동결 건조된 죽력을 물 또는 50% ethanol에 각각 용해시킨 시료(1 mg eq./disc)에 대하여 항세균 활성을 측정한 결과, 물에 용해시킨 죽력은 gram 양성균의 경우 L. monocytogenes이 15 mm의 저해환으로 가장 활성이 강하였고 B. subtilis는 활성이 전혀 나타나지 않았으며 Gram 음성균의 경우는 S. dysenteriae가 저해환이 22 mm로 가장 강한 활성을 보였다. 50% ethanol에 용해시킨 죽력은 gram 양성균의 경우 L. monocytodenes, 가 가장 강한 활성을 보였으나 B. subtilis는 활성이 전혀 없던 물에 용해시킨 경우에 비하여 활성이 크게 나타났다. Gram 음성균의 경우, S. dysenteriae가 23 mm저해 환으로 가장 강한 활성을 보였고 V. parahaemolyticus, V. vulnificus, E. coli O157:H7는 16 mm로 상대적으로 약한 활성을 보였다. 젖산균 2종의 경우는 물 또는 50% ethanol에 용해시킨 경우 모두 전혀 활성을 나타내지 않았다. 최소저해농도는 L. monocytogenes는 50% ethanol에 녹인 경우 MIC가 0.6 mg/disc로 가장 낮았고 물에 용해시킨 죽력의 경우 S. epidermides, S. dysenteriae, L. monocytogenes, Sal. typhimurium, V. parahaemolyticus가 각각 0.8 mg/disc의 MIC값을 나타내 50% ethanol에 용해시킨 경우에 비하여 MIC값이 높은 경향을 보였으며 다른 세균들은 1.0 mg/disc의 거의 유사한 MIC값을 보였다. Model food system에서의 저해활성은 물에 용해시킨 죽력 보다 50%, ethanol에 용해시킨 죽력이 대조구에 비하여 생육을 강하게 저해하였고 MIC가 낮은 이들 4가지 공시균주들이 모두 model food system상에서 상당히 강한 저해활성을 나타내 50% ethanol에 용해시킨 죽력은 적절한 농도에서 부패세균들의 생육 억제제로 사용 가능할 것으로 사료되었다.

Antibacterial activities in each part of watercress(Oenanthe javanica D.C.) grown under different culture conditions were measured to determine the possibility to use watercress as a resource to develop the antibacterial substance. The leaves of watercress were extracted with methanol and the methanol extract was further fractionated with various organic solvents. Antibacterial activities against Shigella dysenteriae ATCC 9361 in all fractions were determined according to the agar diffusion method using paper disc. Methanol extract of watercress leaves was more effectively inhibited the growth of the tested bacteria than the extracts of roots or stems at the concentration of 0.5 g eq./disc, and the extract of watercress from Hwasoon was the most effective one as compared to others. Phenolic and neutral fractions fractionated from methanol extract of watercress had a considerable inhibiting activity on the growth of the bacteria, but acidic and basic fractions did not show any inhibitory effect. Minimum inhibitory concentrations of phenolic and neutral fractions against Shigella dysenteriae ATCC 9361 were 400 μg/disc and 550 μg/disc, respectively.

Bacterial fruit blotch (BFB) is one of most important diseases in Cucurbitaceae due to infection of Acidovorax citrulli, causing huge economic losses damage worldwide. This seedborn disease spread rapidly at period of high temperature and humidity. The eco-friendly farming is getting popular. So far there was no effective agent to control BFB in eco-friendly farming. Therefore, effect of the material based on chinese nut-gall extract with antibacterial activity against BFB to was tested against A. citrulli. Different hosts showed various symptoms of BFB. Liquid formulation among exhibited most effective anti-bacterial activity on A. citrulli. Pot experiment in greenhouse showed the potential as an control agent of BFB in cucurbits. The treatment of material based on chinese nut-gall extract showed the positive effect on survival of the watermelon seedling and on the length of the cucumber seedling treated with A. citrulli. We cautiously conclude that the material based on chinese nut-gall extract used in this study may be good agents against major diseases of cucurbits in the future even though it is require to be tested with more study on field test.