• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.400-406
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• 1997

Chemical composition and antimicrobial activity of Houttuynia cordata Thunb. were investigated to develop a natural food preservative from it. Aspartic acid, glutamic acid, glycine and arginine were major amino acids of Houttuynia cordata Thunb., but were present in a trace amount. Free sugars were composed of glucose, fructose, sucrose and maltose and major fatty acids were linolenic acid, linoleic acid, oleic acid, and palmitic acid. Mineral elements were potassium, calcium, magnesium, iron, zinc, and copper. Antimicrobial activities were shown in acidic, neutral and phenolic fraction of Houttuynia cordata Thunb., but not in basic fraction. Among the four fractions, neutral fraction showed the strongest antimicrobial activities against microorganisms tested, such as Pseudomnas aeruginosa, Micrococcus luteus, Bacillus subtilis, Aspergillus parasiticus and Aspergillus flavus. Minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) of the neutral fraction varied according to microoganisms tested. The lowest values of MIC (0.0075 g eq./mL) and MLC (0.10 g eq./mL) were obtained from Pseudomonas aeruginosa.

• KSBB Journal
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• v.24 no.4
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• pp.334-340
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• 2009

For the isolation of a plant growth-promoting rhizobacteria, strain YK-5 was selected from approximately 400 thermostable strains isolated from special soil samples. Strain YK-5 produced an antifungal compound, and optimum carbon and nitrogen sources for the production of the antifungal compound were investigated against Aspergillus flavus as a test strain. Modified LB medium containing 1% peptone, 1% yeast extract and 5% black sugar was determined to be the optimal medium for growth and antifungal compound production. Culture broth of strain YK-5 potently inhibited growth of the phytopathogenic fungus Fusarium oxysporum KACC 40052 for 7 days. The plant growth-promotion function of strain YK-5 was tested against radish and rice in pot trials. Leaf number, plant height and root length in YK-5-treated radish markedly exceeded (> 60%) those of untreated radish. Leaf length and white rootlet development were markedly more prominent than in commercially-treated rice plants. Strain YK-5 was determined to be Bacillus subtilis YK-5 by physiological, chemotaxonomical, and phylogenetical analyses.