Because Candida species have innately highly variable antifungal susceptibilities, the availability of a fast and reliable species identification test is very important so that suitable and effective therapeutic measures may be taken. Using three oligonucleotide primers, we established a randomly amplified polymorphic DNA (RAPD) analysis method that enabled direct identification of the most common opportunistic pathogenic Candida species. RAPD analysis revealed a characteristic molecular fingerprint for each Candida species. Differences between the profiles for Candida albicans and C. dubliniensis were evident. RAPD analysis is a relatively easy, reproducible, and reliable technique that can be useful in providing genetic fingerprints for the identification of strains. In addition, a collection of different C. albicans strains was identified by a specific PCR based on multiple secreted aspartic proteinase (SAP) genes and the dipeptidyl aminopeptidase (DAP2) gene. Our findings demonstrate that PCR based upon the SAP and DAP2 sequences is a simple, rapid, clear, and direct technique for the identification and differentiation of C. albicans and C. dubliniensis.

Las plantaciones de cacao de Tabasco tienen similitud con las selvas tropicales. Este agroecosistema ayuda a conservar la biodiversidad. En la entidad, los estudios de diversidad en el agroecosistema cacao están relacionados con la vegetación, mamíferos, avifauna, insectos y arañas. La diversidad de hongos no se ha estudiado. El objetivo del presente trabajo fue caracterizar la diversidad de Hypocrea/Trichoderma presente en la rizósfera de Theobroma cacao en Tabasco, México. Para este fin, se obtuvieron e identificaron 96 aislamientos de Hypocrea/Trichoderma mediante morfología y secuencias de ITS. Las especies encontradas fueron Trichoderma asperellum, T. brevicompactum, T. harzianum/H. lixii, T. koningiopsis/H. koningiopsis, T. longibrachiatum/H. sagamiensis, T. pleuroticola, T. reesei/H. jecorina, T. spirale y T. virens/H. virens. Los índices de riqueza (D Mg) y abundancia (H) fueron de 1.75 y 1.69, respectivamente. El índice de uniformidad de Pielou (J) fue de 0.77. La mayor diversidad de Trichoderma/Hypocrea se detectó en la subregión Chontalpa. Trichoderma harzianum/H. lixii fue la especie más abundante. Todas las especies encontradas son primer registro para el agroecosistema cacao en Tabasco. Trichoderma asperellum, T. brevicompactum, T. koningiopsis/ H. koningiopsis, T. pleuroticola, T. reesei/H. jecorina y T. spirale son registros nuevos para la entidad y Trichoderma pleuroticola es registro nuevo para México. Derechos Reservados © 2015 Universidad Nacional Autónoma de México, Instituto de Biología. Este es un artículo de acceso abierto distribuido bajo los términos de la Licencia Creative Commons CC BY-NC-ND 4.0.

Candida albicans STE13ca gene was identified by its homology to the Saccharomyces cerevisiae STE13 gene that encodes for the dipeptidyl aminopeptidase A (DAP A) involved in the maturation of alpha-factor mating pheromone. Our study revealed that C. albicans ATCC 10231 depicts dipeptidyl aminopeptidase activity. We also analyzed the expression of the STE13ca gene homologue from this pathogenic yeast. This gene of 2793 pb is homozygotic and encodes for a predicted protein of 930 amino acids with a molecular weight of 107,035 Da. The predicted protein displays significant sequence similarity to S. cerevisiae Ste13p. This C. albicans gene is located in chromosome R. STE13ca gene increases its levels of expression in conditions of nutritional stress (proline as nitrogen source) and during formation of the germinal tube, suggesting a basic biological function for the STE13ca in this yeast.

Proteases of Candida dubliniensis have been scarcely studied, these enzymes may play an important role in nitrogen metabolism, post-translational processing, nutritional stress, dimorphism, virulence, etc. In this work, we report the presence of five different intracellular proteases and one extracellular proteolytic activity. The intracellular proteases are: aminopeptidase ycdAPE, carboxypeptidase ycdCP, dipeptidyl aminopeptidase ycdDAP, proteinases ycdPrA and ycdPrB, and extracellular protease Sap activity, measured under several nutritional conditions. C. dubliniensis produced the highest level of intracellular proteolytic enzymes, i.e., ycdAPE, ycdCP, ycdDAP, ycdPrA and ycdPrB in media with peptone during stationary growth phase. Chelating agents affected mainly APE activity; whereas ycdCp, ycdDAP, and ycdPrB were affected by serine protease inhibitors; ycdPrA was affected by pepstatin, an aspartyl protease inhibitor. We found Sap activity in C. dubliniensis in YCB-SBA medium, this activity was inhibited by pepstatin inhibitor. Southern analysis revealed the presence of at least four genes encoding Sap in the C. dublinienisis genome (using as probes SAP1, SAP2, SAP3, and SAP4-6 genes from C. albicans).