Patricia do Rocio Dalzoto

RAPD analyses of recombination processes in the entomopathogenic fungus Beauveria bassiana

To understand the nature of recombination processes in Beauveria bassiana, double-auxotrophic complementary mutant strains were used to produce six heterokaryons by three different methods. Conidia from these heterokaryons were plated on selective media and stable haploid (but not diploid) recombinants were isolated. Single colony recombinants were recovered with both parental and non-parental random amplified polymorphic DNA (RAPD) profiles. These results suggest that a range of different recombination mechanisms may be occurring in B. bassiana.

Potential of Fourier Transform Infrared Spectroscopy (FT-IR) to Differentiate Environmental Aspergillus Fungi Species A. niger , A. ochraceus , and A. westerdijkiae Using Two Different Methodologies

We assessed the ability of Fourier transform infrared spectroscopy (FT-IR) to differentiate three important and morphologically similar Aspergillus species: A. ochraceus and A. westerdijkiae, and A. niger. Fungi were processed by two methods, powdered mycelia and conidiospore–saline solution, and then recorded in a spectrometer. Second derivatives with nine points of smoothing were applied as spectra data pretreatment. Partial least squares regression was used for the species comparison models and a prediction test was used to evaluate the models. The powdered-mycelia methodology correctly identified 100% of the prediction test set to discriminate A. niger from A. ochraceus and A. westerdijkiae; in addition, it had a 86.6% success rate in discriminating A. ochraceus and A. westerdijkiae. This is the first time a study assessed the ability of FT-IR to differentiate A. niger, A. ochraceus, and A. west-erdijkiae, and we believe this technique is very promising for classifying and distinguish fungi isolates.

Paecilomyces niveus Stolk & Samson, 1971 (Ascomycota: Thermoascaceae) as a pathogen of Nasonovia ribisnigri (Mosley, 1841) (Hemiptera, Aphididae) in Brazil

Nasonovia ribisnigri is a key pest of lettuce (Lactuca sativa L.) in Brazil that requires alternative control methods to synthetic pesticides. We report, for the first time, the occurrence of Paecilomyces niveus as an entomopathogen of the aphid Nasonovia ribisnigri in Pinhais, Paraná, Brazil. Samples of mummified aphids were collected from lettuce crops. The fungus P. niveus (PaePR) was isolated from the insect bodies and identified by macro and micromorphology. The species was confirmed by sequencing Internal Transcribed Spacer (ITS) rDNA. We obtained a sequence of 528 bp (accession number HQ441751), which aligned with Byssochlamys nivea strains (100% identities). In a bioassay, 120 h after inoculation of N. ribisnigri with pathogenic P. niveus had an average mortality of 74%. The presence of P. niveus as a natural pathogen of N. ribisnigri in Brazil suggests that it may be possible to employ P. niveus to minimize the use of chemical insecticides.

Occurrence of Candida orthopsilosis in Brazilian tomato fruits (Lycopersicum esculentum Mill.)

We aimed to isolate and identify yeasts found in the tomato fruit in order to obtain isolates with biotechnological potential, such as in control of fungal diseases that damage postharvest fruits. We identified Candida orthopsilosis strains LT18 and LT24. This is the first report of this yeast on Lycopersicum esculentum fruits in Brazil.

Occurrence of sulphate reducing bacteria (SRB) associated with biocorrosion on metallic surfaces in a hydroelectric power station in Ibirama (SC) - Brazil

The aim of this study was evaluate, two methods for the detection and identification of sulphate reducing bacteria (SRB): ML medium and PCR with specific primers for SRB groups. SRB were detected through the selective medium only on carbon steel, which showed corrosion. Employing specific PCR primer, SBR were detected from all the metallic components assayed, even those that did not present visible corrosion spots, such stainless steel and copper alloys. Despite the presence or absence of corrosion at the later stages effectively by using the selective medium,, the initial stages of the corrosion could only be detected by the amplification of total DNA with SRB specific primers. The early detection of SRB could be employed for preventing the damages on metal surfaces before the installation of corrosion processes. Strategies for reducing the time spent on SRB isolation and identification could be auxiliary tools for controlling the corrosion of materials.

Potential for biocontrol of melanized fungi by actinobacteria isolated from intertidal region of Ilha Do Mel, Paraná, Brazil

Actinobacteria occur in many environments and have the capacity to produce secondary metabolites with antibiotic potential. Identification and taxonomy of actinobacteria that produce antimicrobial substances is essential for the screening of new compounds, and sequencing of the 16S region of ribosomal DNA (rDNA), which is conserved and present in all bacteria, is an important method of identification. Melanized fungi are free-living organisms, which can also be pathogens of clinical importance. This work aimed to evaluate growth inhibition of melanized fungi by actinobacteria and to identify the latter to the species level. In this study, antimicrobial activity of 13 actinobacterial isolates from the genus Streptomyces was evaluated against seven melanized fungi of the genera Exophiala, Cladosporium, and Rhinocladiella. In all tests, all actinobacterial isolates showed inhibitory activity against all isolates of melanized fungi, and only one actinobacterial isolate had less efficient inhibitory activity. The 16S rDNA region of five previously unidentified actinobacterial isolates from Ilha do Mel, Paraná, Brazil, was sequenced; four of the isolates were identified as Streptomyces globisporus subsp. globisporus, and one isolate was identified as Streptomyces aureus. This work highlights the potential of actinobacteria with antifungal activity and their role in the pursuit of novel antimicrobial substances.

Redução da severidade do mofo cinzento em mudas de Eucalyptus benthamii tratadas com Trichoderma atroviride

O mofo cinzento, causado por Botrytis cinerea, e responsavel por mortalidade em mudas de Eucalyptus benthamii. O controle biologico e uma alternativa, devido a falta de produtos registrados para eucalipto no Brasil. Este estudo avaliou o fungo endofitico Trichoderma atroviride, isolado de eucalipto, para controle de B. cinerea. O ensaio consistiu na aplicacao de uma suspensao de esporos de T. atroviride em mudas de E. benthamii, 24, 48 ou 72 horas antes de inocular B. cinerea. Como controle positivo utilizou-se iprodione. Mudas inoculadas foram mantidas em casa de vegetacao por 21 dias. A severidade foi avaliada com auxilio de escala de sintomas de 0 (sem lesoes) a 4 (alta severidade). Trichoderma atroviride reduziu significativamente a severidade da doenca, independentemente do tempo de aplicacao previo, de modo similar ao fungicida.