Metabolomic Strategies to Improve Chemical Information from OSMAC Studies of Endophytic Fungi

Abstract

Metabolomics strategies are important tools to get holistic chemical information from a system, but they are scarcely applied to endophytic fungi to understand their chemical profiles of biosynthesized metabolites. Here Penicillium sp. was cultured using One Strain Many Compounds (OSMAC) conditions as a model system to demonstrate how this strategy can help in understanding metabolic profiles and determining bioactive metabolites with the application of metabolomics and statistical analyses, as well as molecular networking. Penicillium sp. was fermented in different culture media and the crude extracts from mycelial biomass (CEm) and broth (CEb) were obtained, evaluated against bacterial strains (Staphylococcus aureus and Pseudomonas aeruginosa), and the metabolomic profiles by LC-DAD-MS were obtained and chemometrics statistical analyses were applied. The CEm and CEb extracts presented different chemical profiles and antibacterial activities; the highest activities observed were against S. aureus from CEm (MIC = 16, 64, and 128 µg/mL). The antibacterial properties from the extracts were impacted for culture media from which the strain was fermented. From the Volcano plot analysis, it was possible to determine statistically the most relevant features for the antibacterial activity, which were also confirmed from biplots of PCA as strong features for the bioactive extracts. These compounds included 75 (13-oxoverruculogen isomer), 78 (austalide P acid), 87 (austalide L or W), 88 (helvamide), 92 (viridicatumtoxin A), 96 (austalide P), 101 (dihydroaustalide K), 106 (austalide k), 110 (spirohexaline), and 112 (pre-viridicatumtoxin). Thus, these features included diketopiperazines, meroterpenoids, and polyketides, such as indole alkaloids, austalides, and viridicatumtoxin A, a rare tetracycline.

Complexity of fungal polyketide biosynthesis and function

“…A recent publication combined the OSMAC approach with metabolomic, statistical, and networking analyses to reveal antibacterial properties of endophytic Penicillium sp. and found the polyketides austalides and viridicatumtoxin A, a rare tetracycline (da Silva et al., 2023).…”

Heat shock and iron limitation modulate the metabolic profile of the cyanobacterium Microcystis aeruginosa NIES‐88

“…One such strategy is the one strain many compounds (OSMAC) approach, which is based on the theory that a single strain is able to produce many compounds in different growth conditions to access the cryptic metabolic pathways that are otherwise silent (Pinedo-Rivilla et al 2022). Culture conditions can significantly impact the production of natural products, resulting in either upregulation or downregulation of certain compounds or even the production of new metabolites through the activation of cryptic biosynthetic pathways (Da Silva et al 2023). Many studies have reported the impact of cyanobacterial culture conditions with various objectives: to increase biomass or lipid content, to improve the production of bioactive compounds, or to investigate the ecology and physiology of strains related to harmful algal blooms (Crnkovic et al 2018).…”

“…Culture conditions can significantly impact the production of natural products, resulting in either upregulation or downregulation of certain compounds or even the production of new metabolites through the activation of cryptic biosynthetic pathways (Da Silva et al . 2023). Many studies have reported the impact of cyanobacterial culture conditions with various objectives: to increase biomass or lipid content, to improve the production of bioactive compounds, or to investigate the ecology and physiology of strains related to harmful algal blooms (Crnkovic et al .…”