Multiple proteinases from twoMicrosporumspecies

Extracellular protease expression in Microsporum gypseum complex, its regulation and keratinolytic potential

Two soil isolates of Microsporum gypseum were studied for the production of extracellular proteases. Both the strains secreted protease on glucose-gelatin medium. The enzyme activity peaked on day 15 at 28 °C. Asparagine repressed protease yield. Sugars caused catabolite repression of protease formation. Protease activities of both the isolates were significantly affected by incubation period, culture media and carbohydrates used. Both the strains grew on the skin bait and caused a gravimetrically measurable loss of the substrate. Despite less pronounced differences in the keratinase levels, great variations occurred in the amount of keratin degraded by two isolates. Keratinase production as well as loss in substrate mass was better in glucose-lacking flasks than those containing the sugar. Although the rate of keratin degradation was independent of enzyme production, statistically positive correlations were recorded between loss in substrate mass: yielded dry mycelial weight and substrate degradation: keratinase levels.

Actividad proteolítica extracelular y análisis molecular de cepas de Microsporum canis aisladas de gatos con y sin sintomatología

Microsporum canis is the main zoophylic dermatophyte in dogs and cats, and it is also an important zoonotic agent. The literature showed that cats are asymptomatic carriers of M. canis. This is apparently due to host resistance and/or the presence of strains with lower virulence. This study was aimed to evaluate the keratinolytic, elastinolytic and collagenolytic activities of M. canis strains and their relationship with symptomatic and asymptomatic cats. In addition, these strains were analysed by RFLP. The strains isolated from cats with clinical dermatophytosis had higher keratinase and elastase activity than those isolated from asymptomatic animals (p minus than 0.05). There were not differences in RFLP patterns based on Hind III digestion.

Isolation of dermatophytes and non-dermatophytic fungi from soil in Nigeria

A total of 60 soil samples were collected from Ifite Awka, Nnamdi Azikiwe University and Amawbia, all located in Awka Urban, Anambra State, Nigeria. An additional sample was collected from a household rug-carpet vacuum cleaner from a house located in Enugu city, Enugu State (a neighbouring state). The 61 samples were investigated for the occurrence of dermatophytic and non-dermatophytic fungi, using the hair-bait technique and agar dilution procedure. The medical importance of the isolates in the samples is discussed.

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.

Production of extracellular enzymes by Microsporum canis and their role in its virulence

Microsporum canis is the most prevalent dermatophyte of domestic animals. Several enzymes produced by dermatophytes, particularly keratinases, are considered to play a role in the virulence of this fungus. To investigate the possible relationship between the clinical status of M. canis infection and enzymatic activity of isolates, we studied the relationship between keratinase, elastase, lipase and DNase levels produced in vitro by different isolates and virulence as expressed in a guinea pig model. Samples isolated from symptomatic dogs and cats showed a statistically significantly (P < 0.05) higher keratinase activity than samples isolated from asymptomatic animals. Experimental infection of guinea pigs showed that a strain with high in vitro keratinase activity induced acute infection, which resolved clinically and mycologically faster than the infection induced by a strain with low keratinase activity. This suggested a strong correlation between high keratinase activity and the development of symptoms. The same correlation was not observed for other enzymes tested.

Purification and characterization of a 43.5 kDa keratinolytic metalloprotease from Microsporum canis

A keratinolytic protease secreted by a feline clinical isolate of Microsporum canis cultivated in a broth containing feline keratin as the sole nitrogen source was purified from the culture filtrate by affinity chromatography on bacitracin-agarose and by hydrophobic chromatography on octyl-agarose. The enzyme had an apparent molecular mass of 43.5 kDa and the pI was 7.7. It had a significant activity against keratin azure, elastin-Congo red and denatured type I collagen (azocoll). Using the latter substrate, the optimum pH was around 8 and the apparent optimum temperature around 50 degrees C. The protease was strongly inhibited by 1,10-phenanthroline, phosphoramidon and EDTA. The first 13 N-terminal amino acid sequence showed a 61% homology with that of the extracellular metalloprotease of Aspergillus fumigatus and with the neutral protease I of A. oryzae, confirming that this 43.5 kDa keratinase is a metalloprotease. This keratinolytic metalloprotease could be a virulence-related factor involved in pathophysiological mechanisms of M. canis dermatophytosis.

Partial purification and kinetic studies of exocellular proteinase from Trichophyton mentagrophytes var. erinacei

The dermatophyte Trichophyton mentagrophytes var. erinacei isolated from a patient with tinea cruris was cultured in peptone-glucose broth from which an exocellular proteinase was obtained. The enzyme was partly purified by Sephadex G-100 gel filtration. Its molecular weight was determined to be 33,000 on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The optimal pH was 8.5, the optimal temperature 35 degrees C. The proteolytic activity was specifically increased against casein and inhibited by phenylmethylsulphonyl fluoride. The enzyme was identified as alkaline serine proteinase.

Extracellular enzyme activities of dermatophytes and yeast isolates on solid media

A total of 123 isolates of 14 species of dermatophytes and yeasts were screened for the activity of five extracellular enzymes including elastase, keratinase, protease (gelatinase), lipase and phospholipase, by using solid media. The optimal production and activity of each enzyme was determined with regard to different pH and temperatures. Keratinase activity was high with all the tested fungi with exception of Malassezia furfur. Protease (gelatinase) was produced only by dermatophytes. Elastase was secreted by three dermatophytes viz. Microsporum gypseum, Trichophyton mentagrophytes var. mentagrophytes and T. verrucosum, whereas lipase and phospholipase were detected in all the species except T. violaceum.