Pigment With Bioactivities Of An Endophytic Fungus, Penicillium Minioluteum Ed24 Isolated From Orthosiphon Stamineus Benth

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dc.contributor.authorAng, Swee Ngim
dc.date.accessioned2018-02-01T02:00:55Z
dc.date.available2018-02-01T02:00:55Z
dc.date.issued2017-06
dc.description.abstractMicrobial pigment is an emerging field of research to replace synthetic pigments in numerous industrial applications due to the hazardous effects posed by synthetic pigments. Microbial pigments are notable for their striking colours and therapeutic potentials. The main aim of this study was to investigate pigment with bioactivities of an endophytic fungus, Penicillium minioluteum ED24 previously isolated from the leaves of a medicinal herb, Orthosiphon stamineus Benth. Preliminary studies revealed the production of extracellular red pigment was more favorable when cultivated in the dark with the supplementation of host plant extract in fermentation broth. The pigment yield was enhanced after altering the physical and chemical parameters of cultivation conditions using YES cultivation medium. The optimum physical parameters for maximum pigment production were initial medium pH 6, 30 °C incubation temperature, 150 rpm agitation speed and 1×105 spores/mL inoculum size whereas the optimum chemical parameters for maximum pigment production were 40 g/L sucrose, 20 g/L peptone, 0.4 g/L magnesium sulphate and 8 g/L host plant extract. Cultivation of endophytic fungus under the optimum conditions showed a remarkable improvement in pigment yield by 313.50% (0.859 OD500nm/g before and 3.552 OD500nm/g after enhancement). Results from agar overlay bioautography assay using ethyl acetate crude extract developed on thin layer chromatography strips revealed yellow spot to exhibit antibacterial activity against Gram positive foodborne (B. cereus, B. subtilis and S. aureus) and clinical isolates (B. cereus ATCC 12759 and S. aureus). The yellow spot was then collected using a column chromatography. The collected yellow fraction was subjected to antibacterial activity test using disc diffusion assay as well as minimal inhibitory concentration and minimal bactericidal concentration determinations using microdilution method. The yellow fraction F2 exhibited bactericidal activity against foodborne and clinical isolates tested in a range of 2 mg/ml to 1 mg/mL respectively. Based on the kill-curve study, the action of antibacterial fraction F2 was concentration-dependent. The antibacterial fraction F2 was also subjected to antioxidant study which showed it to exhibit moderate antioxidant activity. The yellow fraction F2 with positive antibacterial and antioxidant activities was determined to be non-toxic in acute toxicity (1281 μg/mL) but toxic in chronic toxicity (688.20 μg/mL). Bioactive yellow fraction F2 was then further purified and characterised using preparative thin layer chromatography and spray reagents. Then the semi-purified sub-fraction F2b was obtained. Further identification of sub-fraction F2b was carried out using reversed-phase high performance liquid chromatography and liquid chromatography-mass spectrometry. LCMS-TOF results showed the presence of five peaks in bioactive sub-fraction F2b. Further purification test was required to identify the pigment compound responsible for the bioactivities in semi-purified sub-fraction F2b.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/5478
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectPigment with bioactivitiesen_US
dc.subjectof an endophytic fungusen_US
dc.titlePigment With Bioactivities Of An Endophytic Fungus, Penicillium Minioluteum Ed24 Isolated From Orthosiphon Stamineus Benthen_US
dc.typeThesisen_US
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