Chitosan oligosaccharide has been widely used in agricultural production. This is because of its excellent biocompatibility, biodegradability, non-toxicity, and adsorption capacity. No matter Agricultural pollution reduction or green ecological agriculture development, chitosan oligosaccharide agriculture grade plays an important role. COS is a good plant growth regulator, soil conditioner, fruit, and vegetable preservative, and seed coating, and can be widely used in crop disease management.
Chitosan oligosaccharide antimicrobial activity is well-known, it has a good ability to inhibit the growth and reproduction of some fungi, bacteria, and viruses. However, The inhibitory effect will influenced by the molecular weight of chitosan, its physical and chemical properties, and the types of pathogenic bacteria.
Dora Agritech has tested three different molecular weights of chitosan products, to test the different chitosan oligosaccharide antimicrobial activity. (C1=1.5k Da, C2=30k Da, C3=300k Da)
For low molecular weight dora chitosan oligosaccharide(C1), the concentration is higher, the small chitosan molecules enter the pathogenic bacteria cells more. There will be more chitosan molecules that can be combined with the pathogenic bacteria DNA and interfere with the DNA structure. Thus more effectively inhibit the growth of pathogenic bacteria.
For the large molecular weight chitosan oligosaccharide C2 & C3, when the concentration arrives at a sufficient concentration and forms a dense enough membrane on the surface of the bacteria cells, it can get the best inhibitory effect. The most effective and economical antibacterial concentrations of C2 and C3 chitosan were 0.5% and 1%.
Discussion on Chitosan Mechanism
Dora Agritech's test results presented that the most important factor affecting the antibacterial properties of COS is molecular weight. And the low molecular weight chitosan has a better effect than high molecular weight chitosan oligosaccharide in antibacterial function.
Low molecular weight chitosan oligosaccharide has a certain ability of bactericidal because its small molecules are easy to enter the void structure of the cell wall and interfere with the metabolism of cells to achieve the purpose of bactericidal.
High molecular weight COS has excellent antibacterial and bactericidal effects, and the antibacterial factor -NH+3 is why it has antibacterial properties. High molecular weight chitosan oligosaccharide has good film-forming properties, it can form a sufficiently dense film on the cell surface to prevent nutrient input from bacteria.
In terms of antagonistic ability, the low-molecular-weight chitosan is better than high-molecular-weight chitosan, because it has film-forming properties and is easier to enter into bacterial cells.
This demonstrates that the most effective mechanisms for chitosan to inhibit bacteria are the regulation of chitosan molecules at the transcriptional level and the inhibition of pathogen growth. It can be seen that one of the effective ways to develop high-effiency biological pesticides is the development and utilization of low molecular weight chitosan.
Application of Small Molecular Weight Chitosan in Agriculture
Chitosan oligosaccharide (ie low molecular weight chitosan) has better water solubility than chitosan because of its low degree of polymerization. So it has good biocompatibility. However, high molecular weight chitosan can only be dissolved in an acidic solution which extremely limits the application.
Low viscosity, good water solubility, and easy absorption by crops are the advantages of chitosan oligosaccharides. Its excellent biological activities and physiological functions are the reasons why it can be widely used in agricultural production.
On one side, COS has broad-spectrum antibacterial activity, on the other side, it can induce disease resistance of fruits and vegetables to pathogenic infection, hence inhibiting postharvest disease and reducing rot loss. COS can inhibit the respiratory metabolism of fruits and vegetables, prevent water loss, maintain fruit firmness, delay color change, and delay the decline of soluble solids, ascorbic acid, and titratable acid to that improve storage quality.
All chitosan oligosaccharides used in the test come from Dora's laboratory. Through the method of high-performance enzyme, chitosan oligosaccharide was prepared by enzymatic hydrolysis of chitosan. The optimum process conditions are pH 4.5, temperature 50℃, enzyme dosage 100 U/g, and reaction time 3 h. Under this condition, the chitosan reaction is complete and the energy consumption is minimal.
If you are interested in our Dora chitosan oligosaccharide, please contact our team.