• Korean Journal of Microbiology
• /
• v.54 no.3
• /
• pp.244-253
• /
• 2018

This study was carried out to evaluate effects of antimicrobial substances produced by isolated soil bacteria. Among two thousands of bacterial isolates Paenibacillus elgii DS381 exhibited high antimicrobial activities against several microbial residents on human skin and pathogenic bacteria. DS381 showed 15.3~26.0 mm inhibition zone diameter against all target bacteria and yeast in agar well diffusion test. Antimicrobial peptide produced by DS381 indicated low minimum inhibitory concentration (0.039-5.000 mg/ml). DS381 produced biosurfactant such as lipopeptide, and surface tension of culture supernatant of DS381 reduced from 60.0 to 40.3 mN/m. DS381 also showed $1.56{\pm}0.13U/ml$ of chitinase activity. These results suggest that Paenibacillus elgii DS381 may be utilized as an efficient biocontrol agent against some important human skin microbes and pathogenic bacteria.

• Journal of Applied Biological Chemistry
• /
• v.49 no.4
• /
• pp.171-175
• /
• 2006

Chitin compost and broth were used to suppress club root. Individual cabbage seedlings were transplanted into pots(3500 ml) containing a mixture of 3% chitin compost and 50 ml of chitin broth (T1) or the same quantity control compost and control compost broth(T2). The media in each pot was then infected with Plasmodiophora brassicae. Samples were taken at 6, 7 and 8 weeks after transplanting. The population of chitinase producing bacteria in T1 was consistently larger than that observed in T2. Chitinase activity in the T1 rhizosphere was two-fold greater than that of T2 at each time point observed. Shoot dry weight, leaf number and leaf area in T1 were enhanced 20%, 10% and 12% relative to those seen in T2, respectively. The disease index and root mortality at 8 weeks after transplanting were reduced by 50% and 25% in T1 compared to T2, respectively. Results presented in this study are strongly indicative that chitin compost and broth suppress clubroot in Chinese cabbage.

• YAKHAK HOEJI
• /
• v.38 no.5
• /
• pp.579-585
• /
• 1994

Antitumor activity was tested by administration of reaction mixture of green onion extract and chitin to mice bearing sarcoma-180 cells. An intraperitoneal injection of mixture(20 mg/kg/day) to mice Have an 52% inhibition of tumor growth. Inhibition of tumor growth was found to be dose-dependent. When eighty miligrams of the mixture were administered, the weight of tumor was reduced significantly. HPLC analysis indicated the mixture was composed of N-acetyl-D-glucosamine, N-acetylchitobiose and N-acetylchitotriose.

• Korean Journal of Environmental Biology
• /
• v.20 no.2
• /
• pp.130-135
• /
• 2002

Species of Genus Trichoderma are commercially applied as biological control agents against fungal Pathogens. A powerful biocontrol agent, Trichoderma sp. SJG-99721 was isolated from 305 isolates by morphological characters, chitinase activities and antifungal activities against Phytophthora capsiei. The isolate was identified as Trichoderma harzianum from various features such as growth rate at $27^\circ{C}$, significant growth ratio of $27^\circ{C}$ to $17^\circ{C}$, amount of aerial mycelium, types of branching: system, and disposition patterns of phialide and phialospore. Trichoderma harzianum SJG-99721 have been shown to act as a powerful biological agent against fungal phytopathogens; Botrytis cinerea, Rhizoctonia solani, Phytophthora cryptogea, Phytophthora capsiei, Sclerotinia sclerotiorum, Mycoshaerella melonis, Alternaria sotani, Fusarium oxysporum, Collectotrichum gloesporioodes, Alternaria alternata, Phythium ultimum, Phytophthora drechsleri, Pyricularia grisea.

• Korean Journal of Soil Science and Fertilizer
• /
• v.39 no.1
• /
• pp.15-20
• /
• 2006

Biological control by chitinolytic microorganisms is being evaluated as management options for soilborne diseases. Forty kilograms of chitin compost (CTC) and control compost (CC) were amended on tomato plots ($15m{\times}0.5m$) 7 d before transplanting to evaluate enzymatic activities and the control of Fusarium wilt. Samples were taken on day 1, 3, 5, and 7, the day 1 corresponded to the 66 d after transplanting, the day on which the initial wilting symptoms occurred in plants of CC treated plots. The chitinase activity in soil of CTC was always higher compared to the control. Pathogenesis related (PR) protein (chitinase, ${\beta}$-1, 3-glucanase and peroxidase) activities in tomato roots in CC increased every day and showed marked differences compared to CTC. Wilting symptoms (96 d after transplanting) were reduced by 25% in CTC compared to the control. Protection of tomato plant may be correlated with the high levels of soil enzyme activities resulting from the chitin compost.

• Korean Journal of Microbiology
• /
• v.42 no.2
• /
• pp.131-134
• /
• 2006

The culture conditions for the enhanced mycelial of Clavicorona pyxidata DGUM 29005 were investigated. The optimal temperature and pH for the mycelial growth were $24^{\circ}C$ and 5.0, respectively. It was shown that trehalose was the best supplement of carbon sources in Czapek-Dox medium as a minimal medium for enhanced mycelial growth. In general, inorganic nitrogen sources were better than organic ones for mycelial growth. Calcium nitrate was the best out of the inorganic nitrogen test. The appropriate phosphorous and vitamin were $Na_2HPO_4$ and p-aminobenzoic acid, respectively. After the mycelial of C. pyxidata DGUM 29005 was cultivated at $24^{\circ}C$ for 20 days in MEM broth(pH 5.0), the specific activities of both exomycelial and endomycelial enzymes were determined. Among the exomycelial enzyme assayed, the specific activity of laccase was much higher than those of other enzymes. However, little or no enzyme activities of ${\alpha}$-amylase, chitinase, lipase and pretense were found.

• The Plant Pathology Journal
• /
• v.31 no.3
• /
• pp.278-289
• /
• 2015

Indigenous strains of Trichoderma species isolated from rhizosphere soils of Tea gardens of Assam, north eastern state of India were assessed for in vitro antagonism against two important tea fungal pathogens namely Pestalotia theae and Fusarium solani. A potent antagonist against both tea pathogenic fungi, designated as SDRLIN1, was selected and identified as Trichoderma viride. The strain also showed substantial antifungal activity against five standard phytopathogenic fungi. Culture filtrate collected from stationary growth phase of the antagonist demonstrated a significantly higher degree of inhibitory activity against all the test fungi, demonstrating the presence of an optimal blend of extracellular antifungal metabolites. Moreover, quantitative enzyme assay of exponential and stationary culture filtrates revealed that the activity of cellulase, ${\beta}$-1,3-glucanase, pectinase, and amylase was highest in the exponential phase, whereas the activity of proteases and chitinase was noted highest in the stationary phase. Morphological changes such as hyphal swelling and distortion were also observed in the fungal pathogen grown on potato dextrose agar containing stationary phase culture filtrate. Moreover, the antifungal activity of the filtrate was significantly reduced but not entirely after heat or proteinase K treatment, demonstrating substantial role of certain unknown thermostable antifungal compound(s) in the inhibitory activity.

• Mycobiology
• /
• v.50 no.4
• /
• pp.244-253
• /
• 2022

Trichoderma fungi have been intensively studied for mycoparasitism, and the latter is closely related to their cell-wall degrading enzymes including chitinase. Here, we studied marine-derived Trichoderma spp., isolated from distinct sources and locations, for chitinolytic and antifungal activity. Based on morphological and phylogenetic analyses, two strains designated GJ-Sp1 and TOP-Co8 (isolated from a marine sponge and a marine alga, respectively) were identified as Trichoderma bissettii. This species has recently been identified as a closely related species to Trichoderma longibrachiatum. The extracellular crude enzymes of GJ-Sp1 and TOP-Co8 showed activities of chitobiosidase and b-N-acetylglucosaminidase (exochitinase) and chitotriosidase (endochitinase). The optimum chitinolytic activity of the crude enzymes was observed at 50 ℃, pH 5.0, 0-0.5% NaCl concentrations, and the activities were stable at temperatures ranging from 10 to 40 ℃ for 2 h. Moreover, the crude enzymes showed inhibitory activity against hyphal growth of two filamentous fungi Aspergillus flavus and Aspergillus niger. To the best of our knowledge, this is the first report of the chitinolytic and antifungal activity of T. bissettii.

• Korean Journal of Microbiology
• /
• v.49 no.3
• /
• pp.262-269
• /
• 2013

The object of this study was to improve the quality of Cheonggukjang with new starter, Bacillus subtilis BC-P1. Twenty strains were isolated from the commercial cheonggukjang and 1 Bacillus strain (BC-P1) with protease activity was selected. The 16S rRNA gene sequence revealed that the BC-P1 was closely related to B. subtilis with 99% homology. The quality characteristics of chunggukjang fermented with B. subtilis BC-P1, Bacillus nato (PC) and commercial chunggukjang (NC) were investigated. The characteristics of fermentation were determined by protease, lipase, xylanase, chitinase, and fibrinolytic activities, reducing sugar, nutrient composition and amino acid contents of cheonggukjang sample. Cheonggukjang fermented with B. subtilis BC-P1 showed the strongest fibrinolytic, xylanase, and chitinase activities. Reducung sugar contents of Cheonggukjang samples were $30.16{\pm}2.11$ mg/g (NC), $28.56{\pm}1.52$ mg/g (PC), $32.39{\pm}1.87$ mg/g (BC-P1). And their total amino acid contents were 338.99 mg% (NC), 445.19 mg% (PC), 741.35 mg% (BC-P1). These results suggested that B. subtilis BC-P1 was suitable to be used as a starter to enhance the quality and effects of cheonggukjang.

• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.4
• /
• pp.490-497
• /
• 2010

A chitinolytic bacterium having a strong antagonistic activity against various pathogens including Phytophtora capsici was isolated from rhizosphere soil, and identified as Lysobacter enzymogenes (named as LE429) based on 16S rRNA gene sequence analysis. This strain produced a number of substances such as chitinase, ${\beta}-1$, 3-glucanase, lipase, protease, gelatinase and an antibiotic compound. This antibiotic compound was purified by diaion HP-20, sephadex LH-20 column chromatography and HPLC. The purified compound was identified as phenylacetic acid by gas chromatography-electron ionization (GC-EI) and gas chromatography-chemical ionization (GC-CI) mass spectrometry. In field experiment, pepper plants were treated by the strain LE429 culture (CB), neem oil solution (NO), combination (CB+NO) or control (CON). Plant height and number of branches, flowers and pods of pepper plant in CB treatment were generally highest, and followed by CB+NO, CON and NO. The fungal pathogens were strongly inhibited, while several insect pests were discovered in CB treatment. Any insect pests were not found, while all fungal pathogens tested were not suppressed in NO treatment. However, in CB+NO treatment, non incidence of fungal pathogens and insect pests were found. The strain LE429 producing secondary metabolites with neem oil should be a potential agent to control fungal diseases and insect pests.