出版社：European HIV/AIDS and Infectious Diseases Academy
摘要：Introduction Detection of new Actinobacteria is significant to discover new antibiotics because
development of new antibiotics is connected to the characterization of novel bacterial taxa. This study
has focused on the identification and isolation of antibiotic-producing Actinobacteria from the sediment
and the water of Ma'in thermal springs (48-59°C) situated in the center area of Jordan.
Methods Samples of sediment and water were transferred to glucose yeast malt agar medium and
Actinobacteria were cultivated, isolated and identified according to scanning electron microscopy and
16S rRNA gene analysis. Antibacterial activities of the isolates were then tested against different test
bacteria by agar well diffusion method.
Results Three different species of Actinobacteria were isolated (M1-1, M2-2, M3-2) from sediment
samples. Based on 16S rRNA gene analysis, isolate M1-1 was found to have only 90% identity percentage
with Nocardiopsis sp., however, isolates M2-2 and M3-2 were found to be closely related Streptomyces sp.
(97%) and Nocardioides luteus (99%), respectively. The antibacterial activity showed that strain M1-1 is
active against P. aeruginosa ATCC 2785 (inhibition zone, 9 mm). Strain M2-2 was found to be active
against S. aureus ATCC 29213 (12 mm), B. cereus ATCC 11778 (11 mm), and E. coli ATCC 25922 (9
mm). In respect to strain M3-2, it was found to be active against S. aureus ATCC 29213 (14 mm) and B.
cereus ATCC 11778 (9 mm). There were no actinobacterial isolates obtained from water samples despite
their significant diversity revealed by our previous metagenomic analysis, which showed the presence of
13 different species dominated by Arthrobacter (an Actinobacterium belonging to family
Actinomycetales).
Conclusion There were 17 different Actinobacteria that could be detected in Ma'in thermal springs
(13 unculturable species and 3 culturable species). The culturable Actinobacteria were found to have
some antimicrobial activity. Further chemical analysis of the bioactive compounds is recommended.
