The Effect Of Sub-stress On The Nutrient Consumption Pattern Of Lactobacillus Acidophilus LA-5

Lactobacillus acidophilus is widely used in the production of fermented food,especially in the production of fermented dairy products.At present,the studies on Lactobacillus acidophilus exposed to stressful environments mainly focus on the determination of stress tolerance mechanism and lyophilized survival rate of a few strains,while the study on the nutrient requirements and nutrient consumption pattern of the strains is less.At the same time,studies on the nutritional requirements of Lactobacillus acidophilus mainly involve the determination of amino acid and vitamin requirements of a few strains,while information on the requirements of bases and metal ions is rarely reported.Lactobacillus acidophilus faces osmotic stress caused by sodium lactate as a neutralizer product and increasing intracellular acid stress during high-density culture.Therefore,in order to explore the nutrient consumption pattern of Lactobacillus acidophilus in a sub-stress environment of osmotic stress and acid stress,to screen the functional nutrient components that enhance Lactobacillus acidophilus resistance to osmotic stress and acid stress,and to provide theoretical and scientific basis for the design of high-density media,the culture medium(CDM)was used to proliferate and cultivate L.acidophilus LA-5 in the study,and the automatic growth curve analyzer was used to screen its two sub-stress levels under different culture conditions(acid stress and osmotic stress).Based on the study of growth kinetics,the consumption of various nutrients(amino acids,vitamins,bases and metal ions)in CDM with fermentation time was analyzed by high performance liquid chromatography.According to the study on the change of amino acid concentration with fermentation time,when L.acidophilus LA-5 was cultured in CDM at p H5.8,the amino acids with higher consumption rate and consumption were Ala and Asp+Asn.The consumption rates of these two amino acids were74.52%and 66.11%,respectively.Consumption accounted for 16.40%and 21.84%of the total amino acid consumption,respectively.When L.acidophilus LA-5 was cultured in CDM at p H4.9,the amino acids with higher consumption rate and consumption were Pro and Ala,with consumption rate of 59.70%and 64.85%,respectively.Consumption accounted for 11.31%and 14.29%of the total amino acid consumption,respectively.When L.acidophilus LA-5 was cultured in CDM at p H4.4,the highest amino acid consumption rate was Thr(60.84%).The largest amino acid consumption was Ala,which accounted for 13.85%of the total amino acid consumption.In addition,with the increase of acid stress,the consumption rate and consumption of Ala,Met,Val,Leu,Lys and Asp+Asn decrease continuously.When L.acidophilus LA-5 was cultured in CDM with 1.5%sodium lactate,the amino acids with high consumption rate and consumption were Val,Pro,Leu and Ala,with consumption rates of 50.69%,66.31%,69.21%and 50.31%,respectively.Consumption accounted for 7.65%,9.23%,9.27%and 10.29%of the total amino acid consumption,respectively.When L.acidophilus LA-5 was cultured in CDM with 9.5%sodium lactate,the amino acid with high consumption rate and consumption was Pro,with a consumption rate of 71.43%.Its consumption accounted for 14.43%of the total amino acid consumption.When L.acidophilus LA-5 was cultured in CDM with 11%sodium lactate,the highest amino acid consumption rate was Thr(59.52%).The largest amino acid consumption was Ala,which accounted for 13.79%of the total amino acid consumption.In addition,with the increase of osmotic stress,the consumption rate and consumption of Gly,Asp+Asn,Lys and Leu decreased significantly.According to the study on the changes of vitamin concentration with fermentation time,vitamin B6 and niacin were the vitamins with high consumption rate and consumption in the fermentation process of L.acidophilus LA-5 in CDM at p H5.8,the consumption rates of these two vitamins were65.09%and 93.90%,respectively.Consumption accounted for 20.34%and 24.54%of the total vitamin consumption,respectively.When L.acidophilus LA-5 was cultured in CDM at p H4.9,the vitamins with high consumption rate and consumption were niacin and para-aminobenzoic acid,the consumption rates of which were 95.88%and 58.15%,respectively.Consumption accounted for13.20%and 61.13%of the total vitamin consumption,respectively.When L.acidophilus LA-5 was cultured in CDM at p H4.4,vitamin B6,niacin and biotin were the vitamins with high consumption rate and consumption,and the consumption rates of these vitamins were 70.74%,93.69%and63.68%,respectively.Consumption accounted for 13.99%,14.85%and 20.91%of the total vitamin consumption,respectively.In addition,with the increase of acid stress,the consumption rate and consumption of thiamine and biotin increased,and the consumption rate and consumption of folic acid and calcium pantothenate decreased.When L.acidophilus LA-5 was cultured in CDM with 1.5%sodium lactate,the vitamin with higher consumption rate and consumption is vitamin B6,and its consumption rate is 61.58%.Consumption accounted for 17.73%of the total vitamin consumption.When L.acidophilus LA-5 was cultured in CDM with 9.5%sodium lactate,the vitamins with higher consumption rate and consumption were niacin and p-aminobenzoic acid.The consumption rates of these two vitamins were 70.50%and 78.27%,respectively.Consumption accounted for 7.55%and66.45%of the total vitamin consumption,respectively.When L.acidophilus LA-5 was cultured in CDM with 11%sodium lactate,the vitamin with high consumption rate and consumption was niacin,with a consumption rate of 64.41%.Consumption accounted for 9.50%of the total vitamin consumption.In addition,with the increase of osmotic stress,the consumption rate and consumption of cobalamin increased,and the consumption rate and consumption of folic acid decreased.According to the study on the changes of the concentration of base and metal ions with fermentation time,when L.acidophilus LA-5 was cultured in CDM at different p H,the bases with higher consumption rate and consumption were uracil,adenine and guanine.The consumption rate of adenine and guanine was 100%,and the consumption rate of uracil was more than 90%.The consumption of adenine and guanine accounted for more than 25%of the total base consumption,and the consumption of uracil accounted for more than 20%of the total base consumption,while the consumption of thymine and xanthine was relatively low.When L.acidophilus LA-5 was cultured in CDM with different concentrations of sodium lactate,the bases with high consumption rate and consumption were guanine,adenine and uracil.The consumption rate of these bases was100%,and the consumption of them accounted for more than 20%of the total base consumption.Among them,the consumption of uracil is the largest.When L.acidophilus LA-5 was cultured in CDM at different p H,the consumption of K⁺was the largest,accounting for more than 50%of the total metal ion consumption,followed by Na⁺,Mg²⁺and Mn²⁺,and the consumption of Fe²⁺was the least.For the consumption rate,the highest is Mn²⁺,which is more than 80%.When L.acidophilus LA-5 was cultured in CDM with different concentrations of sodium lactate,the consumption of K⁺was the largest,accounting for more than 95%of the total metal ion consumption,followed by Mg²⁺and Mn²⁺,and the consumption of Fe²⁺was the least.For the consumption rate,the highest is Mn²⁺,both reaching more than 45%.Among them,when L.acidophilus LA-5 was cultured in CDM with1.5%sodium lactate,the consumption rate of Mn²⁺was the highest,which was 85.3%.