Pedrina Cunha de Oliveira

DIVERSITY OF MICROFUNGI IN THE SANDY SOIL OF IPANEMA BEACH, RIO DE JANEIRO, BRAZIL

The mycobiota of the sandy soil of Ipanema Beach, Rio de Janeiro, Brazil, was investigated in 144 sand samples collected at four different sites along the sea coast, divided into three subsites. for a period of one year. A total of 4285 yeast colonies and of 6956 of colonies filamentous fungi were isolated using conventional media and techniques. Representatives of the filamentous fungi corresponding to a total of 1334 colonies were identified and assigned to 34 genera and 170 species. The genera of highest incidence and their respective numbers of species were as follows: Aspergillus, 30.4%, 32 spp.; Penicillium, 16.2%, 35 spp.; Fusarium, 12,6%, 33 spp.: Trichoderma, 6.4%, 7 spp.; Paecilomyces, 3.7%, 10 spp.: Cladosporium, 3.1 %, 8 spp. and Acremonium, 1.0%, 8 spp. Several other genera and species were detected at quite low occurrences. Non‐sporulating fungi (18.3%) and Coelomycetes (Sphaeropsidales) (1.9%) were also detected. Most of the genera detected belonged to the Deuteroycotina, with fewer proportions belonging to the Ascomycotina and Zygomycotina. Moniliaceae was represented by the largest number of species and Dematiaceae was represented by the largest number of genera. In terms of seasonal distribution, the largest number of filamentous fungi was isolated during the winter and the smallest number the Summer.

Viability and morphological alterations of Paracoccidioides brasiliensis strains preserved under mineral oil for long periods of time

We evaluated the survival and the morphological alteration of 70 strains of Paracoccidioides brasiliensis maintained in the Fungal Culture Collection of Institute Oswaldo Cruz and initially preserved by successive subculturing and later under mineral oil at room temperature from 1923 to 1992. Of the 70 strains preserved under mineral oil, 18 (26%) continued to be viable. The mycelia of the 18 viable strains and the mycelia of four representatives of the non‐viable strains presented transitional micromorphology under mineral oil. Macroscopy and microscopy of the first subcultures of five of the seven strains, taken as random samples from the 18 viable strains and plated onto peptone‐yeast extract‐glucose agar, glucose‐glycine‐yeast extract agar and brain‐heart infusion agar media at room temperature, revealed that all samples appeared to be in a transition phase (Y⇄M). These five strains were unable to grow and complete thermal dimorphism at a temperature of 37°C. Only two strains were able to complete the entire dimorphic process. The period of preservation of these strains under oil was relatively short, i.e. 9 and 10 years. The results demonstrate that less widely spaced subculturing and more appropriate culture and environmental conditions are needed to preserve P. brasiliensis strains under oil.

Penicillium species in mosquitoes from two Brazilian regions

Penicillium species were isolated from 1073 adult mosquitoes and larvae of Aedes spp., Anopheles spp., Culex spp. and Mansonia spp. captured in the northern and southeastern regions of Brazil. In a total of 24 collections, 198 Penicillium strains were identified in 13 species: Penicillium canescens, P. chrysogenum, P. citrinum, P. corylophilum, P. decumbens, P. expansum, P. fellutanum, P. implicatum, P. janthinellum, P. oxalicum, P. purpurogenum, P. viridicatum and P. waksmanii. The total isolation frequency of the Penicillium species in the investigated mosquitoes was: Anopheles spp. (51.5%), Aedes spp. (15.1%), Culex spp. (23.7%) and Mansonia spp. (10.1%). The Penicillium species with the highest incidence in the mosquito genera were: P. corylophilum, P. janthinellum, P. fellutanum and P. waksmanii. The highest number of mosquitoes were captured in the state of Rio de Janeiro, followed by Rond?nia and Minas Gerais.Penicillium species were isolated from 1073 adult mosquitoes and larvae of Aedes spp., Anopheles spp., Culex spp. and Mansonia spp. captured in the northern and southeastern regions of Brazil. In a total of 24 collections, 198 Penicillium strains were identified in 13 species: Penicillium canescens, P. chrysogenum, P. citrinum, P. corylophilum, P. decumbens, P. expansum, P. fellutanum, P. implicatum, P. janthinellum, P. oxalicum, P. purpurogenum, P. viridicatum and P. waksmanii. The total isolation frequency of the Penicillium species in the investigated mosquitoes was: Anopheles spp. (51.5%), Aedes spp. (15.1%), Culex spp. (23.7%) and Mansonia spp. (10.1%). The Penicillium species with the highest incidence in the mosquito genera were: P. corylophilum, P. janthinellum, P. fellutanum and P. waksmanii. The highest number of mosquitoes were captured in the state of Rio de Janeiro, followed by Rondonia and Minas Gerais.

Long-time survival and morphological stability of preserved Sporothrix schenckii strains

Summary. The survival and stability of morphological traits of 33 Sporothrix schenckii strains were evaluated. Strain subcultures were maintained under mineral oil for different periods of time lasting as long as 41 years, or in sterile distilled water for as long as 23 years. Of the 33 strains preserved under mineral oil, 28 (85%) maintained viability and unchanged macro‐ and microscopic characteristics. All of the 4 strains maintained in distilled water also remained viable, with no morphological changes. The results confirm the efficiency of the methods used to preserve strains of the pathogenous and anamorphous fungus Sp. schenckii, especially in laboratories of limited resources.

The entomopathogenic potential of Aspergillus spp. in mosquitoes vectors of tropical diseases

Eleven strains of the most frequent Aspergillus species found in a survey of Brazilian mosquitoes collected in the states of Minas Gerais and Rio de Janeiro, Brazil, were used for bioassays in second‐stage larvae of Aedes fluviatilis and Culex quinquefasciatus.Eleven strains of the most frequent Aspergillus species found in a survey of Brazilian mosquitoes collected in the states of Minas Gerais and Rio de Janeiro, Brazil, were used for bioassays in second-stage larvae of Aedes fluviatilis and Culex quinquefasciatus. Aspergillus ochraceus, A. kanagawaensis and one strain of A. sulphureus were most effective, causing mortality in at least 80% of the larvae of the two mosquito species tested. Variations in entomopathogenic capacity were observed in the experiments with strains of A. sulphureus, A. flavus and A. ochraceus.

Pathogenic action of Penicillium species on mosquito vectors of human tropical diseases.

In vitro bioassays were performed in order to assess the pathogenicity of 13 Penicillium strains in 2nd stage larvae of Aedes aegypti, Aedes fluviatilis, Anopheles aquasalis and Culex quinquefasciatus. Mortality rates began in the first 24 hours, ranging from 0 to 100%. P. corylophilum, P. fellutanum, P. implicatum, P. janthinellum, P. viridicatum and P. waksmanii species tested on Aedes aegypti larvae and at different concentrations presented mortality rates from 0 to 6.6%. These species, when tested on Aedes fluviatilis, Anopheles aquasalis and Culex quinquefasciatus larvae, presented a mortality rate of 3.33% to 100%. Susceptibility of Aedes fluviatilis, Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus mosquitoes to the tested agents, turn P. corylophilum and P. janthinellum into candidates for potential use in biological control of vectors.In vitro bioassays were performed in order to assess the pathogenicity of 13 Penicillium strains in 2nd stage larvae of Aedes aegypti, Aedes fluviatilis, Anopheles aquasalis and Culex quinquefasciatus. Mortality rates began in the first 24 hours, ranging from 0 to 100%. P. corylophilum, P. fellutanum, P. implicatum, P. janthinellum, P. viridicatum and P. waksmanii species tested on Aedes aegypti larvae and at different concentrations presented mortality rates from 0 to 6.6%. These species, when tested on Aedes fluviatilis, Anopheles aquasalis and Culex quinquefasciatus larvae, presented a mortality rate of 3.33% to 100%. Susceptibility of Aedes fluviatilis, Aedes aegypti, Anopheles aquasalis and Culex quinquefasciatus mosquitoes to the tested agents, turn P. corylophilum and P. janthinellum into candidates for potential use in biological control of vectors.

Morphological observations on Absidia corymbifera and Absidia blakesleeana strains preserved under mineral oil

Macro‐ and micromorphology of 30 living subcultures of Absidia corymbifera (10 strains plus three strains of Absidia ramosa) and Absidia blakesleeana (two strains) preserved under mineral oil at room temperature for periods ranging from 3 to 44 years in The Fungal Culture Collection of Instituto Oswaldo Cruz (IOC) were observed and described by permanent mycological preparations mounted in a glycerol 10% and/or Amann lactophenol solution. Vegetative and asexual reproductive structures are illustrated by drawings made with the aid of a camera‐lucida. The study showed that the period of maintenance under mineral oil and the stress which took place during the period of storage did not affect the vegetative and asexual reproductive morphology of the Absidia strains and species studied here.

Evaluation and comparison of the growth and viability of yeast-like cells of Paracoccidioides brasiliensis

Summary. The growth and viability of two Paracoccidioides brasiliensis strains were evaluated in PYG and MMcM media containing no boric acid. The two P. brasiliensis strains exhibited a similar growth pattern in PYG medium, which was considered to be good compared with the growth curves in defined MMcM medium without boric acid. Calculation of cell generation time in the media studied demonstrated that the cells had greater difficulty in forming new generations in MMcM medium containing no boric acid. The present data confirm the literature view that PYG medium is the most complete in terms of nutritive substances for the growth and development of P. brasiliensis.

Reproducción sexual en subcultivos de Absidia blakesleeana preservados en aceite mineral

Resumen Se acoplaron dos subcultivos de Absidia blakesleeana IOC N.° 2425 de la cepa del tipo acoplador (−) preservados en 1959 y en 1981 en un medio de espesa camada de patata dextrosa agar (PDA) bajo aceite mineral esteril y mantenidos a temperatura ambiente en la Coleccion de Hongos del Instituto Oswaldo Cruz-IOC, con la cepa definida de Absidia blakesleeana URM-UFP N.° 2076 de tipo acoplador (+). Despues del acoplamiento, se observaron en el microscopio los segmentos de la linea donde se unieron micelios de ambos tipos. Se observaron cigosporas del subgenero Mycocladus. Los resultados demostraron la conservacion y el restablecimiento de los procesos geneticos y fisiologicos dos subcultivos de tipos de Absidia blakesleeana preservadas en una espesa camada de un medio de patata dextrosa agar bajo aceite mineral esteril.

Ultrastructural differences observed in Paracoccidioides brasiliensis yeast phase cells grown on solid and in liquid medium.

An ultrastructural study was conducted on yeast‐like Paracoccidioides brasiliensis cells grown on liquid and solid peptone—yeast extract—glucose medium. A large proportion of cells grown in liquid medium presented cytoplasmic damage compared with the cells grown on solid medium, which remained intact, suggesting that agar plays an important role in the development of this fungus.