• Journal of Microbiology and Biotechnology
• /
• v.29 no.1
• /
• pp.105-113
• /
• 2019

Although siderophore compounds are mainly biosynthesized as a response to iron deficiency in the environment, they also bind with other metals. A few studies have been conducted on the impact of heavy metals on the siderophore-mediated iron uptake by microbiome. Here, we investigated siderophore production by a variety of rhizosphere fungi under different concentrations of $Zn^{2+}$ ion. These strains were specifically isolated from the rhizosphere of Panax ginseng (Korean ginseng). The siderophore production of isolated fungi was investigated with chrome azurol S (CAS) assay liquid media amended with different concentrations of $Zn^{2+}$ (50 to $250{\mu}g/ml$). The percentage of siderophore units was quantified using the ultra-violet (UV) irradiation method. The results indicated that high concentrations of $Zn^{2+}$ ion increase the production of siderophore in iron-limited cultures. Maximum siderophore production by the fungal strains was detected at $Zn^{2+}$ ion concentration of $150{\mu}g/ml$ except for Mortierella sp., which had the highest siderophore production at $200{\mu}g/ml$. One potent siderophore-producing strain (Penicillium sp. JJHO) was strongly influenced by the presence of $Zn^{2+}$ ions and showed high identity to P. commune (100% using 18S-rRNA sequencing). The purified siderophores of the Penicillium sp. JJHO strain were chemically identified using UV, Fourier-transform infrared spectroscopy (FTIR), and matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MALDI-TOF-MS) spectra.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.439-441
• /
• 2002

Cyanobacteria are the dominant micro flora in rice-fields, contributing significantly to fertility as a natural biofertilizer. Recent studies show a continuous depletion of the stratospheric ozone layer, and the consequent increase in solar UV-B (280-315 nm) radiation reaching the Earth's surface. UV-B radiation causes reduction in growth, survival, protein content, heterocyst frequency and fixation of carbon and nitrogen in many cyanobacteria. UV -B induced bleaching of pigments, disassembly of phycobilisomal complexes, thymine dimer formation and alterations in membrane permeability have also been encounterd in a number of cyanobacteria. However, certain cyanobacteria produce photoprotective compounds such as water soluble colorless mycosporine-like amino acids (MAAs) and the lipid soluble yellow-brown colored sheath pigment, scytonemin, to counteract the damaging effects of UV-B. Cyanobacteria, such as Anabaena sp., Nostoc commune, Scytonema sp. and Lyngbya sp. were isolated from rice fields and other habitats in India and screened for the presence of photoprotective compounds. A circadian induction of the synthesis of MAAs by UV -B was noted in a number of cyanobacteria. Polychromatic action spectra for the induction of MAAs in Anabaena sp. and Nostoc commune also show the induction to be UV-B dependent peaking at 290 nm. Another photoprotective compound, scytonemin, with an absorption maximum at 386 nm (also absorbs at 300, 278, 252 and 212 nm), was detected in many cyanobacteria. In conclusion, a particular cyanobacterium having photoprotective compounds may be a potent candidate as biofertilizer for crop plants.

• Journal of the Economic Geographical Society of Korea
• /
• v.25 no.1
• /
• pp.109-130
• /
• 2022

The Vietnamese government has proposed contract farming through a new type of cooperative as an institutional innovation which aims to restructure the agricultural sector. However, policy changes often impact farmers, who bear the primary effects of the transition process. Understanding households' strategies for land use and livelihood is crucial for policymaking in the agricultural development field. This study was conducted in the rural Binh Dao commune in Central Vietnam. We analyzed household members' labor force changes and their livelihood behaviors after their participation in a contract farming scheme using qualitative analysis methods combined with geographic information system (GIS) support, based on secondary data and in-depth interviews of 190 farmers. Simultaneously, we created a digital map of the cooperative's production area to investigate changes in land use and production activities. The findings show that contract farming shaped the vertical coordination of the value chain from the farmers to the cooperative and agricultural product trading companies. Subsequently, it encouraged land use and labor efficiency due to mechanical support. In addition, it also increased productivity and protected farmers from market risks. However, despite its positive effects on agricultural productivity in this case, the contract farming scheme could not achieve the restructuring of the rural labor force toward non-agricultural sectors. Ironically, farmers in the Binh Dao commune tended to increase cultivable land during the agricultural restructuring program, rather than switching their labor forces to non-agricultural sectors. The lack of stable non-farming job opportunities in rural Vietnam results in challenges to the efficiency of agricultural restructuring programs. Consequently, farmers in the Binh Dao commune are still smallholder farmers, depending on the family labor force.

• Proceedings of the Korean Society of Fisheries Technology Conference
• /
• 2000.10a
• /
• pp.179-180
• /
• 2000

$\beta$-glucan은 단순한 영양 공급원 혹은 식이 섬유로서 뿐 만 아니라 면역 활성증강 등의 생리적 활성이 우수하여 기능성 식품 소재로 활용가능함이 보고되고 있다. $\beta$-glucan은 $\beta$-1,3 glucan의 구조를 기본으로 하여 $\beta$-1,4 혹은 $\beta$-1,6 등의 가지를 함유하고 있어 그 구조에 따라 생리 활성이 달라지는 것으로 알려져 있다. 현재 식품 소재로 이용하고 있는 $\beta$-glucan은 보리, 귀리, 효모 등에서 생산되고 있으나 대량 생산 및 분리, 정제 등의 어려움이 있다. (중략)

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2005.11a
• /
• pp.154-154
• /
• 2005

• Research in Plant Disease
• /
• v.16 no.3
• /
• pp.331-335
• /
• 2010

The purpose of this study was to develop a method to effectively control mosses that are generated in container. To meet the goals, 6 kinds of chemical agents at different concentrations were applied to the container containing seedlings of Pinus densiflora with growing liverwort (Marchantia polymorpha) and Chamaecyparis obtusa with growing haircap moss (Polytrichum commune). It was found that quinoclamine was the most effective chemical agent to control mosses. Quinoclamine was effective in controlling liverwort (100% controlled) and haircap moss (95.5% controlled) at its concentration of 0.9 g/l. Next to quinoclamine, it was found that haircap moss and liverwort was effectively controlled by pyroligneous liquid which was followed by flumioxazin and oxyfluorfen. Seedling damages were observed in both two species treated with higher concentration of flumioxazin and oxyfluorfen.

• Korean Journal of Food Science and Technology
• /
• v.34 no.1
• /
• pp.8-12
• /
• 2002

In order to artificially increase the contents of essential oils from 4 different trees by inducing with elicitors, 5 kinds of chemical elicitors and 4 kinds of biotic elicitors were selected. Before treatment, the contents of essential oils from Japanese Cypress (Chamaecyparis obtusa), Sawara cypress (Chamaecyparis pisifera), Japanese Red Pine (Pinus densiflora), and Korean Pine (Pinus koraiensis) were 2.0, 1.6, 0.4, and 0.7 percent, respectively, and the maximum content of essential oils from all species were reached in July. By most of elicitors, the essential oil content was generally increased after 6 months later, but some of elicitors did not affect the content of essential oil. Finally, the appropriate inducers for artificially increasing the essential oil were respectively selected depending on each species; Schizophyllum commune Fries for Japanese Red Pine and Japanese Cypress, hydrogen peroxide for Korean Pine, and ${\beta}-pyridone$ for Sawara cypress. Especially, hydrogen peroxide and ${\beta}-pyridone$ could be wide spread inducer for all 4 species.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.1
• /
• pp.22-28
• /
• 2005

Gibberellins (GAs) play important roles in plant growth and development. Fifty-four fungi were isolated from the roots of 4 kinds of Sesamum indicum plants, and the production of GAs was spectrophotometrically examined. The number of GA-producing fungi was two strains from S. indicum, four strains from Gold S. indicum, and five strains from Brown S. indicum. Eleven fungi with GAs-producing activity were incubated for seven days in 40 ml of Czapek's liquid medium at $25^{\circ}C$ and 120 rpm, and the amount of each GA in the medium was measured by gas chromatographymass spectrometery (GC-MS). Penicillium commune KNU5379 produced more $GA_3$, $GA_4$, and $GA_7$ than Gibberella fujikuroi, Fusarium proliferatum, and Neurospora crassa which are known as GAs-producing fungi. GAs-producing activity of the P. commune KNU5379 was shown to produce 71.69 ng of $GA_1$, 252.42 ng of $GA_3$, 612.00 ng of $GA_4$, 259.00 ng of $GA_7$, and 202.69 ng of $GA_9$ in 25 ml of liquid medium. Bioassay of culture fluid of GA-producing fungi was also performed on rice sprout.

• Korean Journal of Food Science and Technology
• /
• v.28 no.2
• /
• pp.366-370
• /
• 1996

Gamma irradiation was applied to red ginseng powder for improving its hygienic quality 7.5 kGy of gamma irradiation completely eliminated the microorganisms contaminated in red ginseng powder. And there was no growth of microorganisms after six months of storage at room temperature. The molds isolated from red ginseng powder were identified as Pen. commune, Asp. niger, Asp. versicolor and Asp. Unguis, the conidia of which showed the decimal reduction dose ($D_{10}$ value) of 0.37-0.50 kGy, 0.24-0.31 kGy, 0.25-0.36 kGy and 0.28-0.41 kGy and inactivation factor of 5.0-6.5, 7.4-9.3, 6.5-9.1 and 6.1-8.4, respectively The radiosensitivity of identified molds' conidia decreased in medium containing red ginseng extract.

• The Plant Pathology Journal
• /
• v.36 no.6
• /
• pp.579-590
• /
• 2020

Botrytis cinerea, which causes gray mold disease in more than 200 plant species, is an economically important pathogen that is mainly controlled by synthetic fungicides. Synergistic fungicide mixtures can help reduce fungicide residues in the environment and mitigate the development of fungicide-resistant strains. In this study, we screened microbial culture extracts on Botrytis cinerea to identify an antifungal synergist for tebuconazole. Among the 4,006 microbial extracts screened in this study, the culture extract from Schizophyllum commune displayed the most enhanced activity with a sub-lethal dosage of tebuconazole, and the active ingredient was identified as schizostatin. In combination with 5 ㎍/ml tebuconazole, schizostatin (1 ㎍/ml) showed disease control efficacy against gray mold on tomato leaf similar to that achieved with 20 ㎍/ml tebuconazole treatment alone. Interestingly, schizostatin showed demethylation inhibitor (DMI)-specific synergistic interactions in the crossed-paper strip assay using commercial fungicides. In a checkerboard assay with schizostatin and DMIs, the fractional inhibitory concentration values were 0.0938-0.375. To assess the molecular mechanisms underlying this synergism, the transcription levels of the ergosterol biosynthetic genes were observed in response to DMIs, schizostatin, and their mixtures. Treatment with DMIs increased the erg11 (the target gene of DMI fungicides) expression level 15.4-56.6-fold. However, treatment with a mixture of schizostatin and DMIs evidently reverted erg11 transcription levels to the pre-DMI treatment levels. These results show the potential of schizostatin as a natural antifungal synergist that can reduce the dose of DMIs applied in the field without compromising the disease control efficacy of the fungicides.