Smith, Helen A. (2014) Production of antimicrobials and antioxidants from filamentous fungi. PhD thesis, National University of Ireland Maynooth.

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Abstract

Filamentous fungi have proven throughout history to be a vast source of potential therapeutic activities. They are recognised as nutritious, highly palatable functional foods and are now widely accepted as an untapped source of potentially powerful natural products of pharmacological significance. In the present study, ten species of filamentous fungi were explored on the basis of their curative potential. Submerged liquid fermentation (SLF) was employed and proved to be a promising method for the production of bioactive functional compounds. Crude aqueous mycelial biomass demonstrated a broad range of antibacterial activity against pathogenically significant bacteria. Supplementation with various carbon sources at 1 % (w/v) affected the biomass production of several species significantly (p < 0.05) and in some cases also had a significant impact on cellular composition. Additionally, depending on species specificity, cell wall composition was found to affect the interaction of microbes prior to infection. Various extracts (crude, hot water and methanol) from the mycelium of each of the selected species were demonstrated as effective antioxidants. Additionally, total phenolic content positively attributed to the overall antioxidant capacity of the extracts. Bioassay-guided isolation and purification of extracts from cultured mycelia led to the identification of biologically active phenolic acids and compounds of lipid class. For effective utilisation of natural products or functional food components, quantitative information on the individual phenolic acids in each strain was generated. Compounds separated by TLC were extracted and analysed by LC/MS for fatty acid composition. The fatty acids; linoleic, palmitic, stearic and oleic acid were established as the main lipid metabolites of each fungal species. In addition, the effect of hot water and methanol extraction on fatty acid composition of the fungal cell was analysed by GC/MS. The fractionated extracts demonstrated that a combination of multiple chemical constituents yielded favourable biological activities. Submerged fermentation of mycelium from ten species of filamentous fungi proved to be an effective cultivation method for the production of bioactive and nutritional functional compounds. This research has provided information which could benefit further research in the isolation and characterisation of active chemical components of natural origin.

Item Type:	Thesis (PhD)
Keywords:	antimicrobials; antioxidants; filamentous fungi;
Academic Unit:	Faculty of Social Sciences Faculty of Science and Engineering > Biology
Item ID:	5802
Depositing User:	IR eTheses
Date Deposited:	10 Feb 2015 10:52
URI:
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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