Biomedical subjects

W LITSKY

Publications and source records attributed to W LITSKY.

At least 19 recordsLinked to original sources

PubMed1965

ENRICHMENT PROCEDURE FOR USE WITH THE MEMBRANE FILTER FOR THE ISOLATION AND ENUMERATION OF FECAL STREPTOCOCCI IN WATER.

By the use of PYC enrichment medium, the recovery of fecal streptococci from river water has been increased more than twofold over that of M-Enterococcus Agar. Of the isolates tested, 94.6% could be classified as enterococci or enterococcus biotypes. This method seems to yield a larger number of strains which would not normally be revealed. Serological typing of atypical streptococcus strains isolated indicates that the majority of these "biotypes" can be placed in the enterococcus group.

Agar↗

PubMed1965

THERMAL DESTRUCTION KINETICS OF A LACTIC STREPTOCOCCAL BACTERIOPHAGE.

The aim of the study was to elucidate the kinetics of thermal destruction of a lactic streptococcal bacteriophage, and to determine the effect of varied propagation and heating conditions on its thermoresistance. The propagation medium and temperature affect the degree of thermostability of the phage produced; higher incubation temperature enhances thermostability. The composition and reaction of the heating menstruum are also of significance. Phage thermoresistance increased significantly with the phosphate and whey levels. The effect of various minerals was difficult to resolve, mainly because of the bimodal nature of the survival curve. Thermoresistance was highest at pH 6, intermediate at pH 7, and lowest at pH 8. The kinetics of inactivation of this phage deviated from those of a first-order reaction. Consequently, a special treatment of the data was required in order to compute the various thermodynamic parameters that define the reaction. The high positive values of Q(10), energy of inactivation, and entropy appear to indict protein denaturation as the cause of phage destruction.

Animals↗

PubMed1963

RESTORATION OF AGGLUTININ PRODUCTION AGAINST SHIGELLA PARADYSENTERIAE IN IRRADIATED RATS.

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Agglutinins↗

PubMed1962

Effect of relative humidity on the bactericidal activity of propylene oxide vapor.

Because of the low toxicity of its breakdown product, propylene oxide (PO) vapor will play an increasingly important role in the preservation of foods. It is therefore necessary that the diversified variables which influence effectiveness of PO treatment be thoroughly investigated and understood prior to advocating its general use in industry. Accordingly, the present study was undertaken to determine the effect of relative humidity (RH) upon the bactericidal activity of PO sterilant atmospheres. Death rates were established at increasing RH values of < 1, 52, 65, 80, and 98% and under constant conditions of concentration, pressure, and temperature. Test bacterial populations were preconditioned to corresponding moisture levels. Results indicate that gram-positive cocci were relatively insensitive to PO vapor at dry conditions but became progressively less resistant with the increase in RH up to a maximum of 65 to 70%. Lactic acid bacteria and gram-negative rods were much more sensitive at dry conditions, showing much less dependency upon water vapor. Bacillus subtilis spores elicited the highest degree of resistance but the death rate substantially increased with the increase in RH.

Bacillus subtilis↗

PubMed1961

Studies on thermal destruction of Escherichia coli in milk and milk products.

Escherichia coli (ATCC no. 9637) was shown to have mean D values (slope of destruction rate curve) of 28.2, 5.1, 1.3, 0.00195, 0.00100, 0.00055, 0.00029, and 0.00016 min in milk at temperatures of 125, 130, 135, 168, 170, 172, 174, and 176 F, respectively. The mean D values for this organism in chocolate milk were 32.2, 10.4, 2.6, 0.00265, 0.00133, 0.00069, 0.00035, and 0.00028 min at respective temperatures of 125, 130, 135, 168, 170, 172, 174, and 176 F. Mean D values of 34.4, 10.0, 3.5, 0.00093, 0.00080, 0.00068, 0.00043, and 0.00036 min were found in cream for respective temperatures of 125, 130, 135, 168, 170, 172, 174, and 176 F. In ice cream mix the organism was found to have mean D values of 39.3, 15.2, 5.1, 0.00147, 0.00120, 0.00078, 0.00070, and 0.00053 min for temperatures of 125, 130, 135, 170, 172, 174, 176, and 178 F, respectively. The slopes of the thermal death time curves were found to be 10.2, 10.2, 10.0, and 10.3 F for this organism in milk, chocolate milk, 40% fat cream, and ice cream mix, respectively.

Animals↗

PubMed1961

An evaluation of beta-propiolactone for the sterilization of fermentation media.

Twenty-five bacterial species were cultured in basal broth plus 1 of 19 different carbohydrates which were sterilized by Seitz filtration, autoclaving (112 C, 10 min), or exposure to 0.2% beta-propiolactone (BPL). No significant differences were found either in the visual observations for acid and gas, pH, or titrable acidity determinations after 3 days of incubation with any of the three preparations tested. An effort was made to further determine the effect of BPL and heat on carbohydrates by assaying for glucose before and after treatment. Results indicated that glucose was not degraded by 0.2% BPL, however, it was shown that autoclave temperatures caused extensive degradation. Statistical treatment of the results from Warburg studies indicated that BPL-treated glucose showed no appreciable toxic effects, although the actual oxygen uptake was not as great as with Seitz- or autoclave-treated glucose. The application of the BPL sterilization process was discussed.

Culture Media↗

PubMed1958