Browsing by Author "Valente, Patricia"
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Item Biodecolourisation and biodegradation of leather dyes by a native isolate of Trametes villosa(Institution of Chemical Engineers, 2017-05-04) Ortiz Monsalve, Santiago; Dornelles, Juliana; Poll, Eduardo; Ramirez Castrillón, Mauricio; Valente, Patricia; Gutterres, MarilizDyeing is an important step in the leather manufacture process. Effluent from this stage contains some types of synthetic dye that may be a threat to the environment and human health. Biological treatment of dye-containing wastewaters by microorganisms has been presented as a cost effective and promising environmentally friendly alternative. In the present work, the potential of Brazilian native white-rot fungi strains, collected and screened to produce extracellular ligninolytic enzymes, was evaluated for the biodecolourisation and biodegradation of different azo tannery dyes. The strain SCS-10 showed high activity of ligninolytic enzymes and allowed the colour removal of dyes in solid media. This isolate was characterised morphologically and identified as Trametes villosa, based on a molecular analysis of the internal transcribed spacer (ITS) region sequences. T. villosa SCS-10 showed high biodecolourisation efficiency for the dyes assessed, achieving 95.71 ± 1.29, 92.76 ± 0.99 and 96.84 ± 1.39% for Acid Red 357, Acid Black 210 and Acid Blue 161, respectively, at 100 mg L−1, 30 °C, pH 5.5 and 150 rpm, within 168 h of treatment. Remarkable peaks of laccase activity (1150–1550 U L−1) were observed during specific periods in the biodecolourisation process. The complete inhibition of Lac activity by sodium azide (NaN3, 0.1 mM) led to biodecolourisation values of 13.29 ± 0.93, 12.30 ± 0.46 and 20.05 ± 2.08% for AR357, AB210 and AB161, respectively. These results confirmed the main role of laccase in colour removal, although biosorption also had a minor involvement in biodecolourisation. In vitro assays also showed the efficiency of decolourisation of the leather dyes. The enzymatic crude extract produced by T. villosa allowed 85.45 ± 3.43 (AR357), 76.96 ± 1.39 (AB210) and 90.17 ± 0.97% (AB161) of biodecolourisation when enhanced by the use of the redox mediator 1-hydroxybenzotriazol (HBT, 1 mM). UV–vis and FTIR spectral analyses confirmed the occurrence of enzymatic biodegradation as the mechanism responsible for colour removal. T. villosa SCS-10 was able to tolerate high concentrations of the dyes (200–1000 mg L−1) and a wide range of pH (4.0–8.0) during biodecolourisation. The native isolate T. villosa SCS-10 is considered a suitable candidate for the treatment of dye-polluted wastewater from the leather industry due to the mechanisms of enzymatic biodegradation and biosorption.Item In Vitro Interactions of Amphotericin B Combined with Non-antifungal Agents Against Rhodotorula mucilaginosa Strains(Springer Netherlands, 2019-01-10) Borba Spader, Tatiana; Ramírez Castrillón, Mauricio; Valente, Patricia; Hartz Alves, Sydney; Severo, Luiz CarlosRhodotorula species are emerging as opportunistic pathogens, causing catheter-associated fungemia in patients with compromised immunity. R. mucilaginosa is considered the most common species involved in human infections. Correct identification and susceptibility testing of Rhodotorula isolates recovered from the blood stream or central nervous system are essential to determine the best management of this unusual infection. The antifungal susceptibility tests showed that Rhodotorula was susceptible to low concentrations of amphotericin B (AMB) but was less susceptible to voriconazole. Combinations of AMB plus several non-antifungal medications were evaluated against 35 susceptible (Rm AMB-S) and resistant (Rm AMB-R) clinical Rhodotorula isolates using the broth microdilution checkerboard technique. We showed that in vitro exposure to increasing concentrations of AMB changed the susceptibility profile to these strains, which were named the Rm AMB-R group. The most synergistic interactions were AMB + simvastatin, followed by AMB + amlodipine and AMB + warfarin. Synergism and antagonism were observed in both groups for the combination AMB + cyclosporine A. AMB combined with a fluoroquinolone (AMB + levofloxacin) also demonstrated antagonism for the Rm AMB-S strains, but a high percentage of synergistic interactions was observed for the Rm AMB-R group. A combination drug approach can provide a different strategy to treat infections caused by AMB-resistant R. mucilaginosa.Item Nitrogen source and pH interact and modulate lipase secretion in a non-clinical strain of Candida parapsilosis(Eduem - Editora da Universidade Estadual de Maringa, 2019-09-16) Krüger da Câmara Ribas, Rodolfo; Carbon, Diórgenes dos Santos; Cazarolli, Juciana Clarice; Hickmann Flôres, Simone; Ramirez Castrillon, Maurício; Valente, PatriciaLipases (E.C. 3.1.1.3) are serine-hydrolases, and act on long chain fatty acid ester bonds. They exhibit specific and enantioselective activities, which are desirable for many industrial applications. This study aimed at screening and optimizing the production of lipases by wild yeast strains from a variety of substrates, as well as characterizing the enzyme. An initial selection was made in oxygenated oil-supplemented minimum medium, and the enzymatic activity of the supernatant was tested over p-nitrophenyl palmitate. One-hundred and twenty-four yeast strains from different substrates were tested, and twenty-three showed significantly higher lipolytic activity (p<0.01). One yeast in particular, QU110, showed best lipase production and therefore was selected for the optimization and characterization processes. This yeast exhibits enzyme secretion in initial pH 6.0, with olive oil and tryptone as carbon and nitrogen sources, respectively. There was a strong interaction between nitrogen source and initial pH, and pH 9.0seems to inhibit enzyme secretion. The crude enzyme (cell-free supernatant) shows stability in surfactants and n-hexane, but not in ethanol or methanol. A Response Surface Model was created and optimal enzyme activity conditions were observed at 36°C and pH 8.0. The lipase is appropriate for transesterification reactions, as the enzyme is more stable in strong apolar solvents than moderately apolar ones. Also, secretion by pH was not reported elsewhere, which should be further investigated and contribute for other yeast bioprocesses as well.Item South Brazilian wines: culturable yeasts associated to bottled wines produced in Rio Grande do Sul and Santa Catarina(Springer Netherlands, 2017-03-24) Ramírez Castrillón, Mauricio; Camargo Mendes, Sandra Denise; Valente, PatriciaA comprehensive understanding of the presence and role of yeasts in bottled wines helps to know and control the organoleptic quality of the final product. The South Region of Brazil is an important wine producer, and the state of “Rio Grande do Sul” (RS) accounts for 90% of Brazilian wines. The state of “Santa Catarina” (SC) started the production in 1975, and is currently the fifth Brazilian producer. As there is little information about yeasts present in Brazilian wines, our main objective was to assess the composition of culturable yeasts associated to bottled wines produced in RS and SC, South of Brazil. We sampled 20 RS and 29 SC bottled wines produced between 2003 and 2011, and we isolated culturable yeasts in non-selective agar plates. We identified all isolates by sequencing of the D1/D2 domain of LSU rDNA or ITS1-5.8 S-ITS2 region, and comparison with type strain sequences deposited in GenBank database. Six yeast species were shared in the final product in both regions. We obtained two spoilage yeast profiles: RS with Zygosaccharomyces bailii and Pichia membranifaciens (Dekkera bruxellensis was found only in specific table wines); and SC with Dekkera bruxellensis and Pichia manshurica. Knowledge concerning the different spoilage profiles is important for winemaking practices in both regions.Item Wild Saccharomyces Produced Differential Aromas of Fermented Sauvignon Blanc Must(MDPI, 2022-04) Mendes, Sandra D. C.; Arcari, Stefany Grützmann; Werner, Simone Silmara; Valente, Patricia; Ramirez Castrillon, MauricioNine Saccharomyces strains, previously isolated from vineyards in Southern Brazil, were used as starter cultures in fermentations of Sauvignon Blanc (SB) must at laboratory scale, to study inter-strain differences in aroma profiles. The molecular profiles differentiated the following isolates from the reference strain (SC2048), which is typically used in wine production: 06CE, 11CE, 33CE, 01PP, 12M, 13PP, 26PP, 28AD, and 41PP. Under the same conditions, each of these strains produced different concentrations and combinations of metabolites, which significantly influenced the aroma of the fermented SB must. Volatile compounds such as octanoic acid, diethyl succinate, and ethyl lactate were associated with the strains 26PP, 41PP, 01PP, and 12M, while strains 33CE, 28AD, 13PP, and 06CE were associated with the production of ethyl acetate and 1-hexanol. Strain 06CE produced 592.87 ± 12.35 µg/L 1-hexanol. In addition, the olfactory activity values (OAVs; we considered only values >1) allowed us to evaluate the participation of each compound in the aroma of the final fermented SB. In conclusion, the selected wild strains are promising candidates for improving the regional characteristics of wine.