Rapid dead-end ultrafiltration concentration and biosensor detection of enterococci from beach waters of Southern California

Abstract

Same-day microbial water quality assessments are not possible with standard methods, which increases the possibility of public exposure to fecal pathogens. This study examined the efficacy of high-volume hollow fibre ultrafiltration coupled to biosensor detection for enterococci in marine waters to allow same-day public notification of poor water quality. Fifty-six 100 l ultrafiltered samples and 100 ml grab samples were collected weekly from May to July 2007.Post-ultrafiltration processing included sonication and micron sieve passage to remove interfering particulates, followed by centrifugation for secondary concentration. Levels of enterococci in grab and ultrafiltration samples were determined by a standard method (EPA method 1600) for calculation of recovery efficiencies and concentration factors. Each final retentate was analysed with the RAPTOR evanescent wave biosensor. Enterococci levels increased over 26,000-fold in final retentates. Enterococci were detected when ambient concentrations exceeded the regulatory standard for a single sample ($105 CFU/100 ml), and detection was highly correlated with breaches of the single-sample regulatory limit. The combined procedure required 2.5 h for detection compared with 24 h for EPA method 1600. This field study achieved rapid detection of enterococci by ultrafiltration, secondary concentration and biosensor analysis, and demonstrates its potential usefulness for water quality monitoring.

Recovery of diverse microbes in high turbidity surface water samples using dead-end ultrafiltration

“…DEUF has been shown in previous studies to effectively recover a diverse range of waterborne microbes from large-volume tap water and marine water samples having relatively low turbidity (Leskinen et al, 2009;Leskinen and Lim, 2008;Smith and Hill, 2009). The present study demonstrated that the DEUF method can also be an effective method for recovering diverse microbes and viruses from large volumes of high turbidity surface water and enabling sensitive detection using molecular testing.…”

Assessment of sources of human pathogens and fecal contamination in a Florida freshwater lake

“…Furthermore, at least two possible reasons exist to explain the lack of correlation between MST marker detection and the detection of pathogens: (1) fewer samples and larger water volumes were analyzed for pathogens than for MST, so the samples were not directly comparable; and (2) with the exception of the enteric viruses, all of the pathogens tested can be shed by animals as well as humans Fayer 2004, Traub et al, 2004, Wolff et al (1948. The MST markers used here were chosen in part because of their demonstrated ability to detect sewage pollution in ambient water volumes of several hundred mL or less McQuaig et al, 2006, Liu et al (2006; however, improved methods for sample filtration and purification, which could allow processing of larger sample volumes for MST assays without inhibiting the PCR, would increase the sensitivity of these assays and would probably result in a higher frequency of co-detection of pathogens and MST markers when the contamination is from a human source Leskinen et al (2009). Conversely, the inclusion of markers for fecal contamination from animals such as birds, dogs, and raccoons, all of which are plentiful in the Lake Carroll watershed, may have resulted in better agreement between marker and pathogen detection; however, these methods were not generally available when the study was performed.…”

Automated Dead-End Ultrafiltration for Concentration and Recovery of Total Coliform Bacteria and Laboratory-Spiked Escherichia coli O157:H7 from 50-Liter Produce Washes To Enhance Detection by an Electrochemiluminescence Immunoassay

“…Kim et al (13) used tangential flow ultrafiltration (filter pore size in the kilodalton range compared with the micrometer range for microfiltration) to concentrate and recover multiple types of microorganisms from 5-liter samples of inoculated lettuce and ham washes. Dead-end ultrafiltration through hollow-fiber filters has been evaluated with environmental water samples as large as 100 liters (12,15,16,22), but this technique has not been assessed for concentration of pathogens from produce wash (PW). An automated concentration system (ACS) based on dead-end ultrafiltration (patent pending) developed in our laboratory was used in this study to concentrate bacteria from PWs.…”