/25 g for E. coli O157, and 2 CFU/25 g for Salmonella spp. and L. monocytogenes and regarding the multiplex detection a LoD 95% of 1.7 CFU/25 g was observed. The specificity, relative sensitivity and accuracy of full methodology were 100% and the use of the NC-IAC allowed the reliability of the results without interfering with the sensitivity of the methodology. The described study proved to obtain results comparable to those of probe-based qPCR, and more economically than classical high resolution melting qPCR, being both important aspects for its implementation in the food industry.

scholarly journals Performance of three pilot-scale hybrid constructed wetlands for total coliforms and Escherichia coli removal from primary effluent – a 2-year study in a subtropical climate

2014 ◽  
Vol 13 (2) ◽  
pp. 446-458 ◽  
Author(s):  
Florentina Zurita ◽  
Alejandra Carreón-Álvarez
Keyword(s):  
Escherichia Coli ◽  
Constructed Wetlands ◽  
Pilot Scale ◽  
World Health ◽  
First Year ◽  
Subtropical Climate ◽  
Total Coliforms ◽  
E Coli ◽  
Stage System ◽  
Health Organization

Three pilot-scale two-stage hybrid constructed wetlands were evaluated in order to compare their efficiency for total coliforms (TCol) and Escherichia coli removal and to analyze their performances in two 1-year periods of experimentation. System I consisted of a horizontal flow (HF) constructed wetland (CW) followed by a stabilization pond. System II was also configured with a HF CW as a first stage which was then followed by a vertical flow (VF) CW as a second stage. System III was configured with a VF CW followed by a HF CW. In the first year of evaluation, the HF–VF system was the most effective for TCol removal (p &lt; 0.05) and achieved a reduction of 2.2 log units. With regard to E. coli removal, the HF–VF and VF–HF systems were the most effective (p &lt; 0.05) with average reductions of 3.2 and 3.8 log units, respectively. In the second year, the most effective were those with a VF component for both TCol and E. coli which underwent average reductions of 2.34–2.44 and 3.44–3.74 log units, respectively. The reduction achieved in E. coli densities, in both years, satisfy the World Health Organization guidelines that require a 3–4 log unit pathogen reduction in wastewater treatment systems.

Susceptibility for antibiotics among faecal indicators and pathogenic bacteria in sewage treated effluents

2013 ◽  
Vol 8 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Adel A. S. AL-Gheethi ◽  
Norli Ismail ◽  
J. Lalung ◽  
Azieda Talib ◽  
A. N. Efaq ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
High Resistance ◽  
Pathogenic Bacteria ◽  
Sewage Treatment ◽  
Salmonella Spp ◽  
Sewage Treatment Plants ◽  
Total Coliforms ◽  
E Coli ◽  
Treated Effluents ◽  
Faecal Indicators

The objective of this work was to study the prevalence of antibiotic resistance phenotypes among total coliforms (TC), E. coli, E. faecalis and Salmonella spp. in the sewage treated effluents generated from three sewage treatment plants in Penang Malaysia. Among the isolates tested, TC and E. coli occurred high resistance for cephalexin (100 and 90.47%), ampicillin (80.93 and 95.23%) and ciprofloxacin (19.06 and 14.3%) compared to E. faecalis (42.86, 71.4 and 4.7%) and Salmonella spp. (59.8, 47.46 and 14.3%) respectively. All E. coli strains, 76.18% of TC, 66.66% of E. faecalis and 35% of Salmonella spp. were multi-resistant.

Study of constructed wetlands effluent disinfected with ozone

2014 ◽  
Vol 70 (1) ◽  
pp. 108-113 ◽  
Author(s):  
N. D. Miranda ◽  
E. L. Oliveira ◽  
G. H. R. Silva
Keyword(s):  
Constructed Wetlands ◽  
World Health ◽  
Constant Flow ◽  
Total Coliforms ◽  
E Coli ◽  
Complete Inactivation ◽  
Batch System ◽  
Health Organization ◽  
Almost All ◽  
Concentration Levels

The purpose of this research was to study the disinfection of sanitary effluent from constructed wetlands, evaluating the oxidation of organic matter, the formation of formaldehyde, as well as the efficiency of total coliforms and Escherichia coli inactivation. A constant flow of ozone was applied to the batch system in 5 and 10 mg.O3 L−1 doses with contact times of 5 and 10 min. This study revealed that the average values of formaldehyde formation ranged between 259.00 and 379.00 μg L−1, which means that the values are within World Health Organization recommended values. The total coliforms and E. coli showed complete inactivation in almost all tests. The dose of ozone 5 mg.O3 L−1 and contact time of 5 min were sufficient for a significant reduction of the concentration levels of pathogens in constructed wetlands effluent with similar characteristics, thus allowing for its agricultural reuse.

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