Page 165 - 2025中醫藥與天然藥物聯合學術研討會-中醫藥與天然藥物的挑戰Ｘ機遇與未來大會手冊

PC-47

Searching for new antibiotics from Streptomyces spp. against drug-resistant

pathogens under different culture media

1
1
2
Wei-Tsen Lin, Mao-Xuan Hong, Setya W.A. Permanasari, and Yu-Liang Yang, Chih-
#,1
Chuang Liaw* ,1,3

1 Department of Marine Biotechnology and Resources, National Sun Yat-sen University,
Kaohsiung, Taiwan
2 Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
3 Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University,
Academia Sinica, Kaohsiung, Taiwan.
* E-mail: ccliaw@mail.nsysu.edu.tw

Abstract
The widespread misuse of antibiotics has accelerated the emergence of antibiotic-resistant
pathogens, resulting in an urgent demand for novel antimicrobial agents. Streptomyces, a genus
of Actinobacteria, is a well-recognized source of clinically important antibiotics, such as
macrolides, aminoglycosides, and tetracenomycins. To stimulate the production of diverse
secondary metabolites, selected Streptomyces strains were cultivated in various media (LB, AIA,
ISP2, and ISP4). Antibacterial assays revealed that eight strains exhibited inhibitory activity
against carbapenem-resistant Acinetobacter baumannii (CR-Ab), Klebsiella pneumoniae (CR-
Kp), Pseudomonas aeruginosa (CR-Pa), and Tsp-A. baumannii (Tsp-Ab). Notably, strains
grown under ISP4 culture conditions displayed the strongest inhibitory activities. Among them,
strains 13.19 and 1.17 demonstrated the most significant inhibitory effects across all tested
indicators. Interestingly, strain 13.19 cultured in ISP4 medium showed the inhibition toward
general indicators, Escherichia coli and Staphylococcus aureus, whereas strain 1.17 specifically
suppressed carbapenem-resistant pathogens under the same conditions. It implied that distinct
bioactive compounds are produced by these strains depending on culture conditions,
underscoring the potential of Streptomyces spp. as a valuable reservoir of novel antibiotics
against antibiotic-resistant bacteria. To rapidly identify the active metabolites responsible for
the observed activities, extracts will be subjected to high-resolution MS/MS-based molecular
networking, followed by bioassay-guided fractionation and isolation (BGFI). Results of these
ongoing investigations will be presented in the poster.

Keywords: Streptomyces spp.; Antibiotics; Secondary metabolites; Bioassay-guided
fractionation and isolation (BGFI)