A Novel Chitosanase from Penicillium oxalicum M2 for Chitooligosaccharide Production: Purification, Identification and Characterization

This study discovered a novel chitosanase from Penicillium oxalicum M2 based on a new screening strategy. An extracellular chitosanase was isolated and purified from the fermentation broth of Penicillium oxalicum M2. A 19.34-fold purification was achieved on a cation exchange column. Using sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, chitosanase was determined at approximately 42 kDa without any subunits. The sequence of peptide in the protein was identified as SALNKNYITNFSTLR by MALTI-TOF/TOF MS. The maximum catalytic activity of the purified enzyme was 60.45 U/mg at the optimum pH and temperature of 5.5 and 60 °C. The enzyme activity held stability in the range of 35-50 °C and pH 3-4.5. Ca²⁺, Mn²⁺, non-ionic surfactants (Tween 20/40/60/80 and Trition X-100) and some common reducing agents (DTT and β-ME) could significantly activate chitosanase. The purified enzyme showed rigorous specificity to chitosan as a substrate. The hydrolysate in the final stage of hydrolysis consisted of chitooligosaccharides with a degree of polymerization ranging from 2 to 5 and without glucosamine or acetylglucosamine. The monomeric enzyme obtained by one-step purification reveal applications potential in sugar industry, and expanded our understanding of the GH75 family chitosanases simultaneously.

Isolation and characterization of chitinolytic bacterium, Escherichia fergusonii AMC01 from insectivorous bat, Taphozous melanopogon

Chitinases are capable of hydrolyzing insoluble chitin into its oligo and monomeric parts and have received increased consideration because of their wide scope of biotechnological applications. The commercial application of microbial chitinase is appealing due to the relative ease of enormous production and to meet the current world demands. This study aimed at isolation and characterization of chitin degrading bacteria from the gut of Indian tropical insectivorous black-bearded tomb bat, Taphozous melanopogon. The isolated bacterial strains were characterized through biochemical analysis and nucleic acid-based approaches by 16S ribosomal RNA amplification and sequencing. The BLAST (Basic Local Alignment Search Tool) and phylogenetic analysis showed that the bacterial strain exhibited a close resemblance with Escherichia fergusonii. The chitinolytic activity of the E. fergusonii AMC01 was identified using supplemented colloidal chitin with agar medium. Compiling all, these findings would facilitate in constructing a database and presumably promote the use of E. fergusonii AMC01 as an efficient strain for the chitinase production.

Production of chitinase from Escherichia fergusonii, chitosanase from Chryseobacterium indologenes, Comamonas koreensis and its application in N-acetylglucosamine production

The important platform polysaccharide N-acetylglucosamine (GlcNAc) has great potential to be used in the fields of food, cosmetics, agricultural, pharmaceutical, medicine and biotechnology. This GlcNAc is being produced by traditional methods of environment-unfriendly chemical digestion with strong acids. Therefore, researchers have been paying more attention to enzymatic hydrolysis process for the production of GlcNAc. Hence, in this study, we isolated novel chitinase (Escherichia fergusonii) and chitosanase (Chryseobacterium indologenes, Comamonas koreensis) producing strains from Korean native calves feces, and developed the potential of an eco-friendly microbial progression for GlcNAc production from swollen chitin and chitosan by enzymatic degradation. Maximum chitinase (7.24±0.07U/ml) and chitosanase (8.42±0.09, 8.51±0.25U/ml) enzyme activity were reached in submerged fermentation at an optimal pH of 7.0 and 30°C. In this study, sucrose, yeast extract, (NH₄)₂SO₄, and NaCl were found to be the potential enhancers of exo-chitinase activity and glucose, corn flour, yeast extract, soybean flour, (NH₄)₂SO₄, NH₄Cl and K₂HPO₄ were found to be the potential activator for exo-chitosanase activity. Optimum concentrations of the carbon sources for enhanced chitinase activity were 9.91, 3.21, 9.86, 1.66U/ml and chitosanase activity were 1.63, 1.13, 2.28, 3.71, 9.02, 4.93, and 2.14U/ml. These enzymes efficiently hydrolyzed swollen chitin and chitosan to N-acetylglucosamine were characterized by thin layer chromatography and were further confirmed by high-pressure liquid chromatography. From a commercial perspective, we isolated, optimized and characterized exochitinase from Escherichia fergusonii (HANDI 110) and chitosanase from Chryseobacterium indologenes (HANYOO), and Comamonas koreensis (HANWOO) for the large-scale production of GlcNAc facilitating its potential use in industrial applications.

Novel Acinetobacter parvus HANDI 309 microbial biomass for the production of N-acetyl-β-d-glucosamine (GlcNAc) using swollen chitin substrate in submerged fermentation

BACKGROUND

N-acetyl-β-d-glucosamine (GlcNAc)₆ is extensively used as an important bio-agent and a functional food additive. The traditional chemical process for GlcNAc production has some problems such as high production cost, low yield, and acidic pollution. Therefore, to discover a novel chitinase that is suitable for bioconversion of chitin to GlcNAc would be of great value.

RESULTS

Here, we describe the complete isolation and functional characterization of a novel exo-chitinase from Acinetobacter parvus HANDI 309 for the conversion of chitin. The identified exo-chitinase mainly produced N-acetyl-d-glucosamine, using chitin as a substrate by submerged fermentation. The A. parvus HANDI 309 biofuels producing exo-chitinase were characterized by TLC, and was further validated and quantified by HPLC. Furthermore, the optimal temperature and pH for the exo-chitinase activity was obtained in the culture conditions of 30 °C and 7.0, respectively. The maximum growth of the stationary phase was reached in 24 h after incubation. These results suggest that A. parvus HANDI 309 biofuels producing exo-chitinases may have great potential in chitin to N-acetyl-d-glucosamine conversion.

CONCLUSIONS

The excellent thermostability and hydrolytic properties may give the exo-chitinase great potential in chitin to GlcNAc conversion in industry. This is the first report that A. parvus HANDI 309 is a novel bacterial strain that has the ability to produce an enormous amount of exo-chitinase-producing bio-agents in a short time on an industrial scale without any pretreatment, as well as being potentially valuable in the food and pharmaceutical industries.