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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #340287
Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Assessment of microbial quality of reclaimed water, roof-harvest water, and creek water for irrigation

Author
item YIN, HSIN-BAI - University Of Maryland
item Green, Jennifer
item Patel, Jitu

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/7/2017
Publication Date: 4/26/2017
Citation: Yin, H., Green, J.A., Patel, J.R. 2017. Assessment of microbial quality of reclaimed water, roof-harvest water, and creek water for irrigation. BARC Poster Day. p.67. April 26, 2017.

Interpretive Summary:

Technical Abstract: The availability of water for crop irrigation is decreasing due to droughts, population growth, and pollution. The Food Safety and Modernization Act (FSMA) standards for irrigation water may also discourage growers to use poor microbial quality water for produce crop irrigation. Reclaimed water use for irrigation is restricted on fresh produce. Individual households also collect rainwater for watering vegetable garden. We evaluated microbial quality of alternative water including reclaimed water (RCW), roof-harvest rainwater (RHW), and creek water (CW) to ascertain if it meets FSMA microbial quality criteria. In this study, the microbial quality of alternative water was assessed by monitoring the populations of Escherichia coli, enterococci, total coliforms, fecal coliforms, Bacteroides spp., Clostridium perfringens, and pathogens (Salmonella, Listeria monocytogenes, and E. coli O157:H7). Water samples were analyzed by two detection methods including membrane filter technique and an innovative concentrator analysis. Briefly, 100 ml of each water sample was filtered with 0.45 µm-pore-size filter or concentrated to ~250 µl using the concentrator and were directly enumerated on specific agars. Bacterial counts were recorded after incubation and expressed in log CFU/100 ml in both methods. In total, 25 samples of alternative water were analyzed including 7 RCW, 9 RHW, and 9 CW. Escherichia coli populations from all RHW and CW samples were below the FSMA criteria (2.1 log CFU/100ml). Fecal coliforms of RCW, RHW, and CW analyzed by the membrane filter and the concentrator were 3.51 and 2.82, 0.95 and 0.52, and 1.81 and 1.17 log CFU/100ml, respectively. No significant difference between two detection methods was observed when enumerating total coliforms and enterococci. Of the 25 samples, 6 RCW were Bacteroides positive and 7 RCW, 6 RHW, and 7 CW were C. perfringens positive. In addition, the membrane filter method detected 3 RCW Salmonella positive as well as 1 RHW and 3 CW Listeria monocytogenes positive that were confirmed by the Real Time quantitative PCR (RT-qPCR). Results suggest that RHW and CW can be used for irrigation purpose based on their microbial quality; however, remediation of RCW is required prior to use for irrigation of fresh produce.