Exploring the antibiotic-producing capabilities of Canadian High Arctic bacteria
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Microbial communities in harsh environments, such as the Canadian High Arctic, remain a relatively unexplored source of antimicrobial natural products. In this study, we developed a pipeline for screening and evaluating bacterial isolates cultured from 23 Canadian High Arctic soil, sediment, and active-layer permafrost samples to discover antibacterial compounds. The pipeline incorporated an undergraduate studentsourcing program and produced a collection of over 350 bacterial isolates with preliminary antibacterial activity. Following dereplication, whole genome sequencing and secondary screening by co-culture assays, five isolates were prioritized to test crude extracts for antibacterial activity. Among bioactive crude extracts from these isolates, the Pseudomonas isolate with the most potent activity against S. aureus was analyzed. Using liquid chromatography bioactivity guided fractionation, we identified a potential bioactive compound known as koreenceine A, a compound previously only isolated from a Pseudomonas from temperate soil and involved in gene expression of other bacteria in their microbial community. Here we expanded the known antibiotic activity of koreenceine A and confirmed that a Δ kecBCD genetic knockout of the putative biosynthetic gene cluster significantly abrogated the antibacterial activity.
Importance
Environmental bacteria naturally produce antimicrobial compounds to compete and suppress other microbes around them. Polar bacteria are relatively understudied, especially from the Canadian High Arctic (CHA) region. In this study we report on the development of a pipeline which integrated a studentsourcing program to screen environmental samples from the CHA, followed by characterization of a collection of CHA bacterial isolates with antibacterial activity against human pathogens. This work contributes to a better understanding of the antibacterial-producing capabilities of Arctic bacteria.
