Investigating the Unique Chemical Arsenal of a Plant Disease-Causing Bacterium

Jenn Hoskins
8th May, 2024

Investigating the Unique Chemical Arsenal of a Plant Disease-Causing Bacterium

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Memorial University of Newfoundland found that the bacterium Streptomyces sp. 11-1-2 produces various compounds that can inhibit the growth of other organisms
  • The study revealed that one compound, elaiophylin, increases the toxicity of other bacterial toxins against plants and microbes
  • These findings highlight Streptomyces' potential as a source for discovering new bioactive substances, with implications for antibiotic development
Streptomyces bacteria, a group of soil-dwelling organisms, are like microscopic chemical factories with the ability to produce a vast array of specialized compounds. These substances are not just random by-products; they serve critical roles in the bacteria's survival and interaction with their environment. Researchers at Memorial University of Newfoundland have delved into the metabolic capabilities of one such bacterium, Streptomyces sp. 11-1-2, known to be a plant pathogen[1]. Their findings shed light on how this bacterium uses its chemical arsenal to affect other organisms, including plants and competing microbes. The study used an approach termed 'One Strain Many Compounds' (OSMAC) to explore the metabolic potential of Streptomyces sp. 11-1-2. This method involves cultivating the bacterium on various nutrient media to induce the production of different metabolites. The team prepared organic extracts from cultures grown on six different agar media. These extracts were then tested for their antimicrobial properties against Gram-positive bacteria and yeast, as well as for their phytotoxic (plant-toxic) effects on potato tuber tissue and radish seedlings. The results were quite revealing. Most extracts showed strong bioactivity, suggesting that Streptomyces sp. 11-1-2 can produce a range of compounds that inhibit the growth of other organisms. This ability to interfere with competitors aligns with previous observations that bacteria can engage in both exploitative and interference competition[2]. Exploitative competition involves consuming resources more efficiently, while interference competition involves actively harming competitors, which is what these bioactive compounds may facilitate. Through untargeted metabolomics and molecular networking, the research identified several known specialized metabolites, including compounds like musacin D and elaiophylin, as well as novel compounds with unknown structures and bioactivities. Targeted detection confirmed the presence of elaiophylin in the extracts. Further bioassays with purified elaiophylin showed it enhances the phytotoxic effects of two other toxins produced by the bacterium, geldanamycin and nigericin. These findings are significant for several reasons. First, they provide insight into the complex interactions between Streptomyces and other organisms, including plants and potentially competing bacteria. It is known that Streptomyces can adapt their inhibitory capabilities in response to nearby organisms, especially those that share their habitat or compete for similar resources[3]. The enhanced toxicity of elaiophylin in the presence of other toxins could be an example of such an adaptive mechanism, where multiple compounds work synergistically to fend off competitors or to harm host organisms. Secondly, the study contributes to the broader understanding of the secondary metabolism of actinobacteria, a group known for their rich production of antibiotics and other bioactive compounds[4][5]. The discovery of uncharacterized secondary metabolite biosynthetic gene clusters (smBGCs) in Streptomyces through genome sequencing has opened up new possibilities for identifying novel compounds with potential clinical applications. The current research supports these findings by demonstrating that even a single strain of Streptomyces can produce a plethora of bioactive substances. The implications of this study are twofold. On one hand, it adds to the growing body of knowledge on microbial ecology and the strategies bacteria use to survive and thrive in competitive environments. On the other hand, it highlights the untapped potential of Streptomyces as a source for new and potentially valuable chemical entities. This could be particularly important in the search for new antibiotics, as the rise of antibiotic-resistant pathogens continues to be a global health concern. In summary, the research from Memorial University of Newfoundland offers a glimpse into the intricate chemical interactions that Streptomyces sp. 11-1-2 engages in with its environment. By employing a creative approach to induce the production of a wide range of metabolites, and then characterizing their effects, the study not only advances our understanding of bacterial ecology but also points to a reservoir of chemical diversity with significant potential for drug discovery.

BiochemEcologyPlant Science

References

Main Study

1) Exploring the specialized metabolome of the plant pathogen Streptomyces sp. 11-1-2.

Published 6th May, 2024

https://doi.org/10.1038/s41598-024-60630-5

Related Studies

2) Competition sensing: the social side of bacterial stress responses.

https://doi.org/10.1038/nrmicro2977

3) Nutrient overlap, genetic relatedness and spatial origin influence interaction-mediated shifts in inhibitory phenotype among Streptomyces spp.

https://doi.org/10.1111/1574-6941.12389

4) Mini review: Genome mining approaches for the identification of secondary metabolite biosynthetic gene clusters in Streptomyces.

https://doi.org/10.1016/j.csbj.2020.06.024

5) Genomic basis for natural product biosynthetic diversity in the actinomycetes.

https://doi.org/10.1039/b817069j


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