Fungal metabolite production by combinatorial biosynthesis of 2-pyridones, heterologous expression of a nonribosomal peptide synthetase gene and fermentation of monascus in submerged culture

Name: Gunlatida Promsuk

LCSH: Kasetsart University -- Dissertations. Ph.D. (Bioscience) 2022

Classification :.LCCS: QK623.M63

LCSH: Kasetsart University. -- Faculty of Science -- Dissertations

LCSH: Monascus

LCSH: Paecilomyces

LCSH: Fungal metabolites

LCSH: Biosynthesis

LCSH: Pyridone

LCSH: Polyketides

Abstract: Biosynthetic studies of fungal secondary metabolites have gained a lot of attention from natural product community, and heterologous expression of fungal natural product genes was one of the techniques for metabolite production used in this research. Menisporopsis theobromae BCC 4162 is a seed fungus and one of the BGC was predicted as a PKS-NRPS. This hybrid PKS-NRPS gene cluster was introduced into Aspergillus oryzae NSAR1. However, no 2-pyridones were observed and this could be a result of poor expression of the PKS-NRPS gene as can be seen from low green fluorescence emission in the transformant culture. Moreover, combinatorial biosynthetic studies by swapping an auxiliary gene from different 2- pyridone biosynthetic gene clusters resulted in no novel metabolite production. This might be due to incompatibility of auxiliary genes between M. theobromae BCC 4162 and other 2-pyridone producing fungi. Furthermore, genome of Paecilomyces cinnamomeus BCC 9616, an insect-pathogenic fungus revealed many interesting BGCs including an nrps gene named nrps33. The nrps33 was constructed and introduced to Saccharomyces cerevisiae YPH499 for heterologous expression. The result shows the accumulation of anthranilic acid. The transcriptome and RT-qPCR revealed changes in the expression levels of genes involved in tryptophan biosynthesis (TRP1, TRP3 and TRP5). As a result, the product of nrps33 is expected to inhibit Trp4 function, resulting in anthranilic acid accumulation and this accumulation could cause downregulation of downstream enzymes in tryptophan biosynthesis. This research allowed us to gain a better understanding of anthranilic acid accumulation induced by expression of nrps33 in S. cerevisiae. Monascus kaoliang KB9, a filamentous fungus was studied for metabolite production in submerged culture. The results reveal the production of early intermediates of azaphilone biosynthesis, bicyclic azaphilones, angular tricyclic azaphilones, and linear tricyclic azaphilones. Eleven compounds were isolated and identified by using NMR and ECD spectroscopy techniques. The absolute configurations of isolated compounds were identified as 7S, 8S, and 14E for angular tricyclic azaphilones and 6R, 7R, and 14E for linear tricyclic azaphilones. Our results on absolute configuration of azaphilones are useful for natural product community and medicinal applications.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Pakorn Wattana-Amorn

Role: Thesis Advisor

Name: Pitak Chuawong

Role: Thesis CO-Advisor

Name: Passorn Wonnapinij

Role: Thesis CO-Advisor

Created: 2022

Modified: 2025-07-27

Issued: 2025-07-27

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2565/gunlatida-pro-all.pdf

CallNumber: QK623.M63 .G86

eng

DegreeName: Doctor of Philosophy

Level: Doctoral Degraee

Descipline: Bioscience

Grantor: Kasetsart University

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