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Dissecting and optimizing bioactivities of chitosans by enzymatic modification.
Carolin Richter1, Stefan Cord-Landwehr1, Ratna Singh1
1Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, 48143 Münster, Germany.
Carbohydrate Polymers
|December 5, 2024
Summary
Enzymatic modification of chitosan biopolymers creates distinct molecular structures with tailored agricultural applications. Different chitosan forms exhibit specific antimicrobial, plant defense, and gene expression profiles, enabling targeted agro-biologic development.
Area of Science:
- Biotechnology
- Agricultural Science
- Polymer Chemistry
Background:
- Chitosans are valuable biopolymers in agriculture due to their antimicrobial and plant-strengthening capabilities.
- Limited knowledge of chitosan structure-function relationships hinders the creation of effective chitosan-based agro-biologics.
- Understanding how chitosan modifications impact biological activity is crucial for agricultural applications.
Purpose of the Study:
- To investigate how different hydrolysis methods (acid, chitinase, chitosanase) affect chitosan molecular characteristics.
- To evaluate the impact of these modifications on chitosan's biological activities, including antimicrobial, elicitor, and priming effects.
- To analyze gene expression changes induced by different chitosan forms in plants.
Main Methods:
- Partial hydrolysis of a specific chitosan polymer (DP 800, FA 0.2) using acetic acid, GH18 chitinase, and GH8 chitosanase.
- Characterization of hydrolysate composition, including degree of polymerization (DP), fraction of acetylation (FA), and pattern of acetylation (PA).
- Assessment of antifungal, antibacterial, elicitor, and priming activities in *Arabidopsis* plants, coupled with transcriptomic analysis.
Main Results:
- Hydrolysis methods yielded chitosan mixtures with varying DP, FA, and PA. Chitinase and chitosanase produced distinct acetylation patterns compared to random acid hydrolysis.
- Acid hydrolysis maintained antifungal and antibacterial activities. Chitinase hydrolysis slightly enhanced antibacterial activity but abolished antifungal activity. Chitosanase hydrolysis significantly reduced antifungal activity.
- Chitosanase hydrolysis increased elicitor and priming activities, while chitinase destroyed them. Transcriptomic data showed chitosan polymer induced photosynthesis genes, and chitosanase hydrolysate induced disease resistance genes.
Conclusions:
- Different bioactivities of chitosans are linked to specific molecular structures, necessitating tailored chitosan forms for distinct agricultural uses.
- Enzymatic hydrolysis, particularly with chitosanase, can fine-tune chitosan properties to enhance specific agricultural benefits like disease resistance.
- Tailoring chitosan molecular characteristics through controlled hydrolysis is key to developing effective and targeted chitosan-based agro-biologics.
