Browsing by Subject "Aspergillus"
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(2021)Sienet ovat harvinaisia nenän sivuontelotulehdusten aiheuttajia. Useimmiten sienisinuiitin aiheuttajana on Aspergillus-suvun sienilaji. Tämän tutkielman tavoitteena on selvittää aspergillus-sienisinuiittiin sairastuneiden potilaiden taustoja ja mahdollisia sienisinuiiteille altistavia tekijöitä. Tämän lisäksi tutkitaan, onko eri riskiryhmien välillä eroja taudista parantumisessa. Tutkimusta varten on kerätty vuosilta 2007–2018 kaikki HUS:n Helsingin Korva-, nenä- ja kurkkutautien klinikassa hoidetut potilaat, joilta otetuissa nenän sivuonteloiden sieniviljelynäytteissä on kasvanut Aspergillus-suvun sienilaji. Aineisto koostuu 86 potilaasta, joilta kerättiin tiedot aiemmista sairauksista, lääkityksestä, nenän alueen leikkauksista ja tupakoinnista. Tiedot kerättiin HUS:n alueella käytössä olleista potilastietojärjestelmistä Uranuksesta ja Navitaksesta sekä Kanta-arkistosta. Suurimmalla osalla oli todettavissa vähintään yksi todennäköisesti sieni-infektiolle altistanut riskitekijä. Vain muutamalla ei tullut esiin selkeää altistavaa tekijää. Kolmella potilaalla todettiin invasiivinen tautimuoto. Aineistossa nousi esiin samoja altistavia tekijöitä sienisinuiiteille, kuin mitä muissakin vastaavissa tutkimuksissa on havaittu, merkittävimpänä hematologiset syövät sekä pitkäaikaiset tai voimakkaat immunosuppressiiviset lääkitykset. Uutena löydöksenä havaittiin astmaa sairastavilla taudin kehittyvän todennäköisemmin useamman sinuksen taudiksi. Usean sinuksen tautiin sairastuneet olivat myös selvästi nuorempia kuin yhden sinuksen tautia sairastavat.
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(2015)The literature review presents general information on fungi and mycotoxins and then deals with aflatoxins, in particular aflatoxin B1 and M1, their occurrence, significance, and current methods for controlling the risk of aflatoxin. Particular emphasis was given to studies on lactic acid bacteria (LAB) in controlling the growth of aflatoxigenic molds and binding of aflatoxins. The aim of the experimental work was to assess the ability of 171 LAB isolates originating from Kenyan naturally fermented traditional milk and maize samples (1) to inhibit the growth of Aspergillus and (2) to bind aflatoxin M1 in vitro. All the LAB isolates (n=171) were screened for their antifungal activity against A. flavus by an overlay method with 100 µl LAB culture on potato dextrose agar (PDA) plate. Out of 171 LAB isolates, mold growth was reduced by 33 isolates, of which 19 isolates were confirmed to retain their activity. These 19 LAB isolates were tested against A. flavus with three different amounts of LAB culture (50 µl, 100 µl and 200 µl). Three LAB isolates performed best against A. flavus by inhibiting the growth with all the tested amounts of LAB culture. The three LAB isolates were identified as Lactobacillus plantarum first by 16S rDNA sequence analysis and later confirmed by recA derived primers and multiplex PCR assay. The ability of 171 LAB isolates to bind AFM1 from phosphate-buffered saline (PBS) in vitro was carried out. LAB isolates were incubated with an amount equivalent to 50 ng AFM1 /ml for 4 h and then centrifuged (10 000 rpm, 10 °C) for 15 min to obtain supernatant containing unbound AFM1. The amount of unbound aflatoxin was analysed by HPLC chromatography from 51 samples. Binding ability of the analyzed isolates varied from 15,4 % to 51,5 %, and six LAB isolates were shown to bind more than 42,4 % of AFM1. The results showed that all tested indigenous LAB isolated from fermented milk and maize products manufactured in Kenya had variable ability to control the growth of A. flavus and bind AFM1 in vitro. It is suggested that such LAB strains could be used for reduction of the risk of aflatoxin contamination in food and feed chains.
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(2016)Fungal ferulic acid esterases (FAEs) are important accessory enzymes that participate in degradation of plant cell wall hemicellulose in grasses, including cereals and many energy crops. They could be used to convert agricultural wastes into a variety of value-added products such as biofuel, feed and paper. In non-aqueous media, they have been shown to act as catalysts for enantioselective reactions. Putative faes are widespread in genomes of plant pathogenic and saprotrophic fungi. However, only few FAEs have been characterized in detail. Additionally, despite of their diverse biotechnological potential, fungal FAEs have not been produced recombinantly on a bioreactor scale, which is a necessary step for their commercial applications. The aim of the present study was recombinant production on a bioreactor scale and biochemical characterization of a putative FAE from Aspergillus terreus. The enzyme demonstrated a broad substrate profile and an excellent storage stability. Its catalytic activity was highest against methyl 3,4-dimethoxycinnamate, but the enzyme was also active against methyl ferulate. It preferred methoxy groups to hydroxyl groups on the substrate’s phenyl ring, while shortening of the aliphatic side chain diminished the activity. The enzyme was observed to be fully stable at 37 °C for 1 h, and it demonstrated thermal activation at the same temperature. At 45 ˚C, it retained 75 % of its initial activity for 1 h. McIlvaine’s buffer was observed to increase the activity by 85 % compared to the standardly used MOPS buffer. The results of this study have contributed to the biochemical knowledge of fungal FAEs and elucidated their substrate preferences.
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