000			04496nam a2200301 a 4500
008			2015
082	0	4	_aTHESES PRESS
100	1		_aBrosnan, Bríd. _eauthor
245	1	0	_aMass spectrometry investigation of antifungal compounds from lactic acid bacteria and their application as natural antimicrobials / _cBríd Brosnan.
264		1	_aCork : _bCork Institute of Technology, _c2015.
300			_a339 pages : _billustrations (some color), tables, graphs ; _c30 cm
336			_atext _btxt _2rdacontent
337			_aunmediated _bn _2rdamedia
338			_avolume _bnc _2rdacarrier
490	0		_aPh.D - Physical Sciences
502			_aThesis (Ph.D) - Cork Institute of Technology, 2015.
504			_aIncludes bibliographical references.
520			_aLactic acid bacteria (LAB) have become an important part of the food chain in recent years. The desire of consumers to use natural food preservatives has allowed for much research to be devoted to identifying strains providing such activity without the need for addition of chemical preservatives. Several species of LAB have been recognised to provide antifungal activity, which may facilitate inhibition of food spoilage fungi. LAB have GRAS-status (Generally Recognised as Safe) and QPS status (Qualified Presumption of Safety) allowing them to be safely integrated into food systems as natural food preservatives. LAB have been used as starter cultures in numerous food and feed products ranging from bread to silage to malting. The integration of these strains as starter cultures into products has been used to produce a reduction of fungal growth and prolong shelf life of goods without the use of chemical preservatives. Initially, it was throught that the organic acides produced (such as lactic and acetic acid) were the main mechanism of antifungal activity due to the lowering of the PH. Studies have shown that the MIC (minimal inhibitory concentration ) of these compounds alone is too low to be the main mechanism of activity. Other metabolites from these strains have been identified as the source of the antifungal activity, e.g. cyclic dipeptides, proteinaceous compounds, fatty acids and lower molecular weight compounds. Knowledge about the active metabolites producing the antifungal activity is relatively limited. The main objective of this Ph.D is to develop universal isolation and detection methods that are fast, robust and efficient. The development of such methods will allow for an increased number of compounds to be identified. Improvements in extraction methods will ensure the optimum extract of samples allowing for easier, more comprehensive identification and profiling of both targeted and unknown compounds. The further development of accurate and sensitive identification methods will provide further information and unambiguous confirmation of compounds present. The combination of the improved procedures will provide greater identification and quantitation of these compounds produced by LAB. This will provide further data and aid in the exaplanation of the antifungal activity occurring. Improvement in these methods will also make the discovery of new compounds, variants and metabolites possible. The proposed methodologies will provide quick, efficient, robust procedures for the analytical extraction and identification of antifungal compounds. In comparison with previous detection methods which required both GC-MS and LC-MS, it will allow for a broader range of compounds to be identified within the same analysis using a single analytical technique. Previous methods only identified a maximum of 15 compounds and required a combination of both Gas Chromatography- Mass Spectrometry (GC-MS) and Liquid Chromatography - Mass Spectrometry (LC-MS) complimentary methods to discern these compounds. The methods proposed here have the capability of identifying up to 25 compounds on a single LC-MS method. The combination of all these improvements willl greatly enhance knowledge within this field of research. - (Author's abstract)
650		0	_aFungicides. _937644
650		0	_aLactic acid bacteria. _939043
650		0	_aBacterial genetic engineering. _9116687
650		0	_aMicrobial biotechnology. _944809
650		0	_aBioactive compounds. _9116689
650		0	_aMass spectrometry. _939608
907			_a.b11168109 _b160504 _c150827
942			_n0
998			_ac _b150827 _cm _da _e- _feng _gie _h0
999			_c102094 _d102094