Marine-Derived Streptomyces albidoflavus S20 Shows Breakthrough Biocontrol Against Tobacco Black Shank

A newly characterized marine actinomycete, Streptomyces albidoflavus S20, is emerging as a powerful biocontrol candidate against tobacco black shank, according to a recent study. The disease, caused by Phytophthora nicotianae, is among the most damaging threats to global tobacco farming. Researchers isolated strain S20 from the marine sponge Hymeniacidon perlevis and discovered exceptional antifungal capabilities.

In plate confrontation assays, S20 inhibited P. nicotianae growth by 90.3%, while pot and field trials demonstrated 92.1% and 90.4% biocontrol efficiency, respectively. Morphological and 16S rRNA characterization confirmed the strain as Streptomyces albidoflavus.

Whole-genome sequencing revealed a 6.73 Mb chromosome, a 218 kb plasmid, and over 5,700 protein-coding genes. AntiSMASH analysis identified 23 secondary metabolite biosynthetic gene clusters, including those linked to antifungal compounds and plant-beneficial metabolites.

Strain S20 also produces a suite of potent cell-wall-degrading enzymes—chitinase, cellulase, β-1,3-glucanase, and protease—which contribute directly to its antagonistic activity. Beyond pathogen suppression, S20 displays multiple plant growth–promoting traits, including nitrogen fixation, phosphate solubilization, siderophore production, and IAA biosynthesis.

In seed germination assays, S20 significantly enhanced germination rate, root elongation, soluble protein content, and α-amylase activity in tobacco seedlings, showcasing its dual role as both a biocontrol agent and plant growth promoter.

The authors conclude that S20 is a promising, sustainable solution for managing tobacco black shank and holds potential for broader agricultural applications.

Reference

Wang, Y., Jia, F., Song, R., Chen, C., Pu, T., Xu, Y., … & Fan, Y. (2025). Characterization and genome analysis of marine Streptomyces albidoflavus S20 for the biological control of tobacco black shank. Biological Control, 105908. https://doi.org/10.1016/j.biocontrol.2025.105908