Study On Molecular Mechanism Of Metabolism Of Lactobacillus Plantarum IMAUCD001

As a kind of?-galacto-oligosaccharides,raffinose has various health functions for the human body.However,because of lacking in?-galactosidase in the small intestine of the human body,raffinose cannot be effectively utilized.The strain IMAUCD001 used in this study was obtained by the adaptive evolution of L.plantarum P-8?IMAU10120?under the conditions of carbon source restriction.Compared with IMAU10120,its rate of metabolizing raffinose is higher.And it plays an important role in improving the body's absorption and utilization of soy products and improving the nutritional value of soy products.This study evaluated the safety of IMAUCD001 and IMAU10120 at first.Next,these strains were cultured in medium added 2%raffinose,their growth and metabolism status were determined.Then,this arcticle used iTRAQ proteomics to study the differences in metabolism mechanisms between IMAUCD001 and IMAU10120.The conclusions as below:?1?There was no difference in the phenotypes and genotypes of antibiotics between IMAUCD001 and IMAU10120.They were all resistant to linezolid,vancomycin and ciprofloxacin,and were extremely sensitive to clindamycin.Genes erm?B?and vanX were also detected in both strains.But,vanX,the drug resistance gene of IMAUCD001,did not transfered.?2?At 0-14 hours,the number of viable counts and OD₆₀₀ of IMAUCD001increased faster than IMAU10120.After reaching a same value,IMAUCD001 decreased at a greater rate.The trend of pH of IMAUCD001 and IMAU10120 were the same,two of them,the rate of pH value of IMAUCD001 dropped faster.?3?The test results regarded fold change more than 1.5 and p-value less than 0.05 as choosing condition,and compared with IMAU10120,there are 125 proteins significantly up-regulated?>1.5 fold,p<0.05?and 106 proteins significantly down-regulated?<-1.5 fold,p<0.05?.In the later stage of the exponential phase,with the depletion of raffinose in IMAUCD001,the expression of?-galactosidase and?-galactosidase related to the metabolism of raffinose were down-regulated.And the proteins related to the metabolism of sorbitol and mannitol were up-regulated.It indicates that IMAUCD001 can use sorbitol and mannitol instead of raffinose as a carbon source to participate in energy supply.?4?With the decrease of pH during the growth of the strain,the metabolism of the cells has changed.Compared with IMAU10120,the synthesis rate of peptidoglycan and cyclopropane fatty acids in IMAUCD001 were faster,and chaperone proteins and stress proteins?sHSP,DnaJ and DnaK?were significantly up-regulated,which played an important role in reducing the damage caused by acid stress to cells.Interestingly,by comparing the contents of intracellular amino acid,it was found that IMAUCD001accumulated more aspartic acid,glutamic acid,glycine and valine in the cells than IMAU10120.However,the protein expression associated with aspartate and glutamate metabolism was down-regulated,indicating that engineered strains responded to acid stress by enriching aspartate and glutamate levels in cells to reduce cell damage.This topic has revealed the growth and metabolism mechanism of IMAUCD001 and IMAU10120 on raffinose-added medium from the proteomic level,and systematically analyzed the factors that cause differential protein expression.It provides data support for the addition of aspartic acid and Glutamine to increase the fermentation rate of IMAUCD001,and lays a foundation for consolidating its wide application in the production of soy and soy milk products.