Screening for Antibiotic-Producing Bacteria from Imbak Canyon Conservation Area (ICCA)

Abstract

Antibiotic resistance is an escalating threat to public health. Therefore, there is an urgent need for new antibiotics. This study aims to screen for antibiotic-producing microorganisms from the forest soil of Batu Timbang. Soil samples were collected, diluted and spread plated onto 1/5 Nutrient Agar (NA) and Actinomycete Isolation Agar (AIA) for the isolation of antibiotic-producing microorganisms. A total of 180 bacterial isolates were screened for their antibiotic-producing ability, and ten were tested positive for inhibitory activity against one or more test pathogens via agar overlay assay (Staphylococcus aureus ATCC BAA-1717, Enterococcus faecalis ATCC 700802, and Acinetobacter baumannii ATCC BAA-1605). Ten bacterial isolates were subjected to 16S rRNA gene amplification and gene sequence analysis. The isolates were identified to be closely related to the genus Variovorax, Streptomyces, Kitasatospora, Chromobacterium, Burkholderia, Pseudomonas and Massilia. Three isolates (Variovorax sp. A5, Variovorax sp. A6 and Kitasatospora sp. H8) are potentially novel as these isolates form a different clade from their respective closely related species via phylogenetic tree analysis using reference sequences obtained from GenBank/EMBL/DDBJ databases. The antibiotics produced by the bacterial isolates might potentially be new, as novel species might possess unique biosynthetic gene clusters to produce new compounds. Nevertheless, further taxonomic identification and antibiotic isolation work is required. This study has revealed the potential of antibiotic discovery from Batu Timbang (Imbak Canyon Conservation Area) and its implications in tackling antibiotic resistance.