• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.767-773
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• 1998

In this study, we have investigated the distributions and killing effects of marine bacteria that tend to kill the red tide microalgae, C. polykikoides in the area of Masan bay from June to October, 1996. To summarize, C. polykikoides killing bacteria were detected at $10^2$ to $10^3$ cells/ml of seawater samples during the survey period, and the bloom was observed in September by containing $4.8\times10^3$cells/ml. It appears however that the number of these bacteria is decreased ($2.0\times10^2$cells/ml) in October, A total of 110 strains were isolated from seawater samples and seawater filtrate (pore size, 0.8 $\mu$m)-containing mixed culture of C. polykikoides in which the mixed culture was grown in f/2 medium. As results we have successfully isolated Micrococcus sp. LG-1 which decreased to less than 10cells/ml within 6days and 5days sfter inoculation of Micrococcus sp. LG-1 into the la9 and logarithmic growth phases of C. polykrikoides respectively. Therefore, it appears that inoculation of Micrococcus sp. LG-1 against the logarithmic C. polykrikoides is more effective than the lag growth phase, (n addition, the killing effects were increased in accordance with bacterial cell densities inoculated in a dose dependent manner. Especially, the filtrate of kitling bacterium culture (nore size, 0.2 $\mu$m) revealed a dramatic effect in which C. polykrikoides were decreased to less than 10 cells/mf of culture within 1 hr, 1,5 hrs, 1,5 hrs, 3.5 hrs. and 5,5 hrs after inoculations of the culture filtrate with concentration of $30\%,\;20\%,\;10\%,\;5\%$ and $2.5\%$, respectively. Moreover Micrococcus sp. LG-1 showed a selective specificity against C. polykrikoides and any other killing effects of Micrococcus sp. LG-1 were not observed against Alexandrium tamarense, Prorocentrum micans, Scrippsiella trochoidea. ana Gymnodinium sanguineum.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.244-255
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• 2018

Natural extract in liquid phase was adjusted to 0, 0.25, 0.5, 1, 2, and 4% concentration to check microbial changes and to measure 4, 8, $12^{\circ}C$ for refrigeration temperature. In the case of grapefruit extract, the microbial safety was maintained at all the concentrations at $4^{\circ}C$ storage, but the antimicrobial activity was maintained at $12^{\circ}C$ storage and at $8^{\circ}C$ and 21 days storage. In the case of grape seed extract, only the 4% of the culture at $8^{\circ}C$ satisfied the requirement of safety of food distribution for the last 21 days, and the safety criterion was satisfied only at 4% concentration at $12^{\circ}C$ for 18 days. Complex Scutellaria baicalensis extract showed the total number of microbial cells treated by concentration. It was confirmed that microbial flow safety was maintained at low temperature ($4^{\circ}C$). However, at $8^{\circ}C$ and $12^{\circ}C$, Exceeded the distribution limit. When polylysine was applied to brown rice cake, it showed activity in all groups except $4^{\circ}C$, but these properties were not observed at $8^{\circ}C$ and $12^{\circ}C$. At a concentration of 0.5% or more of chitosan, the growth of the microorganism is suppressed by the 21st day very stably, and a similar tendency is observed at 8 and $12^{\circ}C$, so that it may be an antimicrobial material that inhibits microorganisms. At the first day, the distribution standards for general bacterial counts were exceeded.Ethyl-pyruvate showed that microorganism safety was maintained at $4^{\circ}C$ and 1% concentration, and food safety was stable even at 2 or 4%. Glycine showed very good and stable distribution stability at $4^{\circ}C$. However, at $8^{\circ}C$ and $12^{\circ}C$, the shelf life of 14 days could not be maintained as with the addition of other antimicrobial active substances.

• Current Research on Agriculture and Life Sciences
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• v.4
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• pp.132-140
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• 1986

Eighty one products from 36 kinds of vitamin and mineral feed supplement collected during August, 1984 to February, 1985 were examined for microbiological contamination. In addition, 83 strains of coliform isolated from the samples were tested for the resistance to 8 kinds of antimicrobial drugs and distribution of R plasmid. General bacteria were detected in all of samples tested. Bacterial population was varied from less than 10 per gram of the sample to 1,400,000 per gram and 34 (42%) of 81 samples were contaminated with 100 to 1,000 cells per gram. Coliform isolation, which was more frequent in samples with larger number of general bacteria, was possible in 14 (17.3%) out of 81 samples tested and 6 (33.3%) out of 18 companies were coliform positive in their products. Forty one (49.4%) out of 83 coliform isolates were fecal coliform. The frequency of resistant strains was the highest to sulfadimethoxine (Sa) with 92.8% and followed by streptomycin (Sm, 67.5%), tetracycline (Tc, 50.6%), kanamycin (Km, 26.5%), chloramphenicol (Cm, 18.1%) and ampicillin (Am, 15.7%). No strain was resistant to nalidixic acid (Na) and gentamicin (Gm). The resistance frequency of fecal coliform strains were higher compare to non-fecal coliform strains. There were minimum inhibitory concentration (MIC) of $3,200{\mu}g/m{\ell}$ or higher in 7 strains to Am, 3 to Sm and 3 to Km, and 70 strains had MIC of $1,600{\mu}g/m{\ell}$ of higher to Sa while Tc had MICs from $1.6{\mu}g/m{\ell}$ to $400{\mu}g/m{\ell}$. All strains had MICs of $6.3{\mu}g/m{\ell}$ of lower to Na and $3.1{\mu}g/m{\ell}$ of lower to Gm. Seventy nine (95.2%) of 83 strains were resistant to one or more drugs tested. The most frequent resistance patterns were SaSm (14.5%) and followed by SaSmTc(12%), SaSmTcKm(8.4%) SaTc (8.4%) and SaSmKm (7.2%) ; total 19 different patterns were noted. Thirty two (40.5%) of 79 resistant strains were transferred all of a part of their resistance to Escherichia coli ML 1410. The frequency of transferable resistance was high in Am (100%) and Cm (80%) while low in Tc (38.1%), Sa (18.2%), Sm (17.9%) and Km (4.5%).