• Journal of Apiculture
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• v.32 no.1
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• pp.27-39
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• 2017

PCR-chip-based ultra-rapid multiplex PCRs for detection of six major infectious pathogens in honeybee were developed. The 6 kinds of major infectious pathogens in honeybee included Paenibacillus larvae causing American Foulbrood, Melissococcus plutonius causing European Foulbrood as bacteria, Ascosphaera apis (Chalkbrood), Aspergillus flavus (Stonebrood), Nosema apis and Nosema ceranae (Nosemosis) as fungi. The developed PCR-chip-based ultra-rapid multiplex PCR showed successful amplification for all six major pathogens in the presence of more than $10^3$ molecules. The time for confirming amplification (Threshold cycles; Ct-time) was about 7 minutes for two species, and about 9 minutes for four species. Total 40 cycles of PCR took 11 minutes 42 seconds and time for melting point analysis was 1 minute 15 seconds. Total time for whole PCR detection was estimated 12 minutes 57 seconds (40 cycles of PCR and melting point analysis). PCR-chip based ultra-rapid multiplex PCR using standard DNA substrates showed close to 100% accuracy and no false-amplification was found with honeybee genomic DNA. Ultra-rapid multiplex PCR is expected to be a fast and efficient pathogen detection method not only in the laboratory but also in the apiary field.

• Journal of Microbiology and Biotechnology
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• v.21 no.8
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• pp.777-790
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• 2011

To elucidate the biodiversity of plant growth-promoting rhizobacteria (PGPR) in Korea, 7,638 bacteria isolated from the rhizosphere of plant species growing in many different regions were screened. A large number of PGPR were identified by testing the ability of each isolate to promote the growth of cucumber seedlings. After redundant rhizobacteria were removed via amplified rDNA restriction analysis, 90 strains were finally selected as PGPR. On the basis of 16S ribosomal RNA sequences, 68 Gram-positive (76%) and 22 Gram-negative (24%) isolates were assigned to 21 genera and 47 species. Of these genera, Bacillus (32 species) made up the largest complement, followed by Paenibacillus (19) and Pseudomonas (11). Phylogenetic analysis showed that most of the Grampositive PGPR fell into two categories: low- and high- G+C (Actinobacteria) strains. The Gram-negative PGPR were distributed in three categories: ${\alpha}$-proteobacteria, ${\beta}$- proteobacteria, and ${\gamma}$-proteobacteria. To our knowledge, this is the largest screening study designed to isolate diverse PGPR. The enlarged understanding of PGPR genetic diversity provided herein will expand the knowledge base regarding beneficial plant-microbe interactions. The outcome of this research may have a practical effect on crop production methodologies.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.885-892
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• 2011

The bacterial communities in the intestinal tracts of earthworm were investigated by culture-dependent and -independent approaches. In total, 72 and 55 pure cultures were isolated from the intestinal tracts of earthworms under aerobic and anaerobic conditions, respectively. Aerobic bacteria were classified as Aeromonas (40%), Bacillus (37%), Photobacterium (10%), Pseudomonas (7%), and Shewanella (6%). Anaerobic bacteria were classified as Aeromonas (52%), Bacillus (27%), Shewanella (12%), Paenibacillus (5%), Clostridium (2%), and Cellulosimicrobium (2%). The dominant microorganisms were Aeromonas and Bacillus species under both aerobic and anaerobic conditions. In all, 39 DNA fragments were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Aeromonas sp. was the dominant microorganism in feeds, intestinal tracts, and casts of earthworms. The DGGE band intensity of Aeromonas from feeds, intestinal tracts, and casts of earthworms was 12.8%, 14.7%, and 15.1%, respectively. The other strains identified were Bacillus, Clostridium, Enterobacter, Photobacterium, Pseudomonas, Shewanella, Streptomyces, uncultured Chloroflexi bacterium, and uncultured bacterium. These results suggest that PCR-DGGE analysis was more efficient than the culturedependent approach for the investigation of bacterial diversity and the identification of unculturable microorganisms.

• Microbiology and Biotechnology Letters
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• v.48 no.1
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• pp.57-63
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• 2020

Over the past 20 years, global warming has transformed the marine ecosystem of the Jeju Island into a subtropical zone making it conducive to the production of tropical fishes. Recently, the balloon fish (Diodon holoanthus) has been found off the coast of the Jeju Island. In this study, we analyzed the diversity of its intestinal microorganisms as a representative for the surrounding environment. In addition, the isolates were evaluated for their antibacterial activity. A total of 161 strains of various species were identified and isolated using 16S ribosomal RNA gene sequence analysis. They were separated into three groups, of which Phylum Proteobacteria was found to be the most dominant with 91% sequence similarity. This includes the class γ-proteobacteria that is made up of twelve genera and twenty-four hundred species. The second group comprised strains of the genus Vibrio, made up of 35% Photobacteria, 32% Shewanella, and 6% Psychrobacter. It was also determined that 4% of the isolates were Acinetobacter, 3% were Enterovibrio, while Moraxella_g2 accounted for 1% of the total isolates. Class α-proteobactera includes five genera and five species; Brevundimonas, Allorhizobium, Pseudoceanicola and Erythrobcter, each accounting for 1% of the total isolates. The Firmicute strains belonged to six genera and ten species. 5% of the strains were Terribacillus, while Paenibacillus, Salinicoccus, Staphylococcus and Streptococcus accounted for 1% each of the total isolates. Actinobacteria accounted for the final phylum with strains belonging to three genera and ten species with Janibacter, Micrococcus and Isoptericola each accounting for 1% of the total isolates.

• Korean Journal of Microbiology
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• v.54 no.4
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• pp.410-419
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• 2018

It is urgently required to construct safety data on agricultural by-products imported for use as medium materials for domestic mushroom production. However, research on microorganisms is insufficient. This study was conducted to investigate the presence of bacteria that have the possibility of harmful effects on human, plants and mushroom in wheat straw, peatmoss, cottonseed hull, cottonseed meal, and beet pulp imported from Australia, Canada, China, Egypt, Germany. Bacteria were found in the range of $1.35{\times}10^2$ to $8.34{\times}10^6CFU/g$. As a result of 16S rDNA sequence analysis, total of 19 genera and 45 species of bacteria were identified. Bacillus genus was dominant, followed by Paenibacillus genus. At the species level, diverse species was in the order of Firmicute, Proteobacteria and Actinobacteria. Regarding the agricultural by-products, straw and peat moss had more diverse bacteria than other agricultural by-products. Among the indentified bacteria, 6 species of 5 genera (Enterobacter asburiae, Enterobacter ludwigii, Stenotrophomonas maltophilia, Pseudomonas monteilii, Bacillus anthracis, and Cellulosimicrobium funkei) were present as potent harmful bacteria to human. Surprisingly, both the human and plant pathogenic Klebsiella pneumoniae subsp. pneumonia was present. Bacillus altitudinis was present as a plant pathogen. Lysinibacillus sphaericus, an insect pathogen, and Ochrobactrum pseudogrignonense, a mushroom pathogen, were also present. The results of this study confirmed that several kinds of pathogenic bacteria were present in the agricultural by-products for the mushroom cultivation medium imported into Korea. Our work suggests that hygiene inspection and management is urgently needed for imported agricultural by-products to be safely used for mushroom production.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.2
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• pp.169-175
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• 2007

The Bio Best Bacillus(B3) and Rotating Activated Bacillus Contactor(RABC) processes, in which Bacillus strains are predominating, are reported to remove nitrogen and phosphorus as well as organic matter effectively. Nevertheless the nutrient removal characteristics of the Bacillus strains have not been studied in detail so far. This study investigated the organic and nutrient removal by Bacillus strains, Bacillus megaterium(KCTC 3007), Paenibacillus polymyxa(KCTC 3627), and Bacillus sp. A12, C21, F12, and L1(isolated from a B3 process), by incubating the strains in 0.2% nutrient broth at $30^{\circ}C$. Burkholderia cepacia(KCTC 2966), a common activated sludge organism, was used as a reference species for comparison. Although the degradation rate was affected by the population sire, the specific removal rates of organic matter by Bacillus strains were greater by $2\sim5$ times than that of Burkholderia. In particular, the culture bottles inoculated with the endospores of Bacillus megaterium and Bacillus sp. C21, F12, and N12 showed significantly higher degradation rate than those of vegetative cells.

• Korean journal of applied entomology
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• v.39 no.3
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• pp.171-179
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• 2000

- Turfgrass insect pests and natura.l enemies for biological control were investigated to develop pest management effectively in golf courses at several golf clubs. Twenty eight insect pest species of 10 families in 6 orders were collected from golf courses. The zoysiagrass mite, Eriophyes zoysiae and root-knot nematode, Meloidogyne incognita were also collected from zoysiagrass. White grubs of several scarab beetles and cutworms (Agrotis spp.) damaged seriously at most surveyed golf clubs. In addition, bluegrass webworm (Crambus sp.), Japanese lawngrass cutworm (Spodoptera depravata), scale insects, Tipula sp., and ants (Camponitus japonicus, Formica japonica, and Lasins japonicus) damaged turfgrasses directly or indirectly in golf courses. The entomopathogenic nematodes, Heterorhabditis spp., Steinernema glaseri, and S. longicaudum, entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, and milky disease, Paenibacil/us popil/iae were isolated from white grubs or turfgrass soil as microbial control agents. Besides, dipteran predators, Cophinopoda chinensis, Philonicus albiceps, and Promachus yesonicus and hymenopteran parasitoid, Tiphia sp. were also collected. The P. yesonicus was the most active in golf courses. The root-knot nematode, M. incognita was found from Zoysia japonica, Z. matrella. and Cynodon dactylon.

• Journal of Life Science
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• v.31 no.1
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• pp.73-82
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• 2021

Throughout history, barley was the typical crop of the soils of Jeju Island due to its topographical features. People in Jeju eat Shindari or Dansul. Shindari or Dansul is a fermented drink of Jeju, made from the leftovers of cooked barely and nuruk of short fermentation periods. Although Makgeolli and Shindari share a similar fermentation period and materials, research on Shindari or Dansul is still in its early stages. In this study, we examined major bacterial species of Shindari or Dansul. In addition, we confirmed the antibacterial activities of an isolated strain against fish and human-harmful bacteria. Among the isolates, Firmicutes consisted of 73% and the Proteobacteria of 27%, indicating that the Firmicutes phylum was the dominant one. In addition, the Pediococcus genus and the Bacillus genus were the most prevalent consisting of 25%, followed by the Cronobacter genus (25%), the Enterococcus genus (16%), the Aneurinibacillus genus (5%), the Klebsiella genus (4%), and the Paenibacillus genus (2%). We conclude that the Lactobacillus genus predominated in Makgeolli, but the Pediococcus genus predominated in Shindari. In a study of the antibacterial activity, growth inhibition was observed for all bacteria, except for the fish disease bacterium Photobacterium damselae subsp. piscicida and the human-harmful bacterium Streptococcus mutans.

• Journal of Microbiology and Biotechnology
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• v.31 no.9
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• pp.1241-1255
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• 2021

This study was carried out to explore a non-chemical strategy for enhancing productivity by employing some antagonistic rhizobacteria. One hundred eighteen bacterial isolates were obtained from the rhizospheric zone of various crop fields of Gangwon-do, Korea, and screened for antifungal activity against Fusarium wilt (Fusarium oxysporum f. sp. lactucae) in lettuce crop under in vitro and in vivo conditions. In broth-based dual culture assay, fourteen bacterial isolates showed significant inhibition of mycelial growth of F. oxysporium f. sp. lactucae. All of the antagonistic isolates were further characterized for the antagonistic traits under in vitro conditions. The isolates were identified on the basis of biochemical characteristics and confirmed at their species level by 16S rRNA gene sequencing analysis. Arthrobacter sulfonivorans, Bacillus siamensis, Bacillus amyloliquefaciens, Pseudomonas proteolytica, four Paenibacillus peoriae strains, and Bacillus subtilis were identified from the biochemical characterization and 16S rRNA gene sequencing analysis. The isolates EN21 and EN23 showed significant decrease in disease severity on lettuce compared to infected control and other bacterial treatments under greenhouse conditions. Two bacterial isolates, EN4 and EN21, were evaluated to assess their disease reduction and growth promotion in lettuce in field conditions. The consortium of EN4 and EN21 showed significant enhancement of growth on lettuce by suppressing disease caused by F. oxysporum f. sp. lactucae respectively. This study clearly indicates that the promising isolates, EN4 (P. proteolytica) and EN21 (Bacillus siamensis), can be commercialized and used as biofertilizer and/or biopesticide for sustainable crop production.

• Food Science and Preservation
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• v.16 no.2
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• pp.286-291
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• 2009

Microorganisms in seafood cooking drips were counted and identified. Total viable cell counts were 6.40 and 3.10 log CFU/g in cooking drips of Hizikia fusiformis and Thunnus thynnus, respectively. However, microbial populations fell with increased irradiation doses. In H. fusiformis cooking drips, a 5-log reduction in total aerobic bacteria was obtained by irradiation with 5 kGy. In T. thynnus cooking drips, however, contaminating microorganisms were more resistant to gamma irradiation and only a 1-log reduction was seen. DNA sequence analysis showed that the principal contaminating microorganisms in H. fusiformis and T. thynnus cooking drips were Lactobacillus and Bacillus species, respectively. Therefore, the high irradiation resistance of T. thynnus cooking drips microbes may result from spore formation by Bacillus species.