Gelatin 액화세균의 생장억제에 관한 연구 = Studies on the Inhibition of Growth and Liquefying Ability in Gelatin-Liquefying Bacteria.

국문 초록 (Abstract)

Gelatin 을 재료로 이용하는 식품의 폐기물에서 gelatin 을 액화시키는 능력이 특히 뛰어난 4종의 세균을 분리·동정하였으며, 배지내에 NaCI, KI·I₂, CuSO₄등의 억제제를 농도별로 처리했을때 나타나는 4균주의 생존도 및 액화능의 변화를 비교·검토하였고, 생존도에 미치는 pH의 영향도 조사하였다. 또한 MIC(Minimal Inhibitory Concentration) Test를 시행하여 항생제에 대한 4균주의 MIC도 조사하였다. 그 결과는 다음과 같다.
1. 4균주중 H strain은 Serratia liquefaciens로, Y₁strain은 Enterobacter속으로, Y₂와 Y₃strain 은 Pseudomonas 속으로 동정되었다.
2. 배지내에 억제제로 NaCl을 처리했을 경우, 7% 농도에서 생장이 100% 억제되었으며, KI·I₂처리시에는 20ppm 에서부터 생장이 억제되기 시작하여 100ppm에서는 4개의 균주 모두 100% 생장이 억제되었다. CuSO₄처리시에는 100ppm에서부터 억제효과를 나타내기 시작하여 300ppm에서는 거의 100% 억제 효과를 보였다. 생존도에 미치는 pH의 영향을 살펴본 결과, pH 5.0, 5.5, 6.0에서는 대조군과 동일한 생존도를 나타냈으나 pH 4.0, 4.5 에서는 100% 생장이 억제되었다. 분리 균주들의 액화능 비교에 있어서는 H strain 이 가장 뛰어난 액화능을 나타내었다. CuSO₄와 KI·I₂를 각각 3ppm, 10ppm의 저농도로 처리했을 경우 4균주의 액화능은 대체로 10∼20% 감소되었다.
3. 액화 능력이 가장 뛰어난 H strain 의 MIC 는 Penicillin G; 1∼5 ㎍/ml, Spectinomycin; 12.5∼25㎍/ml, Ampicillin; <0.05㎍/ml, Cefobid; <1㎍/ml, Claforan; 0.02∼0.3㎍/ml, Tetra-cycline; >10㎍/ml로 나타났다. Tetracycline을 제외한 5가지 항생제에 대하여 H strain이 Y strain들에 비해 민감한 것으로 나타났다. 그러나 Tetracycline의 경우에는 H strain이 Y strain들에 비하여 저항성을 갖는 것으로 나타났다.

다국어 초록 (Multilingual Abstract)

Four strains of gelatin-liquefying bacteria were isolated from the sewage of the food using gelatin as the material. Treated with various concentration of NaCl, KI-I₂and CuSO₄in the culture medium and with various gradient of pH, viability of the four strains was examined and compared with each other. And also, gelatin liquefying ability was investigated in the normal culture condition and in accordance with the concentration of the inhibitor. Morever, MIC(Minimal Inhibitory Concentration) test for these strains was also carried out.
The results were as follows:
1. Of the four isolated strains, the H strain was identified as Serratia liquefaciens, Y₁as the genus Enterobacter, Y₂and Y₃strains as the genus Pseudomonas.
2. Treating the culture medium with NaCl as the growth inhibitor, 7% concentration of NaCl inhibited completely the viability of all the isolated strains.
Adding KI-I₂solution to the medium at the level of 20ppm, viability began to decrease and the inhibitory effect was shown 100% at 100ppm.
Treated with CuSO₄at the level of 10ppm, viability began to decrease, and at 300ppm growth inhibition showed almost 100%.
There was no significant difference in viability according to the pH gradient at the range of 5.0-6.0.
However, at pH 4.0 and 4.5, 100% inhibitory effect on the growth was shown.
Considered with the ability of gelatin liquefaction, the H strain among the four strains had the most rapid and strong ability in gelatin liquefaction. (That is, about 23 times more effective in gelatin liquefaction than that of Y₁strain)
3. Considered the MIC test, the H strain was more sensitive to Penicillin G(1-5 ㎍/ml), Spectinomycin(12.5-25㎍/ml), Ampicillin(＜0.05㎍/ml), Cefobid(＜1㎍/ml) and Claforan (0.02-0.3㎍/ml) than to those of the strains. Compared with the other strains, the H strain was more insensitive up to the level of 10㎍/ml to the minimal inhibitory concentration of Tetracycline.