80%
to 51%. Similarly, the exposure of C. parvum oocysts to 5 mg
NH3 l−1 and 50 mg NH3 l−1
for 4 days reduced their viability from between 
80%
to 41·5% and 14·8%, respectively.
Volume 104 Issue 4 Page 1112-1118, April 2008
H. Kodaka, S. Mizuochi, M. Saito, H. Matsuoka (2008) Evaluation
of a new medium for the enumeration of total coliforms and Escherichia
coli in Japanese surface waters
Journal of Applied Microbiology 104 (4) , 1112–1118 doi:10.1111/j.1365-2672.2007.03627.x
Aim: A new medium, EC-Blue-10, containing chromogenic and fluorogenic substrates, KNO3 and sodium pyruvate has been developed for the rapid simultaneous detection and enumeration of total coliforms and Escherichia coli in water.
Methods and Results: Two evaluations of EC-Blue-10 were carried out. Firstly, EC-Blue-10 was compared with Colilert-MPN for 96 water samples using MPN for total coliforms and E. coli. Secondly, the detection of coliforms and E. coli were compared using 2400 tubes of EC-Blue-10 and Colilert-MPN. The regression coefficients between EC-Blue-10 and Colilert-MPN for total coliforms and E. coli were 0·91 and 0·89, respectively. For the detection results, the Cohen’s kappa values between the two media were 0·79 for coliforms and 0·72 for E. coli.
Conclusions: EC-Blue-10 is almost same as Colilert-MPN for the detection of coliforms and E. coli in surface waters. Further evaluation for EC-Blue-10 is needed to verify in different geographical areas.
Significance and Impact of the Study: EC-Blue-10 is
useful method for the rapid and simultaneous detection of total coliforms
and E. coli in water sample.
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Evaluation of RT-PCR and reverse line blot hybridization
for detection and genotyping F+ RNA coliphages from estuarine waters and
molluscan shellfish
D.C. Love, J. Vinjé, S.M. Khalil, J. Murphy, G.L. Lovelace,
M.D. Sobsey (2008) Evaluation of RT-PCR and reverse line blot hybridization
for detection and genotyping F+ RNA coliphages from estuarine waters and
molluscan shellfish
Journal of Applied Microbiology 104 (4) , 1203–1212 doi:10.1111/j.1365-2672.2007.03646.x
Aims: To evaluate a PCR-based detection and typing method for faecal indicator viruses (F+ RNA coliphages) in water and shellfish, and apply the method for better understanding of the ecology and microbial source tracking potential of these viruses.
Methods and Results: Water and shellfish samples were collected over 3 years at nine estuaries in the East, West and Gulf Coasts of the USA, providing 1033 F+ RNA coliphage isolates. F+ RNA coliphage genotyping rates by reverse transcriptase-PCR – reverse line blot (RLB) hybridization ranged from 94·7% to 100% among estuaries, and were not significantly different in oysters, clams, mussels or water (P = 0·8427). Twenty samples negative by RLB were nucleotide sequenced for confirmation, and to refine RLB probes. More F+ RNA coliphages were genotyped from colder water than warmer waters, while the water salinity did not affect F+ RNA coliphage levels.
Conclusions: RT-PCR–RLB was a robust method for detecting and genotyping F+ RNA coliphages from diverse coastal areas, which provided new information on the ecology of F+ RNA coliphages.
Significance and Impact of the Study: This performance-validated F+ RNA coliphage method can be used for faecal indicator monitoring and microbial source tracking, to protect recreational bathers and shellfish consumers from exposure to pathogenic virus and their disease risks.
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Effect of various environmental factors on the viability
of Cryptosporidium parvum oocysts
R. Reinoso, E. Becares, H.V. Smith (2008) Effect of various
environmental factors on the viability of Cryptosporidium parvum
oocysts
Journal of Applied Microbiology 104 (4) , 980–986 doi:10.1111/j.1365-2672.2007.03620.x
Aims: To evaluate individual and combined effects of temperature (4, 18 and 25°C), pH (7 and 10), ammonia (5 and 50 mg l−1) and exposure time (1, 2, 4 and 6 days) on the viability of Cryptosporidium parvum oocysts in water.
Methods and Results: The viability of oocysts was
evaluated using the fluorogenic vital dyes assay (4',6-diamidino-2-phenylindole
and propidium iodide). All the factors analysed (temperature, pH, ammonia
and exposure time) and their interaction were statistically significant
(P < 0·005). Exposure of oocysts to pH 10 for 6 days
at 25°C reduced oocyst viability from 80%
to 51%. Similarly, the exposure of C. parvum oocysts to 5 mg
NH3 l−1 and 50 mg NH3 l−1
for 4 days reduced their viability from between 80%
to 41·5% and 14·8%, respectively.
Conclusions: The interaction between pH, temperature and exposure time may have adverse effects on the survival of C. parvum oocysts in water. Low concentrations of ammonia, as commonly found in alga-based wastewater systems, over a long period of time can produce high C. parvum oocyst inactivation rates.
Significance and Impact of the Study: This study provides relevant data on the inactivation of C. parvum oocysts in alga-based wastewater-treatment systems in the northwest of Spain.
Murulee Byappanahalli, Ph. D.
Research Microbiologist
U.S. Geological Survey, Great Lakes Science Center
Lake Michigan Ecological Research Station,
1100 N. Mineral Springs Road
Porter, Indiana 46304
Phone: (219) 926-8336 ext. 421
Fax: (219) 929-5792
E-mail: byappan@usgs.gov