Modulation of a lichen-associated fungus for improved biosynthesis of bioactive secondary metabolites

PM Eze, BO Umeokoli, H Chen, Z Liu, FBC Okoye, CO Esimone, P Proksch

Research output: Contribution to journalMeeting abstractpeer-review

Abstract

In this study, Apiospora montagnei isolated from a lichen-Cladonia sp was modulated to improve its biosynthesis of bioactive secondary metabolites. A solid state fermentation of A. montagnei was carried out on rice medium for 21 days at 22 °C and the fungal secondary metabolites were extracted using ethyl acetate. The crude extract was subjected to several chromatographic separation methods and the resulting fractions were subjected to HPLC-DAD analysis. Detected compounds were then isolated and characterized using various techniques such as NMR spectroscopy, MS analysis, etc. The metabolic profile of A. montagnei was then established. Manipulation of cultural conditions of the fungus by addition of carbon and nitrogen sources, and also several sodium salts; cultivation of the fungus at different temperatures; as well as co-cultivation with Bacillus subtilis and Streptomyces lividans, respectively, were carried out to improve the biosynthesis of identified bioactive compounds. Several bioactive compounds which were undetected or those detected at very low levels in the initial crude extract of A. montagnei were up-regulated after manipulation of the cultural conditions of the fungus. These compounds include-Anomalin B, Anomalin A, Norlichexanthone, N-hydroxy-apiosporamide, Apiosporamide, Decarboxycitrinone, Decarboxyhydroxycitrinone, Myrocin A, and 8-hydroxy-3-methyl-9-oxo-9 H-xanthene-1-carboxylic acid methyl ether. Cultivation of fungus at 28oC, co-cultivation with B. subtilis, and the addition of various sodium salts, nitrogen, and carbon sources triggered expression of silent fungal genes. Addition of NaCl (5%) and NH4Cl (1%), as well as co-cultivation with S. lividans, induced the production of new compounds. Results of this study indicate that co-cultivation, as well as manipulation of cultural conditions, can result in increased yields of previously described metabolites and previously undetected metabolites.
Original languageEnglish
JournalPlanta Medica
Volume82
Issue numberS 01
DOIs
Publication statusPublished - 2016
Externally publishedYes
Event9th Joint Natural Product Conference 2016 (Joint Meeting with ASP, AFERP, JSP, PSE and SIF) and 64th International Conference and Annual Meeting of the Society for Medicinal Plant and Natural Product Research (GA) - Copenhagen, Denmark
Duration: 24 Jul 201627 Jul 2016

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