Diversity and antimicrobial activity of the tropical ant-derived actinomycetes isolated from Thailand

Tuangrat Tunvongvinis; Weeyawat Jaitrong; Yudthana Samung; Somboon Tanasupawat; Wongsakorn Phongsopitanun

doi:10.3934/microbiol.2024005

Diversity and antimicrobial activity of the tropical ant-derived actinomycetes isolated from Thailand

AIMS Microbiol. 2024 Jan 22;10(1):68-82. doi: 10.3934/microbiol.2024005. eCollection 2024.

Authors

Tuangrat Tunvongvinis¹, Weeyawat Jaitrong², Yudthana Samung³, Somboon Tanasupawat¹, Wongsakorn Phongsopitanun^{1

4}

Affiliations

¹ Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences. Chulalongkorn University, Bangkok 10330, Thailand.
² Office of Natural Science Research, National Science Museum, 39, Moo 3, Khlong 5, Khlong Luang, Pathum Thani 12120, Thailand.
³ Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
⁴ Natural Products and Nanoparticles Research Units (NP2), Chulalongkorn University, Bangkok 10330, Thailand.

Abstract

Antibiotic resistance is one of the most important global healthcare challenges and is responsible for the mortality of millions of people worldwide every year. It is a crisis attributed to misuse of antibiotics and a lack of new drug development. Actinomycetes constitute a group of Gram-positive bacteria known for their distinctive high guanine-cytosine (G+C) content in their genomic DNA. These microorganisms are widely recognized for their capability to generate a wide range of secondary metabolites with diverse biological activities. These versatile microorganisms are ubiquitous in diverse ecosystems, including soil, freshwater, marine sediments, and within the bodies of insects. A recent study has demonstrated that social insects, such as ants, host a diverse array of these bacteria. In this study, we involved the isolation and characterization of a total of 72 actinomycete strains obtained from 18 distinct ant species collected from various regions across Thailand. Utilizing 16S rRNA gene analysis, these isolated actinomycetes were classified into four distinct genera: Amycolatopsis (2 isolates), Micromonospora (1 isolate), Nocardia (8 isolates), and Streptomyces (61 isolates). Among the Streptomyces strains, 23 isolates exhibited antimicrobial activity against a panel of Gram-positive bacteria, including Bacillus subtilis ATCC 6633, Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus ATCC 25923, Kocuria rhizophila ATCC 9341, and Methicillin-resistant Staphylococcus aureus (MRSA) DMST 20646. Additionally, two isolates displayed antifungal activity against Candida albicans TISTR 5554. Based on 16S rRNA gene sequence similarity studies, these two isolates, ODS25 and ODS28, were demonstrated to be closely related to Streptomyces lusitanus NBRC 13464^T (98.07%) and Streptomyces haliclonae DSM 41970^T (97.28%), respectively. The level of 16S rRNA gene sequence similarity below 98.65% cutoff indicates its potential as a novel actinomycete species. These findings underscore the potential of actinomycetes sourced from ants as a valuable reservoir of novel antimicrobials.

Keywords: Actinomycetes; antimicrobial activity; ants; social insect.