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The depletion of petroleum and other platform chemical resources are a global concern; therefore alternative substrates must be identified to replace these current sources. Thus allowing research in fungal biotechnology to prosper, as filamentous fungi can utilize second-generation feedstocks or agricultural waste to produce these petroleum derived platform chemicals. This research focuses on the ability of filamentous fungi to use different second-generation feedstocks such as wheat bran and sugar cane bagasse to generate platform chemicals of interest, namely being itaconic acid (IA) and other organic acids of interest, such as citric acid. This study focused on the metabolite producing capabilities of Aspergillus terreus, initially in a shake flask fermentation environment and then in an Airlift Bioreactor environment utilizing hydrolyzed wheat bran and sugar cane bagasse as a substrate source to produce metabolites of interest. The initial shake flask fermentation experiment involved inoculation and incubating A. terreus in hydrolyzed wheat bran with additional minerals at 30°C for 5 days at a pH range of between 3-4. The result yielded itaconic acid and citric acid concentrations of 1.01g/l and 6.23g/l at their peaks, respectively. The airlift bioreactor was run for 16 days with a constant pH range between 3-4, at a temperature of 30°C with a dissolved oxygen level of 20g/l. The result of the study yielded a high itaconic acid and citric acid concentration peaking at 59.4 g/l and 59.2 g/l, respectively.

Fusarium verticillioides is a pathogen of maize causing ear rot and stalk rot. The fungus also produces fumonisins, a group of mycotoxins linked to disorders in animals and humans. A cluster of genes, designated FUM genes, plays a key role in the synthesis of fumonisins. However, our understanding of the regulatory mechanism of fumonisin biosynthesis is limited. It was previously demonstrated that Cpp1, a protein phosphatase type 2A (PP2A) catalytic subunit, negatively regulates fumonisin production and is involved in cell shape maintenance. Typically, a structural A subunit, a catalytic C subunit, and a regulatory B subunit form PP2A heterotrimer complex. Significantly, there are two PP2A regulatory subunits in F. verticillioides genome, Ppr1 and Ppr2, which are homologous to Saccharomyces cerevisiae Cdc55 and Rts1, respectively. Based on preliminary data, I hypothesized that Ppr1 and Ppr2 are independently involved in the regulation of fumonisin biosynthesis and/or cell development, and to test this hypothesis I generated gene-deletion mutants of PPR1 and PPR2. The ppr1 deletion strain (Δppr1) resulted in drastic growth defect, but with increased microconidia production. The ppr2 deletion mutant strain (Δppr2) showed elevated fumonisin production similar to the Δcpp1 strain. Germinating Δppr1 conidia formed abnormally swollen cell with central septation. Δppr2 showed early hyphal branching during conidia germination. Results from this study suggest that two PP2A regulatory subunits in F. verticillioides carry out unique roles in regulating fumonisin biosynthesis and fungal development.

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abstract: Telomerase ribonucleoprotein is a unique reverse transcriptase that adds telomeric DNA repeats to chromosome ends. Telomerase RNA (TER) is extremely divergent in size, sequence and has to date only been identified in vertebrate, yeast, ciliate and plant species. Herein, the identification and characterization of TERs from an evolutionarily distinct group, filamentous fungi, is presented. Based on phylogenetic analysis of 69 TER sequences and mutagenesis analysis of in vitro reconstituted Neurospora telomerase, we discovered a conserved functional core in filamentous fungal TERs sharing homologous structural features with vertebrate TERs. This core contains the template-pseudoknot and P6/P6.1 domains, essential for enzymatic activity, which retain function in trans. The in vitro reconstituted Neurospora telomerase is highly processive, synthesizing canonical TTAGGG repeats. Similar to Schizosaccharomycetes pombe, filamentous fungal TERs utilize the spliceosomal splicing machinery for 3' processing. Neurospora telomerase, while associating with the Est1 protein in vivo, does not bind homologous Ku or Sm proteins found in both budding and fission yeast telomerase holoenzyme, suggesting a unique biogenesis pathway. The development of Neurospora as a model organism to study telomeres and telomerase may shed light upon the evolution of the canonical TTAGGG telomeric repeat and telomerase processivity within fungal species. / Dissertation/Thesis / Ph.D. Biochemistry 2011

Made available in DSpace on 2014-06-11T19:27:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-28Bitstream added on 2014-06-13T19:56:06Z : No. of bitstreams: 1 simoes_mlg_me_rcla.pdf: 924529 bytes, checksum: 4fd62ec448289172b02333ca84efaa63 (MD5) / Neste estudo, foram isoladas 67 linhagens de fungos filamentosos de solo de área de caatinga, sendo as coletas efetuadas em períodos seco e chuvoso, com o objetivo de se conhecer a biodiversidade deste bioma não explorado e avaliar o potencial destes fungos na produção de xilanase. Algumas linhagens não foram identificadas por inexistência de metodologias específicas e outras foram identificadas através de métodos microscópicos e bioquímicos. Foi efetuada uma triagem dos fungos potencialmente produtores desta enzima em meio de Vogel contendo xilano 1% como única fonte de carbono e avaliou-se através do Método Turbidimétrico Automatizado (Bioscreen-C), a melhor fonte de carbono para crescimento dos fungos selecionados. Os resultados obtidos nos cultivos em MFS, foram inexpressivos quando comparados aos obtidos em MFT. Os melhores produtores de xilanase em MFT foram cultivados em meio líquido de Vogel e MFT com adição individual de outras fontes de carbono a 1% (carbometilcelulose- CMC, xilano e a melhor fonte de carbono para crescimento, determinada pelo Bioscreen-C) em temperaturas apropriadas, pH 5, por 5 dias, inóculo de 1 x 107 esporos/mL. O CMC causou repressão catabólica na síntese de xilanase por estes fungos tendo a adição do xilano apresentado o mesmo efeito, com exceção de Trichoderma viride, que teve sua atividade aumentada para 143,0 U/mL e Aspergillus niger 11 que teve sua atividade aumentada de 33,4 U/mL para 57,1 U/mL. / In this study, 67 strains of filamentous fungi were isolated from caatinga area, the collections were performed during the dry and rainy period, aiming to know the biodiversity of this not explored bioma and to evaluate the potential of these fungi to produce xylanase. Some of the strains were not identified due to the lack of specific methodologies and others were identified through microscopic and biochemical methods. A selection of the fungi which were considered potentially producers of xylanase was carried out in Voguel medium containing 1% of xylan as an only carbon source, and through a Automatized Turbidimetric Method (Bioscreen - C) the best carbon source for the fungi growth was evaluated. The results obtained in SBM were not expressive when compared to the ones obtained in WBM. The best xylanase producers in WBM were cultivated in Voguel liquid medium and WBM adding individually other carbon sources at 1% (carboxymethylcellulose -CMC; xylan; and the best growth carbon source determined by Bioscreen-C) at appropriated temperatures, pH 5,0 ; for 5 days, and a spore concentration of 1 x107 spores/mL. The CMC addition caused catabolic repression in xylanase production by these fungi, xylan addition showed the same effect, but Trichoderma viride 13 and Aspergillus niger 11 which have their activities increased from 39,21 U/mL to 143,0 U/mL and from 33,4 U/mL to 57,1 U/mL, respectively.

Foram estudadas trinta e uma cepas fúngicas não identificadas, as quais foram denominadasX1 a X31. O potencial fotoprotetor foi avaliado pela medida espectrofotométrica da absorçãodos extratos na região do UV (280-400 nm). Os extratos com os melhores perfis de absorção em cultura estacionária foram X1, X2, X6, X12, X13, X18, X19, X22, X24 e X31 e, em cultura agitada X4 e X17. A reprodutibilidade do processo foi avaliada e as cepas fúngicas que apresentaram coeficiente de variação menor que 15% foram selecionadas para o estudo de fotoestabilidade. A fotoestabilidade dos extratos foi avaliada pela medida da viabilidade celular de fibroblastos L929 tratados com extratos previamente irradiados sob radiação UVA (11,2 J/cm2) e UVB (3,43 J/cm2) e extratos não irradiados, bem como, pela comparação das áreas sob as curvas de absorção na região do UV dos extratos irradiados e não irradiados. Os extratos selecionados para o estudo de fotoestabilidade foram X4, X12, X19, X22, X24 e X31. Os extratos não irradiados apresentaram os seguintes valores deIC50 para viabilidade celular (citotoxidade): X4-130µg/ml, X19-20µg/ml, X22-10 µg/ml e X24-60µg/ml. Após a radiação UVA e UVB, os extratos apresentaram redução significativa da viabilidade celular em relação ao IC50 dos extratos não irradiados. Sob luz UVB, os extratos X12 (IC50 35µg/ml) e X31 (IC50 70µg/ml) mantiveram a mesma porcentagem de redução da viabilidade celular quando comparado ao IC50 dos extratos não irradiados. No entanto após exposição à luz UVA, o extrato X12 aumentou a viabilidade celular de 50% (quando não irradiado) para 75% (irradiado). Enquanto que o extrato X31, mesmo após a radiação UVA, manteve a mesma redução de 50% da viabilidade celular. Nessa etapa os extratos selecionados foram os X12 e X31. O espectro de absorção na região do UV obtido para o extrato X12 mostrou uma redução da absorbância de 28,3% sob radiação UVB e de 60% sob radiação UVA em relação ao extrato não irradiado. O extrato X31 apresentou uma redução da absorbância de 17,6% e30% sob radiação UVB e UVA respectivamente, em relação ao extrato não irradiado. Os fungos selecionados foram identificados por PCR, sugerindo que o fungo X12 seja o Aspergillus terreus e o X31 seja o Talaromyces pinophilus. Por fim, foi feita a identificação da substância ativa do extrato X12 empregando a técnica de desreplicação, a qual fez o uso da instrumentação analítica acoplada UHPLC-DAD-(ESI)-HRMS associada ao banco de dados Chapman& Hall\'s Dictionary of Natural Products (DNP). No extrato X12 o composto majoritário foi identificado como sendo a citreoviridina. Assim, os resultados do presente trabalho permitiu estabelecer um procedimento para a seleção de fungos produtores de compostos absorvedores de radiação UV, que poderia ser aplicado na obtenção de novos filtros orgânicos naturais para protetores solares. / It were studied thirty-one fungal strains not identified, which were named X1 to X31. The photoprotective potential was assessed spectrophotometrically by measuring absorption of the extract in the UV region (280-400 nm). The extracts that presented the best absorption profiles in stationary culture were X1, X2, X6, X12, X13, X18, X19, X22, X24 and X31, and X4 and X17 in stirred culture. The reproducibility of the process was evaluated and fungal strains that showed a coefficient of variation lower than 15% were selected for the study of photostability. The photostability of the extracts was assessed by measuring cell viability of L929 fibroblasts treated with extracts previously irradiated under UVA light (11,2 J/cm2) and UVB (3,43 J/cm2) and not irradiated extracts, as well as by comparison of the areas under the curves of absorption in the UV region of the irradiated and non-irradiated extracts. The extracts selected for the study of photostability were X4, X12, X19, X22, X24 and X31. The non-irradiated extracts showed the following IC50 values for cell viability (cytotoxicity): X4- 130?g/ml X19-20?g/ml, X22-10/ml and X24-60?g/ml. After UVA and UVB radiation, the extracts showed significant reduction in cell viability compared to the IC50 of the unirradiated extracts. Under UVB light, the X12 extracts (IC50 35?g/ml) and X31 (IC50 70mg/ml) maintained the same percentage of cell viability reduction when compared to the IC50 of the unirradiated extracts. However after exposure to UVA light, X12 extract increased the cell viability from 50% (when not irradiated) to 75% (irradiated). While X31 extract even after the UVA irradiation, remained the same 50% of reduction in cell viability. At this stage the selected extracts were X12 and X31. The absorption spectrum in the UV region obtained for X12 extract showed a decrease in absorbance of 28.3% under UVB and 60% under UVA radiation relative to non-irradiated extract. The X31extract showed a reduction in absorbance of 17.6% and 30% in UVA and UVB radiation, respectively, compared to non-irradiated extract. The selected fungi were identified by PCR, suggesting that X12 fungus is Aspergillus terreus and X31 is the Talaromyces pinophilus. Finally it was identified the active substance of X12 extract employing dereplication technique which makes use of coupled analytical instrumentation UHPLC-DAD- (ESI) HRMS associated to the Chapman and Hall\'s Dictionary of Natural Products (DNP) database. The majority compound of X12 extract was identified as the citreoviridin. Thus, the results of this study allowed us to establish a procedure for the selection of producers of UV absorbing compounds from fungi, which could be applied in obtaining new natural organic filters for sunscreens.

Orientador: Luis Henrique Souza Guimarães / Banca: Saulo Santesso Garrido / Banca: Hamilton Cabral / Resumo: As invertases ou β-D-frutofuranosidases (EC 3.2.1.26) são responsáveis pela produção da mistura equimolar de glicose e frutose, conhecida como açúcar invertido, através da hidrólise da ligação β 2-1 da molécula de sacarose. Essa mistura apresenta sabor mais doce que a sacarose e é destinada à diversos fins na indústria alimentícia (doces, xaropes, leite condensado e bebidas). É importante destacar que o produto obtido por hidrólise enzimática é bastante superior ao obtido por hidrólise ácida. A hidrólise catalisada pela enzima β-D-frutofuranosidase produz um xarope de alta qualidade com ausência de hidroximetilfurfural e sem desenvolvimento de cor. Diante do interesse industrial e biotecnológico, e das diversas aplicações dessa enzima, o objetivo deste trabalho foi investigar a produção de β-D-frutofuranosidase extracelular pelo fungo filamentoso Aspergillus niveus através de Fermentação em Estado Sólido (FES) purificando-a e caracterizando-a bioquimicamente. Entre os substratos testados em FES, a maior produção β-D-frutofuranosidásica foi obtida em casca de mandioca, com granulometria de 10 mesh, umidificada na proporção de 1:1 com água de torneira, a uma temperatura de 30ºC com umidade relativa de 30%, por um período de 9 dias de incubação. A β-D-frutofuranosidase extracelular obtida em FES foi purificada 6,53 vezes com recuperação de 5,27%, obtendo-se em SDS-PAGE 8% uma única banda protéica (37 kDa), e massa molecular nativa de 91,2 kDa estimada por Sepharose CL-6B. A temp... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The invertases or β-D-fructofuranosidases (EC 3.2.1.26) are responsible for the production of an equimolar mixture of glucose and fructose, known as invert sugar, by hydrolysis of β 2-1 bond of the sucrose molecule. This mixture is sweeter than sucrose and is intended for various purposes in the food industry (sweets, syrup, condensed milk and drinks). It is important to note that the product obtained by enzymatic hydrolysis is much higher than that obtained by acid hydrolysis. The hydrolysis catalyzed by β-D-fructofuranosidase enzyme produces a high-quality syrup without hydroxymethylfurfural and color development. Before the industrial and biotechnological interest, and the various applications of this enzyme, the aim of this study was to investigate the production of the extracellular β-D-fructofuranosidase by filamentous fungus Aspergillus niveus under Solid Fermentation State (SSF) purifying it and characterizing it biochemically. Among the substrates tested in the SSF, the highest yield of β-D-fructofuranosidase was obtained in cassava hulls with a particle size of 10 mesh, humidified in the ratio 1:1 with tap water and maintained at 30°C with a relative humidity of 30%, for 9 days of incubation. The extracellular β-Dfructofuranosidase obtained in SSF was purified 6.53-folds with a recovery of 5.27%. A single protein band (37 kDa) was obtained in 8% SDS-PAGE and the native molecular mass was estimated as 91.2 kDa by Sepharose CL-6B. The optimum temperature and pH for ac... (Complete abstract click electronic access below) / Mestre