• Korean Journal Plant Pathology
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• v.3 no.3
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• pp.168-173
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• 1987

The constancy of the patterns of esterase isozymes in the mycelium of Pyricularia oryzae grown under various cultural conditions was observed by $10\~25\%$ polycrylamide gradient slab gel. The position of the isozyme was not affected by cultural age for 24 days. However the intensity of the band was affected. The band patterns were not affected by the carbon sources (glucose, maltose, fructose, sucrose or starch), single spore isolates, successive transfer culture and regenerated isolates from protoplast cultures.

• Microbiology and Biotechnology Letters
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• v.49 no.2
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• pp.217-224
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• 2021

Rice blast caused by Pyricularia oryzae, which is a major threat to food security worldwide, markedly decreases the yield of rice. Some rhizobacteria called 'plant growth-promoting rhizobacteria' inhibit plant pathogens and improve plant growth by secreting iron-chelating siderophores. The decreased availability of iron adversely affects the survival of pathogens, especially fungal pathogens, in the rhizosphere. This study aimed to determine the morphological diversity of siderophore-producing bacteria, analyze the type of siderophores produced by the bacteria, and examine their growth-inhibitory activity against Pyricularia oryzae. The rhizobacteria were isolated from the rhizosphere of Sembada Hitam variety of black rice plants in Pakem, Sleman, Yogyakarta, Indonesia. In total, 12 distinct isolates were screened for the production of siderophores. It was found that 9 out of 12 bacteria produced siderophore and most of them were Gram positive bacteria. The best siderophore-producing isolates with different type of siderophore were used in further studies. The IS3 and IS14 isolates were found to be the best siderophore producer that produced hydroxamate and mixed type of hydroxamate-carboxylate type of siderophore, respectively. In the dual culture assay, IS14 showed a strong antagonistic effect against Pyricularia oryzae by the 81.17% inhibition.

• Korean Journal of Microbiology
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• v.23 no.3
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• pp.209-214
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• 1985

The optimum conditions of protoplasts formation from Pyricularia oryzae were investigated with lytic enzymes and osmotic stabilizers. The mycelia were begun to refease the protoplasts in response to the complex enzyme solution after 30-60 minutes and reached to maximum after 2-3hrs. Among the lytic enzymes tested, the mixture solution containing ${\beta}-Glucuronidase$(0.01 ml/ml), Cellulase ONOZUKA-RS(20mg/ml), Driselase (10mg/ml), and Macerozyme R-10 (10mg/ml) resulted in the highest rate of protoplasts releasing of Pyricularia oryzae. The best stabilizer was 0.6M KCl at pH 7.0. Shen the mycelia were digested with enzyme mixture, the stationary culture was better than shaking culture for higher protoplast formation.

• Fisheries and Aquatic Sciences
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• v.5 no.2
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• pp.97-102
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• 2002

Pyricularia oryzae (P. oryzae), the cause of rice blast, is one of the most important fungal pathogens of rice. Seventy strains of marine fungi were isolated from marine algae, and it was measured antifungal activity against P. oryzae. Metabolites of marine fungus A-248 which isolated from marine algae showed strong antifungal activity against P. oryzae. The antifungal substance from the metabolites of marine fungus A-248 was extracted with ethylacetate, and then purified by preparative TLC and reverse-phase HPLC. The minimum inhibitory concentration (MIC) value was $0.18\mu g/mL$ for the antifungal activity of the substance purified from A-248 metabolites. The purified substance was similar to antifungal activity of rhizoxin, which is a commercial antifungal agent.

• Korean journal of applied entomology
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• v.11 no.2
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• pp.101-107
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• 1972

This experiment was conducted in order to determine the fungi associated with ear blight of rice and their chemical control. 1, Pyricularia oryzes, Helminthosporium oryzne, Epicoccum purpurascens, Curvularia lunata, Cladosporium cladosporoides and Alternaria tenuis et al. were mainly detected in large quantities from the discolored seeds of recommended varieties but Trichoconis padwickii, Fusarium dimerum, and Nigrospora oryzae were mainly detected from Tongil. 2. Pyricularia oryzae, Nigrospora oryzae, and Curvularia lunate et at. were from the necks; Helminthosporium oryzae, Trichoconis padwickii, Stemphylium sp. , Cladosporium cladosporoides, and Alternaria tenuis et at. were from the branches of ear; and Phoma spp. was mainly detected from the kernels. 3. In the laboratory Difolatan WP $0.13\%$ gave good control of Helminthosporium oryzae, Cladosporium cladosporoides, and Alternaria tenuis, et al.; and Dithane M-45 WP $0.2\% gave especially good control of Pyricularia oryzae, Trichoconis padwickii, and Curvularia lunate. 4. In field experiments, the appropriate date of chemical spray was milk ripening stage or panicle emergence stage. Under these conditions Hinosan Ec and Kasugamin Ec were more effective than Difolatan WP and Dithane M-45 WP. However, the assessment of ear blight was complicated by a severe outbreak of neck blast.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.307-312
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• 1989

Strain No.77-AG-567 showed antifungal activity against Pyricularia oryzas and Sphaerotheca fuliginea. In the process of purification of active component this strain was found to produce blasticidin S together with another antibiotic. This compound was identified as being acetoxycyc-heximide, also referred to as E-73, by UV and $^1$H NMR spectral data. Identification of this strain led us to conclude that strain No.77-AG-567 is most probably be Streptomyces atratus. It showed different characteristics from S. atbutus, so far known to produce both blasticidin S and acetoxycycloheximide. Particularly worthy of note was the difference in spore surface. In addition, acetoxycycloheximide has been known to have activity only against yeast and tumor cells but we found that it also has activity against Pyricularia oryzae and Sphasrotheca fuliginea.

• Journal of Microbiology and Biotechnology
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• v.13 no.6
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• pp.984-988
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• 2003

The actinomycete strain KH-6l4 possessed strong antifungal activity, especially antagonistic to the rice blast fungus, Pyricularia oryzae. Diaminopimelic acid (DAP) type and morphological and physiological characteristics, examined by scanning electron microscopy (SEM), indicated that KH-614 belonged to the genus Streptomyces. Antifungal agent produced by this strain was found to be most active, when the strain was cultured in the presence of glucose, polypeptone, and yeast extract (PY) medium for 6 days at $27^{\circ}C$. Based on the spectral report data, MS and NMR, the antifungal agent was identified as cyclo(L-leucyl-L-prolyl). According to the antimicrobial activity test measured by minimal inhibitory concentration (MIC), the cyclo(1eu-pro) exhibited the activity against Candida albicans IAM 4905, Mucor ramannianus IAM6218, Rhizoctonia solani IFO 6218, Aspergilus fumigatus ATCC 42202, Glomerella cingulata IFO 9767, Trichophton mentagrophytes ATCC 18749, and Trichophyton rubrum ATCC 44766, the order of MIC values were 50, 12.5, 5, 50, 25, 5, $5\;\mu\textrm{g}/ml$, respectively. Specifically, cyclo(1eu-pro) was one of the most effective elements against Pyricularia oryzae IFO 5994 with the MIC value of $2.5\;\mu\textrm{g}/ml$, thus indicating that cyclo(leu-pro) is a potential antifungal agent.

• Journal of Microbiology and Biotechnology
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• v.10 no.6
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• pp.811-816
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• 2000

An antagonistic bacterium PM-1 which strongly inhyibits the growth of Pyricularia oryzae was isolated and identified as paenibacillus macerans. The antifungal substances of the strain PM-1 showed the broad antifungal spectra against P.oryzae races. Relating to the localization test, it was found that the antifungal substances existed not only in the cytoplasm but also in the culture supernatant, and importantly the antifungal activity of the latter was stronger than that of the former. The extracellular antifungal substances were extremely heat-stable up to $121^{\circ}C$ for 15 min. The substances were optimally produced at $20^{\circ}C$ and pH 10.0 in a potato dextrose broth. The culture filtrate of the strain PM-1 caused a partial swelling of the mycelia of P.oryzae, and it prevents the normal growth of the fungus as well. This result suggested that the antifungal substances secreted by the strain PM-1 potentially inhibited the germination of P.oryzae.

• Korean Journal Plant Pathology
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• v.3 no.2
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• pp.124-130
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• 1987

The optimum conditions for protoplast formation and regeneration from Pyricularia oryzae Cav. were selected as follows. As a basic solution, 0.02M potassium phosphate buffer solution plus 0.6M KCl adjusted to pH 5.2 with 1N HCl was used. A mixture of enzyme combinations with 20mg Cellulase R-l0/ml, 5mg Macerozyme R-l0/ml and l0mg Driselase/ml used as a lytic enzyme showed better lytie effect than any single enzyme treatment for protoplast formation. Two-day-old mycelia of P. oryzae grown in the mixture of three lytie enzyme solution at $30^{\circ}C$ for 3 hr showed best condition for protoplasts formation. For regeneration from the protoplasts of P. oryzae, potato dextrose agar containing 0.02M potassium phosphate plus 0.6M KCl used as a stabilizer was best for regeneration medium.

• Microbiology and Biotechnology Letters
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• v.25 no.6
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• pp.537-545
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• 1997

The aim of the present research program was to isolate a strain of actinomycetes producing antifungal substance. Soil samples were collected from various sites in Korea and a number of actinomycetes were isolated from the soil samples by applying selective agar for actinomycetes. Among isolates, a strain (NA -52) producing antifungal substance against Pyricularia oryzae was selected. Chemotaxonomic and numerical identification were carried out for the isolate. Fifty taxonomic unit characters were tested and the data were analyzed numerically using TAXON program. The isolate was identified as a synonym of streptomyces diastaticus belong to cluster No. 19 (Streptomyces diastaticus). But it showed a low similarity to S. diastaticus in simple matching coefficients, hence it was considered as one new species in Streptomyces.