Effects of soybean protein isolates and peptides on the growth and metabolism of Lactobacillus rhamnosus

Abstract

The purpose of this study was to investigate whether soybean protein isolates (SPIs2 PEP: soybean peptides; dPEPs: digested soybean peptides; SPIs: soybean protein isolates; dSPIs: digested soybean protein isolates; MRS: Man Rogosa Sharpe broth; LN: MRS reduced nitrogen content by half; LN+PEP: LN supplemented with an equivalent nitrogen content from soybean peptides; LN+SPI: LN supplemented with an equivalent nitrogen content from soybean protein isolates; LN+dPEP: LN supplemented with an equivalent nitrogen content from digested soybean peptides; LN+dSPI: LN supplemented with an equivalent nitrogen content from digested soybean protein isolates.2) and soybean peptides (PEPs), as well as their hydrolysates after simulated gastrointestinal digestion (dSPIs and dPEPs), can promote the growth and short chain fatty acid (SCFA) production of Lactobacillus rhamnosus (L. rhamnosus) in vitro under mono-culture and co-culture with Escherichia coli (E. coli). We found that all the treatment groups could enhance the viable cell numbers, while the effects of PEP and dPEP occurred earlier than those of SPI and dSPI, and the production of SCFAs was improved mainly by the dPEP and dSPI groups in mono-culture. In the co-culture system, dPEP weakened the competitiveness of E. coli and improved the competitive capacity of L. rhamnosus, and the viable cell numbers of L. rhamnosus were higher than the numbers in the treated mono-culture after 8 h and 12h of cultivation.

Keywords

• Soybean protein isolates
• Soybean peptides
• Simulated gastrointestinal digestion
• Lactobacillus rhamnosus
• Co-culture