Cledir Santos

Structural diversity of aspergillus (section nigri) spores

The taxonomy of fungal species, similar to that of many other microorganisms, suffers frequent revisions due to the discovery of new species and to the development and gathering of characterization data and morphological information. Morpho-taxonomy helps in the identification of many species. This work presents the macro, micro-morphological, and spectral mass analyses for phenotypic characterization of 13 species of Aspergillus section Nigri, showing that the characterization of spores (conidia) by scanning electron microscopy can be used as a tool to discriminate key morphological characteristics and separate closely related fungi. These results were corroborated by colony plates, stereomicroscopy, light microscopy, and spectral mass data.

Filamentous fungal characterizations by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Matrix‐assisted laser desorption/ionization time‐of‐flight intact cell mass spectrometry (MALDI‐TOF ICMS) is coming of age for the identification and characterization of fungi. The procedure has been used extensively with bacteria. UV‐absorbing matrices function as energy mediators that transfer the absorbed photoenergy from an irradiation source to the surrounding sample molecules, resulting in minimum fragmentation. A surprisingly high number of fungal groups have been studied: (i) the terverticillate penicillia, (ii) aflatoxigenic, black and other aspergilli, (iii) Fusarium, (iv) Trichoderma, (iv) wood rotting fungi (e.g. Serpula lacrymans) and (v) dermatophytes. The technique has been suggested for optimizing quality control of fungal Chinese medicines (e.g. Cordyceps). MALDI‐TOF ICMS offers advantages over PCR. The method is now used in taxonomic assessments (e.g. Trichoderma) as distinct from only strain characterization. Low and high molecular mass natural products (e.g. peptaibols) can be analysed. The procedure is rapid and requires minimal pretreatment. However, issues of reproducibility need to be addressed further in terms of strains of species tested and between run variability. More studies into the capabilities of MALDI‐TOF ICMS to identify fungi are required.

Fourier transform infrared as a powerful technique for the identification and characterization of filamentous fungi and yeasts

Fourier transform infrared is considered a powerful technique for characterizing chemical compositions of complex probes such as microorganisms. It has successfully been applied to fungal identification. In this paper, the current state of identification and characterization of filamentous fungi and yeasts by Fourier transform infrared is reviewed.

Species identification of Aspergillus section Flavi isolates from Portuguese almonds using phenotypic, including MALDI-TOF ICMS, and molecular approaches.

Aims:  Section Flavi is one of the most significant sections in the genus Aspergillus. Taxonomy of this section currently depends on multivariate approaches, entailing phenotypic and molecular traits. This work aimed to identify isolates from section Flavi by combining various classic phenotypic and genotypic methods as well as the novel approach based on spectral analysis by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF ICMS) and to evaluate the discriminatory power of the various approaches in species identification.

Filamentous fungi from the Atlantic marine sponge Dragmacidon reticulatum

Dragmacidon reticulatum is a marine sponge of wide occurrence in the Eastern and Western Atlantic. Little is known about D. reticulatum fungal diversity. Filamentous fungi recovered from D. reticulatum were assessed in the present study using a polyphasic taxonomic approach, including classical morphology, molecular biology and MALDI-TOF ICMS. Ninety-eight fungal strains were isolated from two D. reticulatum samples by using six different culture media, which were identified up to the genus level. Sixty-four distinct fungal ribotypes were obtained, distributed among twenty-four different genera belonging to the Ascomycota and Zygomycota. Representatives of Penicillium and Trichoderma were the most diverse and abundant fungi isolated. Amongst Penicillium spp. three isolates belonged to the same ribotype can be considered as a putative new species. Data derived from the present study highlight the importance of using a polyphasic approach to get an accurate identification in order to structure a reliable culture collection.

Filamentous fungi in drinking water, particularly in relation to biofilm formation

The presence of filamentous fungi in drinking water has become an area worthy of investigation with various studies now being published. The problems associated with fungi include blockage of water pipes, organoleptic deterioration, pathogenic fungi and mycotoxins. Fungal biofilm formation is a less developed field of study. This paper updates the topic and introduces novel methods on fungal biofilm analysis, particularly from work based in Brazil. Further recommendations for standard methodology are provided.

Matrix-assisted laser desorption/ionization time-of-flight intact cell mass spectrometry to detect emerging pathogenic Candida species.

Matrix-assisted laser desorption/ionization time-of-flight intact cell mass spectrometry (MALDI-TOF-ICMS) was used to differentiate pathogenic Candida species, difficult to identify by traditional methods such as growth and biochemical reactions. Results showed that species complexes like C. parapsilosis, C. orthopsilosis, and C. metapsilsosis, and very closely related species like C. glabrata and C. bracarensis, and C. albicans and C. dubliniensis could be clearly separated. MALDI-TOF-ICMS stands out as a promising tool for the rapid detection of emerging pathogens.

Development and optimization of a new MALDI-TOF protocol for identification of the Sporothrix species complex

Accurate species identification of the Sporothrix schenckii complex is essential, since identification based only on phenotypic characteristics is often inconclusive due to phenotypic variability within the species. We used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for species identification of 70 environmental and clinical isolates of the Sporothrix complex. A reference database was established for MALDI-TOF MS-based species identification according to minor adjustments in the manufacturers guidelines. The MALDI-TOF MS clearly distinguished strains of Sporothrix brasiliensis, Sporothrix globosa, Sporothrix mexicana, S. schenckii, Sporothrix luriei and Sporothrix pallida, enabling identification of all isolates at the species level, as confirmed by partial calmodulin gene sequence analyses. The present methodology is simple, reliable, rapid and highly suitable for routine identification in clinical mycology laboratories and culture collections, particularly for updating and reclassifying of deposited Sporothrix isolates.

Synthesis, characterization and antifungal activity of chemically and fungal‐produced silver nanoparticles against Trichophyton rubrum

To characterize and explore the potential in extracellular biosynthesis of silver nanoparticles (AgNPs) by Penicillium chrysogenum and Aspergillus oryzae and to investigate the antifungal effect of chemically vs biologically synthesized AgNPs comparing with conventional antifungal drugs against Trichophyton rubrum.

Deciphering the Contribution of Biofilm to the Pathogenesis of Peritoneal Dialysis Infections: Characterization and Microbial Behaviour on Dialysis Fluids

Infections are major complications in peritoneal dialysis (PD) with a multifactorial etiology that comprises patient, microbial and dialytic factors. This study aimed at investigating the contribution of microbial biofilms on PD catheters to recalcitrant infections and their interplay with PD related-factors. A prospective observational study was performed on 47 patients attending Centro Hospitalar of Porto and Vila Nova de Gaia/Espinho to whom the catheter was removed due to infectious (n = 16) and non-infectious causes (n = 31). Microbial density on the catheter was assessed by culture methods and the isolated microorganisms identified by matrix-assisted laser desorption/ionization time-of-flight intact cell mass spectrometry. The effect of conventional and three biocompatible PD solutions on 16 Coagulase Negative Staphylococci (CNS) and 10 Pseudomonas aeruginosa strains planktonic growth and biofilm formation was evaluated. Cultures were positive in 87.5% of the catheters removed due infectious and 90.3% removed due to non-infectious causes. However, microbial yields were higher on the cuffs of catheters removed due to infection vs. non-infection. Staphylococci (CNS and Staphylococcus aureus) and P. aeruginosa were the predominant species: 32% and 20% in the infection and 43.3% and 22.7% in the non-infection group, respectively. In general, PD solutions had a detrimental effect on planktonic CNS and P. aeruginosa strains growth. All strains formed biofilms in the presence of PD solutions. The solutions had a more detrimental effect on P. aeruginosa than CNS strains. No major differences were observed between conventional and biocompatible solutions, although in icodextrin solution biofilm biomass was lower than in bicarbonate/lactate solution. Overall, we show that microbial biofilm is universal in PD catheters with the subclinical menace of Staphylococci and P. aeruginosa. Cuffs colonization may significantly contribute to infection. PD solutions differentially impact microbial species. This knowledge is important for the development of infection diagnosis, treatment and preventive strategies.