Galactomyces geotrichum MK017 is an anamorphic and non-pathogenic fungus-like yeast included in Hemiascomycetes that was isolated from raw-milk and is widely used as adjunct culture in the maturation of cheese like raclette, münster, limburger, cottage cheese and sheep cheese [1]. Succinic acid (C₄H₆O₄), also known as amber acid, butanedioic acid or butanedicarboxylic acid, is precursor of numerous pharmaceuticals and chemicals including adipic acid, 1,4-butanediol, tetrahydrofuran, N-methyl pyrrolidinone, 2-pyrrolidinone, succinate salts, gamma-butyrolactone and biodegradable polymers. Galactomyces geotrichum MK017 produce metabolic products by fermentation such as succinic acid and acetic acid from glucose and others such as ethanol, formic acid, lactic acid [2]. The central carbon metabolism of Galactomyces geotrichum MK017 and its metabolic network is analyzed and integrated by combining biochemical and physiological information. Metabolic flux analysis (MFA) as powerful methodology was used for calculation of the intracellular fluxes by using a stoichiometric model (metabolic pathway map) for the major intracellular reactions and mass balances around intracellular metabolites. A set of measured rates of substrates and metabolites was used for the calculations [3, 4]. The metabolic flux map or diagram of the biochemical reactions include production of pyruvate and phosphoenolpyruvate carboxylation pathways examined in the case of succinic acid production in G. geotrichum MK017. In silico succinic acid pathway was compared with experimental succinic acid pathway of G. geotrichum MK017. The resulting flux distributions were visualized and analysed, and the simulation parameters were adjusted until the model correctly predicted the phenotype. Simulations were used to form hypotheses and predict the yields of in silico succinic acid pathway. The predictions were then validated experimentally.

[1] Mało poznany grzyb pleśniowy Galactomyces geotrichum w wyrobach mlecznych, A. Grygier, K. Myszka, M. Rudzińska, P. Spozywczy, 5, 2016.
[2] Purification and characterization of an extracellular lipase of Galactomyces geotrichum, A. Phillips, G.H. Pretorius, G.H. van Rensburg, Biotechnology letters, 13(5), 1979.
[3] In Silico Metabolic Pathway Analysis and Design: Succinic Acid Production by Metabolically Engineered Escherichia coli as an Example, S.Y. Lee, S.H. Hong, S.Y. Moon, Genome Informatics 13(9), 2002.
[4] The Metabolic Pathway Engineering Handbook: Fundamentals, Ch. D. Smolke, CRC Press USA, 2010.

Phytosterols are increasingly used as health supplements in functional foods and are associated with having both positive and negative effects on health.¹ In contrast to the heavily promoted health benefits of dietary phytosterol supplementation, a number of groups have identified adverse health effects of phytosterols: induction of endothelial dysfunction and increased size of ischaemic stroke; inhibition of cell growth; aggressive vascular disease in sitosterolaemic patients.^2,3 Given this disparity, an investigation of their full individual biological profile is imperative in order to assure food safety. Herein we describe the de novo synthesis of pure phytosterols in multigram scale and report the first synthesis of the key phytosterol Dihydrobrassicasterol and its oxides along with a comparison of routes to Campesterol.^4,5 A detailed spectroscopic analysis is included with full assignment of the ¹³C NMR of both phytosterols, mixtures and their precursors leading to the potential use of NMR as a tool for analysis of these sterol mixtures. A comprehensive toxicological profile of these key phytosterol oxide products (POPs) identifies critical problems with the use of phytosterol mixtures as food additives.^5,6,7

References

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2. Weingartner, O.; Lutjohann, D.; Ji, S.; Weisshoff, N.; List, F.; Sudhop, T.; von Bergmann, K.; Gertz, K.; Konig, J.; Schafers, H. J. Endres, M.; Bohm, M.; Laufs, U. J. Am. Coll. Card., 2008, 51, 1553-1561.
3. Ryan, E.; Chopra, J.; McCarthy, F. O.; Maguire, A. R.; O'Brien, N. M. Brit. J. Nut. 2005, 94, 443-451.
4. McCarthy, F.O.; Chopra, J.; Ford, A.; Hogan, S.A.; Kerry, J.P.; O'Brien, N.M.; Ryan, E.; Maguire, A.R. Org. Biomol. Chem. 2005, 3, 3059-3065; Hang, J.; Dussault, P. Steroids 2010, 75, 879-883.
5. O’Connell N., O’Callaghan Y.C., O’Brien N.M., Maguire A.R., McCarthy F.O. Tetrahedron, 2012, 68 (25):4995-5004
6. O'Callaghan, YC; Foley, DA; O'Connell, NM; McCarthy, FO; Maguire, AR; O'Brien, NM; J. Agric. Food Chem., 2010, 58 (19):10793-10798; Foley, DA; O'Callaghan, Y; O'Brien, NM; McCarthy, FO; Maguire, AR; J. Agric. Food Chem., 2010, 58 :1165-1173
7. O. Kenny, Y. O'Callaghan, N.M. O'Connell, F.O. McCarthy, A.R. Maguire and N.M. O'Brien J. Agric. Food Chem., 2012, 60 (23):5952-5961.O'Callaghan Y, Kenny O, O'Connell NM, Maguire AR, McCarthy FO, O'Brien NM. Biochimie, 2013, 95(3), 496-503.