Xu Zi-Rong, Hu Cai-Hong, Wang Ming-Qi
ZheJiang University, Feed Science Institute, The Key Laboratory of Molecular Animal Nutrition, Ministry of Education, HangZhou, 310029, P.R. China.
J Gen Appl Microbiol. 2002 Apr;48(2):83-90. doi: 10.2323/jgam.48.83.
An in vitro study was conducted to examine the effects of fructooligosaccharide (FOS) at levels of 0.5, 1.0, and 1.5% on conversion of L-tryptophan to skatole and indole by a mixed bacterial population from the large intestines of pigs. Microbial suspensions were anaerobically incubated at 38 degrees C for 24 h. Samples were periodically removed for determination of pH and indole compounds. After 24 h incubation, microbial populations in each culture media were analyzed. Addition of 0.5, 1.0, and 1.5% FOS to the slurries with L-tryptophan significantly decreased the skatole concentration, the peak value of indole-3-acetic acid and the medium pH. The viable counts of Bifidobacterium were significantly higher as compared with the control. Addition of 1.0 and 1.5% FOS significantly decreased the rate of tryptophan degradation and the relative rate of skatole production. The relative rate of indole production was significantly increased. The viable counts of Clostridium and Escherichia coli were significantly reduced. The total viable counts of anaerobes were significantly increased. These results suggest that the reduced concentration of skatole observed in the presence of FOS may be caused by the decreased tryptophan degradation due to the increased need for amino acids in the synthesis of bacterial cellular protein, and by shifting microbial metabolism of tryptophan toward indole production at the expense of skatole, which might result from the changed microbial ecosystem and pH. Our observations open the possibility of inhibiting microbial production of skatole and decreasing the skatole concentration in backfat by feeding pigs diets containing FOS, but it remains to be demonstrated in vivo.
进行了一项体外研究，以考察低聚果糖（FOS）水平为0.5%、1.0%和1.5%时，对猪大肠混合菌群将L-色氨酸转化为粪臭素和吲哚的影响。将微生物悬浮液在38℃厌氧培养24小时。定期取出样品测定pH值和吲哚化合物。培养24小时后，分析每种培养基中的微生物种群。在含L-色氨酸的浆液中添加0.5%、1.0%和1.5%的FOS显著降低了粪臭素浓度、吲哚-3-乙酸的峰值和培养基pH值。与对照组相比，双歧杆菌的活菌数显著更高。添加1.0%和1.5%的FOS显著降低了色氨酸降解率和粪臭素的相对产生率。吲哚的相对产生率显著增加。梭菌和大肠杆菌的活菌数显著减少。厌氧菌的总活菌数显著增加。这些结果表明，在FOS存在下观察到的粪臭素浓度降低可能是由于细菌细胞蛋白质合成中对氨基酸需求增加导致色氨酸降解减少，以及色氨酸的微生物代谢转向以粪臭素为代价的吲哚产生，这可能是由微生物生态系统和pH值变化引起的。我们的观察结果为通过给猪喂食含FOS的日粮来抑制微生物产生粪臭素并降低背膘中粪臭素浓度提供了可能性，但这仍有待在体内进行验证。
