Production of Enzymes by Paenibacillus chitinolyticus and Paenibacillus ehimensis to Obtain Chitooligosaccharides

Enzymatic degradation of glucosaminoglucan and cellulase resistance of cellulose nanofiber coated with glucosaminoglucan

AIMS

Enzymatic degradation of β-1,4-linked glucose and glucosamine (glucosaminoglucan, GG), which is prepared from Thiothrix nivea and can act as a cellulose-aminating agent with a strong affinity to cellulose, was attempted.

METHODS AND RESULTS

A chitosanase-secreting fungal strain was isolated as a GG-degrading microbe. GG was found to be degraded by not only chitosanases but also cellulases. Based on nuclear magnetic resonance spectroscopy, both enzymes were found to produce GlcN-Glc from GG. The cellulases also produced GlcN-Glc-GlcN-Glc as an additional final digest. Furthermore, aminated (GG-coated) cellulose nanofibers exhibited cellulase resistance. The flexibility of GG adsorbed onto a cellulose crystal was almost identical to that of cellulose, as estimated via the molecular dynamics calculations.

CONCLUSIONS

The chitosanase and cellulase hydrolyzed the β-1,4-linkage from Glc to GlcN and were expected to recognize the tetramer and hexamer units of GG depending on their final products. The cellulose nanofibers acquired cellulase resistance via amination with GG, probably because of the lower activity of cellulase to GG than cellulose.

Purification of chitosanases produced by Bacillus toyonensis CCT 7899 and functional oligosaccharides production

Chitooligosaccharides (COS) have a great potential to be used by pharmaceutical industry due to their many biological activities. The use of enzymes to produce them is very advantageous, however it still faces many challenges, such as discovering new strains capable to produce enzymes that are able to generate bioactive oligosaccharides. In the present study a purification protein protocol was performed to purify chitosanases produced by Bacillus toyonensis CCT 7899 for further chitosan hydrolysis. The produced chitooligosaccharides were characterized by mass spectroscopy (MS) and their antiedematogenic effect was investigated through carrageenan-induced paw edema model. The animals were treated previously to inflammation by intragastric route with COS at 30, 300 and 600 mg/kg. The purification protocol showed a good performance for the chitosanases purification using 0.20 M NaCl solution to elute it, with a 9.54-fold purification factor. The treatment with COS promoted a decrease of paw edema at all evaluated times and the AUC0-4h, proving that COS produced showed activity in acute inflammation like commercial anti-inflammatory Dexamethasone (corticosteroid). Therefore, the strategy used to purification was successfully applied and it was possible to generate bioactive oligosaccharides with potential pharmacological use.

Influence of Resistance-Inducing Chemical Elicitors against Pine Wilt Disease on the Rhizosphere Microbiome

Pine wilt disease (PWD) caused by Bursaphelenchus xylophilus is a major threat to pine forests worldwide. Induction of resistance is a promising and safe management option that should be investigated in relation to its possible influence on the pine tree ecosystem, including the surrounding microbial communities. In this study, two main resistance-inducing chemical elicitors, methyl salicylic acid (MeSA) and acibenzolar-s-methyl (ASM), were tested for their control efficiency against PWD and their influence on the rhizosphere microbial composition. Foliar treatment of pine seedlings with the chemical elicitors resulted in a reduction in PWD severity, with ASM showing better control efficacy, reaching up to 73% compared to the untreated control. Moreover, bacterial community analysis of the rhizosphere revealed significant changes in several microbial taxa that were present at low relative abundance. In particular, ASM treatment resulted in a significant increase in specific microbial taxa, including members of the Rhodanobacter, Devosia, Bradyrhizobium, Acidibacter, Mesorhizobium, and Hyphomicrobium genera, which are known to play ecological and plant growth-promoting roles. Furthermore, chitinolytic bacteria were shown to be reduced in response to treatment with both MeSA and ASM. Altogether, the present findings demonstrate the occurrence of significant alterations in several ecologically important microbial taxa after treatment with resistance-inducing chemicals. As compared to MeSA treatment, ASM treatment was more effective at suppressing PWD and resulted in more beneficial changes in rhizosphere microbial composition.

Tailored Enzymatic Synthesis of Chitooligosaccharides with Different Deacetylation Degrees and Their Anti-Inflammatory Activity

By controlled hydrolysis of chitosan or chitin with different enzymes, three types of chitooligosaccharides (COS) with MW between 0.2 and 1.2 kDa were obtained: fully deacetylated (fdCOS), partially acetylated (paCOS), and fully acetylated (faCOS). The chemical composition of the samples was analyzed by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry. The synthesized fdCOS was basically formed by GlcN, (GlcN)2, (GlcN)3, and (GlcN)4. On the contrary, faCOS contained mostly GlcNAc, (GlcNAc)2 and (GlcNAc)3, while paCOS corresponded to a mixture of at least 11 oligosaccharides with different proportions of GlcNAc and GlcN. The anti-inflammatory activity of the three COS mixtures was studied by measuring their ability to reduce the level of TNF-α (tumor necrosis factor) in murine macrophages (RAW 264.7) after stimulation with a mixture of lipopolysaccharides (LPS). Only fdCOS and faCOS were able to significantly reduce the production of tumor necrosis factor (TNF)-α at 6 h after stimulation with lipopolysaccharides.