https://doi.org/10.1016/j.cej.2025.169916.Chemical Engineering Journal，2025

Abstract

The exploration of biological control products to reduce the reliance on agricultural chemical inputs has become increasingly critical for sustainable crop protection. Despite this, the availability of effective biological control agents remains limited, and chemical pesticides continue to dominate the prevention and management of tobacco diseases. Herein, an antifungalStreptomycesstrain 83 (S83) was screened and identified through antifungal bioassay and whole genome sequencing. The cell-free supernatants (CFS) of S83 demonstrated significant antimicrobial activity against tobacco leaf spot disease (Rhizoctonia solani). Key antimicrobial compounds, including toyocamycin and nystatin, were identified by HPLC-MS/MS. Furthermore, chitosan derivatives, carboxylated chitosan (CMCS) and quaternary ammonium chitosan (HTCC), were employed as carriers to prepare S83 CFS-based nanoemulsion via electrostatic interaction. These nanoemulsion were successfully synthesized with diameters ranging from 60 to 200nm. The nanoemulsion exhibited superior foliar adhesion, with a leaf deposition rate 2.3–2.7 times higher than that of CFS after washing. Filed experiments revealed that the effectiveness of CFS in controlling target spot disease was 57.28%, comparable to that of the commercial validamycin aqueous formulation (57.52%), whereas nanoemulsion achieved a higher disease control efficacy of 72.97%. More importantly, the chitosan derivatives carriers enhanced the activity of antioxidant enzymes and increase chlorophyll, nitrogen, and alkaloids content in tobacco seedlings, demonstrating synergistic effects for plant growth. Overall, this work not only enrich microbial strain resources for the biological control of plant disease, but also proposes a promising, eco-friendly strategy to for the development and application of environmentally friendly biopesticides.

Graphical abstract

Chemical Engineering Journal，IF=13.2

https://www.sciencedirect.com/science/article/pii/S1385894725107596