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The survival of seven F+RNA phages (MS2 Group I ATCC type strain, two Group I environmental isolates, a Group II environmental isolate, a Group III environmental isolate, and two Group IV environmental isolates) and six F+DNA phages (M13, fd, f1, and ZJ/2 ATCC type strains, and two environmental isolates) were examined in microcosms using a surface drinking water source. Phages were spiked into replicate aliquots of a source water at about 20,000 pfu/ml. Replicate spikes were incubated at 4 and 20 degrees C and monitored for 110 days. At 4 degrees C, Groups I and II F+ RNA phages were detectable through 110 days, with reductions of about 1 and 3 log10, respectively. The Group III F+RNA phage demonstrated 5 log10 reduction after 3 weeks, and the Group IV F+RNA phages were reduced to detection limits (5 log10 reduction) within 10 days. Of the F+DNA phages, all four type strains were detectable with about 2.5 log10 reduction after 110 days at 4 degrees C. The F+DNA environmental isolates were detectable with about a 4 log10 reduction after 110 days at 4 degrees C. All phages demonstrated faster decay at 20 degrees C. These results suggest that differences in F+ phage survival may influence their prevalence in environmental waters and the ability to attribute their prevalence to specific human and animal sources of faecal contamination.
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Four methods for the concentration of human enteroviruses in the waters of the river Furan were surveyed: the original method described by WALLIS, of adsorption of viruses on PE-60 polyelectrolyte; a modified version of the Wallis method; a method using a different polyelectrolyte available in France, the POE; the two-phase system described by SHUVAL. The best results were obtained when using the method of adsorption on polyelectrolytes, and the second method was finally chosen for field surveys.
It has been found out that a coli-phage is a more reliable indirect indicator of viral pollution of drinking water that the existing indirect bacterial indicators. Coli-phages concentration in drinking water on the level of single PFU/1 is evidence of disturbances in the barrier function of water-treatment facilities with respect to viral microflora and of the possible epidemic danger of water with respect to viral infection. The absence of coli-phages in I 1 of water sample should be considered the standard level of coli-phages of drinking water.
Mutant strains of Escherichia coli that lack one or all of the intact components of mannose permease do not support the growth of phage N4. Complementation experiments using three recombinant plasmids containing DNA fragments coding for the subunits of mannose permease revealed that among the three component subunits, II-PMan and II-MMan alone are sufficient to confer N4 sensitivity.
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Two DNA fragments of cytochrome b gene in yeast mitochondrial DNA were sequenced by Messing's M13 cloning system and Sanger's ddXTP chain-termination method. M13mp8 and M13mp9 serve as vectors for insert fragment. The recipient strain is E. coli JM103 for transfection. When the ratio of insert/vector was 3:1, high frequencies of recombination and positive recombination were obtained. The two fragments, which have 575 bp and 709 bp, were sequenced. To read more bases, the ratio of ddXTP/dXTP must be reduced. On one X-ray film of 80 x 17 cm 394 bp were read.
The study on the rate of initiation of model gene cat transcription under the control of E. coli (Plac UV5, Ptrp, Pcat, Ptac), phage lambda (PL, PR), phi X174 (PD) promotors was carried out by means of hybridization of pulse labelled in vivo mRNA with the DNA coding parts. The presence of gene bla(Apr) with its own constitutive promoter in all the recombinants permitted to use the level of appropriate mRNA in the cell as an internal standard. This method allowed to evaluate the true efficiency of the promoters in question. The strength of the promoters studied is shown to be equal within the limit of one order value.
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Seasonal data for raw sewage indicated a higher concentration of bacteriophages in the warmer months compared with the cooler months. Regardless of the amount of phages in the raw sewage and the time of year the efficiency of removal was as high as 83-96% for effluent II and 93-98% for sludge II. Four major types of plaque sizes were identified as Q1, Q2, Q3 and Q4. Although all isolates contained DNA, they showed variation in host range and heat sensitivity from 50 degrees C to 80 degrees C.
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