• Korean Journal of Microbiology
• /
• v.48 no.1
• /
• pp.8-15
• /
• 2012

Bioaerosols generated from composting facilities and landfills may create health risks for workers and nearby residents. To determine the levels of culturable airborne bacteria and fungi in bioaerosols, samples were seasonally collected at a composting facility and a landfill in Ulsan, Korea with an impaction-type sampler. Concentrations of heterotrophic bacteria averaged (in $MPN/m^3$) $6.5{\times}10^3$ (range $1.5{\times}10^2-1.5{\times}10^4$) in the composting facility and $3.9{\times}10^3$ (range $6.0{\times}10^1-9.3{\times}10^3$) at the entrance of the facility. These concentrations were 460 and 280 times higher than those of reference sites. Coliform bacteria were detected both inside and entrance of the facility. On the landfill, heterotrophic bacterial concentrations averaged (in $MPN/m^3$) $4.9{\times}10^2$ (range $1.7{\times}10^2-1.0{\times}10^3$), while they averaged $3.7{\times}10^2$ (range $4.8{\times}10^1-1.3{\times}10^3$) at the parking lot of the landfill. These concentrations were 35 and 26 times higher than those of reference sites. When we isolated and tentatively identified heterotrophic bacteria, Pseudomonas luteola was the most dominant species in bioaerosols from the composting facility, whereas the most abundant one in reference samples was Micrococcus sp. Average concentrations of airborne fungi were measured between $4.8{\times}10^2$ and $7.9{\times}10^2\;MPN/m^3$ depending on sites, which were 2.1-3.4 times higher compared to those of reference sites. While Cladosporium, Alternaria, and Penicillium were commonly identified fungal genera, genus Aspergillus was identified only in bioaerosols from the composting facility.

• Research in Plant Disease
• /
• v.24 no.2
• /
• pp.123-131
• /
• 2018

Kiwifruit has been cultivated in southern coastal regions of Korea since late 1970s. New cultivars have been successively released in recent years. In this study, we investigated major disease and pest incidences in new kiwifruit cultivars 'Goldone', 'Redvita' and 'Garmrok' at open field in Sacheon for 3 years and rain-proof field in Jeju for 2 years. For the bacterial canker, the 3 new cultivars showed more disease occurrence in Sacheon but rare in Jeju. For leaf spot disease, compared to disease incidence of 20% on 'Hayward' in Sacheon, cv. 'Garmrok' had high incidence about 60% but cv. 'Goldone' and cv. 'Redvita' had low incidence less than 20%. However, in Jeju, diseases incidences of all the new cultivars were lesser than 20%. In the case of Hemiptera, many Halyomorpha halys and Nezara antennata appeared in Sacheon but in Jeju Plautia stali was dominated. Isolated bacterial canker pathogen was identified as Pseudomonas syringae pv. actinidiae biovar 3. Leaf spots pathogens were Phomopsis sp., Phoma sp., Fusarium tricinctum and Alternaria alternata. This study shows the disease information on new kiwifruit cultivars and the adequate disease managements will be required.

• Research in Plant Disease
• /
• v.11 no.2
• /
• pp.93-97
• /
• 2005

In order to detect casual agents associated with ear blight of rice, seed samples of 'Ilmi-byeo' and 'Daesan-byeo', susceptible cultivars were collected from 28 regions on a nationwide scale. Finally 23 fungi including Bipolaris oryzae($10.3\%$), Alternaria alternata ($10.2\%$), Cladosporium sp. ($7.5\%$), Nigrospora oryzae($5.2\%$) and Phoma sorghina ($6.3\%$) from seeds of 'Ilmi-byeo', and 13 fungi including N. oryzae ($15.1\%$), A. alternata ($9.6\%$) and Curvularia lunata ($2.2\%$) from seeds of 'Daesan-byeo' were detected. In case of discolored seeds caused by rice ear blight, B. oryzae($15.5\%$), A. alternata ($5.5\%$), Fusarium graminearum ($8.0\%$), N. oryzae($5.2\%$) and P. sorghina ($4.5\%$) were detected even from the hulled rice of Ilmi-byeo.

• The Korean Journal of Pesticide Science
• /
• v.15 no.4
• /
• pp.495-501
• /
• 2011

Bacterial strains were isolated from forest soils of Halla mountain, Jeju island in Korea. The soil samples were collected at each altitude of 100m from 1,000 m above sea level. Total 398 strains were isolated and tested for their physiological characteristics of antagonistic and proteolytic activities, and auxin production. Among the isolates, 172 strains were selected as antifungal strains showing antagonistic activity against at least one of 8 plant fungal pathogens (Alternaria alternata, Botrytis cinerea, Collectotrichum acutatum, Fusarium oxysporum, Phytophthora capsici, Pythium ultimum and Sclerotinia sclerotiorum). In addition 203 strains for proteolytic activity and 26 strains for auxin production were characterized for further study. Je28-4 (Rhodococcus sp.) were showed 80% of control value against tomato gray mold in vivo. Thus, it is suggested that soil bacteria isolated from forest soils of Halla mountain can be important sources of bioactive compounds for improving plant growth or promising biocontrol agents.

• Korean Journal of Microbiology
• /
• v.48 no.2
• /
• pp.134-140
• /
• 2012

Asian dust storms originating in the arid desert of China and Mongolia usually occur from late winter through spring, and more than one million tons of dust per year is transported to the Korean Peninsula by the prevalent westerly winds. We supposed that these dust particles could include bioaerosols and act as carriers of microorganisms. In order to clarify the dynamics of microorganisms moving with these particles, the concentration and composition of microorganisms associated with settled particles were compared between samples collected during Asian dust events and those under non-dust periods. From February to April 2008, settled dust particles were collected at one location in Ulsan using rainfall meter of 200 mm diameter. During this period, there was one Asian dust event in Ulsan. The bacterial concentrations were higher in samples collected during Asian dust event than those under non-dust period, whereas fungal concentrations were rather similar regardless of the Asian dust event. We analyzed 16S rRNA gene sequences of 45 bacterial isolates obtained from the settled particle samples. These isolates belonged to either genus Bacillus or genus Streptococcus and were tentatively identified as B. amyloliquefaciens, B. aryabhattai, B. atrophaeus, B. licheniformis, B. megaterium, B. methylotrophicus, B. pumilus, B. sonorensis, B. subtlis, B. vallismortis, S. epidermidis, and S. succinus. In cases of fungal isolates, genera such as Mucor, Alternaria, Cladosporium, and Aspergillus were tentatively identified from samples collected at both Asian dust and non-Asian dust periods. It appears that endospore-forming bacteria such as Bacillus sp. rather than fungal spores are more likely to be associated with Asian dust particles.

• Korean Journal of Medicinal Crop Science
• /
• v.5 no.3
• /
• pp.206-210
• /
• 1997

The pathogenic fungi associated with blight of leaf and stem in peony were leaf spot (Alternaria sp.), powdery mildew (Erysiphe aquilegiae) and rust (Cronartium flaccidum). The infection of leaf spot and powdery mildew begins from late April to midMay and rust was infected in early June. Blight time of aerial part in peony started from late May and the ratio of blight on leaf and stem was more than 50% in late Aug. Yields of root by the incidence time of blight of leaf and stem were 69.1% in late June, 65.4% in late July and $87.6{\sim}92.7$% in August and September. The number of root of more than 10mm in root diameter blighted in late June and July was much lower than in August, but the paeoniflorin content in the former was much higher than the latter.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.27 no.5
• /
• pp.462-468
• /
• 1994

Extraction yields of Hizikia fusiforme with four kinds of solvents and $0{\sim}90\%$ ethanol solutions, and antimicrobial activities of the extracts against Escherichia coli, Bacillus subtilis, Saccharomyces cerevisiae and Alternaria sp. were investigated. Determination of extraction yield with several solvents showed the highest value, $33\%$ (wt/wt), when distilled water was used. However, the extraction yields by hexane, ethyl ether and ethanol were less than $1\%$ (wt/wt). When dried Hizikia fusiforme was extracted at various concentrations of ethanol, 0 to $50\%$ solution gave similar yields and the extraction yields decreased rapidly as the ethanol concentrations increased above $70\%$, Ethanol-extract demonstrated antimicrobial activities against E. coli and B. subtilis, and ethyl ether- and hexane-extracts against E. coli. 70 and $90\%$ ethanol-extracts had potent antimicrobial activities against E. coli, and B. subtilis.

• Korean journal of applied entomology
• /
• v.20 no.3 s.48
• /
• pp.135-145
• /
• 1981

Vegetables including Chinese cabbage and radish have been grown in alpine areas such as Muju, Namweon, Jinan and Jangsu during the shortage period of vegetables. The incidence of various diseases, environmental factors such as temperatures and rainfalls, and aphid populations as virus vector were observed at 10-day intervals from July to September in those areas. Disease incidence showed no significant difference among locations. Major diseases in Chin ese cabbage were bacterial soft rot, white spot, downy mildew, mosaic virus, Alternaria leaf spot and Fusarium seedling blight. Major diseases in radish were virus, white rust, black rot, root rot, leaf spot and Fusarium seedling blight. Disease incidence reached peak on Aug. 20 with $27\%$ infection in radish and with $20\%$ infection in Chinese cabbage during the growing season, and declined thereafter. Percentage of infection in each growth stage showed $25\%$ at root thickening stage and $26\%$ at the harvest time in radish; and the head formation stage, $24\%$ at the harvest time. The data indicate that disease incidence in radish increased rapidly at late growing stage and progressively increased in Chinese cabbage Seedling blight caused by Fusarium sp. and root rot caused by Aphanomyces sp. were also observed in those areas. Cool and wet weather appeared to be favorable for disease incidences during the rainy period of growing season although average temperature was about $25^{\circ}C$. Populations of aphids were lower in the alpine vegetable growing area than that of flat areas. Aphids as virus vectors from total aphids collected were $73.5\%$ or 289 virus vectors /993 total aphids in Namweon and $18.1\%$ or 31 virus vectors/171 total aphids in Muju. The most prerevalent species of aphids was Myzus persicae Sulz.

• 한국균학회소식:학술대회논문집
• /
• 2014.10a
• /
• pp.25-25
• /
• 2014

Three species of Fusarium, F. fujikuroi, F. verticillioides and F. proliferatum, are known to be associated with bakanae disease of rice [1, 2]. F. fujikuroi infects rice flowers and survive in endosperm and embryo of the seeds. Infected seed is an important source of primary inoculum of pathogens [3]. Seeds of rice (Oryza sativa cv. Boramchan) collected from bakanae-infected field were found to be 96% infected with Fusarium sp., 52% with F. fujikuroi, 42% with F. verticillioides, and 12% with F. proliferatum as determined by incubation method and species-specific PCR assays. F. fujikuroi was detected at lemma/palea, endosperm and embryo whereas F. verticillioides and F. proliferatum were recovered only from lemma/palea by means of component plating test. Seed disinfection methods have been developed to control bakanae disease and prochloraz has been most widely used for rice seeds. Two chemicals formulated with prochloraz (PC 1) and prochloraz + hexaconazole (PC 2) that inhibit biosynthesis of ergosterol strongly reduced the incidence of Fusarium spp. on selective media to 4.7% and 2.0%, respectively. Disease symptoms of rice seedlings in nursery soil were alleviated by chemical treatment; seedlings with elongated leaves or wide angle between leaf and stem were strikingly reduced from 15.6 to 3.2% (PC 1) and 0 (PC 2), stem rots were reduced from 56.9 to 26.2% (PC 1) and 32.1% (PC 2), and normal seedling increased from 0.4 to 13.3% (PC 2). Prochloraz has some disadvantages and risks such as the occurrence of tolerant pathogens [4] and effects on the sterol synthesis in animals and humans [5]. For these reasons, it is necessary to develop new disinfection method that do not induce fungal tolerance and are safe to humans and animals. Chlorine dioxide ($ClO_2$), that is less toxic, produces no harmful byproducts, and has high oxidizing power, has been reported to be effective at disinfection of several phytopathogenic fungi including Colletotrichum spp. and Alternaria spp. [6]. Gaseous $ClO_2$ applied to rice seeds at a concentration of 20 ppm strongly suppressed mycelial growth of Fusarium fujikuroi, F. verticillioides and F. proliferatum. The incidence of Fusarium spp. in dry seed with 8.7% seed moisture content (SMC) tended to decrease as the concentration of $ClO_2$ increased from 20 to 40 ppm. Applying 40 ppm $ClO_2$ at 90% relative humidity, incidence was reduced to 5.3% and resulted in significant reduction of disease symptoms on MS media. In nursery soil, stem rot was reduced from 56.9 to 15.4% and the number of normal seedlings increased from 0.4 to 25.5%. With water-soaked seeds (33.1% SMC) holding moisture in the endosperm and embryo, the effectiveness of disinfection using $ClO_2$ increased, even when treated with only 20 ppm for four hours. This suggests that moisture was a key element for action of $ClO_2$. Removal of the palea and lemma from seeds significantly decreased the incidence of Fusarium spp. to 3.0%. Seed germination appeared to decrease slightly by water-soaking at $30^{\circ}C$ because of increased SMC and by physical damage of embryos from hulling. These results indicate that the use of gaseous $ClO_2$ was effective as a means to disinfect rice seeds infected with Fusarium spp. and that moisture around the pathogens in the seed was an important factor for the action of $ClO_2$. Further investigations should be conducted to ascertain the best conditions for complete disinfection of Fusarium spp. that infect deep site of rice seeds.