高产苯乳酸菌株的筛选及其在豆粕发酵中的应用

Screening of high-yield phenyllactic acid strain and its application in soybean meal fermentation

以实验室保存的性能优良的乳酸菌为研究对象,采用薄层层析(TLC)法和高效液相色谱(HPLC)法筛选出高产苯乳酸的菌株,并利用该菌株对豆粕进行固体发酵,研究其对发酵豆粕的微生物、pH值、水分含量、粗蛋白、酸溶蛋白、总酸和苯乳酸含量的影响。结果表明,筛选得到3株产苯乳酸的菌株,其中植物乳杆菌(Lactobacillus plantarum)BLCC2-0069为高产苯乳酸的菌株,其以3 g/L苯丙酮酸为底物发酵48 h时发酵液中苯乳酸含量最高为4.39 g/L。利用该菌株固态发酵豆粕3 d时,乳酸菌活菌数>109 CFU/g,霉菌活菌数≤10 CFU/g,大肠杆菌未检出;pH值降至4.5左右,水分、粗蛋白、酸溶蛋白、总酸和苯乳酸含量分别为36.78%、46.65%、10.51%、26.37 g/kg和424.02 mg/kg,发酵效果显著优于对照组(P<0.05)。

Using lactic acid bacteria with excellent performance stored in the laboratory as research objects,the high-yield phenyllactic acid strain was selected by thin layer chromatography(TLC)and high performance liquid chromatography(HPLC).The strain was used for solid-state fermentation of soybean meal,and the effects on microorganism,pH value,moisture,crude protein,acid-soluble protein,total acid and phenyllactic acid content were studied.The results showed that 3 phenyllactic acid producing strains were screened.Among them,Lactobacillus plantarum BLCC2-0069 was a strain with high phenyllactic acid production,and the highest content of phenyllactic acid in the fermentation broth was 4.39 g/L when fermented with 3 g/L phenylpyruvate as a substrate for 48 h.When using the strain to ferment soybean meal in solid state for 3 d,the viable lactic acid bacteria number was>109 CFU/g,the viable mold number was≤10 CFU/g,and Escherichia coli was not detected.The pH value dropped to about 4.5,the moisture,crude protein,acid-soluble protein,total acid and phenyllactic acid content was 36.78%,46.65%,10.51%,26.37 g/kg and 424.02 mg/kg,respectively.The fermentation effect was significantly better than that of the control group(P<0.05).