Scalable production of highly enriched chitobiose shows promise in agriculture, promoting plant growth and bolstering immunity

Abstract Chitobiose is a high-value, chitin-derived disaccharide with promising potential for agricultural application. Unfortunately, current production methods rely on hazardous chemical and costly enzymatic processing and the resulting high cost prohibits its commercial application. In this work, we report a simple, scalable fermentation platform, based on a Streptomyces venezuelae ΔdasBC transporter mutant that converts raw chitin directly into chitobiose. By tuning production parameters to maximize titer, the process yielded an estimated ~ 450 mg/L chitobiose without chitin pretreatment or enzymatic steps. Liquid chromatography/mass spectrometry showed the product to be highly enriched for chitobiose with the absence of detectable longer N-acetylglucosamine oligomers. To explore the potential agricultural application, we tested the crude spent medium as a biostimulant. As a soil additive, it increased Arabidopsis thaliana rosette size by up to 22% and induced beneficial changes to root development, while foliar pretreatment decreased Botrytis cinerea infection symptoms and increased the immunity-related responses to fungal elicitors. Notably, this immune-priming activity surpassed that of a commercially available chitin oligomer mix at an equivalent mass concentration, highlighting its potency. Together, this work establishes a cost-effective microbial platform for the production of highly enriched chitobiose and demonstrates its utility as a bioproduct that promotes plant growth and defense. The approach enables sustainable valorization of chitin waste streams into a defined, bioactive molecule for agriculture applications.