Antimicrobial potential of Aspergillus oryzae secondary metabolites against carbapenem-resistant Klebsiella pneumoniae

Rachma, Lailia Nur ORCID: https://orcid.org/0000-0003-0199-9656 and Ulhaq, Zulvikar Syambani ORCID: https://orcid.org/0000-0002-2659-1940 (2026) Antimicrobial potential of Aspergillus oryzae secondary metabolites against carbapenem-resistant Klebsiella pneumoniae. Medicine in Microecology, 27 (100161). ISSN 2590-0978

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Abstract

The antibacterial potential of Aspergillus oryzae (A. oryzae) EO product (AOEP) extract against Klebsiella pneumoniae (K. pneumoniae) strains BAA-1706 and BAA-1705 was investigated through minimal inhibitory concentration (MIC), biofilm inhibition assays, electron microscopy, and gene expression analysis. AOEP extract exhibited inhibitory activity with MIC50 values ranging from 3.1 % to 50 % for both strains. Notably, AOEP suppressed biofilm formation at low concentrations (3.1 %–12.5 %), outperforming the positive control, kanamycin, at 6.25 %. Morphological examination revealed significant alterations upon AOEP treatment, including reduced colony size and fragmented cells, distinct from kanamycin-induced changes. qRT-PCR demonstrated that AOEP significantly downregulated key virulence genes ompA, lppA, and mrkA in strain BAA-1706, and ompA and lppA in strain BAA-1705, while pal and wzi expression remained unaffected. LC-MS/MS profiling identified several lactone-related secondary metabolites, including acyl homoserine lactone (AHL) analogs and butyrolactone I analogs, suggesting possible quorum sensing interference as a mechanism of action. These findings highlight AOEP extract as a promising multifunctional antibacterial agent that disrupts K. pneumoniae growth, biofilm formation, and virulence, with potential applications in combating antibiotic-resistant infections.

Item Type:	Journal Article
Keywords:	Aspergillus oryzae; Klebsiella pneumoniae; Quorum sensing; Lactone metabolites
Subjects:	11 MEDICAL AND HEALTH SCIENCES > 1108 Medical Microbiology > 110801 Medical Bacteriology
Divisions:	Faculty of Medical and Health Sciences > Department of Medical Education
Depositing User:	Lailia Rachma
Date Deposited:	31 Dec 2025 10:54

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