Thermostable chitosanase from Bacillus sp. strain CK4: its purification, characterization, and reaction patterns

Production and purification of a protease, a chitosanase, and chitin oligosaccharides by Bacillus cereus TKU022 fermentation

A protease- and chitosanase-producing strain was isolated and identified as Bacillus cereus TKU022. The protease and chitosanase were both produced using 1.5% (w/v) shrimp head powder (SHP) as the sole carbon/nitrogen source, and these enzymes were purified from the culture supernatant. The molecular masses of the TKU022 protease and chitosanase determined using SDS-PAGE were approximately 45 and 44kDa, respectively. The high stability of the TKU022 protease toward surfactants, an optimal pH of 10 and an optimal temperature of 50-60°C suggest that this high-alkaline protease has potential applications for various industrial processes. Concomitant with the production of the TKU022 chitosanase, N-acetyl chitooligosaccharides were also observed in the culture supernatant, including (GlcNAc)(2), (GlcNAc)(4), (GlcNAc)(5), and (GlcNAc)(6) at concentrations of 201.5, 12.4, 0.5, and 0.3μg/mL, respectively, as determined using an HPLC analysis. The chitin oligosaccharides products were also characterized using a MALDI-TOF mass spectrometer. A combination of the HPLC and MALDI-TOF MS results showed that the chitin oligosaccharides of the TKU022 culture supernatant comprise oligomers with degree of polymerization (DP) from 2 to 6. Using this method, the production of a protease, a chitosanase, and chitin oligosaccharides may be useful for various industrial and biological applications.

Biodegradation of shellfish wastes and production of chitosanases by a squid pen-assimilating bacterium, Acinetobacter calcoaceticus TKU024

Two chitosanases (CHSA1 and CHSA2) were purified from the culture supernatant of Acinetobacter calcoaceticus TKU024 with squid pen as the sole carbon/nitrogen source. The molecular masses of CHSA1 and CHSA2 determined by SDS-PAGE were approximately 27 and 66 kDa, respectively. The optimum pH, optimum temperature, pH stability, and thermal stability of CHSA1 and CHSA2 were (pH 6, 50°C, pH 4-10, <90°C) and (pH 7, 60°C, pH 6-11, <70°C), respectively. CHSA1 and CHSA2 had broad pH and thermal stability. CHSA1 and CHSA2 were both inhibited by EDTA and were inhibited completely by 5 mM Mn(2+). CHSA1 and CHSA2 degraded chitosan with DD ranging from 60 to 98%, and also degraded some chitin. The most susceptible substrate was 60% deacetylated chitosan. Furthermore, TKU024 culture supernatant (1.5% SPP) incubated for 5 days has the most reducing sugars (0.63 mg/ml). With this method, we have shown that shellfish wastes may have a great potential for the production of bioactive materials.

Gene cloning and biochemical analysis of thermostable chitosanase (TCH-2) from Bacillus coagulans CK108

The DNA sequence of the thermostable chitosanase TCH-2 gene from Bacillus coagulans CK108 showed a 843-bp open reading frame that encodes a protein of 280 amino acids with a signal peptide corresponding to 32 kDa in size. The deduced amino acid sequence of the chitosanase from Bacillus coagulans CK108 has 61.6%, 48.0%, and 12.6% identities to those from Bacillus ehemensis, Bacillus circulans, and Bacillus subtilis, respectively. C-Terminal homology analysis shows that the enzyme belongs to the Cluster I group. The size of the gene was similar to those from mesophiles of the Cluster I group with regard to higher preference for codons ending in G or C. The recombinant chitosanase was electrophoretically purified to homogeneity by only two steps with column chromatography. The half-life of the enzyme was 40 min at 90 degrees C. The purified protein was also highly stable, retaining above 50% residual activities during treatment with denaturants such as urea (8 M) and guanidine x HCl (4 M) at 37 degrees C for 30 min. The enzyme had a useful reactivity and a high specific activity for producing functional oligosaccharides as well, producing the tetramer as a major product.