• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1386-1391
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• 1999

The methanol extract of Gardenia jasminoides Ellis showed antimicrobial activity against bacteria and yeasts. The extract was successively purified with solvent fractionation, silica gel adsorption column chromatography, Sephadex LH-20 column chromatography, octadecylsilane column chromatography. The purified active substance was isolated by high performance liquid chromatography. The isolated compound was 3,4-dihydroxybenzoic acid which was determined by mass spectrometer, gas chromatograph-mass spectrometer, $^{1}H-nuclear$ magnetic resonance, $^{13}C-nuclear$ magnetic resonance and two-dimensional nuclear magnetic resonance. The content of 3,4-dihydroxybenzoic acid was $32.7\;{\mu}g/g$ in dried fruits of Gardenia jasminoides Ellis.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.254-259
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• 2016

Acinetobacter sp. B-W producing siderophore, 2, 3-dihydroxybenzoic acid (DHB) was analyzed for plasmid content. Strain B-W harbored plasmid of 20 kb in size. Growth at $43^{\circ}C$ was effective in producing mutant cured of plasmid of strain B-W. This mutant lost the ability to produce 2, 3-DHB. Formation of siderophore halos on the chrome azurol S (CAS) agar medium was not detected by cured strain B-W. pHs of supernatants of wild type strain B-W and cured mutant grown in glucose and $MnSO_4$ containing medium at $28^{\circ}C$ for 3 days were 4.5 and 8.5, respectively. Antibiotic resistance against ampicillin, actinomycin D, bacitracin, lincomycin, and vancomycin was lost in cured mutant. Plasmid curing of strain B-W resulted in drastic reduction of minimal inhibitory concentration (MIC) of several antibiotics. E. coli $DH5{\alpha}$ was transformed with plasmid isolated from strain B-W. The transformant E. coli $DH5{\alpha}$ harbored a plasmid of the same molecular size as that of the donor plasmid. Transformant E. coli $DH5{\alpha}$ produced 2, 3-DHB and contained antibiotic resistant ability. Thus a single plasmid of 20 kb seemed to be involved in 2, 3-DHB production. Genes encoding resistance to antibiotics were also supposed to be located on this plasmid.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.322-327
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• 2008

Antifungal activities of natural substrances from Eucalyptus darlympleana, E. globules, E. gunnii and E. unigera were evaluated against postharvest pathogens of kiwifruits, Botrytis cinerea, Botryosphaeria dothidea, and Diaporthe actinidiae, to screen effective natural substances as an alternative to chemical fungicides. Methanol extract of the Eucalyptus trees showed strong antagonistic activity against the pathogenic fungi. Among them, E. unigera and E. darlympleana effectively inhibited mycelial growth of the pathogens. For chemical identification of the antifungal substances, the methanol extract of E. darlympleana leaves was successively partitioned with $CH_2Cl_2$, EtOAc, n-BuOH and $H_2O$. Among the fractions, $CH_2Cl_2$ and n-BuOH showed strong inhibitory activity of mycelial growth of the fungi. Five compounds were isolated from EtOAc and n-BuOH fractions subjected to $SiO_2$ column chromatography. Two phenolic compounds(gallic acid and 3,4-dihydroxybenzoic acid) and three flavonoid compounds(quercetin, quercetin-3-O-$\alpha$-L-rhamnoside, quercetin-3-O-$\beta$-glucoside) were identified by $^1H$-NMR and $^{13}C$-NMR spectroscopy. Among them, only gallic acid was found to be effective in mycelial growth and spore germination of B. cinerea at relatively high concentrations. The results suggest that gallic acid can be a safer and more acceptable alternative to current synthetic fungicides controlling soft rot decay of kiwifruit during postharvest storage.