SPARC 2023 conference - INVITED KEY NOTE LECTURE

Exploring the Icy Treasures: Biosynthetic potential of Antarctic bacteria from James Ross Island

Abstract:

Background: The growing problem of antimicrobial resistance motivated scientists to re-explore natural sources of bioactive secondary metabolites. Antarctica represents an extreme environment colonized by bacteria with unique adaptation mechanisms allowing them to thrive under harsh conditions. Such adaptations include production of secondary metabolites to inhibit competitors or sustain abiotic stresses, which predestines these microbes as source of natural products for biomedical use.

Objectives: The aim of this work was to recover novel bacterial taxa from Antarctic soils to access th biosynthetic potential hidden in yet uncultivated bacteria. The main objective is the activation and subsequent upregulation of silent biosynthetic gene clusters enabling discovery of novel secondar metabolites, through diverse cultivation and co-cultivation strategies, as well as genetic manipulations.

Methods: Three isolation methods (pre-selection of spore-forming bacteria, modified low-nutrient and soil-extract based media) were applied to recover novel bacteria from Antarctic soils, predominantly targeting phyla with high biosynthetic potential such as Actinomycetota Pseudomonadota and Bacillota. Activation of silent biosynthetic gene clusters was attempted through targeted cultivation and co-cultivation. Screening for bioactive molecules and evaluation of their novelty was achieved by application of genomics, metabolomics, and bioactivity testing.

Results: A collection of 1023 isolates was established. Recovered isolates were associated with four bacterial phyla including 123 isolates of novel species. Pseudomonadota and Actinomycetota represented the most abundant phyla. Specific media stimulated biosynthesis of several unknown natural products. One of these unknown compounds showed strong antimicrobial activity against Gram-negative bacteria including multidrug-resistant clinical strains. This compound has been linked to the specific gene cluster responsible for its production. Plans for upregulation to obtain sufficient concentration for isolation involve cluster-specific genetic manipulations.

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