Probiotics는 살아있는 미생물로서 섭취했을 때 숙주에게 건강증진효과를 나타내는 미생물이다. 식품 및 제약에서 가장 많이 사용되는 probiotics로는 Lactobacillus와 Bifidobacterium 균주가 있다. 이 유산균들은 장내 정상균총의 유지, 설사 예방 및 개선, 항암, 항대장염, 면역조절, 항고지혈, 항당뇨 효과 등 많은 건강증진 효과를 나타낸다. 최근에 장내 미생물이 에너지 대사, 특히 지방 대사에 영향을 주어 체중을 조절하는데 있어 중요한 역할을 한다는 것이 알려졌다. 이와 더불어 몇몇 probiotic Lactobacillus가 비만 실험동물 뿐만 아니라 비만인에서도 체지방을 조절하는 것으로 나타나 당뇨 및 비만 등과 같은 대사성질환의 예방 및 치료에 있어 유산균의 사용 가능성이 점쳐지고 있다. 그러나 유산균의 항비만 효과 그리고 그에 관한 기전에 대해서는 많은 연구들이 수행되지 않았다. 따라서 유산균의 항비만 효과를 검증하기 위해서는 앞으로 이에 관한 기전에 대해 더 많은 연구들이 진행되어야 하고 궁극적으로 사람에서 그 효과가 검증되어야할 것이다.

Lactobacillus acidophilus NCFM, Lactobacillus casei YIT 9018, Bifidobacterium longum 8001, and Bifadobacterium longum 8025 at the level of 10^6 cfu/ml were cultured with 10⁴ cfu/ml of Escherichia colt O157:H7 KSC 109 or Salmonella typhimurium ATCC 14028, in order to verify the effects of lactic acid bacteria and bifidobacteria on the growth of the pathogens. In the mixed culture of lactic acid bacteria with E. colt O157:H7 KSC 109, growth inhibition and atypical microcolonies of E. colt O157:H7 KSC 109 were observed. The pathogens inoculated grew for 5 hours (pH 5.3), by the time L. acidophilus NCFM reached the exponential growth phase, and then the surviving pathogens were decreased to 10¹ cfu/ml after 35 hours. When L. casei YIT 9018 was grown with the pathogens, they grew for 10 hours (pH 4.6), by the time L. casei YIT 9018 reached the end of exponential growth phase, and then the surviving pathogens were decreased drastically. Up to the stationary growth phase of lactic acid bacteria, L. acidophilus NCFM exhibited stronger inhibition against the pathogens than L. casei YIT 9018 did, which might be attributed to its faster growth. Likewise bifidobacteria inhibited the growth of the pathogens. tested, bifidobaceria was weaker in the inhibitory activity than lactic acid bacteria. When Bifidobacterium longum 8001 was cultured with the pathogens, E. colt O157:H7 KSC 109 was gradually inhibited at the stationary growth phase of bifidobacteria, atypical microcolonies were formed on Levine EMB medium after 48 hours, and Salmonella grew up to 10^6 cfu/ml, then was drastically inhibited at the exponential growth phage of Bifxdobacterium longum 8001. But when Bifidobacteriuam longum 8025 was cultured with the pathogens, the pathogens grew to the same level of Bifidobacteriuam longum 8025 after 10 hours, then the surviving pathogens were decreased drastically.

Escherichia coli O157:H7 and Salmonella ser. typhimurium are pathogens involved in food poisoning in numerous countries. This study aimed to obtain knowleges on the survival of E. coli O157:H7 KSC 109 and S. ser. typhimurium ATCC 14028 in fermented milk products which were on sale in Suwon Yakult supplier. To the final concentration of 10³-10⁴ cfu/ml of E. coli O157:H7 KSC 109 or S. ser. typhimurium ATCC 14028 in the fermented milks, Metchnikoff, Ace, Yakult, Mastoni and Super100 were inoculated with these pathogens and then were stored at 4 and viable cells of these pathogens were periodically counted. The results showed that the survival of two pathogens differed in the different types of fermented milks tested. Number of surviving E. coli O157:H7 KSC 109 and S. ser. typimurium ATCC 14028 cells (initial inoculum, 10³-10⁴ cfu/ml) were decreased to 10', 102 cfu/ml in Ace after 100 hours, and were decreased gradually to 10¹ cfu/ml in Yakult after 250 hours. In the other fermented milks, viable cells of E. coli O157:H7 KSC 109 was not drastically decreased but those of S. ser. typhimurium ATCC 14028 was decreased gradually to 10² (Mastoni), and to 10¹ cfir/ml (Super100) after 250 hours. It appeared that S. ser. typhimurium ATCC 14028 was more susceptible than E. coli O157: H7 KSC 109 at low pH. Vibale cells of E. coli O157:H7 KSC 109 was not drastically decreased in most of fermented milks tested except Ace and Yakult, but in general, S. ser. typhimurxum ATCC 14028 was drastically decreased in most of the fermented milks. The major inhibition factor against these pathogens in the fermented milks during storage at 4℃ appeared to be the acidity and the metabolites produced by the starters bacteria used in fermented milk products.

The cholesterol lowering effect of vegetables fermented by Lactobacillus plantarum HY7712 was evaluated in rats fed high fat/high cholesterol diet. SD Rats were randomly divided into three groups, then fed a normal diet (ND), a highfat high-cholesterol diet (HFCD), or HFCD and vegetables fermented by HY7712 (VFLAB) for 5 weeks, and the biomarkers in the blood, liver, and feces of rats were measured. Antioxidant status such as SOD, CAT, GSH/GSSG, and MDA was significantly deteriorated in HFCD compared with ND (p<0.01) but was improved in VFLAB to the level of ND. In addition, the level of MDA in VFLAB was significantly decreased in comparison with HFCD (p<0.05). Total cholesterol, LDLcholesterol, and atherogenic index (AI) were significantly increased in HFCD, but significantly decreased in VFLAB (p<0.05). In addition, administration of a HFCD diet increased the fecal bile acid in rats and the concentration of fecal bile acid was higher in VFLAB than in HFCD. In conclusion, the vegetables fermented by L. plantarum HY7712 improved antioxidant status and hypercholesterolemia induced by HFCD diet, which may be due to the synergic effect of lactic acid bacteria and fermented vegetables.

L. brevis HY7401, L. helveticus HY7801 및 B. longum HY8004의 복합유산균 R&B Balance^®의 대장염 개선 효과를 DSS 처리 마우스에서 평가하였다. R&B Balance^® 섭취에 의해 대장길이 축소, MPO 활성과 같은 대장염 증상이 감소하였으며, 분변내 chondrointinase 활성과 분변 유전독성을 현저하게 감소시키는 것으로 나타났다. T-RFLP pattern의 군집 분석 결과, DSS-유도 대장염 마우스의 미생물총은 정상적인 마우스와 다르며, R&B Balance^®의 투여는 장내 미생물총의 다양성에 영향을 미칠 수 있음을 확인하였다. 따라서 R&B Balance^®는 DSS로 유도된 대장염 동물에서 대장염 증상을 개선해주고 분변 내 독성 효소나 유독한 대사산물을 생성을 억제함으로써 대장염을 개선하는 것으로 판단되고 대장염 동물의 장내 미생물 다양성에도 영향을 미치는 것으로 확인되었다.