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The length of immunoelectrophoretic separation patterns obtained with a reference mycobacterial antigen was reduced significantly when a continuous buffer system was used in place of the recommended discontinuous system. Varying the supporting medium by using 1% concentrations of different agar preparations in the discontinuous system also affected the separation length and resolution of the reference pattern. Measurement of the electrical resistivity of the agar medium provided an explanation of these differences on the basis of current density or field intensity applied per slide. Variation in the reference pattern obtained in differently designed electrophoresis chambers also was attributed to differences in field intensity. To avoid these obvious alterations in the separation pattern of the reference antigen, it was suggested that separation procedures described originally for the reference system be used without modification.

Rose, Michael J., Jr. (Veterans Administration Hospital, Washington, D.C.), Stephen A. Aron, and Bernard W. Janicki. Effect of various nonionic surfactants on growth of Escherichia coli. J. Bacteriol. 91:1863-1868. 1966.-Escherichia coli cultivated in media containing 0.5, 1.0, 2.0, or 4.0% concentrations of surface-active polyoxyethylene derivatives of formaldehyde polymers of octyl phenol (Triton WR-1339; Macrocyclon) or of sorbitan mono-fatty acid esters (Tween 20, 40, 60, and 80) exhibited significantly retarded growth only at the highest concentration. To determine the mechanism of bacteriostasis, certain derivatives and compounds related to the surfactants were investigated. Experiments with compounds related to the Triton-type agents demonstrated that incorporation of monomeric substances (Triton X-205, X-305, Igepal CA-730, or Dowfax 9N20) into the medium at a concentration of 4.0% did not inhibit the growth of E. coli. It was concluded that the formaldehyde polymer was essential for growth inhibition by the polyoxyethylene derivatives of octyl phenol. The inhibitory activity of the Tween compounds, in contrast, appeared to result from the unesterified fatty acids which contaminate the commercial preparations. Polyol (60), the sorbitan polyoxyethylene derivative of Tween 60 and the basic structural unit of all the Tween-type compounds, and a Tween 80 preparation which was purified by extraction of the unesterified oleic acid, were not inhibitory. Moreover, the amount of free oleic acid present as a contaminant of Tween 80 was found to be sufficient to cause significant growth inhibition. These results and the observation that E. coli does not appear to hydrolyze the esterified fatty acid of Tween 80 led to the conclusion that growth inhibition obtained with various Tween compounds probaby is a function of their respective fatty acid contaminants.

Rose, Michael J., Jr. (Veterans Administration Hospital, Washington, D.C.), Stephen A. Aron, and Bernard W. Janicki. Influence of nonionic surfactants on bacteriophage infections. I. Effect of Triton WR-1339 on T(2) coliphage infection. J. Bacteriol. 87:933-938. 1964.-Plaques formed by T(2) phage on cultures of Escherichia coli strain B from nutrient broth which contained 0.5% Triton WR-1339 were considerably smaller than those formed on cultures from control broth. Pretreatment of phage particles with Triton did not result in small plaques. Results of population studies showed that treated and control cultures had the same growth rates. Similarly, characteristic physiological reactions of treated cultures were the same as those of the controls. Investigation of the phage growth cycle demonstrated that neither the adsorptive phase nor the latent period was affected by cultivation of the host in Triton. However, the burst size of treated cultures was significantly less than that of control cultures. Analysis of the one-step growth curve data showed that Triton did not inhibit bursting of infected cells. It was concluded that the smaller plaque size was a reflection of a reduced yield of mature virulent phage particles from the Triton-treated cultures.