Serum proteins of gnotobiotic rats

Cellulose-acetate and agar gel immunoelectrophoresis were used to study the serum protein patterns of germfree rats before and after monoassociation with a pure culture of Staphylococcus aureus (phage type 80/81), Streptococcus faecalis, Lactobacillus acidophilus, Bacteroides fragilis, Pseudomonas aeruginosa, or Proteus vulgaris. All six bacteria quickly established themselves in the gastrointestinal tract of the germfree rat, and all six increased the animals' total serum proteins. Only S. aureus and P. aeruginosa caused a noticeable rise in gamma globulins. L. acidophilus, S. faecalis, and B. fragilis multiplied readily in the gastrointestinal tract but caused only minimal alterations in the serum proteins. P. vulgaris caused a marked increase in the alpha and beta, but not the gamma globulins.

Closed-loop intestinal obstruction in Candida albicans monocontaminated rats

Closed-loop intestinal obstruction, with and without hemorrhagic or ischemic strangulation, was studied in germ-free rats individually contaminated with one of three strains of Candida albicans. The principal findings were (a) C. albicans monocontamination of the unoperated germ-free rat was innocuous; (b) contamination of the segment, alone, was as lethal as contamination and strangulation; (c) monocontamination of the closed segments, with and without strangulation, with either strain NIH 792 or ATCC 10261 killed over 30% of the animals although ATCC 10259 had no obvious effect; and (d) ATCC 10261 was associated with late postoperative intestinal bleeding and death. Ancillary findings in a group of C. albicans monocontaminated, but unoperated, germ-free rats were (a) there were rather uniform concentrations of viable C. albicans throughout the gastrointestinal tract; and (b) the serum proteins of these animals showed increased levels of total protein, alpha-2, and beta, but not gamma globulins, in comparison to germ-free rats.

Germ-tube production by Candida albicans in minimal liquid culture media

Candida albicans formed germ tubes within 3 h at 37C in a glucose–salts–biotin (GSB) medium containing L-alpha-amino-n-butyric acid as the nitrogen source. Optimal germ-tube production was obtained when the inoculum was grown on Sabouraud dextrose agar. The GSB medium containing L-alpha-amino-n-butyric acid promoted germ-tube formation more effectively than GSB medium plus gamma-amino-butyric acid or Sabouraud dextrose broth.Carbon-14 incorporation studies revealed that during germ-tube formation (0–4 h) the 3 carbon of alpha-amino-n-butyric acid was incorporated intracellularly to a greater extent than the 1 carbon. However, during blastospore formation (5–16 h), this difference was less pronounced.When six other Candida species were grown in GSB plus L-alpha-amino-n-butyric acid medium, few germ tubes were observed with the exception of one Candida stellatoidea strain. However, even this strain of C. stellatoidea produced far fewer germ tubes in this minimal culture medium than any strain of C. albicans tested.

Methionine biosynthesis in Candida albicans. I. S-adenosyl-L-methionine (or S-methyl-L-methionine): homocysteine methyltransferase in cell-free extracts from yeast-like cells

Six isolates of C. albicans were tested for their capacities to form methionine via S-adenosyl-L-methionine (or S-methyl-L-methionine): homocysteine methyltransferase (EC. 2.1.1.e). Cell-free extracts from all organisms were obtained from cultures containing predominantly (greater than 85%) yeast-like cells. Assay conditions with respect to pH, time of incubation, substrate, and protein concentrations for the methyltransferase reaction were determined.Extracts from all six strains formed methionine when either L-homocysteine, L-homocysteine thiolactone, or L-homocystine was used as the methyl acceptor, and more methionine was synthesized when S-methyl-L-methionine was the methyl donor than when S-adenosyl-L-methionine was used. The methyltransferase reaction was inhibited by methionine, L-methionine-ethyl-ester, and DL-N-hydroxy-methyl-methionine. Substantially less inhibition was observed with L-ethionine and S-methyl-L-cysteine, while no inhibition occurred when six other methionine analogs were tested.

Intestinal Strangulation in Clostridium perfringens -Monocontaminated Rats

Ischemic and hemorrhagic strangulation of closed intestinal segments was studied in germ-free rats individually contaminated with one of seven separate strains of Clostridium perfringens type A. The principal findings were that (i) the monocontaminated rats with ischemic or hemorrhagic intestinal strangulation died at the same rapid rate; (ii) intraintestinal blood did not augment the action of C. perfringens in the presence of ischemic strangulation; (iii) although some strains were more toxic than others, several food-poisoning strains were as rapidly fatal as the classical strains; and (iv) the massive amounts of gas produced by some of these strains probably led to the early rupture of the closed segments and rapid death of the animals. The secondary findings were that (i) the injection of C. perfringens into the lumen of the distal small intestine of the germ-free rat produced the typical lesions of pneumatosis cystoides intestinalis; and (ii) most of the strains of C. perfringens established themselves throughout the gastrointestinal tract of the unoperated germ-free rat.

Morphology, Physiology, and Virulence of Some Mutants of Candida albicans

Five mutagens were used to induce mutants of Candida albicans. Ultraviolet light, N -nitroso- N ′-methyl- N -nitrosoguanidine, and N -nitroso- N -methylurethane were effective mutagens which induced stable auxotrophs. N -nitroso- N -methylurethane produced the largest number and variety of mutants. Nitrous acid and hydroxylamine were ineffective as mutagens although they killed C. albicans. All mutagenic agents employed induced colonial variants, especially small colony forms. The morphology, physiology, and virulence of one methionine and two adenine auxotrophs was compared to that of the prototroph. The auxotrophs exhibited yeast-like morphology in complex media and had sugar fermentation patterns typical of C. albicans , and all were agglutinated by C. albicans antiserum. Chlamydospore production was absent in the nonpigmented adenine mutant, and the chlamydospores produced by the methionine auxotroph were distorted. Germ tubes were formed in human serum by the auxotrophs and prototroph. Virulence for mice was retained by all auxotrophs but generally at a reduced level. The methionine auxotroph, only slightly less virulent than the prototroph, was more virulent than a pigmented adenine mutant and a practically avirulent nonpigmented adenine auxotroph.

Unusual Sphaerophorus species from the large intestine of man

An obligately anaerobic, gram-negative microorganism identified as a Sphaerophorus species was recovered from the fecal material of two cancer (chronic myelogenous leukemia and idiopathic thrombocythemia) patients receiving cobalt radiation therapy. The organism, isolated on sheep blood-agar, exhibited extreme pleomorphism (rods, filaments, and spheroids) and was a major component of the anaerobic fecal microflora. In one patient the numbers of Sphaerophorus species (designated as isolate 6-13-68), Bacteroides species, and Clostridium perfringens declined after irradiation; however, they were stable in this same patient after a second therapeutic dose of radiation. The numbers of anaerobes in the other patient remained fairly consistent after radiation. The biochemical and morphological characteristics and carbohydrate fermentation reactions of isolate 6-13-68 most closely resembled those of Sphaerophorus ridiculosis.

Control of dimorphism in a biochemical variant of Candida albicans

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 CO(2) to O(2) ratio of 2:1 and (ii) without the addition of carbon dioxide, when either glycine, d- or 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 CO(2). 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.

Modifications in a French pressure cell-laboratory press system

Two removable steel plates, a shortened valve handle, lengthened outlet nozzle, and an added test tube holder facilitate use of a cell disruption system.

Ultraviolet microscopy of purines and amino acids in the vacuole of Candida albicans

Ultraviolet (UV) microscopy was used to study the capacity of yeast (ATCC 10231 and 10261) and filamentous (ATCC 10259) strains of Candida albicans to accumulate UV-absorbing materials from a medium supplemented with purines, pyrimidines, amino acids, or related compounds as the main nitrogen source. All strains accumulated UV-absorbing compounds when adenine, adenosine, isoguanine, xanthine, or uric acid was supplied as a nitrogen source, but they did not accumulate UV-absorbing compounds when pyrimidines were supplied. The filamentous strain accumulated UV-absorbing material from medium supplemented with hypoxanthine, but the yeast strains did not. In contrast, the yeast strains accumulated more UV-absorbing material than did the filamentous strain when guanine was the nitrogen source. Yeast strain 10231 not only accumulated UV-absorbing material from tyrosine-supplemented medium, but it became filamentous in form as well. Yeast strain 10261 and filamentous strain 10259 did not accumulate detectable amounts of UV-absorbing material, nor was their morphology noticeably affected by the supplement. The two yeast strains accumulated more lipid than the filamentous strain when they were incubated in a nitrogen-deficient medium.

Ultraviolet microscopy of Candida albicans

Balish, Edward (Argonne National Laboratory, Argonne, Ill.), and George Svihla. Ultraviolet microscopy of Candida albicans. J. Bacteriol. 92:1812-1820. 1966.-Yeast and mycelial strains of Candida albicans were grown in medium supplemented with sulfur amino acids in an effort to determine factors that control the morphology and pathogenicity of the organism. Ultraviolet microscopy revealed a greater concentration of S-adenosylmethionine in the vacuoles of the mycelial phase than in those of yeast phases. Supplementation with amino acids greatly increased the concentration of S-adenosylmethionine in the mycelial phase, and made these cells more sensitive to the lytic action of snail gut enzymes than two yeast phase strains. This indicates a difference in cell wall structure that may be related to the pathogenicity of the mycelial phase.

Cystathionine as a precursor of methionine in Escherichia coli and Aerobacter aerogenes

Balish, Edward (Argonne National Laboratory, Argonne, Ill.), and Stanley K. Shapiro. Cystathionine as a precursor of methionine in Escherichai coli and Aerobacter aerogenes. J. Bacteriol. 92:1331-1336. 1966.-Cystathionine has been shown to be a precursor of methionine biosynthesis in Escherichia coli and Aerobacter aerogenes. A double enzyme assay was developed to show the formation of homocysteine from cystathionine. The results obtained support the concept that cystathionine serves as a precursor of methionine via the intermediate formation of homocysteine. The latter compound is methylated by the homocysteine methyltransferase of these microorganisms. Sulfhydryl and keto acid assays were used to demonstrate cystathionase activity. Methionine represses both homocysteine methyltransferase formation and cystathionase formation. However, the presence of methionine in reaction mixtures resulted in product inhibition of homocysteine methyltransferase activity, but not of cystathionase activity.

Growth and invasiveness of Candida albicans in the germ-free and conventional mouse after oral challenge

Candida albicans was established in large numbers throughout the gut after one oral challenge in the germ-free and in the conventional mouse. Of the strains tested, only the germ-free ND 1 mouse appeared to be susceptible to infection, and this was confined to the stomach mucosa; lesions contained large numbers of hyphal and mycelial forms with blastospores. These forms were also seen in the gut of resistant germ-free ND 4 mice after challenge. Only budding yeast forms were seen in the gut contents from conventional animals. The concentration of sulfhydryl-containing compounds was decreased in the stomach contents from germ-free mice. The stomach tissue of conventional animals seemed to be more acidic than that of germ-free animals, and association of C. albicans with conventional mice neutralized some of this acidity. E(h) values of contents from the gut of unchallenged mice were usually higher in conventional than in germ-free animals; after challenge, the E(h) in both groups decreased. Some reciprocal effects of intestinal microorganisms and host are discussed in relation to intestinal candidiasis.

Growth, morphogenesis, and virulence of Candida albicans after oral inoculation in the germ-free and conventional chick

Balish, Edward (Syracuse University, Syracuse, 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 yeast-like 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 E(h) of the above crop contents were only slightly decreased in the germ-free crop. Thus the E(h) 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 gamma-globulin which increased after challenge, whereas this value was unchanged in conventional birds after challenge.

Growth and virulence of Candida albicans after oral inoculation in the chick with a monoflora of either Escherichia coli or Streptococcus faecalis

Balish, Edward (Syracuse University, Syracuse, 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 diflora containing E. coli and C. albicans had a few microscopic 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 E(h) values were found in chicks with S. faecalis and positive E(h) values in those with E. coli. Challenge did not greatly change these values. These data on pH and E(h) 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.