Orville Wyss

Enzymatic oxidation of p-nitrophenol

Abstract A Moraxella sp. capable of growth with p-nitrophenol was isolated from activated sludge. Differential centrifugation of crude cell extracts gave a membrane preparation that oxidized p-nitrophenol to hydroquinone and nitrite. Enzymatic activity was dependent on the presence of oxygen and reduced pyridine nucleotides and was stimulated by the addition of flavin adenine dinucleotide. Experiments with 18O2 showed that the incoming hydroxyl group was derived from molecular oxygen. The soluble fraction prepared from crude cell extracts oxidized hydroquinone to a product whose spectral properties were identical to those reported for γ-hydroxymuconic semialdehyde.

Antarctica: The Microbiology of an Unfrozen Saline Pond

A saline pond in a region in Antarctia where other lakes and ponds are frozen remains unfrozen at the prevailing low temperatures. The ecology of the pond is unique. A distinctive aerobic microbial population, though restricted to this natural habitat, adapts to growth in artificial culture. The growth habit of these organisms, as seen in nature and in laboratory culture, indicates a possible relationship between growth at high salt concentration, at low temperatures, and in media of low organic content.

Microbial Inhibition by Food Preservatives

Publisher Summary This chapter discusses the mechanism of the antimicrobial action brought about by chemical substances and possible applications of this knowledge in the food industries. Most in vitro tests of the activity of chemical agents on microbial cells concentrate the attention of the investigator on the limiting cases. The actual measurements made and reported is either in terms of the lowest concentration of a chemical agent required to bring about an effect, or in terms of the shortest time of action required for a certain concentration of the chemical to exhibit its antimicrobial action under stated environmental conditions. By such methods, one presumably studies the inhibition of that one mechanism in the cell most sensitive to the chemical under test. Several cell-destroying mechanisms are exhibited by a single chemical agent and the effectiveness of the chemical is a summation of the several actions.

Regulation of competence development in Bacillus subtilis

Abstract The number of cells in a population of Bacillus subtilis which become ompetent can be either enhanced or reduced by several amino acids which includes arginine, histidine or lysine. Which effect is observed, depends upon the time of addition and the concentration. Inhibitors of protein synthesis block competence development at low concentrations during the early stages but become less effective when cells are committed to competence. These results indicate de novo protein synthesis occurs during competence development and that it is subject to regulation. Monofluoroacetate, which specifically inhibits aconitase activity also blocks competence development during these early stages. Since it prevents sporulation but has no effect on vegetative growth, some relationship between competence and sporulation through the tricarboxylic acid cycle seems to exist.

Derepression of nitrogenase in Azotobacter

Abstract When nitrogenase in Azotobacter vinelandii 12837 is repressed by ammonia, the derepression is accelerated by endotoxin or cyclic AMP. The phenomenon appears neither to be a consequence of accelerated ammonia utilization nor altered activity of preformed enzyme. This is a unique example of an effect of endotoxin on a procaryotic system.

Transformation in Bacilluscereus 569: A correction of strain designation

Abstract Recently Goldberg and Gwinn (1968) reported that the strain designated Bacillus cereus 569 reported by Felkner and Wyss (1964) was in fact Bacillus subtilis . We would like to substantiate the findings of this critique with observations made in our laboratory. First, it should be said that this culture was secured at Fort Detrick and was labelled B. cereus strain 569, Pollock. This strain had at least 2 characteristics which identified it as an atypical B. cereus . Goldschmidt and Felkner (unpublished data) made the observation that this strain was easily disrupted with egg white lysozyme at a concentration of 0.4 mg/ml and/or 2% sodium lauryl sulfate. Since all other B. cereus .strains were insensitive to this treatment, McDonald, et al. (1963) had to use an alternate procedure to obtain DNA. In this report, it was shown that the Tm for B. cereus 569 was 85.45 C (which corresponds to 40.1% guanine + cytosine) whereas the mean value for all other B. cereus strains studied was 82.25 C (which corresponds to 32.2% guanine + cytosine). These values are in excellent agreement with those reported by Goldberg and Gwinn for “ B. cereus ” 569-S r and B. cereus NRRL B-569 ie, 85.5 C and 82.4 C respectively.

Formation of protoplasts in Azotobacter vinelandii

Protoplasts of Azotobacter vinelandii were formed by incubating whole cells in lysozyme and EDTA in Tris-HCl buffer (0.05 M, pH 8.0) supplemented with sucrose (15% w/v). This appeared to be related to the special chelating ability of EDTA and Tris-HCl since substitution of the former by nitrilotriacetic acid or by trisodium citrate and the latter by veronal-acetate buffer or tris-maleate buffer over a pH range of 5.2 to 8.6 yielded only spheroplasts. Of nine strains of Azotobacter studied, only A. vinelandii strain 12837 and strain 0 formed protoplasts.

Capsule degradation in azotobacter

Abstract Enzymic degradation of Azotobacter capsular polysaccharide by the depolymerases from azotophage lysates of A . vinelandii , and from a strain of A . chroococcum was examined. The molecular size of the capsular polysaccharide was examined by molecular sieve chromatography both before and after exposure to the capsule depolymerase. The depolymerase appears to attack the polysaccharide substrate in a random fashion which results in polysaccharide fragments of a random size distribution. The ester linkages and hexuronic acids were proportionally the same in all fractions before degradation, but ester linkages were absent from the smaller polysaccharide molecules after enzyme action. The ester linkages were not the substrate bonds broken by the enzyme, but, in the case of some azotophage enzymes, they appeared to play a role in enzyme activity, possibly as recognition sites.

Fractionation of nucleic acids from dormant and germinated Azotobacter cysts

Abstract Chromatography of nucleic acid extracts of Azotobacter vinelandii cysts and of phased germinated cysts was performed using methylated albumin-kieselguhr(MAK) columns. After 4 hours germination, DNA and ribosomal RNA peaks are seen to elute at higher NaCl concentrations than those of dormant cysts. The elution profile of transfer RNA did not change during cyst germination. Evidence is presented which suggests that shifts in elution profiles are due to changes in nucleic acid configuration during the process of germination. This evidence may indicate an additional mechanism for cyst survival in a deleterious environment.

Gasometric determination of hydrogen peroxide.

Summary Determinations of the peroxide content of irradiated broth using catalase in a Warburg respirometer were found to be inaccurate. In the presence of excess catalase the oxygen evolved approaches a value of twice that indicated by the accepted general equation for enzymatic decomposition of H2O2; if too little enzyme is used the reaction is slow and incomplete. The method is unsatisfactory for the quantitative determination of peroxide.