体外法探究果寡糖对猪后肠微生物代谢苯丙氨酸和色氨酸的影响

摘要

旨在采用体外发酵技术探究不同剂量果寡糖(FOS)对猪后肠发酵液中苯丙氨酸和色氨酸代谢的影响.以育肥猪回肠、盲肠和结肠的食糜为接种物,发酵液中苯丙氨酸(Phe)和色氨酸(Trp)终浓度为10 mmol·L-1,分别添加果寡糖(FOS)0、0.5和0.75g,37℃培养24h后采集样品,分析氨基酸、氨态氮(NH3-N)、微生物蛋白(MCP)、吲哚和粪臭素浓度,利用Real-time PCR定量细菌总菌数量变化.结果表明,Phe和Trp均存在肠段差异性,FOS显著影响Phe在盲肠的降解率、NH3-N、MCP、粪臭素浓度和总菌数量(P＜0.05),但对吲哚无显著影响(P＞0.05);0.75 g FOS显著降低后肠Trp降解率(P＜0.05);Trp是影响发酵液中吲哚和粪臭素产生的主要因素.FOS可改变Phe和Trp的发酵类型,降低发酵液中Trp向粪臭素的转化.%This experiment aimed to study the effect of FOS on metabolism of phenylalanine(Phe) and tryptophan (Trp) in pig hindgut bacteria fermentation broths in vitro.Ileum,cecum and colon chyme in pigs were used as inoculum.Phe and Trp concentrations were kept at 10 mmol · L-1 in fermentation broth.The dose of FOS was 0,0.5 and 0.75 g,respectively.Fermentation samples collected at 24 h and 37 ℃ were used to measure concentrations of amino aicds,ammonia nitrogen (NH3-N),microbial crude protein (MCP),indole and skatole.Real-time PCR was used to quantify the bacterial numbers.The results showed that the fermentation characteristic of Phe and Trp differed in different gut locations.The degradation rate of Phe was significantly affected by FOS(P＜0.05).The concentrations of NH3-N,MCP,skatole and number of total bacterial were significantly affected by FOS (P＜0.05),while indole was not affected by FOS (P＞0.05).In 0.75 g FOS group,Trp degradation rate decreased significantly in the hindgut intestine (P＜0.05).Trp was the major factor affecting indole and skatole production in fermentation broths.Collectively,FOS could alter the metabolic patterns of phenylalanine and tryptophan by gut bacteria,and decreased the conversion of tryptophan to skatole.