Publications in May & June 2016 - Chitosan Oligosaccharides
This time the focus is on the small ones - Production and application of chitosan oligosaccharides:
In May and June 2016, 639 articles about chitosan, regarding mostly the topics nanoparticles, pharmaceutical preparations und evaluation studies, were published. China (128 articles), United States (42) and India (21) were leading countries in chitosan research.
|International journal of biological macromolecules||52|
|Materials science & engineering. C, Materials for biological applications||17|
|Colloids and surfaces. B, Biointerfaces||13|
|Journal of Nanoscience and Technology||6|
Table: Journals with the most publications about chitosan and chitosan derivates in July and August 2016. Source: www.gopubmed.org
The application of chitosan in medicine and food industry is often limited by its poor solubility under physiological conditions. Solubility can be improved by reducing the degree of polymerization by creating chitosan oligosaccharides. The following studies present ways to produce different oligosaccharide and their application as plant immunity regulator.
Cellobiohydrolases Produce Different Oligosaccharides from Chitosan
Tegl G., Oehlknecht C., Vielnascher R. et al., Biomacromolecules; 17(6):2284-92. June 2016 doi: 10.1021/acs.biomac.6b00547.
Chitosan oligosaccharides can be produced enzymatically or chemically. Large scale production of chitosan oligosaccharides (COS) requires readily available enzymes and knowledge about their chitosan hydrolysis products. The authors performed hydrolysis of chitosans for production of COS with readily available glycosidases. Thereby, cellobiohydrolases were compared to chitosanases concerning applicability in COS production. Fractions were analyzed by mass spectroscopy and NMR.
- Applied enzyme produced oligomers with a polymerization degree of 2-6 and different acetylation patterns
- pH optima of 5-6 and temperature optima was 37-60 °C for applied enzymes
- Enzymes with chitosanase and chitinase activity had preferred cleavage sites (NMR analysis), enable the production of different chitosan oligosaccharides
Conclusion: The study shows that cheap and commercial available enzymes, like cellobiohydrolases, can be applied to synthesis bioactive COS with desired properties.
Chitosan oligosaccharide induces resistance to Tobacco mosaic virus in Arabidopsis via the salicylic acid-mediated signalling pathway
Jia X., Meng Q., Zeng H. et al. Scientific Reports, 6:26144, May 2016. doi: 10.1038/srep26144.
Chitosan oligosaccharides can be applied as plant immunity regulator. The authors investigated the ability of COS (degree of polymerization: 2-10, degree of deacetylation: 95%) to induce resistance against tobacco mosaic virus (TMV) in Arabidopsis. To confirm the effect of COS, phenotype data, expression and levels of TMV coat protein were measured. The two plant hormones salicylic acid (SA) and jasmonic acid (JA) are important for defense signal transduction. To reveal the participating signaling pathways of TMV resistance by COS, jar1 and NahG (defective SA pathway) Arabidopsis mutants were examined.
- Best results of TMV resistance were found for pretreatment with 50 mg/L COS one day prior to inoculation with TMV.
- Effect of COS treatment in WT and jar1 plants, but not in NahG plants:
- Induced TMV resistance
- Enhanced salicylic acid amount
- Induced PR1 gene expression (biomarker of salicylic acid signaling pathway)
Conclusion: For induction of TMV resistance in Arabidopsis an optimal pretreatment dose of 50 mg/L for one day before inoculation with TMV was determined. COS induces TMV resistance by activation of the SA signaling pathway.