• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.647-652
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• 2004

Thermophilic microorganisms capable of producing chitinase enzymes were screened from samples collected from several crater and geothermal areas. The chitinolytic microorganisms were grown in a selective medium containing colloidal chitin. The Bacillus K29-14 isolate was found to exhibit the highest chitinase and chitin deacetylase activities. When grown in a chitin-containing medium, the isolate produced extracellular chitinase after 24 h of incubation. The optimum temperature and pH for the chitinase were $55^\circ{C}$ and pH 7, respectively, while those for the chitin deacetylase were $55^\circ{C}$ and pH 8, respectively. The thermostable chitinase and chitin deacetylase also retained 80- 90% of their activity after incubation for 5 h at $70^\circ{C}$. The divalent cations $CoCl_2\;and\;NiCl_2$, increased the chitinase activity, while $ZnCl_2$, inhibited the enzyme. The chitin deacetylase was also activated by the presence of $MgCl_2$ and inhibited by $MnCl_2,\;NiCl_2,\;and\;CaCl_2$. A zymogram analysis revealed several forms of chitinase, with a 67 kDa form being the major enzyme.

• Journal of Radiation Industry
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• v.4 no.1
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• pp.65-71
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• 2010

Two chitinase producing strains CHI2 and CHI4 were isolated from soybean rhizosphere soil. Both the strains belonged to Lysobacter enzymogenes as indicated by 16S rDNA sequence analysis. Though strain CHI2 and CHI4 produced extracellular chitinase, they differ in their chitinolytic activity. CHI4 produced approximately three times the higher amounts of enzyme than that of CHI2 under specified conditions. CHI2 produced $535.67U\;l^{-1}$ of chitinase after 48 h incubation with a specific activity of $3.91U\;mg^{-1}$ of protein while strain CHI4 produced $1584.13U\;l^{-1}$ of chitinase with a specific activity of $10.88U\;mg^{-1}$ protein. SDS-PAGE analysis indicated that the molecular weight of chitinase enzyme was approximately 45 kDa. A faint band with a molecular weight of 55 kDa reveals the possibility for the presence of another kind of chitin binding protein. Mutant library was developed by exposing the isolates to gamma rays at their $LD_{99}$ value (0.23 kGy). Totally, 11 mutants of CHI2 and CHI4 are reported to have enhanced chitinase activity. Several leaky mutant clones with decreased enzyme activity and a defective mutant (CHI2-M16) with complete loss of chitinase activity were also identified. CHI4-M18, CHI4-M8 and CHI4-M29 showed 78.8, 41.5, and 31.9% increased chitinase activity over wild type CHI4.

• Korean Journal of Microbiology
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• v.40 no.3
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• pp.230-231
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• 2004

The mycelia of Sparassis crispa DSMZ 5201 were cultivated at $24^{\circ}C$ for 15 days in yeast-malt extract-glucose broth (pH 4.0) and the filtrate was used as crude enzyme solution to determined the extracellular enzyme activity. The specific activity of $\alpha$-amylase was 44.27 unit/protein. The specific activities of protease, CMCase, $\beta$-glucosidase, chitinase, exo-$\beta$-l,4-glucanase were relatively high. However, a very little activity of xylanase was found.

• Journal of Applied Biological Chemistry
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• v.42 no.1
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• pp.7-11
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• 1999

An extracellular chitinase of the selected strong antifungal microorganism, Serratia sp. 3095, was purified by salting out, affinity adsorption, Sepadex G-100 gel fitration, Sepadex G-75 gel fitration and DEAE Sepadex A-50 chromatography. The molecular weight of the purified chitinase was estimated to be 62,000 dalton by SDS-PAGE. Optimal pH and temperature of the chitinase were pH 7.5 and 45, respectively. The enzyme retained more than 80% of the activity between pH 5.5 and pH 10.5, and below $50^{\circ}C$ but was unstable above $60^{\circ}C$, below pH 5.0. The activity of the chitinase was inhibited about 60% by $Sn^{2+}$, 40% by $Hg^{2+}$ and $Ag^+$, 70% by AHA, 40% by iodoacetate, 35% by thiourea and p-CMB, but stabilized by SDS. $K_m$ value of the purified chitinase was 3.68 mg/ml for colloidal chitin. The chitinase from Serratia sp. 3095 showed antifungal activity to Fusariurm solani.

• Korean Journal of Microbiology
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• v.38 no.1
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• pp.50-53
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• 2002

The optimum temperature and pH for mycelial growth of B. bassiana DGUM 34001 were $24^{\circ}C$ and pH 7.0, respectively. Among the complex media used, mushroom complex medium (MCM) was the most favorable for mycelial growth. When Czapek-Dox medium was used as a minimal medium, glucose was an excellent source for carbon and energy. Soytone and sodium phosphate were favorable constituent for culture medium as a source of organic nitrogen and phosphorus, respectively. When the fungus was grown in MCM broth, the specific activity of extracellular enzyme of ${\alpha}$-amylase, lipase, chitinase, CMCase and pretease were 297.0, 0.058, 0.33, 0.21 and 22.8 units/mg protein, respectively. When various sources of organic nitrogen and chitin were supplemented to determine the production of enzymes, casein and soluble chitosan enhanced the production of extracellular protease and chitinase.

• Applied Biological Chemistry
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• v.42 no.3
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• pp.181-187
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• 1999

For the selection of an effective antagonistic biocontrol agent, we have isolated an antagonistic bacterium which produced extracellular chitinase, from a local soil of Kyongju, Korea. The selected strain was identified as Serratia proteamaculans 3095. The chitinase produced from Serratia sp. 3095 showed antifungal activity which can attack the hypha surface of Fusarium oxysporum and F. solani. The carbon and nitrogen sources for chitinase production were 0.15% colloidal chitin and 0.1% ammonium sulfate, respectively. Glucose in the chitinase production medium might inhibit the production of chitinase by feed back repression. The antagonistic Serratia sp. 3095 also showed a powerful biocontrol activity against F. oxysporum through in vitro test and in vivo pot test.

• The Korean Journal of Mycology
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• v.51 no.4
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• pp.265-276
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• 2023

This study aimed to isolate and characterize fungi from freshwater environments in South Korea and evaluate their extracellular enzyme activities. Fungal strains were collected from various freshwater sources and identified using phylogenetic analysis. The isolated fungi included known aquatic hyphomycetes and previously unreported species. Extracellular enzyme, including those of protease, amylase, lipase, cellulase, laccase, and chitinase, activities were evaluated. Among the isolated strains, several showed high enzyme activity, suggesting their potential role in organic matter decomposition in freshwater ecosystems. This research expands our knowledge of the diversity and enzyme activities of the fungi in freshwater environments, contributing to our understanding of their ecological roles.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.839-846
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• 1999

An extracellular chitinase-producing bacterial strain induced by colloidal chitin was isolated from sea sand and was identified to be a member of the genus Cytophaga. The chitinase was purified successively by 30-60% ammonium sulfate fractionation, and DEAE-Bio gel A column, Octyl-Sepharose CL-4B column, and DEAE-Bio gel A column chromatographies. The enzyme had a molecular mass of 59.75 kDa, and the amino terminal amino acid sequence was ATPNAPVISW MPTDXXLQNXS. The enzyme acted better on colloidal chitin as a substrate than on chitosan. For colloidal chitin and chitosan (Degree of Acetylation, 15-25%), $K_{cat}$ values were 0.60U/mg and 0.08U/mg, respectively. HPLC analysis of the enzymatic reaction products showed that the chitinase produced mostly N-acetyl-D-glucosarnine and di-N-acetylchitobiose. The optimum temperature and pH for the enzyme were $50^{\circ}C$ and 4.0, respectively. N-Bromosuccinimide and $Hg^{2+}$ inhibited the chitinase activity as much as 90%, and $Sb^{3+}$, diethylpyrocarbonate, and $Ag^{+}$ inhibited it by 50-70%.

• Korean Journal of Microbiology
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• v.38 no.4
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• pp.224-224
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• 2002

Chitin-degrading marine bacterial strain 98CJ11027 was isolated from bryozoa from the coastal area of Cheju Island, Korea, and identified as a member of the genus Vibrio. The molecular mass of the main extracellular chitinase (chitinase I), purified from strain 98CJ11027, was estimated to be 98 kDa. The optimal condition for chitinase I activity is pH 6.0 and 45℃. The activity was inhibited by $Fe^+2$ and$Cu^+2$. Chitinase I displayed the hydrolysis type of chitobiosidase and catalyzed reversed hydrolysis leading to the synthesis of tetraacetylchitotetraose.

• Journal of Microbiology
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• v.33 no.4
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• pp.295-301
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• 1995

An antifungal Pseudomonas stutzeri YPL-1 produced extracellular chitinase and .betha.-1, 3-glucanase that were key enzymes in the decomposition of fungal hyphal walls. These lytic extracellular enzymes markedly inhibited mycelial growth of the phytopathogenic fungus Fusarium solani. A chitinase from P. stutzeri YPL-1 inhibited fungal mycelial growth by 87%, whereas a .betha.-1, 3-glucanase from the bacterium inhibited growth by 53%. Furthermore, co-operative action of the enzymes synergistically inhibited 95% of the fungal growth. The lytic enzymes caused absnormal swelling and retreating on the fungal hyphal walls in a dual cultures. Scanning electron microscopy clearly showed hyphal degradation of F. solani in the regions interacting with P. stutzeri YPL-1. In an in vivo pot test, P. stutzeri YPL-1 proved to have biocontrol ability as a powerful agent in controlling plant disease. Planting of kidney bean (Phaseolus vulgaris L.) seedlings with the bacterial suspension in F. solani-infested soil significantly suppressed the development of fusarial root-rot. The characteristics of a crude preparation of .betha.-1, 3-glucanase produced from P. stutzeri YPL-1 were investigated. The bacterium detected after 2 hr of incubation. The enzyme had optimum temperature and pH of 40.deg.C and pH 5.5, respectively. The enzyme was stable in the pH range of 4.5 to 7.0 and at temperatures below 40.deg.C, with a half-life of 40 min at 60.deg.C.