• Journal of Life Science
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• v.14 no.3
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• pp.467-471
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• 2004

Bacillus sp. SD-10 was investigated to develope biological pesticides for control of mushroom diseases. Bacillus sp. SD-10 showed high antifungal activity when cultured at 35∼4$0^{\circ}C$ for 30∼4$0^{\circ}C$. The culture filtrate of the bacterium inhibited the growth of mycelium of T. virens which is a kind of mushroom pathogene. On the test of inhibition of spore germination of T. virens, more than 5% of the culture filtrate in the media inhibited completely the germination of the spores. An antimicrobial substance, UPX-1 was purified from the culture filtrate of the Bacillus. From the $^1H$-NMR and $^{13}C$-NMR spectrum analysis, the substance was indentifed as disaccharide composed to six carbon sugars. UPX-1 has not only strong antifungal activity against T. virens but also antibacterial activity against Pseudomonas tolaassi.

• The Plant Pathology Journal
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• v.24 no.4
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• pp.453-460
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• 2008

In the course of in vitro and in vivo screening for bioherbicidal agents, a hyphomycete fungus, Myrothecium sp. F0252 was selected as a candidate for the biocontrol of weeds. The isolate was identified as Myrothecium roridum Tode ex. Fries based on the morphological characteristics and 18S ribosomal DNA sequence analysis and registered as Myrothecium roridum F0252. In order to evaluate the in vitro effect of M. roridum F0252 on germination of ladino clover and white clover (Trifolium repens L.) seeds, spore solution of the fungus was employed in two concentrations, $6.5{\times}10^6$ and $2.5{\times}10^7$ spores per mL and then inoculated to the seeds. The fungal spores inhibited the seed germination, infected the seedlings, and caused an abnormal withering and inhibition of seedling growth. In addition, when the herbicidal activity of crude ethyl acetate extract from the liquid culture was assessed on a mini-plant, duck-weed (Lemna paucicostata (L.) Hegelm.), the extract showed high inhibitory effect at the level of $12.5{\mu}g$ per mL. On the other hand, in vivo herbicidal activity of M. roridum F0252 was evaluated by a whole plant spray method. M. roridum F0252 exhibited strong and broad-spectrum herbicidal activity. The herbicidal values ranged from 95-100% against 7 weeds, including Abutilon avicennae and Xanthium strumarium, and 70-80% against Digitaria sanguinalis and Sagittaria pygmaea. When the nutritional utilization (95 carbon sources) pattern of M. roridum F0252 was investigated, it varied with water activity ($a_w$) and temperature conditions, supplying good, basic information in regard to nutritional utilization for proper cultivation and formulation. Our results showed that M. roridum F0252 might be used as a potential biocontrol agent against weedy plants.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.42-51
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• 2013

One of the most important limiting factors for the production of the grafted cactus in Korea is the qualitative and quantitative yield loss derived from stem rots especially caused by Bipolaris cactivora. This study is aimed to develop microbial control agents useful for the control of the bipolaris stem rot. Two bacteria (GA1-23 and GA4-4) selected out of 943 microbial isolates because of their strong antibiotic activity against B. cactivora were identified as Bacillus subtilis and B. amyloliquefaciens, respectively, by the cultural characteristics, Biolog program and 16S rRNA sequencing analyses. Both bacterial isolates significantly inhibited the conidial germination and mycelial growth of the pathogen with no significant difference between the two, of which the inhibitory efficacies varied depending on the cultural conditions such as temperature, nutritional compositions and concentrations. Light and electron microscopy of the pathogen treated with the bacterial isolates showed the inhibition of spore germination with initial malformation of germ tubes and later formation of circle-like vesicles with no hyphal growth and hyphal disruption sometimes accompanied by hyphal swellings and shrinkages adjacent to the bacteria, suggesting their antibiotic mode of antagonistic activity. Control efficacy of B. subtilis GA1-23 and B. amyloliquefaciens GA4-4 on the cactus stem rot were not as high as but comparable to that of fungicide difenoconazole when they were treated simultaneously at the time of pathogen inoculation. All of these results suggest the two bacterial isolates have a good potential to be developed as biocontrol agents for the bipolaris stem rot of the grafted cactus.

• The Korean Journal of Mycology
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• v.24 no.1 s.76
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• pp.49-55
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• 1996

This study was conducted to find out antifungal activities of entomopathogenic fungus, Metarhizium anisopliae, against phytopathogenic fungi, Fusarium oxysporum, Botrytis cinerea and Alternaria solani. M. anisopliae was confirmed its antagonistic effect through mycelial inhibition zone of phytopathogenic fungi by culture filtrate of the antagonist. The filtrate (30%: v/v) inhibited the conidial germination of B. cinerea and F. oxysporum to 21.5% (control: 88.2%) and 53.0% (control: 78.6%), respectively and delayed the start of spore germination about 8hours. Microscopic observations proved that the addition of 10% culture filtrate of M. anisopliae restricted the growth of phytopathogenic fungus, F. oxysporum, to the formation of chlamydospore. From these results, we concluded that an addition effect of the filtrate from M. anisopliae on culturing F. oxysporum was fungistatic.

• Korean journal of applied entomology
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• v.13 no.4 s.21
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• pp.245-249
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• 1974

In order to establish a dose limits for subsequent induced mutation research itl Pyricularia oryzae, X-ray sensitivity of the conidia and the vegetative hypae of the fungus, race N-1, was investigated. Conidia of the fungus irradiated with X-rays reduced significantly in spore germination inversely with radiation doses. A severe suppression of conidia germination in about $80\%$ was found at the dose of 120kR, and the rests of the conidia produce very short and lysed germ tubes. A stimulated effect was observed in the elongation of hyphae from the conidia of 10 kR irradiation at initial stage of the growth. The radiosensitivity of hyphae was exremely higher than that of conidia with the increase of radiation doses. It was also recognized that the frequency of X-ray induced mutation in pathogenicity was directly proportional to radiation doses.

• The Korean Journal of Mycology
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• v.9 no.3
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• pp.133-139
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• 1981

Two hundred forty seven isolates obtained from 21 white or cream-colored mushroom strain by single spore isolation or multiple spore germination were compared type of mycelial growth in vitro and yield trial in a preliminary test. As a result of these tests, four isolates were selected and compared the yields of sporophores with those of 505 and 702 which are leading strains in mushroom production. The newly selected isolate No. 705 showed high yield of mushroom with good quality as described below. 1. The isolate No. 705 produced 13% more mushrooms than those from the strain No. 703. Both produced creamy type of mushroom. The isolate No. 705 showed high blanching yield ratio and moderate resistance to Mycogone perniciosa. 2. For the isolate No. 705 obtained by multiple spore germinations, the optimum temperature of mycelial growth was $25^{\circ}C$, also the mycelial growth was better at $15^{\circ}C$ than others, optimum moisture content of the compost was 65% and optimum casing soil pH for mycelial growth was 7.8. 3. The new isolate No. 705 produced more number of sporophores and the ratio between parts of sporophores were intermediate of those from the strains No. 505 and No. 703.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.257-265
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• 2011

During 2002-2008 in Korea, 455 extracts from myxobacteria consisting of 318 cellulolytic and 137 bacteriolytic myxobacteria were isolated, which were then screened for antifungal activity against the phytopathogens Botrytis cinerea, Colletotrichum acutatum, Penicillium sp., Pyricularia grisea, and Phytophthora capsici. 204 isolates had antifungal activity, causing both a clear zone due to blocked spore germination and inhibition of mycelial growth; most (199) were from cellulolytic (Sorangium cellulosum) and only five were from bacteriolytic myxobacteria. B. cinerea, the best controlled among the five tested pathogens, had a unique group of antifungal isolates of myxobacterial extracts compared to the other pathogens' groups. Among seventy-nine bioactive myxobacteria, four isolates, KYC 3130, KYC 3247, KYC 3248 and KYC 3270, were selected and all were cellulolytic. Liquid culture filtrates of these four myxobacteria were applied to tomato, cherry tomato, strawberry, and kiwi fruits 5 h before inoculation with gray mold conidia; then the treated fruits were placed in an airtight container and the experiment was repeated six to eight times. Incidence (%) of gray mold on fruit of the infected control treatment was 84-98%, whereas it was only 5-21% after the KYC 3270 treatment. After KYC 3270 treatment of the four fruits, mold control was 79-95%, which was highest among the filtrates and statistically the same as treatment with fludioxonil, a registered chemical against gray mold of stored fruits.

• Microbiology and Biotechnology Letters
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• v.25 no.5
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• pp.527-533
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• 1997

From apple skin, we isolated a bacterial strain which strongly inhibited the growth of apple white rot fungus, Botryosphaeria dothidea. The isolated strain, designated as SS279, was identified to be the genus Bacillus. The antifungal activity of Bacillus sp. SS279 was found in the culture filtrate. The production of antifungal substances occurred during logarithmic phase and was the highest when cultures reached the stationary growth phase. The optimum ranges of temperature and pH for its production were 25-30$\circ$C and 4.5-9.0, respectively. The culture filtrate of Bacillus sp. SS279 exhibited a strong inhibitory effect on the spore germination and germ tube elongation of B. dothidea. Autoclaved culture filtrate of Bacillus sp. SS279 showed only a slight decrease in antifungal activity, indicating that the Bacillus sp. SS279 produce heat-stable antifungal substances. In in vivo bioassay, Bacillus sp. SS279 also showed antagonistic activity against apple white rot caused by B. dothidea.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.332-335
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• 2009

Rhizo-bacteria were isolated from organic-farming soils to select antagonistic agent for controlling citrus melanose disease. Among several antagonistic bacteria, KB-401 effectively inhibited mycelial growth of several plant fungal pathogens, including the pathogen of citrus melanose, Diaporthe citri. KB-401 also inhibited spore germination of the fungal pathogen. The tip of germ tube was swollen when conidia of D. citri were co-culture with KB-401 in PD broth amended 1% glucose. KB-401 was identified as Bacillus subtilis through the investigation for physiological characters and the analysis of nucleotide sequences of 16S rDNA.

• The Korean Journal of Mycology
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• v.8 no.3
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• pp.159-166
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• 1980

Aspergillus niger van Tieghem was cultured by the method of submerged and synchronized culture for the study of differentiation. Acid-phenol soluble cell proteins of the fungus were extracted from four stages during development. Those acid-phenol soluble proteins were separated by polyacrylamide gel electrophoresis to determine the protein patterns. A new protein band was observed from the pre-sporulation body, color density of the stained protein bands in four tubes differed according to the differentiation stages. The number of protein bands in 10% gels varied from 18 to 16, 17, and 19 according to the course of spore germination stage, conidiophore stage, phialide maturation stage and sporulation stage.