发酵全混合日粮中优质乳酸菌的分离鉴定

Isolation and Identification of High-Quality Lactic Acid Bacteria in Fermented Total Mixed Ration

对8种发酵全混合日粮中的乳酸菌进行分离鉴定,以期获得适宜调控发酵全混合日粮的优质乳酸菌菌株,解决发酵全混合日粮因pH值过低而造成的适口性差和干物质采食量下降等问题。采用改良的乳酸菌分离培养技术,从8种日粮中共分离到38株乳酸菌,根据菌落形态及发酵葡萄糖产气特性可分为7组。16S rDNA序列分析表明,7组菌株为副干酪乳酪杆菌、干酪乳酪杆菌、鼠李糖乳酪杆菌、葡萄芽孢乳杆菌、酸鱼联合乳杆菌、谷糠迟缓乳杆菌和布氏迟缓乳杆菌。菌株生理生化分析表明,酸鱼联合乳杆菌TY29在发酵前期具有较强的生长及产酸能力,3 h进入生长及产酸对数期,最终pH值维持在适宜范围内(pH值4.2~4.5);对酸的耐受性适中,菌株在pH值3.5时不能生长,在pH值4.0时弱生长;对温度和盐浓度耐受范围广,可在温度15~45℃、NaCl浓度3.0%~6.5%下正常生长;表明其具有作为优质乳酸菌调控发酵全混合日粮的潜力。

Isolating and identifying high-quality lactic acid bacteria(LAB)strains in eight fermented total mixed ration(FTMR)was conducted to obtain suitable strains for regulating FTMR fermentation,and solve problems such as decreased palatability and dry matter intake caused by low pH values.A modified LAB isolation and culture technique was used to isolate a total of 38 LAB strains,which were divided into seven groups according to their colony morphology and gas production characteristics during glucose fermentation.16S rDNA sequence analysis showed that the seven groups of strains were Lacticaseibacillus paracasei,L.casei,L.rhamnosus,Sporolactobacillus vineae,Ligilactobacillus acidipiscis,Lentilactobacillus farraginis,and L.buchneri subsp.silagei.Physiological and biochemical analysis showed that L.acidipiscis TY29 had strong growth and acid production capabilities in the early fermentation stage,entered the logarithmic growth and acid production phase at 3 hours,and maintained the pH value in the appropriate range(4.2-4.5).It had moderate tolerance to acid,weak growth at pH 4.0 and go growth at pH 3.5,and wide tolerance to temperature and salt concentration,with normal growth at temperatures of 15-45℃and NaCl concentrations of 3.0%-6.5%.These findings suggest that L.acidipiscis TY29 has the potential to be used as a high-quality LAB strain for regulating the fermentation of fermented total mixed ration.