Navegando por Assunto "Filamentous fungus"

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Acesso aberto (Open Access)
Hidrólise da quitosana: obtenção de um extrato enzimático e caracterização do produto hidrolisado
(Universidade Federal do Pará, 2022-08-09) GONÇALVES, Cleidiane Gonçalves e; FERREIRA, Nelson Rosa; http://lattes.cnpq.br/3482762086356570; https://orcid.org/0000-0001-6821-6199; LOURENÇO, Lúcia de Fátima Henriques; http://lattes.cnpq.br/7365554949786769; https://orcid.org/0000-0001-5009-8235
Chitin, extensively found in crustaceans exoskeletons, insects, and microorganisms, has limited usage due to its low solubility in aqueous solution, requiring its partial deacetylation to obtain chitosan. Chitosan's depolymerization has attracted considerable attention, as its oligomers have high water solubility, biocompatibility, and non-toxicity, as well as beneficial properties such as antimicrobial, antioxidant, and antitumor properties. For this reason, in this research, a review article was produced (Chapter I) based on the main methods of chitosan hydrolysis, besides analyzing the parameters that influence the acquisition, and characteristics of hydrolysis results, effectively and at a lower cost. Among the approaches studied, enzymatic hydrolysis excels due to its control ease and performance under milder conditions, making it possible to use low-cost enzymes belonging to the glycoside hydrolases group. Thus, enzymatic hydrolysis was defined as a technique for various sizes of chitosan acquisition (Chapter II) through the production of an enzymatic extract (integral enzymatic extract - IEE) from a filamentous fungus strain. The enzyme identification present in the IEE showed exo-chitinases, endo-chitinase, and cellobiohydrolase. Considering the same reaction conditions, the IEE showed greater efficiency than the commercial enzyme (Celluclast 1.5 L®), which was used as a parameter because it is an enzyme capable of cleaving the β-1,4-glycosidic bond of chitosan - similar to chitosanase, besides presenting a lower cost. The IEE reduced the molecular weight of chitosan by 47.80; 75.24 and 93.26% at 2.0; 5.0, and 24 h, respectively. Through the FTIR analysis, a lower absorbance of the spectral signals of chitosan oligomers was detected, and the crystallinity reduced after 3.0 h of hydrolysis. Based on this study, we can infer that enzymatic hydrolysis, under established conditions, is effective at obtaining lower molecular weight chitosan using unpurified crude extract.
Acesso aberto (Open Access)
Influência do fungo cladosporium cladosporioides no índice de qualidade e perfil aromático de sementes de cacau (Theobroma cacao L.) fermentadas
(Universidade Federal do Pará, 2020-11-17) KONAGANO, Evelyn Mayumi Hanawa; FERREIRA, Nelson Rosa; http://lattes.cnpq.br/3482762086356570; LOPES, Alessandra Santos; http://lattes.cnpq.br/8156697119235191
Cocoa is a fruit that has great scientific and economic importance. However, the existing microbial diversity between lots and locations, results in different products, in relation to physical, chemical and sensory attributes. Thus, Araujo et al. (2014) proposed variables that can be used in order to standardize the quality indices of this raw material, in addition to what is already governed by legislation. In addition, there are several studies that use starter cultures of bacteria and yeasts in the fermentation of cocoa seeds, in order to obtain beans with superior quality and desirable aromas, in addition to resulting in a more homogeneous fermented raw material between different batches and locations. However, there are still no reports of the use of filamentous fungi as a starter culture, despite having biotechnological potential, mainly due to the excretion of several enzymes. A species that has already been reported in the fermentation of cocoa seeds is Cladosporium cladosporioides, which produces antifungal metabolites aimed at plant pathogens, in addition to having pectinase, laccase, glucanase, amylase, cellulase and xylanase enzymatic activity, important for the improvement of the cocoa bean fermentation process. The objective of this study is, therefore, to evaluate the influence of this filamentous fungus during the fermentation process, in an unprecedented way, through physicochemical and microbiological analyses. For this, two fermentation experiments were carried out: without inoculum (control) and with starter culture. The use of filamentous fungus did not significantly impact the formation of aromatic compounds in the almonds, compared to the control experiment. However, the presence of C. cladosporioides had a significant influence on the percentage of well-fermented almonds (p ≤ 0.05), through the cutting test, as a probable consequence of the lower content of total phenolic compounds, and of catechin and epicatechin. In addition, there was a lower concentration of acetic acid and a higher content of bioactive amines (p ≤ 0.05), when compared to the control experiment. These observed aspects were confirmed through multivariate analysis. Based on these results, it can be said that the use of C. cladosporioides proved to be promising and could provide improvements in fermented and dried cocoa beans.