, N.Y.), AND A. W. PHILLIPS. Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick. J. Bacteriol. 91:1736-1743. 1966.-The effects of intestinal bacteria on the multiplication, morphogenesis, and infectivity of Candida albicans in the alimentary tract were investigated by comparing results obtained in germ-free and conventional chicks after oral inoculation. This challenge resulted in the establishment of large numbers of the pathogen in the alimentary tract of each group of chicks; these numbers were increased in crop contents from challenged bacteria-free chicks wherein hyphae predominated over the yeast form. These animals also had lesions of the crop epithelium containing numerous hyphae and few yeastlike forms. In contrast, challenged conventional chicks receiving an adequate diet displayed no evidence of infection. Their alimentary tract contained the yeast form of C. albicans; no hyphae were seen. Although we found bacterial inhibition of C. albicans multiplication in the alimentary tract, this in itself did not seem to explain the resistance to intestinal candidiasis in our conventional chicks. We argued that this resistance to infection was due chiefly to the prevention of hyphal development in C. albicans by intestinal bacteria. C. albicans in the gut of our conventional chicks resulted in some increase in numbers of enterococci in contents from the crop. Increased pH values in contents from the gut of germ-free chicks were not clearly related to infection after challenge. The Eh of the above crop contents were only slightly decreased in the germ-free crop. Thus the Eh did not appear to be involved in susceptibility to infection. Invasion of the blood stream and kidneys of conventional chicks by the yeast form of C. albicans occurred in challenged animals receiving a purified diet which had been radiation-sterilized and stored for 6 months at room temperature (25 C). Their growth rate decreased and they became moribund; no hyphae were observed in tissues or intestine of these animals. Challenged bacteria-free chicks receiving the same diet were resistant to the above invasion, although they had crop lesions containing hyphae as described. The resistance of these chicks to systemic invasion was attributed to absence of intestinal bacteria competing for low levels of vitamins in the stored diet. Germ-free chicks had decreased levels of serum-y-globulin which increased after challenge, whereas this value was unchanged in conventional birds after challenge. The occurrence of Candida albicans as a tract (and other sites) in man and other animals commensal or as a pathogen in the alimentary was reported by many workers (31). Others 'Taken in part from a thesis submitted by the suggested that certain members of the intestinal senior author in partial fulfillment of the require-flora may hinder infection of a host by C. albicans. ments for the Ph.D. degree, Syracuse University, For example, chicks and turkey poults were Syracuse, N.Y. resistant to...

The purification and properties of a tumor inhibitory L-asparaginase from SeOratia marcescens are described. The following properties of the enzyme were examined: kinetics of the enzyme reaction, catalytic activity as a function of pH, boundary sedimentation velocity, electrophoresis on polyacrylamide gel, immunoelectrophoresis against homologous and heterologous antisera, immunodiffusion, blood clearance rate in mice, and inhibition of the 6C3HED lymphoma in C3H mice. Complete regression of this tumor was obtained with a smaller dose of the enzyme from S. marcescens than with enzyme from Escherichia coli. The reason for this difference was not evident from a comparison of several properties of the two enzymes.Eazyme assays. Routine L-asparaginase assays were conducted by a modified method based on that of Meister et al. (20). Portions (1 to 100 Mliters) of enzyme solution were added to 0.05 M tris(hydroxmethyl)aminomethane (Tris)-hydrochloride buffer (pH 7.4) to give a final volume of 1.5 ml. The reaction was initiated by the addition of 0.5 ml of 0.04 M L-asparagine in the same buffer and conducted at 37 C in a reciprocal water bath shaker. The reaction was stopped by the addition of 0.1 ml of 1.5 M trichloroacetic acid. If necessary, the mixture was centrifuged to remove precipitated proteins. Ammonia released in the reaction was determined by the addition of Nessler's reagent to the diluted supernatant fluid and, after 15 min, observing the absorbancy at 500 nm. Our studies on enzyme kinetics utilized a reduced nicotinamide adenine dinucleotide (NADH)-dependent coupled assay for ammonia producing systems (15). NADH and ammonia are required in equimolar amounts for the synthesis of glutamate from a-ketoglutarate by glutamic dehydrogenase. The rate of ammonia production from L-asparaginase may be calculated from the rate of NADH oxidation 578 on July 31, 2020 by guest http://jb.asm.org/ Downloaded from on July 31, 2020 by guest

, N.Y.), AND A. W. PHILLIPS. Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis. J. Bacteriol. 91:1744-1749. 1966.-Bacterial protection against intestinal infection by Candida albicans was investigated in chicks with a monoflora of either Escherichia coli or Streptococcus faecalis. These animals were obtained by orally inoculating germ-free chicks (3 days old) with pure cultures of bacteria. Each bacterial species was established in large numbers in the gut of separate groups of animals within 24 hr of inoculation; these numbers were similar in chicks examined 34 days later, at which time all animals were killed. The numbers of bacteria from contents of the crop, small intestine, and ceca were similar in chicks with the E. coli monoflora. Comparable results were obtained in chicks with the S. faecalis monoflora, except for decreased numbers in the duodenum and jejunum. Some of the monoflora chicks (7 days old) were transferred into separate isolators, orally inoculated with C. albicans, and observed for 34 days. All chicks grew well and appeared healthy. However, examinations at autopsy revealed severe crop infections in chicks with a diflora containing S. faecalis. Preferential growth of hyphae (C. albicans) occurred in the lesions and throughout the gut. The numbers of S. faecalis in the gut were comparable to those found in unchallenged animals. Agglutinins against C. albicans were not detected in our test or control chicks. Chicks with a difloracontaining E. coliand C. albicanshadafewmicroscopic crop lesions containing small numbers of hyphae. C. albicans was well established in the gut of these animals, largely as the yeast form. The numbers of E. coli in the gut were similar to those in control chicks. Thus, it was concluded that E. coli provided protection against crop infection by C. albicans. In crop contents from unchallenged animals, chicks with S. faecalis monoflora were about pH 5, whereas birds with E. coli monoflora were about pH 7. The challenge did not greatly change the former value, and the latter was slightly decreased. In the crop of unchallenged birds, negative Eh values were found in chicks with S. faecalis and positive Eh values in those with E. coli. Challenge did not greatly change these values. These data on pH and Eh were related to conditions for morphogenesis of C. albicans and virulence. No major difference in the concentrations of serum proteins was seen in chicks with E. coli or S. faecalis after challenge with C. albicans. Possible mechanisms of the protective effect of E. coli are discussed. ITakeninpartfroma thesisubmittoccur, several studies suggest that a prerequisite is iTknm part from athesis submitted by the covrin fthyesfrm nohpae r senior author in partial fulfillment of the requirements conversion of the yeast form into hyphae or for the Ph.D. degree, Syracuse University, Syracuse, mycelia with blastospores [reviewed by Winner N.Y. and Hurley (23)]. The susceptibility of the ...

The cellular morphology of a biochemical variant of Candida albicans could be controlled by the ratio of carbon dioxide to oxygen in the culture system or by individual amino acids. Predominantly pseudohyphal morphology was observed (i) at a CO2 to 02 ratio of 2:1 and (ii) without the addition of carbon dioxide, when either glycine, Dor L-ornithine, L-serine, L-methionine, L-phenylalanine, or L-tyrosine was the sole nitrogen source in the culture medium. When ammonium chloride, ammonium sulfate, L-glutamic acid, L-glutamine, or L-proline was the nitrogen source, yeastlike growth was observed in the presence or absence of CO2. More adenosylmethionine was present in pseudohyphal than in yeastlike cells, and pseudohyphal cell wall preparations contained less methionine than cell walls from the yeastlike form. These results suggest a correlation between sulfur amino acid metabolism and dimorphism.

Candida albicans and six other medically important Candida species were cultured on glucose–salts–biotin media containing tryptophan as the major nitrogen source. Candida albicans, C. tropicalis, and C. parapsilosis produced a pink pigment; C. krusei, C. pseudotropicalis, and C. gulliermondii formed brown pigments. Pigmentation of C. stellatoidea was variable, some strains produced brown pigments and others a pink pigment. Production of pink pigment was catalyzed by light. Cultures incubated in the dark produced only trace amounts of the pink pigment. Iron enhanced pigment production. Intense autofluorescence was observed for strains producing the brown pigment and weak autofluorescence for strains producing the pink pigment.