Aspergillus tubingensis S23 as a promising source of pharmaceutically important secondary metabolites

Dorivor Eremostachys isochila o‘simligidan ajratilgan endofit zamburug‘ Aspergillus tubingensis S23 shtammining biosintetik salohiyati butun genomni sekvenirlash va qiyosiy genom tahlili (genome mining) yordamida baholandi. Molekulyar filogeniya va filogenomika ma‘lumotlari shtammning A. tubingensis turiga mansubligini tasdiqladi. antiSMASH dasturi 95 ta biosintetik gen klasteri (BGC) hududini bashorat qildi, ular orasida kojik kislota, yanuthone D, klavarik kislota, TAN-1612, nidulanin A va burnettiene A bilan bog‘liq tavsiflangan klasterlarga o‘xshash hududlar ham bor. Natijalar genom ma‘lumotlariga tayangan holda tabiiy birikmalarni izlash uchun katta imkoniyat borligini ko‘rsatadi, biroq bashorat qilingan birikmalarning hosil bo‘lishi va biologik faolligi tajribada tasdiqlanishi lozim.

FUNDAMENTAL VA AMALIY MIKROBIOLOGIYANING BUGUNGI HOLATI VA RIVOJLANISH ISTIQBOLLARI: YOSH OLIMLAR NIGOHI Respublika ilmiy-amaliy anjumani · Toshkent, 2026-yil 30-oktabr

III PROBIOTIKLAR, OZIQ-OVQAT VA FARMATSEVTIK MIKROBIOLOGIYA DOI 10.66073/ReFocus-Conf/3010082

ASPERGILLUS TUBINGENSIS S23 AS A PROMISING SOURCE OF PHARMACEUTICALLY IMPORTANT SECONDARY METABOLITES Kholikova Mavjuda Jonizoqovna¹, Khan Asifullah2, and Eshboev Farhod Bakir o‘g‘li²* ¹ Department of Biotechnology and Microbiology, National University of Uzbekistan, 100174 Tashkent, Uzbekistan ² Institute for Advanced Studies at New Uzbekistan University, 100007 Tashkent, Uzbekistan Corresponding author: f.eshboev@newuu.uz Abstract: The biosynthetic potential of Aspergillus tubingensis S23, an endophytic fungus isolated from the medicinal plant Eremostachys isochila, was evaluated through whole-genome sequencing and comparative genome mining. Molecular phylogeny and phylogenomics supported its identification as A. tubingensis. antiSMASH predicted 95 biosynthetic gene cluster (BGC) regions, including regions similar to characterized clusters associated with kojic acid, yanuthone D, clavaric acid, TAN-1612, nidulanin A, and burnettiene A. These results indicate substantial potential for genome-guided natural-product discovery, although the production and biological activities of the predicted compounds require experimental verification. Keywords: Aspergillus tubingensis; endophytic fungi; secondary metabolites; biosynthetic gene clusters; kojic acid; natural-product discovery. Introduction Endophytic fungi represent a promising source of structurally diverse secondary metabolites with potential applications in pharmaceutical biotechnology and drug discovery. These microorganisms inhabit internal plant tissues without causing apparent disease symptoms and possess complex biosynthetic pathways responsible for producing numerous biologically active compounds. Among endophytic fungi, species belonging to the genus Aspergillus are particularly attractive because of their ability to synthesize polyketides, nonribosomal peptides, terpenoids, and other specialized metabolites exhibiting a wide range of biological activities. However, the pharmaceutical potential of many fungal isolates remains insufficiently explored, particularly at the genomic and biosynthetic levels. The integration of whole-genome sequencing, biosynthetic gene cluster (BGC) mining, and metabolite characterization offers a powerful approach for identifying promising microbial producers of pharmaceutically relevant natural products. The present study investigates the biosynthetic potential of Aspergillus tubingensis S23, an endophytic fungus isolated from the medicinal plant Eremostachys isochila, with particular emphasis on its capacity to produce secondary metabolites of potential pharmaceutical importance. Materials and Methods The fungal strain S23 was isolated from healthy, asymptomatic tissues of Eremostachys isochila (Lamiaceae), a medicinal plant collected in Uzbekistan. Taxonomic identification was performed using internal transcribed spacer (ITS) sequencing, multilocus phylogenetic analysis of three protein-coding genes (benA, CaM, and RPB2), and genome-scale phylogenomic analysis. Whole-genome sequencing was conducted using the MGI DNBSEQ-T7 platform with 150 bp pairedend reads. Sequencing data were quality-filtered using fastp, and genome assembly was performed

FOR CITATION Kholikova M., Khan A., Eshboev F. Aspergillus tubingensis S23 as a promising source of pharmaceutically important secondary metabolites // Proceedings of the Republican Scientific and Practical Conference “Status and Development Prospects of Fundamental and Applied Microbiology: The Viewpoint of Young Scientists”. – Tashkent, 2026. – P. 285–288. DOI: https://doi.org/10.66073/ReFocus-Conf/3010082 using SPAdes v3.15.5. The biosynthetic potential of the strain was evaluated using antiSMASH v8.0.4, while predicted gene clusters were compared with experimentally characterized biosynthetic pathways available in the MIBiG database. Results and Discussion Molecular identification and phylogenomic analyses confirmed that strain S23 belongs to Aspergillus tubingensis, a member of the section Nigri. Genome mining revealed substantial biosynthetic diversity, with 95 predicted biosynthetic gene cluster regions, including clusters associated with polyketide synthases, nonribosomal peptide synthetases, terpene biosynthesis, and other specialized metabolic pathways. This extensive biosynthetic repertoire indicates the potential of A. tubingensis S23 to produce chemically diverse secondary metabolites, including compounds of pharmaceutical interest.

Comparative analysis of the predicted BGCs revealed several pathways associated with known bioactive fungal metabolites, including yanuthone D, burnettiene A, nidulanin A, TAN-1612, and kojic acid. Notably, the yanuthone D-associated BGC was found to be complete in strain S23, whereas corresponding genomic regions were disrupted in its closest relatives (Table 1).

This observation suggests distinctive biosynthetic capabilities that may differentiate S23 from other closely related strains. The burnettiene A-associated cluster exhibited a distribution consistent with vertical inheritance and differential gene loss (Figure 1), while clusters related to nidulanin A and TAN-1612 were broadly conserved across the examined fungal lineages. In contrast, the kojic acid biosynthetic pathway showed lineage-specific patterns of gene retention, relocation, and loss, highlighting the evolutionary plasticity of fungal secondary metabolism.

Table 1. Biosynthetic gene clusters in strain S23 with similarity to characterized compounds of reported pharmaceutical, cosmetic, or antimicrobial potential Compound MIBiG Chemical class Documented/reported bioactivity similarity Kojic acid 66% Pyranone Cosmetic potential, Antioxidant, Antimicrobial Yanuthone D 90% Meroterpenoid Antifungal activity Clavaric acid 100% Triterpenoid Anticancer activity TAN-1612 100% Anthraquinone-type Broadly reported for antimicrobial polyketide and anticancer bioactivity Nidulanin A 75% Polyketide– Secondary metabolite of Aspergillus nonribosomal peptide nidulans, bioactivity potential is hybrid uncharacterized. Burnettiene A 100% Polyketide Bioactive potential has not yet been reported.

Figure 1. Burnettiene A biosynthetic gene cluster comparative and evolutionary analysis. (A) Gene architecture across all 14 genomes compared to the A. burnettii reference cluster (BGC0002139) The findings demonstrate that Aspergillus tubingensis S23 possesses considerable potential as a microbial source of pharmaceutically relevant secondary metabolites. The identification of 95 predicted biosynthetic gene clusters, including pathways associated with kojic acid, yanuthone D, burnettiene A, nidulanin A, and TAN-1612, highlights the strain's extensive biosynthetic capacity. These results establish A. tubingensis S23 as a promising candidate for genome-guided natural-product discovery and provide a foundation for future metabolomic investigations, isolation of novel bioactive compounds, and development of potential pharmaceutical applications. Discussion The diverse predicted BGC repertoire suggests that S23 may synthesize multiple classes of specialized metabolites. The conservation and divergence of individual clusters across related genomes highlight the evolutionary complexity of fungal secondary metabolism. However, sequence similarity to characterized BGCs does not establish the production, chemical identity, yield, or pharmacological activity of the corresponding metabolites in S23. Metabolomic profiling, compound isolation, and targeted bioactivity assays are required to validate these predictions. Conclusion Aspergillus tubingensis S23 harbors 95 predicted BGC regions and several candidate pathways related to compounds of pharmaceutical or biotechnological interest. The findings support its selection for further genome-guided metabolite discovery and experimental characterization.