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At least 919 records · Page 51Linked to original sources
PubMed2005

Comparison of bacteriophage and enteric virus removal in pilot scale activated sludge plants.

AIMS: The aim of this experimental study was to determine comparatively the removal of two types of bacteriophages, a somatic coliphage and an F-specific RNA phage and of three types of enteric viruses, hepatitis A virus (HAV), poliovirus and rotavirus during sewage treatment by activated sludge using laboratory pilot plants. METHODS AND RESULTS: The cultivable simian rotavirus SA11, the HAV HM 175/18f cytopathic strain and poliovirus were quantified by cell culture. The bacteriophages were quantified by plaque formation on the host bacterium in agar medium. In each experiment, two pilots simulating full-scale activated sludge plants were inoculated with viruses at known concentrations, and mixed liquor and effluent samples were analysed regularly. In the mixed liquor, liquid and solid fractions were analysed separately. The viral behaviour in both the liquid and solid phases was similar between pilots of each experiment. Viral concentrations decreased rapidly following viral injection in the pilots. Ten minutes after the injections, viral concentrations in the liquid phase had decreased from 1.0 +/- 0.4 log to 2.2 +/- 0.3 log. Poliovirus and HAV were predominantly adsorbed on the solid matters of the mixed liquor while rotavirus was not detectable in the solid phase. In our model, the estimated mean log viral reductions after 3-day experiment were 9.2 +/- 0.4 for rotavirus, 6.6 +/- 2.4 for poliovirus, 5.9 +/- 3.5 for HAV, 3.2 +/- 1.2 for MS2 and 2.3 +/- 0.5 for PhiX174. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates that the pilots are useful models to assess the removal of infectious enteric viruses and bacteriophages by activated sludge treatment. Our results show the efficacy of the activated sludge treatment on the five viruses and suggest that coliphages could be an acceptable indicator of viral removal in this treatment system.

Coliphages↗
PubMed2005

A national study on the residential impact of biological aerosols from the land application of biosolids.

AIMS: The purpose of this study was to evaluate the community risk of infection from bioaerosols to residents living near biosolids land application sites. METHODS AND RESULTS: Approximately 350 aerosol samples from 10 sites located throughout the USA were collected via the use of six SKC Biosamplers. Downwind aerosol samples from biosolids loading, unloading, land application and background operations were collected from all sites. All samples were analysed for the presence of HPC bacteria, total coliform bacteria, Escherichia coli, Clostridium perfringens, coliphage, enteroviruses, hepatitis A virus and norovirus. Total coliforms, E. coli, C. perfringens and coliphage were not detected with great frequency from any sites, however, biosolids loading operations resulted in the largest concentrations of these aerosolized microbial indicators. Microbial risk analyses were conducted on loading and land application operations and their subsequent residential exposures determined. CONCLUSIONS: The greatest annual risks of infection occurred during loading operations, and resulted in a 4 x 10(-4) chance of infection from inhalation of coxsackievirus A21. Land application of biosolids resulted in risks that were <2 x 10(-4) from inhalation of coxsackievirus A21. Overall bioaerosol exposure from biosolids operations poses little community risk based on this study. SIGNIFICANCE AND IMPACT OF THE STUDY: This study evaluated the overall incidence of aerosolized micro-organisms from the land application of biosolids and subsequently determined that microbial risks of infection were low for residents close to biosolids application sites.

Aerosols↗
PubMed2005

Removal of micro-organisms in a small-scale hydroponics wastewater treatment system.

AIMS: To measure the microbial removal capacity of a small-scale hydroponics wastewater treatment plant. METHODS AND RESULTS: Paired samples were taken from untreated, partly-treated and treated wastewater and analysed for faecal microbial indicators, i.e. coliforms, Escherichia coli, enterococci, Clostridium perfringens spores and somatic coliphages, by culture based methods. Escherichia coli was never detected in effluent water after >5.8-log removal. Enterococci, coliforms, spores and coliphages were removed by 4.5, 4.1, 2.3 and 2.5 log respectively. Most of the removal (60-87%) took place in the latter part of the system because of settling, normal inactivation (retention time 12.7 d) and sand filtration. Time-dependent log-linear removal was shown for spores (k = -0.17 log d(-1), r(2) = 0.99). CONCLUSIONS: Hydroponics wastewater treatment removed micro-organisms satisfactorily. SIGNIFICANCE AND IMPACT OF THE STUDY: Investigations on the microbial removal capacity of hydroponics have only been performed for bacterial indicators. In this study it has been shown that virus and (oo)cyst process indicators were removed and that hydroponics can be an alternative to conventional wastewater treatment.

Clostridium perfringens↗
PubMed1984

Comparison of microporous filters for concentration of viruses from wastewater.

The 1-MDS Virosorb filter and the 50S and 30S Zeta-plus filters, all with a net positive charge, were compared with the negatively charged Filterite filter for concentration of naturally occurring coliphages and animal viruses from sewage effluent. When Filterite filters were used, the effluent was adjusted to pH 3.5 and AlCl3 was added before filtration to facilitate virus adsorption. No adjustment was required with the positively charged filters. Sets of each filter type were eluted with 3% beef extract (pH 9.5) or eluted with 0.05 M glycine (pH 11.5). A maximum volume of 19 liters could be passed through 142-mm diameter Filterite filters before clogging, whereas only 11, 11, and 15 liters could be passed through the 1-MDS, 50S, and 30S filters, respectively. For equal volumes passed through the filters, coliphage recoveries were 14, 15, 18, and 37% in primary effluent and 40, 97, 50, and 46% in secondary effluent for the Filterite , 1-MDS, 50S, and 30S filters, respectively. No statistically significant difference was observed in the recovery of animal viruses among the filters from secondary effluent, whereas in the Filterite and 50S filters, higher numbers of viruses from primary effluent were recovered than in the 1-MDS and 30S filters in two of three collections. Glycine was found to be a less-efficient eluent than beef extract in the recovery of naturally occurring viruses.

Animals↗
PubMed1994

Effect of gamma irradiation on shelf life and bacterial and viral loads in hard-shelled clams (Mercenaria mercenaria).

The feasibility of using 60Co gamma irradiation to inactivate total coliforms, fecal coliforms, Escherichia coli, Clostridium perfringens, and F-coliphage in hard-shelled clams, Mercenaria mercenaria, was investigated. The results of three trials indicated average D10 values of 1.32 kGy for total coliforms, 1.39 kGy for fecal coliforms, 1.54 kGy for E. coli, 2.71 kGy for C. perfringens, and 13.50 kGy for F-coliphage. Irradiation doses of > 0.5 kGy were significantly lethal to the shellfish.

Animals↗
PubMed2000

Selective accumulation may account for shellfish-associated viral illness.

From 1991 through 1998, 1,266 cases of shellfish-related illnesses were attributed to Norwalk-like viruses. Seventy-eight percent of these illnesses occurred following consumption of oysters harvested from the Gulf Coast during the months of November through January. This study investigated the ability of eastern oysters (Crassostrea virginica) to accumulate indicator microorganisms (i.e., fecal coliforms, Escherichia coli, Clostridium perfringens, and F(+) coliphage) from estuarine water. One-week trials over a 1-year period were used to determine if these indicator organisms could provide insight into the seasonal occurrence of these gastrointestinal illnesses. The results demonstrate that oysters preferentially accumulated F(+) coliphage, an enteric viral surrogate, to their greatest levels from late November through January, with a concentration factor of up to 99-fold. However, similar increases in accumulation of the other indicator microorganisms were not observed. These findings suggest that the seasonal occurrence of shellfish-related illnesses by enteric viruses is, in part, the result of seasonal physiological changes undergone by the oysters that affect their ability to accumulate viral particles from estuarine waters.

Animals↗
PubMed2003

Molecular surveillance of enterovirus and norwalk-like virus in oysters relocated to a municipal-sewage-impacted gulf estuary.

An 18-month survey was conducted to examine the prevalence of enteric viruses and their relationship to indicators in environmentally polluted shellfish. Groups of oysters, one group per 4 weeks, were relocated to a coastal water area in the Gulf of Mexico that is impacted by municipal sewage and were analyzed for enteroviruses, Norwalk-like viruses (NLV), and indicator microorganisms (fecal coliform, Escherichia coli, and male-specific coliphages). The levels of indicator microorganisms were consistent with the expected continuous pollution of the area. Fourteen of the 18 oyster samples were found by reverse transcription (RT)-PCR to harbor NLV and/or enterovirus sequences. Of the four virus-negative oysters, three had exposure to water temperatures of >29 degrees C. Concomitant with these findings, two of these four oysters also accumulated the lowest levels of coliphages. PCR primers targeting pan-enteroviruses and the NLV 95/96-US common subset were utilized; NLV sequences were detected more frequently than those of enteroviruses. Within the 12-month sampling period, NLV and enterovirus sequences were detected in 58 and 42%, respectively, of the oysters (67% of the oysters tested were positive for at least one virus) from a prohibited shellfish-growing area approximately 30 m away from a sewage discharge site. Eight (4.6%) of the 175 NLV capsid nucleotide sequences were heterogeneous among the clones derived from naturally polluted oysters. Overall, enteric viral sequences were found in the contaminated oysters throughout all seasons except hot summer, with a higher prevalence of NLV than enterovirus. Although a high percentage of the oysters harbored enteric viruses, the virus levels were usually less than or equal to 2 logs of RT-PCR-detectable units per gram of oyster meat.

Animals↗
PubMed2005

Validity of the indicator organism paradigm for pathogen reduction in reclaimed water and public health protection.

The validity of using indicator organisms (total and fecal coliforms, enterococci, Clostridium perfringens, and F-specific coliphages) to predict the presence or absence of pathogens (infectious enteric viruses, Cryptosporidium, and Giardia) was tested at six wastewater reclamation facilities. Multiple samplings conducted at each facility over a 1-year period. Larger sample volumes for indicators (0.2 to 0.4 liters) and pathogens (30 to 100 liters) resulted in more sensitive detection limits than are typical of routine monitoring. Microorganisms were detected in disinfected effluent samples at the following frequencies: total coliforms, 63%; fecal coliforms, 27%; enterococci, 27%; C. perfringens, 61%; F-specific coliphages, approximately 40%; and enteric viruses, 31%. Cryptosporidium oocysts and Giardia cysts were detected in 70% and 80%, respectively, of reclaimed water samples. Viable Cryptosporidium, based on cell culture infectivity assays, was detected in 20% of the reclaimed water samples. No strong correlation was found for any indicator-pathogen combination. When data for all indicators were tested using discriminant analysis, the presence/absence patterns for Giardia cysts, Cryptosporidium oocysts, infectious Cryptosporidium, and infectious enteric viruses were predicted for over 71% of disinfected effluents. The failure of measurements of single indicator organism to correlate with pathogens suggests that public health is not adequately protected by simple monitoring schemes based on detection of a single indicator, particularly at the detection limits routinely employed. Monitoring a suite of indicator organisms in reclaimed effluent is more likely to be predictive of the presence of certain pathogens, and a need for additional pathogen monitoring in reclaimed water in order to protect public health is suggested by this study.

Animals↗
PubMed1969

Effect of prehumidification on sampling of selected airborne viruses.

Studies were undertaken to determine if a prewetting device (humidifier bulb) used in combination with an all glass impinger (AGI-30) would increase the recovery of airborne mengovirus-37A, vesicular stomatitis virus (VSV), and the S-13 coliphage. Suspensions of T3 coliphage with mengovirus-37A, VSV, or S-13 were aerosolized and collected by using the AGI-30-humidifier bulb combination to sample the aerosols before and after shifts in relative humidities (RH). These studies revealed the following. (i) At low RH values there was a 3 to 4 log increase in recovery of airborne T3 phage; (ii) concomitantly, the recovery of mengovirus-37A and VSV decreased; and (iii) only at the mid-range RH values was the recovery of S-13 enhanced. The prehumidification technique significantly increased the recovery of airborne T3 phage but decreased the recovery of the two animal viruses tested.

Aerosols↗
PubMed1972

Uptake of bacteriophage and their subsequent survival in edible West Coast crabs after processing.

Edible West Coast crabs (Cancer magister and Cancer antennarius), when in seawater contaminated with coliphage T4, were found to accumulate high titers of this virus. To study the extent of the hazard presented by crabs contaminated with virus, samples of edible crabs were contaminated with coliphage T4 and then processed by boiling. Results indicated that virus in crabs withstood this method of processing. The survival rate varied from 2.5 to 20%, depending upon the processing time. Heat penetration studies showed that, although internal temperature in the crabs was sufficient to inactivate virus, the processing times normally used to cook crabs were not. These results suggest that processed crabs could serve as vectors for the dissemination of virus diseases if the crabs are harvested from a polluted area.

Animals↗
PubMed1966

Bacteriophage infecting the myxobacterium Chondrococcus columnaris.

Kingsbury, David T. (University of Washington, Seattle), and Erling J. Ordal. Bacteriophage infecting the myxobacterium Chondrococcus columnaris. J. Bacteriol. 91:1327-1332. 1966.-During a series of screening experiments, seven bacteriophages which infect the pathogenic myxobacterium Chondrococcus columnaris were isolated. Of these, one was chosen for detailed study. This phage has a wide host range among strains of C. columnaris, but does not infect other myxobacterial species tested. Morphologically, this phage resembles coliphage T2, though it is smaller. It has a head diameter of 600 A, a tail length of 1,000 A, and a tail width of 200 A. The head is attached to the tail by a well-defined neck. The turbid plaques produced by this phage are similar in appearance to those produced by coliphage lambda, and average 1 mm in diameter. The phage has a latent period of 100 min, a rise period of an additional 90 min, and a burst size of 23. Calcium ions at a concentration of 0.004 m are required for adsorption. This requirement cannot be met by substitution of magnesium ions. A purified preparation of 2 x 10(12) phage particles was extracted with phenol, and the nucleic acid was identified as deoxyribonucleic acid (DNA). Base ratios of the phage DNA and the DNA of two propagating strains were similar. Streptomycin at a concentration of 70 mug/ml inhibits phage infection at an early stage, probably by inhibiting injection of the phage DNA.

Adsorption↗
PubMed1973

Characteristics and purification of PRR1, an RNA phage specific for the broad host range Pseudomonas R1822 drug resistance plasmid.

A new drug resistance plasmid-dependent RNA containing phage resembling coliphage f2 in its particle size and density is described. The phage, PRR1, will only productively infect some R(+) hosts containing the Pseudomonas drug resistance plasmid R1822. The membrane filter-salt elution patterns, RNase sensitivity, inactivation in low ionic strength solutions, and host range serve to distinguish PRR1 from coliphage f2 and two other Pseudomonas RNA phages, 7s and PP7.

Bacteriophages↗
PubMed1972

Comparisons of the distribution of nucleotides and common sequences in deoxyribonucleic acid from selected bacteriophages.

Results from comparisons of deoxyribonucleic acid (DNA) from several classes of bacteriophages suggest that most phage chromosomes contain either a homogeneous distribution of nucleotides or are made up of a few, rather large segments of different quanine plus cytosine (G + C) contents which are internally homogeneous. Among those temperate phages tested, most contained segmented DNA. Comparisons of sequence similarities among segments from lambdoid phage DNA species revealed the following order in relatedness to lambda: 82 (and 434) > 21 > 424 > phi80. Most common sequences are found in the highest G + C segments, which in lambda contain head and tail genes. Hybridization tests with lambda and 186 or P2 DNA species verified that the lambdoids and 186 and P2 belong to two distinct groups. There are fewer homologous sequences between the DNA species of coliphages lambda and P2 or 186 than there are between the DNA species of coliphage lambda and salmonella phage P22.

Base Sequence↗
PubMed1989

Use of a bacteriophage-encoded glycanase enzyme in the generation of lipopolysaccharide O side chain deficient mutants of Escherichia coli O9:K30 and Klebsiella O1:K20: role of O and K antigens in resistance to complement-mediated serum killing.

Coliphage K30 lysates contain free and phage-associated forms of a bacteriophage-encoded capsule depolymerase (glycanase) enzyme, active against the serotype K30 capsular polysaccharide of Escherichia coli. The free glycanase has been purified to apparent homogeneity. The molecular weight of the enzyme was estimated at 450,000, and when heated in SDS at 100 degrees C, the enzyme dissociated into two subunits of 90,000 and 52,000. The glycanase enzyme was used as a reagent to reversibly degrade the capsular layers on cells of Escherichia coli O9:K30 and Klebsiella O1:K20. This treatment rendered these bacteria sensitive to their respective lipopolysaccharide-specific bacteriophages, coliphage O9-1 and Klebsiella phage O1-3. This novel approach facilitated isolation of lipopolysaccharide O antigen side chain deficient mutants which retained the ability to synthesize the capsule. The response of defined mutants, O+:K-, O-:K+, and O-:K-, to exposure to nonimmune rabbit serum was measured. Results showed that the primary barrier against complement-mediated serum killing in both Escherichia coli O9:K30 and Klebsiella O1:K20 was the O antigen side chains of the lipopolysaccharide molecules. In both strains, the capsule played no role in the determination of serum resistance.

Antigens, Bacterial↗
PubMed1999

Fate of Cryptosporidium oocysts, Giardia cysts, and microbial indicators during wastewater treatment and anaerobic sludge digestion.

The extent of reduction in selected microorganisms was tested during both aerobic wastewater treatment and anaerobic digestion of sludge at the wastewater treatment plant in Ottawa to compare the removal of two encysted pathogenic protozoa with that of microbial indicators. Samples collected included the raw wastewater, the primary effluent, the treated wastewater, the mixed sludge, the decanted liquor, and the cake. All of the raw sewage samples were positive for Cryptosporidium oocysts and Giardia cysts, as well as for the other microorganisms tested. During aerobic wastewater treatment (excluding the anaerobic sludge digestion), Cryptosporidium and Giardia were reduced by 2.96 log10 and 1.40 log10, respectively. Clostridium perfringens spores, Clostridium perfringens total counts, somatic coliphages, and heterotrophic bacteria were reduced by approximately 0.89 log10, 0.96 log10, 1.58 log10, and 2.02 log10, respectively. All of the other microorganisms were reduced by at least 3.53 log10. Sludge samples from the plant were found to contain variable densities of microorganisms. Variability in microbial concentrations was sometimes great between samples, stressing the importance of collecting a large number of samples over a long period of time. In all cases, the bacterial concentrations in the cake (dewatered biosolids) samples were high even if reductions in numbers were observed with some bacteria. During anaerobic sludge digestion, no statistically significant reduction was observed for Clostridium perfringens, Enterococcus sp., Cryptosporidium oocysts, and Giardia cysts. A 1-2 log10 reduction was observed with fecal coliforms and heterotrophic bacteria. However, the method utilized to detect the protozoan parasites does not differentiate between viable and nonviable organisms. On the other hand, total coliforms and somatic coliphages were reduced by 0.35 log10 and 0.09 log10, respectively. These results demonstrate the relative persistence of the protozoa in sewage sludge during wastewater treatment.

Animals↗
PubMed2002

Sunlight inactivation of human enteric viruses and fecal bacteria.

Three human enteric viruses (poliovirus, echovirus, coxsackievirus) suspended in seawater or buffer were stable for 6 hr in the absence of sunlight but were inactivated at the same rate in the presence of sunlight. Under summer sunlight conditions, at least 3 logs of these viruses were inactivated by one-hit kinetics while under winter sunlight conditions only 1 log of these viruses was inactivated by two-hit kinetics. Under these same conditions, 6 logs of E. coli were inactivated within 1 hr by one-hit kinetics under summer and winter conditions. In comparison, E. faecalis was inactivated by two-hit kinetics and only 2.5 logs of inactivation were observed after 4 hr of exposure to winter sunlight. Since human enteric viruses are considerably more resistant to sunlight inactivation than E. coli and moderately more resistant than E. faecalis, marine recreational water quality standards should be based on concentrations of enterococci and not on coliform bacteria. Since the mechanism and rate of inactivation of coliphage and human enteric viruses are similar, coliphages appear to be the best indicator for the presence of human enteric viruses in recreational waters, especially coastal waters where abundant sunshine is available.

Coliphages↗
PubMed1992

[Bacteriologic and virologic hygienic studies on waste water ponds].

Many problems arise with the overflow of wastewater after heavy rainfalls. Therefore a research project was started to investigate the possibilities of biological treatment for such sporadically occurring sewage. In this paper a helophyte bed is compared with a simple wastewater pond regarding virological and bacteriological hygiene parameters. The number of coliphages is an evident indicator for enteroviruses and its enumeration can be done easily and safely. It is suggested that the kind of sewage treatment described here is not suitable for municipal wastewater but for domestic sewage in the countryside. Furthermore the quantification of coliphages should become a constant part of routine hygiene examination.

Bacteria↗