A total of 269 soil samples collected from different habitats in Madras, India, were screened for the presence of dermatophytes by the hair-baiting technique. Three strains of Trichophyton mentagrophytes and 16 strains of Microsporum gypseum complex were isolated. These strains were subjected to the mating experiment. 2/3 soil isolates of Trichophyton mentagrophytes belonged to Arthroderma vanbreuseghemii (+) mating type, and 1/3 was Arthroderma vanbreuseghemii (-) mating type. Similarly 6/70 clinical strains of Trichophyton mentagrophytes isolated in our previous study also belonged to Arthroderma vanbreuseghemii (+) mating type. These 6 strains were isolated from severe cases of tinea capitis in children belonging to rural Madras. The teleomorphic and mating type homology between the clinical and soil isolates of T. mentagrophytes suggest that soil may act as reservoir for these organisms. The incompatible clinical strains of T. mentagrophytes var. interdigitale and A. vanbreuseghemii showed DNA homology, thereby establishing the epidemiologic link which supports the above findings.

1. A strain of Azotobacter chroococcum which could use 2,4-dichlorophenoxyacetic acid (2,4-D) as sole carbon source was isolated. 2. The strain metabolized 2,4-D via p-chlorophenoxyacetic acid, p-chlorophenol and 4-chlorocatechol; the last metabolite was cleaved by catechol 1,2-dioxygenase. 3. The enzyme exhibited broad substrate specificity.

The paper reports the anti-Cryptococcus activity of combination of ethanolic extracts of leaves of Cassia alata and Ocimum sanctum. The activity of combination of the extracts was heat-stable and worked at acidic pH.

The mating patterns of Trichophyton mentagrophytes var. interdigitale (74 isolates) and the Microsporum gypseum complex (17 isolates) of diverse origin and T. rubrum (25 isolates) and T. tonsurans (10 isolates) of clinical origin were studied. The results of the study showed that the teleomorph of the Indian isolates of T. mentagrophytes belong to Arthroderma vanbreuseghemii, undetermined teleomorphs of T. mentagrophytes var. interdigitale (+) mating types, and undetermined teleomorphs of T. mentagrophytes var. interdigitale indeterminate mating types. All the isolates of T. rubrum and T. tonsurans were found to be of the (-) mating type.

The role of ABO blood groups in the carriage rate of dermatophytosis was studied. Blood grouping was done for 108 culture-proven dermatophytosis patients. Forty-nine patients belonged to blood group A, 54 to blood group O, three to blood group B and two to blood group AB. The incidence of dermatophytosis was found to be high in patients of blood group O and A. However, chronicity of the disease was more frequent in those in blood group A. The control group consisted of 100 healthy subjects. Sixteen out of 29 control subjects belonging to blood group A had a history of skin infections. None of the O blood group control subjects had a history of skin infections. Our study suggests that A blood group subjects may be prone to chronic dermatophytosis.