A Preliminary Note on Yeasts Associated With Fecal Pellets of Rodents and Marsupials of Atlantic Forest Fragments in Rio de Janeiro, Brazil

A PRELIMINARY NOTE ON YEASTS ASSOCIATED WITH FECAL PELLETS OF RODENTS AND MARSUPIALS OF ATLANTIC FOREST FRAGMENTS IN RIO DE JANEIRO, BRAZIL

Jacqueline Abranches¹; Hilda N. Nóbrega¹; Patrícia Valente^1,2; Leda C. Mendonça-Hagler¹; Allen N. Hagler^1*

¹Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil; ² Escola Técnica Federal de Química, Rio de Janeiro, RJ, Brasil

Submitted: March 03, 1997; Returned to authors for corrections: October 28, 1997;

Approved: July 23, 1998

ABSTRACT

Yeasts had mean counts of above 10⁶ CFU/g in the fecal pellets of small mammals from tropical forest fragments. Most of the 55 species isolated were fermentative ascomycetes, with the most frequent being Debaryomyces hansenii, Pichia membranifaciens and Issatchenkia orientalis, whereas Rhodotorula mucilaginosa was the most frequent yeast of basidiomycetous affinity.

Key words: Small mammals, yeast diversity, yeast vectors

Drosophila

Small mammals like rodents and marsupials feed on a wide variety of substrates found on the ground such as ripe and rotting fruits, fallen leaves, insects and mushrooms (2, 14). Some of the animals have been reported as vectors of mycorrhizal fungi in Australia and North America (2, 7, 8, 9, 10). Since they have a more generalist diet than drosophilids, these animals could be used as a tool for more random sampling of the yeast diversity from a given habitat. If these animals actually function as yeast vectors, the yeast flora present in their fecal pellets should include many transient organisms. Some opportunist pathogenic yeasts should also be expected as residents of their intestinal tract. In the present work we studied the ocurrence of different yeast species in the fecal pellets of small mammals from forest fragments of Rio de Janeiro, Brazil.

Fecal pellets from the marsupials Didelphis marsupialis (common opossum) and Philander frenata (grey four-eyed opossum) and from the rodents Akodon sp. (South American field mouse), Oryzomys sp. (rice rat) and Nectomys squamipes (water rat) were studied. These animals were trapped in small tropical forest fragments in Sumidouro county of Rio de Janeiro, Brazil. Fecal pellets were collected asseptically from the traps in which the animals were caught during the previous night. The traps consisted of cages with the bottoms covered with sterile surgical caps where the fecal pellets were retained. Fecal pellets were transported on ice to the laboratory, stored in the refrigerator, and then 0.5g portions were suspended in 4.5ml of sterile distilled water by agitation with a vortex mixer. 0.1ml of serial dilutions were spread in triplicate on AYM (acidified Yeast Extract - Malt Extract) agar (1% glucose, 0.3% malt extract, 0.3% yeast extract, 0.5% peptone, 2% agar, pH4.5) with 400mg/l of chloranphenicol and acidified Yeast Nitrogen Base (YNB) agar with 0.5% of glucose, pH4.5 + 400mg/l of chloranphenicol and incubated at 22

^oet al.

159 different yeast cultures were isolated from the fecal pellets. The yeasts were identified to 55 species mostly of ascomycetous affinity (130 isolates representing 46 species), many of which were fermentative. Basidiomycetous yeasts were represented by 29 isolates including 9 species (Table 1). Geometric means of plate counts from D. marsupialis fecal samples on YNB + glucose were 1.1x10

⁶⁶P. opossum⁶⁶⁶⁶

Table 1 - ^ab

a= Didelphis marsupialis and Philander frenata.

b= Akodon sp., Nectomys squamipes and Oryzomys sp.

Debaryomyces hansenii, Pichia membranifaciens and Issatchenkia orientalis were the most frequent ascomycetous yeasts, and Rhodotorula mucilaginosa was the most frequent basidiomycetous yeast. Opportunistic pathogenic yeasts like Candida albicans, Candida parapsilosis and Candida tropicalis were mainly found associated with marsupials. The dermatophyte Trichosporon beigelii was also found but in low frequency.

Yeasts reported from tropical fruits in Brazil have been mostly species with low assimilation profiles and with counts on ripe fruits often in the range of 10

⁵⁷

Small mammals are often reported as natural reservoirs of pathogenic microorganisms, and some human diseases are related with them. Although opportunistic pathogenic yeasts were in low frequency, our data suggests that these animals could disperse some opportunistic pathogenic yeasts, including C. albicans, in the environment. The presence of a diverse yeast flora associated with the fecal pellets of small mammals is consistent with these animals using a wide variety of food items and allows them to act as vectors of yeasts in nature.

^o

RESUMO

Uma nota preliminar sobre leveduras associadas a pelotas fecais de roedores e marsupiais de fragmentos de Mata Atlântica do Rio de Janeiro, Brasil.

Leveduras em pelotas fecais de pequenos mamíferos provenientes de fragmentos de Mata Atlântica tiveram contagem média acima de 10⁶ UFC/g. A maioria das 55 espécies isoladas foi de ascomicetos fermentativos, com as mais freqüentes sendo Debaryomyces hansenii, Pichia membranifaciens e Issatchenkia orientalis, enquanto Rhodotorula mucilaginosa foi a levedura mais freqüente de afinidade basidiomicética.

Palavras-chave: Pequenos mamíferos, diversidade de leveduras, vetores de leveduras.

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*

Corresponding author. Mailing address: Instituto de Microbiologia Prof. Paulo de Góes, Bloco I, CCS, Universidade Federal do Rio de Janeiro, Ilha do Fundão, CEP 21941-590, Rio de Janeiro, RJ, Brasil.

Publication Dates

• Publication in this collection
  26 Feb 1999
• Date of issue
  Sept 1998

History

• Reviewed
  28 Oct 1997
• Received
  03 Mar 1997
• Accepted
  23 July 1998