Abstract
Chitosan oligosaccharide (COS) has become of great interest in recent years because of its worthy biological activities. This study aims to produce COS using the enzymatic method, and investigates Paenibacillus sp. TKU047, a chitinolytic-producing strain, in terms of its chitosanase productivity on several chitinous material-containing mediums from fishery process wastes. The highest amount of chitosanase was produced on the medium using 2% (w/v) squid pens powder (0.60 U/mL) as the single carbon and nitrogen (C/N) source. The molecular mass of TKU047 chitosanase, which could be the smallest one among chitinases/chitosanases from the Paenibacillus genus, was approximately 23 kDa according to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) method. TKU047 chitosanase possessed the highest activity at 60 °C, pH 7, and toward chitosan solution with a higher degree of deacetylation (DDA) value. Additionally, the hydrolysis products of 98% DDA chitosan catalyzed by TKU047 chitosanase showed the degree of polymerization (DP) ranging from 2 to 9, suggesting that it was an endo-type activity chitosanase. The free radical scavenging activity of the obtained chitosan oligosaccharide (COS) was determined. The result showed that COS produced with Paenibacillus sp. TKU047 chitosanase expressed a higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity than that from the commercial COSs with maximum activity and IC50 values of 81.20% and 1.02 mg/mL; 18.63% and 15.37 mg/mL; and 15.96% and 15.16 mg/mL, respectively. As such, Paenibacillus sp. TKU047 may have potential use in converting squid pens waste to produce chitosanase as an enzyme for bio-activity COS preparation.
Highlights
Chitosan is a linear polymer that is produced from chitin via the deacetylation process [1].Chitosan comprises some excellent properties including non-toxicity, adsorption, biocompatibility, Polymers 2020, 12, 1163; doi:10.3390/polym12051163 www.mdpi.com/journal/polymersPolymers 2020, 12, 1163 and biodegradability, it can potentially be used in many fields such as medicine, wastewater treatment, agriculture, and functional food [2,3,4,5,6,7]
TKU047 exhibited chitosanase activity on the culture media containing chitinous sources and non-activity on Nutrient broth (NB) indicating that chitin was a key factor for chitosanase production by Paenibacillus sp
A similar phenomenon was observed in other reports, which showed that squid pens powder (SPP) was the most suitable chitinous source for chitosanase production via Paenibacillus strains [13,31]
Summary
Chitosan is a linear polymer that is produced from chitin via the deacetylation process [1].Chitosan comprises some excellent properties including non-toxicity, adsorption, biocompatibility, Polymers 2020, 12, 1163; doi:10.3390/polym12051163 www.mdpi.com/journal/polymersPolymers 2020, 12, 1163 and biodegradability, it can potentially be used in many fields such as medicine, wastewater treatment, agriculture, and functional food [2,3,4,5,6,7]. One of the most challenging applications of chitosan is its poor solubility in a neutral aqueous solution. The three major processes to convert chitosan into COS include physical, chemical, and enzymatic methods. Compared to physical and chemical methods, the enzymatic method seems to be more advantageous because it enables controlling the molecular mass of the COS product and the reaction condition is gentler [2]. To reduce the cost of the enzyme and that of COS produced by the enzymatic method, some solutions include reducing the enzyme purification steps [18], using a commercial enzyme complex to hydrolyze chitosan [19], immobilizing the enzyme [20], using ultrafiltration membrane enzymatic system [21], and utilizing low-cost materials to produce chitinolytic enzymes via microbial fermentation [22]
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