• 대한소아치과학회지
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• 제25권3호
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• pp.619-626
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• 1998

The critical etiologic factor in the development of dental caries is dental plaque. The main component of dental plaque is the mutan produced by Streptococcus mutans. The following results were obtained by using blue mutan to assess the factors affecting the mutan-digesting activity of Micromonospora aurantiaca isolated from oral cavity. Micromonospora aurantiaca digested more blue mutan in the minimal essential broth at pH 7.0 than at pH 5.5 or 8.5, and at $37^{\circ}C$ than at $32^{\circ}C\;or\;42^{\circ}C$. Blue mutan was similarly digested at the range of 1mM to 16mM of $CaCl_2$ and 0.1mM to 6.4 mM of $MgCl_2$, while being significantly digested at the concentration of 2.5mM of KCl. When the concentration of glucose was decreased in the minimal essential broth, the digestion of blue mutan was increased. When the culture supernatant of Micromonospora aurantiaca in the RL broth with 1% glucose or 0.5% mutan was mixed with 2 ${\times}$ BHIYS broth containing 0.5% yeast extract and 10% sucrose, the formation of artificial plaque on the orthodontic wires by Streptococcus mutans was inhibited(p<0.05). These results indicated that the production of mutanase was identified in the culture supernatant of Micromonospora aurantiaca, suppressing the formation of artificial plaque by Streptococcus mutans.

• The Plant Pathology Journal
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• 제22권1호
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• pp.75-89
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• 2006

The actinomycete strain JK-1 that showed strong inhibitory activity against some plant pathogenic fungi and oomycetes was isolated from Jung-bal Mountain in Ko-yang, Korea. The strain JK-1 produced spores singly borne on sporophores and the spores were spherical and 0.9-1.2 11m in diameter. The cell wall of the strain JK-1 contained meso-diaminopimelic acid. The actinomycete strain JK-1 was identified as the genus Micromonospora based on the morphological, physiological, biochemical and chemotaxonomic characteristics. From the 168 rDNA analysis, the strain JK-1 was assigned to M aurantiaca. The antibiotic MA-1 was purified from the culture broth of M aurantiaca JK-1 using various purification procedures, such as Diaion HP20 chromatography, C18 flash column chromatography, silica gel flash column chromatography and Sephadex LH-20 column chromatography. $^{1}H-$, $^{13}C-NMR$ and EI mass spectral analysis of the antibiotic MA-1 revealed that the antibiotic MA-1 is identical to phenylacetic acid. Phenylacetic acid showed in vitro inhibitory effects against fungal and oomycete pathogens Alternaria mali, Botrytis cinerea, Magnaporthe grisea, Phytophthora capsici and yeast Saccharomyces cerevisiae at < 100 $\mug$ $ml^{-1}$. In addition, phenylacetic, acid completely inhibited the growth of Sclerotinia sclerotiorum, Bacillus subtilis, Candida albicans, Xanthomonas campestris pv. vesicatoria at < $\mug$ $ml^{-1}$. Phenylacetic acid strongly inhibited conidial germination and hyphal growth of M grisea and C. orbiculare. Phenylacetic acid showed significantly high levels of inhibitory' effect against rice blast and cucumber anthracnose diseases at 250 $\mug$ $ml^{-1}$. The control efficacies of phenylacetic acid against the two diseases were similar to those of commercial compounds tricyclazole, iprobenfos and chlorothalonil .n the greenhouse.