Streptomyces specialized metabolites for agricultural applications

Clarke, Jody-Ann (2021) Streptomyces specialized metabolites for agricultural applications. Masters thesis, Memorial University of Newfoundland.

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Abstract

Streptomyces biosynthesize a wide variety of specialized metabolites, including volatile organic compounds (VOCs). Streptomyces VOCs are diverse and used in different capacities, including competition for resources and intra- and inter-species communication. And so, VOCs may be exploited in farming as inhibitors to plant pests and pathogens. The demand for safer alternatives to synthetic chemicals in agricultural practices makes these naturally occurring compounds ideal for applications. In this study, 133 Streptomyces isolates obtained from different locations in St. John’s, Newfoundland, were phylogenetically typed using the rpoB housekeeping gene, and different strains were selected for fermentation and pooled culture VOC screening. Six of the phylogenetically different isolates (JAC25, JAC45, JAC60, JAC74C, JAC81, and JAC95) were subjected to replicate VOC analysis and phytotoxic effects on plants. These isolates were shortlisted based upon the number and types of VOC they produced, i.e., various VOCs with published bioactivities, including insect repellency making them good targets for pest management in crop farming. Ninety-five bacterially derived compounds were identified among the six isolates in the replicate VOC analysis. One isolate (JAC60) significantly inhibited the development of plant seedlings suggesting its capacity to make a possible natural herbicidal compound.

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