Single-cell Encapsulation of Lactococcus lactis and Evaluation of Its Performance within the Gastrointestinal Environment
The development of novel and effective probiotic encapsulation systems is imperative in light of the susceptibil-ity of probiotics to the acidic and highly-concentrated bile salts environment within the gastrointestinal tract.Car-boxymethylated β-glucan(mGN)was utilized in this study to adhere to the surface of Lactococcus lactis(LL)through the bridging of a metal-phenolic network(Fe-TA),aiming to achieve the single-cell encapsulation of LL(LL@Fe-TA@mGN)and assess the gastrointestinal stress resistance and intestinal retention capacity of LL@Fe-TA@mGN.The re-sults demonstrated that the particle size and zeta-potential of LL@Fe-TA@mGN reached maximum values when 0.12 mg/mL mGN was applied,indicating the full encapsulation of LL at the single-cell level.No significant difference was ob-served for the growth curve between LL@Fe-TA@mGN and LL in the MRS medium,ruling out the potential toxicity of mGN.Both SEM and TEM clearly revealed the presence of a distinct'film'layer on the surface of LL,providing further evidence that LL was encapsulated within the mGN.With the protection of mGN,the survival rate of LL@Fe-TA@mGN could be up to 14.63 and 1.94 times higher than that of bare LL after exposure to simulated gastric fluid and bile salts for 2 h,respectively.In vivo fluorescence imaging corroborated the prolonged intestinal retention ability of LL@Fe-TA@mGN.In summary,the single-cell encapsulation strategy we developed here could significantly enhance gastrointesti-nal resistance and prolong the intestinal retention of LL.These results offer novel insights for the development and appli-cation of probiotic encapsulation systems.
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