Subtilisin 3 production from Microsporum canis is independent of keratin substrate availability

Dermatophytes are highly infectious fungi that cause superficial infections in keratinized tissues in humans and animals. This group of fungi is defined by their ability to digest keratin and encompasses a wide range of species. We investigated a critical adhesion protein, subtilisin 3, utilized by Microsporum canis during initial stages of infection, analyzing its production and expression under varying growth conditions. Additionally, as this protein must be expressed and produced for dermatophyte infections to occur, we developed and optimized a diagnostic antibody assay targeting this protein. Subtilisin 3 levels were increased in culture when grown in baffled flasks and supplemented with either l-cysteine or cat hair. As subtilisin 3 was also produced in cultures not supplemented with keratin or cysteine, this study demonstrated that subtilisin 3 production is not reliant on the presence of keratin or its derivatives. These findings could help direct future metabolic studies of dermatophytes, particularly during the adherence phase of infections.

Digital gene expression analysis of Microsporum canis exposed to berberine chloride

Berberine, a natural isoquinoline alkaloid of many medicinal herbs, has an active function against a variety of microbial infections including Microsporum canis (M. canis). However, the underlying mechanisms are poorly understood. To study the effect of berberine chloride on M. canis infection, a Digital Gene Expression (DGE) tag profiling was constructed and a transcriptome analysis of the M. canis cellular responses upon berberine treatment was performed. Illimina/Hisseq sequencing technique was used to generate the data of gene expression profile, and the following enrichment analysis of Gene Ontology (GO) and Pathway function were conducted based on the data of transcriptome. The results of DGE showed that there were 8476945, 14256722, 7708575, 5669955, 6565513 and 9303468 tags respectively, which was obtained from M. canis incubated with berberine or control DMSO. 8,783 genes were totally mapped, and 1,890 genes have shown significant changes between the two groups. 1,030 genes were up-regulated and 860 genes were down-regulated (P<0.05) in berberine treated group compared to the control group. Besides, twenty-three GO terms were identified by Gene Ontology functional enrichment analysis, such as calcium-transporting ATPase activity, 2-oxoglutarate metabolic process, valine catabolic process, peroxisome and unfolded protein binding. Pathway significant enrichment analysis indicated 6 signaling pathways that are significant, including steroid biosynthesis, steroid hormone biosynthesis, Parkinson’s disease, 2,4-Dichlorobenzoate degradation, and tropane, piperidine and Isoquinoline alkaloid biosynthesis. Among these, eleven selected genes were further verified by qRT-PCR. Our findings provide a comprehensive view on the gene expression profile of M. canis upon berberine treatment, and shed light on its complicated effects on M. canis.

Phenotypical and molecular characterization of Microsporum canis strains in North-Tunisia

In this study, 40 Microsporum canis isolates were obtained from different patients from the Mycology Unit of the Hospital La Rabta (Tunis) during a 3 month period. The phenotypic identification was done by morphological characterization and biochemical tests. Molecular analysis was performed by amplification of the ITS region of rDNA, the amplified region was subjected to enzymatic digestion and sequenced to evaluate phylogenetic relationships. The morphological analysis showed a considerable diversity of colonies as well as different morphologies of conidia and we have noted variability in the assimilation of the nitrogen and carbon sources. The PCR-RFLP results showed only one restriction pattern for each enzyme. The phylogenetic tree proves that all the strains from Tunisian patients are clonal and related with other strains from different origins. The classical methods used in the mycological laboratories are time-consuming, the PCR-RFLP analysis of the ITS is a reliable tool for the identification of M. canis strains. M. canis from infected Tunisian patients are clonal, although the isolates had different phenotypic characteristics.

Antimetastasis effect of anthraquinones from marine fungus, Microsporum sp

This chapter discusses about obtaining natural products which have anticancer metastasis activities from selected marine-derived fungus (Microsporum sp.) and investigates their biological activities such as cytotoxicity on viability cell lines, anticancer cell migration and invasion, protease inhibition, and expression of matrix metalloproteinase (MMP-2 and -9). Moreover, the correlative mechanisms behind these activities were studied.

Extracellular production of silver nanoparticles by using three common species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis

BACKGROUND

To develop a new green approach for biosynthesis of silver nanoparticles, myconanotechnology has been represented as a novel field of study in nanotechnology. In this study, we have reported the extracellular synthesis of highly stable silver nanoparticles using three species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis.

METHODS

Clinical strains of these species were grown in a liquid medium containing mineral salt and incubated at 25°C for 5-7 days. The cell-free filtrate of each culture was obtained and subjected to synthesize silver nanoparticles in the presence of 1 mM AgNO3.

RESULTS

The reduction of Ag+ ions in metal nanoparticles was investigated virtually by tracing the solution color which was switched into reddish-light brown after 72 h. For T. mentagrophytes, a UV-visible spectra demonstrating a strong, quite narrow peak located between 422 and 425 nm was obtained. For M. canis, a fairly wide peak centering at 441 nm and for T. rubrum, a weak spectrum to decipher were observed. According to transmission electron microscopy (TEM) results, fairly uniform, spherical, and small in size with almost less than 50 nm particles were forms in case of T. mentagrophytes. For the other two species, TEM images showed existence of small spherical nanosilvers but not as small as nanoparticles synthesized by T. mentagrophytes.

CONCLUSION

We observed that species belong to a single genus of the fungi have variable ability to synthesize silver nanoparticles extracellulary with different efficiency. Furthermore, the extracellular synthesis may make the process simpler and easier for following processes.

Isolation, characterization, and disruption of dnr1, the areA/nit-2-like nitrogen regulatory gene of the zoophilic dermatophyte, Microsporum canis

A homolog of the major nitrogen regulatory genes areA from Aspergillus nidulans and nit-2 from Neurospora crassa was isolated from the zoophilic dermatophyte, Microsporum canis. This gene, dnr1, encodes a polypeptide of 761 amino acid residues containing a single zinc-finger DNA-binding domain, which is almost identical in amino acid sequence to the zinc-finger domains of AREA and NIT-2. The functional equivalence of dnr1 to areA was demonstrated by complementation of an areA loss-of-function mutant of A. nidulans with dnr1 cDNA. To further characterize this gene, dnr1 was disrupted by gene replacement based on homologous recombination. Of 100 transformants analyzed, two showed the results expected for replacement of dnr1. The growth properties of the two dnr1(-) mutant strains on various nitrogen sources were examined. Unlike the A. nidulansareA(-) mutant, these dnr1(-) mutants showed significantly reduced growth on ammonia, a preferred nitrogen source for fungi. These mutant strains were also able to utilize various amino acids for growth. In comparison with wild-type M. canis, the two dnr1(-) mutants showed reduced growth on medium containing keratin as the sole nitrogen source. This is the first report describing successful production of targeted gene-disrupted mutants by homologous recombination and their phenotypic analysis in dermatophytes.

Fluconazole upregulates sconC expression and inhibits sulphur metabolism in Microsporum canis

Azole derivatives such as fluconazole are the mainstay of therapeutic agents for the treatment of fungal infections. Their mode of action involving alteration in the conversion of lanosterol to ergosterol is well established. Here we report the effect of fluconazole on the sulphur metabolism negative regulator gene (sconC) in Microsporum canis. Characterization of the M. canis sconC gene revealed that its ORF is comprised of 495bp interrupted by four introns of 47-70bp. Exposure of M. canis in suspension to fluconazole upregulates sconC mRNA level and protein expression as determined by Northern and Western blot analysis, respectively. Upregulation of sconC was accompanied by inhibition of sulphur metabolism of the fungus resulting in a greatly reduced incorporation of radioactive labelled sulphuric acid into fungal proteins. These data establish that in addition to its action on ergosterol synthesis, fluconazole acts on other biological pathways in fungal cells.

The novel azole R126638 is a selective inhibitor of ergosterol synthesis in Candida albicans, Trichophyton spp., and Microsporum canis

R126638 is a novel triazole with in vitro activity similar to that of itraconazole against dermatophytes, Candida spp., and Malassezia spp. In animal models of dermatophyte infections, R126638 showed superior antifungal activity. R126638 inhibits ergosterol synthesis in Candida albicans, Trichophyton mentagrophytes, Trichophyton rubrum, and Microsporum canis at nanomolar concentrations, with 50% inhibitory concentrations (IC(50)s) similar to those of itraconazole. The decreased synthesis of ergosterol and the concomitant accumulation of 14 alpha-methylsterols provide indirect evidence that R126638 inhibits the activity of CYP51 that catalyzes the oxidative removal of the 14 alpha-methyl group of lanosterol or eburicol. The IC(50)s for cholesterol synthesis from acetate in human hepatoma cells were 1.4 microM for itraconazole and 3.1 microM for R126638. Compared to itraconazole (IC(50) = 3.5 microM), R126638 is a poor inhibitor of the 1 alpha-hydroxylation of 25-hydroxyvitamin D(3) (IC(50) > 10 microM). Micromolar concentrations of R126638 and itraconazole inhibited the 24-hydroxylation of 25-hydroxyvitamin D(3) and the conversion of 1,25-dihydroxyvitamin D(3) into polar metabolites. At concentrations up to 10 microM, R126638 had almost no effect on cholesterol side chain cleavage (CYP11A1), 11 beta-hydroxylase (CYP11B1), 17-hydroxylase and 17,20-lyase (CYP17), aromatase (CYP19), or 4-hydroxylation of all-trans retinoic acid (CYP26). At 10 microM, R126638 did not show clear inhibition of CYP1A2, CYP2A6, CYP2D6, CYP2C8, CYP2C9, CYP2C10, CYP2C19, or CYP2E1. Compared to itraconazole, R126638 had a lower interaction potential with testosterone 6 beta hydroxylation and cyclosporine hydroxylation, both of which are catalyzed by CYP3A4, whereas both antifungals inhibited the CYP3A4-catalyzed hydroxylation of midazolam similarly. The results suggest that R126638 has promising properties and merits further in vivo investigations for the treatment of dermatophyte and yeast infections.

Fluorescent method for studying the morphogenesis and viability of dermatophyte cells

The dermatophyte Microsporum canis is commonly isolated from human and animal infection. The morphogenesis of this fungus was studied during its developmental stages through the fluorescent method Fluorescein Diacetate and Ethidium Bromide. To this end, 50 microl dermatophyte suspension were transferred onto cellophane wrapping esterilized discs (2.5 cm of diameter) placed over the surface of Sabouraud dextrose agar on Petri dishes and incubated at 25 degrees C for 30 days. Every 60 minutes during the first 24 hours and every 12 hours for next 29 days, one disc was transferred onto glass slide, covered with equal volumes of freshly prepared fluorescein diacetate (FDA) and ethidium bromide (EB) solution, mounted with a coverslip and incubated in the dark for 30 minutes, at 25 degrees C. Each preparation was then examined on a fluorescent microscope. M. canis presented well defined growth stages: (1) tumescence of cells; (2) germination; (3) development of hyphae; (4) production of conidia and (5) tumescence and formation of arthroconidiae. Using the fluorescent method, non viable cells showed a light bright red coloration and viable cells presented green fluorescence. The principal morphological changes have occurred between the 3rd until the 18th day of culture. The method is very useful to demonstrate the dermatophyte growth stages as well as the perfect differentiation between viable and non viable cells.

Fluconazole downregulates metallothionein expression and increases copper cytotoxicity in Microsporum canis

Azole antifungals are widely used to treat infections with dermatophyte fungi. Whereas it is well established that this class of drugs interferes with fungal ergosterol synthesis, little is known about its potential other biological effects. Here we report the isolation and structural organization of Microsporum canis metallothionein gene and demonstrate that fluconazole is able to downregulate the baseline as well as copper-induced expression of this gene. Since this effect occurred within 30 min after exposure of the fungus to fluconazole, it is unlikely that it is due to impaired ergosterol synthesis. Our additional demonstration that fluconazole enhances copper toxicity for M. canis suggests that inhibition of metallothionein expression by fluconazole is biologically relevant and may represent an important additional mode of the antifungal action of this drug. Therefore our data indicate that antifungal effects of azole derivatives might not only be due to interference with cell wall synthesis but may also affect other biological circuits within the fungal cells.

Phenotypic characterization of Microsporum canis isolated from cats and dogs

To characterize strains of Microsporum canis that infect dogs and cats in São Paulo city, 30 isolates of this dermatophyte were tested for their ability to assimilate carbon and nitrogen sources, for proteinase and phospholipase secretion, for susceptibility to yeast killer toxins, and for susceptibility to the antifungals fluconazole, ketoconazole, itraconazole, 5-fluorocytosine and amphotericin B, in E test. All samples assimilated the nitrogen sources asparagine, ammonium sulphate, urea and sodium nitrate, as well as the carbon sources inulin, mannitol, trehalose, meso-erythritol, maltose, mannose, sorbitol, cellobiose, fructose and dextrin. Not all the samples assimilated adonitol, galactose, arabinose, rhamnose, raffinose, melibiose, ribose and sucrose, and none of them was capable of growing with dulcitol, lactose, or xylose as the only carbon source. Proteinase and phospholipase secretion was observed for most isolates. In the test of yeast killer toxin, 10 types could be identified, with four types exclusively observed in isolates from dogs and two types exclusively observed in isolates from cats. In the E test, all isolates were found to be resistant to the fluconazole and 5-fluorocytosine, while they were variably sensitive to amphotericin B, ketoconazole and itraconazole. When the data were submitted to the qualitative analysis in the matrix distance program FITOPAC, the similarity of the isolates could be assessed.

Keratinolytic activity of five human isolates of the dermatophytes

The keratinolytic activity of five species of the dermatophytes which include Trichophyton rubrum, T. mentagrophytes, T. tonsurans, Microsporum audouinii and M. gypseum isolated from school children were tested using human hair as the substrate. M. gypseum was found to possess the highest keratinolytic activity with a net value of released protein being 78.8 ug/ml after five weeks of incubation. Also the net value of released protein for T. tonsurans, T. rubrum, T. mentagrophytes and M. audouinii were 55.5 ug/ml, 52.5 ug/ml, 43.8 ug/ml and 26.3 ug/\ml respectively. Only T. mentagrophytes and M. gypseum were able to cause structural damage in form of perforations on the hair shaft. Also during the degradation of the hair, the pH of the basal medium for each dermatophyte increased. The increase in pH was highest in the medium with M. gypseum but lowest in that of M. audouinii.

Possible involvement of Ca2+/calmodulin-dependent protein kinase in the regulation of phospholipid biosynthesis in Microsporum gypseum

The mechanism of action of Ca2+/calmodulin on phospholipid synthesis in Microsporum gypseum has been studied. These second messengers were observed to mediate their function through phosphorylation mechanism as altered protein kinase activity was seen in calcium/trifluoperazine (calmodulin antagonist) grown cells. The activity of protein kinase was dependent on calcium (200 microm) and calmodulin (1 microm). In vitro studies of phosphorylation and dephosphorylation in relation to phospholipid synthesis in Microsporum gypseum have been carried out. Addition of KN-62 (a specific inhibitor of Ca2+/calmodulin-dependent protein kinases) and polyclonal antibodies raised against purified Ca2+/calmodulin-kinase (CaMPK) of M. gypseum in the cell extract, leads to the inhibition in the incorporation of labelled acetate into total phospholipids in this fungus. These results suggest a possible involvement of Ca2+/calmodulin via Ca2+/calmodulin-dependent phosphorylation in phospholipid synthesis in M. gypseum.

Alteration in protein kinase(s) level affects the phospholipid content in M. gypseum with modulated levels of calcium/cyclic AMP

Protein kinase(s) have been identified for the first time in Microsporum gypseum. It phosphorylated exogenous protein acceptors preferentially histone IIs and casein and are mainly localized in the cytosolic fraction of M. gypseum. Alterations in protein kinase activity was observed in calcium/aminophylline and atropine (cAMP modulators) grown cells which is due to the modulation in the Ca2+/cAMP levels. Alteration in the protein kinase(s) activity finally affected the total phospholipid content in these modulated cells of M. gypseum. These observations suggest a correlation between the activity of protein kinase(s) and phospholipid synthesis in M. gypseum. This protein kinase(s) has a broad substrate specificity and is a seryl-threonyl type protein kinase(s) as it phosphorylates exogenous (histone) and endogenous proteins at serine and threonine residues.

Calcium induced alterations in structural and functional role of phospholipids in Microsporum gypseum

The effect of calcium on the structural and functional aspects of phospholipids in Microsporum gypseum was examined. Cells grown in presence of calcium exhibited increased content of phospholipids and enhanced synthesis of phospholipids as monitored by the incorporation of [32P] orthophosphoric acid. The rise in the levels of phospholipids was found to be due to increased synthesis of fatty acids as observed from [14C] acetate incorporation studies. The rise in the levels of phospholipids were reflected in the subcellular fractions also. Change in the phospholipid composition increased the fluidity of the membrane as is evident from fluorescence polarization studies using 1-anilinonaphthalene-8-sulfonate (ANS) and 1,6-diphenyl-1,3,5-hexatriene (DPH). The increased membrane fluidity was consistent with the enhanced uptake of [3H] proline in calcium grown cells.

Dermatophytes and other keratinophilic fungi causing ringworm of horses

From 60 horses showing skin lesions, 42% were positive for fungal infection. Horses less than 2-year old were more susceptible to this infection. Fourteen species belonging to nine genera of keratinophilic and cycloheximide-resistant fungi were recovered from collected specimens. Trichophyton was the dominant genus of which T. equinum was the most common. This species proved to be the main causative agent of ringworm in horses. In addition to dermatophytes, many species of the isolated fungi were keratinophilic. The presence of such fungi on hairs and skin of horses may create an opportunity for them under special circumstances to become invasive to the skin or hair and thus cause primary or secondary infection of the animals.

Identification, localization and possible role of calmodulin like protein in phospholipid synthesis of Microsporum gypseum

Calmodulin like protein has been identified for the first time in dermatophyte--M. gypseum (by specific radioimmunoassay). Maximum amount of this protein was present in the early and mid log phase of growth and was mainly localized in the cytosolic fraction. Cells treated or grown with calmodulin antagonists (phenothiazine and trifluoperazine) exhibited lower uptake of [14C]acetate or labelled phosphate into phospholipids. This is probably due to lower levels of calmodulin seen in these cells. Our results suggest the relationship between calmodulin levels and phospholipid synthesis in Microsporum gypseum.

Possible role of calcium in phospholipid synthesis of Microsporum gypseum

The effect of calcium on lipid synthesis in Microsporum gypseum was examined by growing these cells in calcium supplemented (1 mM to 10 mM) medium. Maximum incorporation of [14C]acetate into total lipids and phospholipids was observed in cells grown with 6 mM calcium. This was probably due to a 3-fold increase in total calcium levels as incorporation of label was inhibited in total lipids (33%) and phospholipids (20.5%) in calcium-grown cells which were preincubated with the calcium specific chelator ethylene glycolbis (beta-aminoethyl ester) N,N,N',N',-tetracetate (EGTA). Increased incorporation of [14C]acetate into phospholipids was further supported by increase in the activity of key phospholipid biosynthetic enzymes (glycerolkinase and glycerol-3-phosphate acyltransferase) as well as the increase in phospholipid content in calcium-grown cells, which suggests a correlation between increased calcium levels and phospholipid biosynthesis in M. gypseum.

Screening of different keratin baits for isolation of keratinophilic fungi

Twenty different keratin-rich substrates were screened as keratin baits for isolation of keratinophilic fungi from different soil sample of Chhindwara District, India. Fungi easily formed colonies on different baits. However, hair, feathers and horns were found to be more suitable than nails, fish fins and fish scales.

Influence of cyclic AMP on the biosynthesis of phosphatidylcholine in Microsporum gypseum

The influence of intracellular cAMP on phosphatidylcholine biosynthesis in Microsporum gypseum has been examined using radiolabelled precursors. The incorporation of labelled choline, methionine and ethanolamine into total lipids, phospholipids and choline containing phospholipids increased in aminophylline and decreased in atropine grown cells as a result of rise and fall in cAMP levels in these cells. The enhanced uptake of labelled methionine and ethanolamine in comparison to labelled choline in choline containing phospholipids in aminophylline grown cells suggests that methylation pathway is more influenced by cAMP than CDP-choline pathway.

Further studies on the influence of aminophylline on lipids of Microsporum gypseum

Aminophylline added to the growth medium of Microsporum gypseum for varying periods exhibited varied effects on lipid synthesis. A decreased incorporation of [14C]acetate into both lipids and phospholipids was initially observed which showed increase after 24 hr of incubation. Short-time exposure of aminophylline also resulted in decreased activity of glycerol-3-phosphate acyltransferase, the key enzyme of lipid synthesis, which, however, got stimulated on longer incubation, supporting the decreased/increased synthesis of lipids during short/long time exposure. Changes in the intracellular levels of cAMP at different time points account for the induced alterations in lipid synthesis, possibly due to formation of metabolites of aminophylline during growth of the organism.

Effect of reducing agents on proteolytic and keratinolytic activity of enzymes of Microsporum gypseum

The effect of sodium sulphite, cysteine, glutathione, mercaptoethanol and dithioerythritol (0.1-10 mmol l-1) on the activity of proteases of Microsporum gypseum was studied using azocasein, cross-linked bovine serum albumin and keratin as substrates. With the substrate without disulphide bonds (casein) no stimulation was found, and reducing agents inhibited proteolysis in most cases. With the remaining two substrates, all substances enhanced the activity of proteases probably through the cleavage of the substrate disulphide bonds. Sulphite was more effective than the four used thiols and enhanced the activity against serum albumin up to 3.2 times and against keratin up to 2.9 times. Using sulphitolysed sheep wool, keratinolytic activity increased after sulphitolysis of more than 20% of disulphide bonds. With the fully sulphitolysed wool the activity increased 43 times. The obtained results support the author's hypothesis on keratin degradation by sulphite excretion prior to attack by fungal proteases. Stimulation of proteolysis and keratinolysis by cleavage of disulphide bonds is not specific for dermatophytic proteases because trypsin and pronase behaved similarly in the experiments.

Morphological and biochemical variability of Microsporum canis strains

Seventy-two strains of Microsporum canis, of different origins, were examined from a morphological point of view and tested in relation to their hydrolytic activity on tyrosine, xanthine, casein, gelatin, their ureasic activity and their capacity to assimilate different nitrogenous substances. The morphological aspects, that vary within the M. canis isolates, were constant in the strains isolated from rabbits. A strain with particular features was isolated many times from the dogs and cats coming from the same breeder. In one case of pseudomycetoma, different isolates suggested the co-existence in animals of two different strains, one present on fur, the other responsible for deep lesions.

Biotypes of the dermatophyte Microsporum distortum

During a study of the epidemiology of Microsporum canis and closely related species, sub-specific variation was demonstrated within thirteen isolates of Microsporum distortum based on the pattern of carbohydrate utilization. Strains from three continents could be differentiated by their utilization of trehalose and erythritol. Isolates from New Zealand yielded the same patterns as M. canis (Arthroderma otae (-)); examination of 120 isolates indicated that M. canis could not be biotyped by carbohydrate utilization, although limited variation had been noted. Examination of total native protein patterns by gel electrophoresis showed that variations existed within the M. distortum group; the much larger number of M. canis (A. otae (-)) strains had appeared to be homogenous.

Correlation between intracellular cAMP levels and phospholipids of Microsporum gypseum

Atropine, a modulator of cAMP has been used to examine the relationship between phospholipids and intracellular levels of cAMP in Microsporum gypseum. A decreased phospholipid content was observed in atropine grown cells as a result of reduced levels of intracellular cAMP. This decline was caused by the inhibitory effect of atropine on adenylate cyclase. Lowered phospholipid content was supported by decreased [14C]acetate incorporation as well as reduced activities of key enzymes of phospholipid biosynthesis. In vitro supplementation of atropine in control cells also caused inhibition in lipid synthesis indicating similar effects of atropine and its metabolites. These results in conjunction with our previous report, in which enhanced levels of cAMP resulted in increased phospholipid synthesis, suggest a direct correlation between phospholipid biosynthesis and intracellular levels of cAMP in M. gypseum.

Occurrence of keratinolytic fungi and related dermatophytes in soils in Cairo, Egypt

120 soil samples collected from various sites of Cairo were processed for the isolation of keratinophilic fungi by "ToKaVa" hair baiting technique. 22 species belonging to 6 genera were isolated viz.: Chrysosporium tropicum, C. indicum, C. keratinophilum, C. queenslandicum, C. merdarium, C. anamorph of Arthroderma curreyi, C. pannicola, C. lobatum, C. anamorph of Renispora flavissima, C. pseudomerdarium, Microascus mangini, Malbranchea gypsea, Ml. State of Uncicarpus reesii, Ml. State of Coccidioides immitis, Microsporum gypseum, Mr. distortum Mr. audouinii, Mr. fulvum, Trichophyton mentagrophytes, T. terrestre, T. verrucosum and Epidermophyton floccosum. The frequency of occurrence of the isolated fungi was determined. Microsporum gypseum, Chrysosporium tropicum and Chrysosporium indicum were the most frequent species recovered from soil. Most species of keratinophilic fungi were isolated from university, public garden and zoo garden. The distribution of the isolates are discussed.

Screening the keratinolytic activity of dermatophytes in vitro

Sixteen strains out of 12 species dermatophytes were examined in respect to their ability of utilizing keratin substrates as the only sources of C and N. The employed keratin substrates included a solubilized preparation of feather keratin (KS) and native keratin, guinea pig hair and chicken feathers. It has been shown that the preparation KS constitutes a convenient model for a preliminary estimation of fungal keratinolytic activity and it can be a source of information about the localization of these enzymes. It has been found that, among the 16 fungal strains, 13 strains synthesize mainly intracellular keratinases while 3 strains of T. verrucosum release enzymes mainly to the medium. Native keratin from hair and feathers was degraded only by some of the examined strains which, under the experimental conditions, developed characteristic spore forms. Keratin of guinea pigs hair was attacked only by the T. mentagrophytes strains, T. verrucosum and K. ajelloi, and only T. gallinae grew on native keratin from chicken feathers.

Influence of aminophylline on the lipids in Microsporum gypseum

The effect of aminophylline on the lipid synthesis of Microsporum gypseum has been examined. A decreased incorporation of [14C]acetate into lipids was observed when the cells were incubated for 1 h with aminophylline which was reflected in all the individual lipid fractions. However, cells grown with aminophylline in the growth medium exhibited increased levels of total phospholipids, which was probably due to a rise in intracellular cAMP as these cells exhibited 4-fold increased levels of cAMP. Decreased activity of phosphodiesterase by aminophylline accounts for the increased cAMP levels. Increased phospholipid content in aminophylline grown cells was further supported by the increased incorporation of [14C]acetate into phospholipids as well as increased activities of phospholipid biosynthetic enzymes in comparison to non-supplemented cells.

Wool-colonizing micro-organisms capable of utilizing wool-lipids and fatty acids as sole sources of carbon and energy

Two keratinolytic fungi, Chrysosporium keratinophilum and Malbranchea anamorph of Uncinocarpus reesii, and another three wool-colonizing fungi not previously reported to be keratinolytic, Aspergillus fumigatus, A. Flavus and Scopulariopsis candida, were isolated from soil samples baited with animal wool. These fungi were tested for their ability to utilize wool-lipids as sole source of carbon and energy. The lipid contents of wool of various animals ranged between 2 and 5%. The different lipid extracts were similar in composition; they contained steryl esters, sterols, fatty acids, fatty alcohols and monoacylglycerols. The predominant acyl moiety in wool-lipids of different animals was linolenic acid (18:2). The five fungi tested grew well on an inorganic medium supplemented with total wool-lipids as sole sources of carbon and energy. Individual lipid classes fractionated by preparative thin layer chromatography and suspended into inorganic medium were able to support fungal growth as sole carbon sources. These fungi and another eight wool-colonizing strains, C. tropicum, C. zonatrum, C. anamorph of Arthroderma curryei, Microsporum canis, M. distortum, Trichophyton interdigitale, Emmonsia parva and Myceliophthora vellerae could also utilize standard lipids and fatty acids (cholesterol and palmitic and linoleic acids). Evidence fo the uptake and degradation of cholesterol by C. keratinophilum is presented.

Cycloheximide enhances factor binding to the native 40S ribosomal subunit of Microsporum canis

Native and derived ribosomal particles from the mycelial cells of Microsporum canis grown in the presence and absence of cycloheximide were compared by CsCl equilibrium density gradient centrifugation. Since the buoyant densities of ribonucleoprotein complexes are dependent on the protein-RNA ratio, they reflect the composition of these particles. The native monosomes from cells grown in the presence and absence of cycloheximide had a buoyant density of 1.585 g/cc. The native 60S subunits showed a density of 1.540 g/cc from cells grown in both presence and absence of cycloheximide, while the derived subunits showed a density of 1.610 g/cc. The derived 40S subunits had a density of 1.550 g/cc while the native 40S showed a major species of density 1.535 g/cc with three other minor species ranging in densities from 1.450-1.390 g/cc. The mycelia grown in the presence of cycloheximide showed an increased proportion of native 40S subunits in the density range of 1.450-1.390 g/cc, indicating that the drug enhances factor binding to native ribosomal subunits in M. canis.

Further studies on the influence of dibutyryl cAMP, theophylline and prostaglandin E1 on composition and biosynthesis of phospholipids in Microsporum gypseum

Exogenous supplementation of dibutyryl cAMP and cAMP modulators like theophylline and prostaglandin E1 in the growth medium of Microsporum gypseum lead to increase in the levels of phosphatidylcholine and lysophosphatidylcholine and thereby in total phospholipid content. These observations were further confirmed by the increased incorporation of [32P]orthophosphoric acid into total phospholipid and [14C]choline into phosphatidylcholine and lysophosphatidylcholine. The activity of sn-glycerol-3-phosphate acyltransferase, the enzyme involved in phospholipid synthesis, was stimulated in the presence of dibutyryl cAMP, theophylline and PGE1 supporting the increased synthesis of phospholipids.

Hair perforation by keratinophilic fungi

The in vitro hair perforation test as described by Ajello and George, was applied to eight species of Chrysosporium and one species each of Microsporum and Trichophyton. Six of them were found to perforate hair while four were negative. Chr. keratinophilum, M. gypseum and Tr. vanbreuseghemii were able to perforate and degrade hair rapidly. The micromorphological changes were also described.

Dermatophyte-hormone relationships: characterization of progesterone-binding specificity and growth inhibition in the genera Trichophyton and Microsporum

We reported previously that Trichophyton mentagrophytes contains a cytoplasmic macromolecule which specifically binds progesterone. Progesterone is also an effective inhibitor of growth of the fungus. We report here studies which characterize more fully the specific binding properties and the functional responses of T. mentagrophytes and taxonomically related fungi to a series of mammalian steroid hormones. Scatchard analysis of [3H]progesterone binding in both the + and - mating types of Arthroderma benhamiae and in Microsporum canis revealed a single class of binding sites with approximately the same affinity as that in T. mentagrophytes (Kd, 1 X 10(-7) to 2 X 10(-7) M). Trichophyton rubrum had a protein with a higher binding affinity (Kd, 1.6 X 10(-8) M). Characterization of the [3H]progesterone-binding sites in T. mentagrophytes showed the binder to be a protein which was destroyed by trypsin and heating to 56 degrees C. Previous examination of the steroid-binding specificity in T. mentagrophytes had demonstrated that deoxycorticosterone (DOC) and dihydrotestosterone (DHT) were effective competitors for [3H]progesterone binding. Expansion of this study to include other competitors revealed that R5020 (a synthetic progestin), androstenedione, and dehydroepiandosterone possessed relative binding affinities which were 20, 11, and 9% of that of progesterone, respectively. Other ligands tested were less effective. Competition studies for the binder in M. canis resulted in similar findings: DOC and DHT were effective competitors for [3H]progesterone binding. The growth of A. benhamiae + and -, M. canis, and T. rubrum were all inhibited by progesterone in a dose-responsive manner, with 50% inhibition achieved at concentrations of 9.8 x 10(-6), 1.2 x 10(-5), 1.5 x 10(-5), and 2.7 x 10(-6) M. respectively,.

Effect of dibutyryl cyclic AMP on lipid synthesis in Microsporum gypseum

The influence of intracellular levels of cAMP on the lipid synthesis of Microsporum gypseum has been examined by exogenous supplementation of dibutyryl cAMP and its activators/inhibitors. Incorporation of [14C]acetate into various lipid fractions of M. gypseum was markedly enhanced in the presence of dibutyryl cAMP and its modulators, probably as a consequence of increased intracellular cAMP levels, which, in turn, affected the lipid biosynthesis. Increased activities of phosphatidic acid phosphatase, glycerol kinase, ethanolamine kinase and choline kinase in the presence of these additives supports the enhanced synthesis of phospholipids and suggests that lipid biosynthesis is being controlled by cAMP in M. gypseum.

Effect of choline, ethanolamine and serine supplementation on the membrane properties of Microsporum gypseum

Phospholipid bases, choline and ethanolamine, when supplemented in the growth medium of Microsporum gypseum resulted in an increase in the corresponding phospholipid and total phospholipid content. However, when serine was supplemented, marginal changes were observed. The fatty acid profile of phospholipids remained almost unchanged. The uptake of lysine, leucine and aspartic acid in the spheroplasts of choline- and ethanolamine-grown cells was higher as compared to the control. 1-Anilinonaphathalene-8-sulfonate (ANS) binding to the spheroplast membrane, as calculated from Scatchard plots, demonstrated an increase in the number of binding sites in choline- and ethanolamine-grown cells, while a decrease was observed in the serine-supplemented cells. The results are discussed in terms of the effect of phospholipid polar head group composition on the membrane structure and function of this fungus.

Utilization of various concentrations of free cystine by the fungus Microsporum gypseum

The dermatophyte Microsporum gypseum was cultivated on two liquid media enriched with 50 to 1000 micrograms/ml free L-cystine. The presence of cystine in concentrations above 250 micrograms/ml (gelatin medium) or 500 micrograms/ml (glucose-glutamate medium) inhibited the growth. In all variants, however, cystine was utilized from the very beginning of growth and exhausted completely until stationary phase. The rate of cystine metabolization grew with its concentration to 500 micrograms/ml but decreased again with 1000 micrograms/ml. The excess sulfur was oxidized and excreted back into the medium mainly as inorganic sulfate. Moreover, sulfite was also produced which immediately reacted with the residual cystine in the medium giving rise to S-sulfocysteine. Sulfite excretion was higher in the initial phases of growth and on the medium with poorer growth (gelatin medium). The sulfate-to-sulfite ratio was different on the two media used but was little influenced by cystine concentration. The excretion of strongly acidic compounds (sulfate, sulfite, and S-sulfocysteine) reduced the usual alkalinization of the medium in the course of growth.

Cystine catabolism in mycelia of Microsporum gypseum, a dermatophytic fungus

The fate of 35S label was studied during cystine degradation by mycelia of the dermatophytic fungus Microsporum gypseum. Excess free cystine in the medium was readily taken up and its sulfur moiety excreted as inorganic sulfate and sulfite. At intervals after 3-60 min of incubation with 35S cystine the products of cystine catabolism were extracted from the mycelia by boiling water and separated by thin layer chromatography and electrophoresis. A total of 10 sulfur-containing compounds were identified, and their relative radioactivity was assessed. After 3 min the mycelia contained, in addition to cystine, labeled cysteine and particularly cysteine sulfinic acid which was accompanied by a smaller amount of cysteic acid. Later on, oxidized and reduced glutathione, inorganic sulfate and taurine appeared consecutively. In all extracts, small amounts of labeled S-sulfocysteine were found, not, however, sulfite. The results suggest that the intermediates of cysteine degradation in the fungal mycelia are cysteine, cysteine sulfinate, unstable sulfinylpyruvate, sulfite and sulfate, i.e., that the catabolic pattern is similar to that of higher organisms. The formation and the role of S-sulfocysteine, cysteic acid, and of taurine is not yet completely understood, although certainly autoxidative processes are involved in the formation of the latter two compounds, and sulfitolysis in that of the former compound.

Metabolism of sulfur-containing amino acids in the dermatophyte Microsporum gypseum. I. Neutral amino acids

The dermatophyte Microsporum gypseum was cultivated on a glucose-arginine medium to which on out of six sulfur-containing amino acids was added (L-cystine, L-djenkolic acid, DL-lanthionine DL-homocystine, L-methionine, or L-methionine-sulfone at a concentration of 5 mM with respect to sulfur content). The addition of these substances did not stimulate the growth and some amino acids (djenkolic acid and particularly methionine and methionine-sulfone) were inhibitory. All tested compounds were utilized during the growth not only as sulfur source but as a source of carbon and nitrogen as well. In four substrates excess sulfur was excreted after oxidation into the medium in the form of sulfate. Small amounts of sulfite were also observed. It usually reacted with remaining disulfides in the medium forming S-sulfo compounds (R-S.SO3H). Cystine and djenkolic acid were oxidized rapidly and completely. In contrast, lanthionine and particularly homocystine were oxidized slowly and only after a longer adaptation. To some extent lanthionine was already oxidized extracellularly in the medium. With methionine and its sulfone, excess sulfur was not removed by oxidation but by demethiolation to methane thiol and further volatile products.

Lipids of dermatophytes II. Effect of growth condition on the lipid composition and membrane transport of Microsporum gypseum

Supplementation of glucose-containing medium with ethanol and replacement of glucose by glycerol in the Sabouraud's growth medium of Microsporum gypseum altered the levels of total phospholipids as well as their apolar and polar head groups. The levels of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) increased under these growth conditions; also, the ratio of unsaturated/saturated phospholipid fatty acids decreased on ethanol supplementation but increased in the presence of glycerol. Steady state accumulation of labelled amino acids (glycine, lysine and aspartic acid) was affected under these conditions.

Metabolism of sulfur-containing amino acids in the dermatophyte Microsporum gypseum. II. Acidic amino acid derivatives

The dermatophyte Microsporum gypseum was cultivated on a glucose-arginine medium supplemented with five strongly acidic derivatives of cysteine (L-cysteine sulfinic acid, L-cysteic acid, L-serine-O-sulfate and taurine at a concentration of 5 mmol/l, and L-S-sulfocysteine at a concentration of 2.5 mmol/l). The addition of these substances did not stimulate the growth as compared with the control containing 0.5 mmol/l cystine. Cysteine sulfinic acid and cysteic acid showed rather inhibitory effects. A strong inhibition of the growth was caused by the presence of serine sulfate. During the growth, all substances investigated were gradually consumed and utilized not only as a source of sulfur but of nitrogen and carbon as well. Cysteine sulfinic acid and S-sulfocysteine were utilized most rapidly. Cysteic acid was also rapidly utilized but after a certain adaptation. Taurine was utilized slowly and serine sulfate very slowly. Excess sulfur contained in the substances used was excreted into the medium in the form of sulfate. Sulfate excretion was most rapid with cysteine sulfinic acid and slowest with taurine. With cysteine sulfinic acid, S-sulfocysteine and cysteic acid, small amounts of sulfite were found in the medium. The results obtained are in accordance with the presumption that cysteine sulfinic acid (but not cysteic acid and taurine) is an intermediate of cysteine catabolism in dermatophytes.

Correlation between morphological and physiological characteristics in species of microsporum

The correlations between the physiological and morphological characteristics of various Microsporum strains were studied together with the inhibitory activities toward different microorganisms.

Studies in the differentiation between Microsporum ferrugineum Ota and Trichophyton soudanense Joyeux

A study, conducted with 20 isolates of Microsporum ferrugineum and 12 isolates of Trichophyton soudanense, revealed that some of the discrepancies in the literature regarding their characteristics and differentiation were due to methodology, strain variation and the use of an insufficient number of isolates. We found all isolates of T. soudanense to be urease negative and gelatinase positive (usually by the first week); to produce brown to black colonies on Lowenstein-Jensen medium; to rapidly decompose casein and more slowly tyrosine; to grow well or better at 37 degrees C as compared to room temperature; to produce reflexive branching on cornmeal Tween agar and abundant microconidia on casero medium and to exhibit no sexual reaction with either mating type of arthroderma simii. All but one isolate demonstrated restricted growth on lactose agar and only three isolates perforated hair. In contrast, we found 18 of 20 isolates of M. ferrugineum to be urease positive in urea broth (most isolates were negative on urea agar); all produced light-colored colonies on Lowenstein-Jensen medium; spreading colonies on lactose agar and failed to perforate hair in vitro or to produce reflexive branching. Most isolates manifested poorer to no growth at 37 degrees C compared to room temperature and all but one failed to decompose casein and tyrosine. A few strains produced macroconidia and/or microconidia on casero medium and some reacted sexually with A. simii (a) (-) mating type. Gelatin hydrolysis was variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Utilization of L- and DL-cystine by the fungus Microsporum gypseum

Growth of the fungus Microsporum gypseum and utilization of cystine during this growth was studied in a glucose-arginine medium containing either sodium sulphate, and L-cystine or DL-cystine. Replacement of sulphate with L-cystine brought about no significant changes in the growth of the microorganism. Utilization of L-cystine as a source of carbon and nitrogen was rapid and complete and excess sulphur was excreted into the medium in the form of sulphate. Similarly excreted were also minute amounts of sulphite which immediately reacted with the remaining cystine to form S. sulphocysteine. Growth of M. gypseum in a medium with DL-cystine was slow. Although this substance was not utilized as readily as L-cystine, its utilization was still complete and excess sulphur was similarly excreted in the form of sulphate and sulphite. The initial step in the utilization of the D-isomer is probably its extracellular deamination.

Nutritional requirements of keratinophilic fungi and dermatophytes for conidial germination

Germination of spores of Chrysosporium crassitunicatum, Nannizzia fulva (+), Nannizzia fulva (-) and Trichophyton equinum was studied in the presence of various carbon and nitrogen sources. Effect of different temperatures on spore germination was also determined. Maximum spore germination within 24 hours was recorded when glucose was used as a carbon source for all the test fungi. Except sodium nitrate all the inorganic nitrogen sources enhanced the spore germination at 0.05% concentration. Most of the organic nitrogen sources used were found to be stimulatory for the spore germination of test fungi. Optimum temperature i.e. 28 degrees C supported maximum spore germination of all the test fungi within 24 hours. C. Crassitunicatum, N. fulva (+), N. fulva (-) could germinate upto 35 degrees C but beyond that no spore germination was noticed in these fungi. T. equinum could germinate at a higher temperature of 40 degrees C but the percentage of germination was very low.