<i>Lactobacillus acidophilus</i>—Rutin Interplay Investigated by Proteomics

<div><p>Dietary polyphenols are bioactive molecules that beneficially affect human health, due to their anti-oxidant, anti-inflammatory, cardio-protective and chemopreventive properties. They are absorbed in a very low percentage in the small intestine and reach intact the colon, where they are metabolized by the gut microbiota. Although it is well documented a key role of microbial metabolism in the absorption of polyphenols and modulation of their biological activity, molecular mechanisms at the basis of the bacteria-polyphenols interplay are still poorly understood. In this context, differential proteomics was applied to reveal adaptive response mechanisms that enabled a potential probiotic <i>Lactobacillus acidophilus</i> strain to survive in the presence of the dietary polyphenol rutin. The response to rutin mainly modulated the expression level of proteins involved in general stress response mechanisms and, in particular, induced the activation of protein quality control systems, and affected carbohydrate and amino acid metabolism, protein synthesis and cell wall integrity. Moreover, rutin triggered the expression of proteins involved in oxidation-reduction processes.This study provides a first general view of the impact of dietary polyphenols on metabolic and biological processes of <i>L</i>. <i>acidophilus</i>.</p></div

Growth curves of <i>L</i>. <i>acidophilus</i> in control conditions and in the presence of rutin.

<p>(A) Growth curves of <i>L</i>. <i>acidophilus</i> obtained by plate counting. (B) Growth curves of <i>L</i>. <i>acidophilus</i> obtained measuring the optical density at 600 nm. Arrows indicate the times of bacterial cell collection for the further proteomic analyses. Values are the means of four independent experiments.</p

Interaction network (as displayed by EMBL STRING) of the identified proteins.

<p>Green lines indicate neighborhood, blue lines indicate co-occurrence, black lines indicate co-expression, purple lines indicate experiments, light blue lines indicate databases and yellow lines indicate text-mining. The network was obtained with a confidence score of 0.600. Main functional modules are circled.</p

Representative 2-DE gels of <i>L</i>. <i>acidophilus</i> proteome.

<p>(A) 2-DE gel obtained from the proteome of <i>L</i>. <i>acidophilus</i> grown under control conditions. (B) 2-DE gel obtained from the proteome of <i>L</i>. <i>acidophilus</i> grown in the presence of rutin. Spots exhibiting significant differences in mean intensities are indicated.</p

Functional classification of the identified proteins and regulation of their abundance.

<p>^aChanges in protein levels are reported as the ratio between the relative spot volume from <i>L</i>. <i>acidophilus</i> grown in the presence of rutin and <i>L</i>. <i>acidophilus</i> grown in control conditions (Vrutin/Vcontrol) for increased proteins and as the negative reciprocal values (-Vcontrol/Vrutin) for decreased proteins. Changes in protein levels >1.5 have been considered significant.</p><p>^bAverage fold change for proteins contained in more than one spot has been calculated considering the relative spot volume of all the spots containing the same protein and a fold change >1.5 has been considered significant.</p><p>Functional classification of the identified proteins and regulation of their abundance.</p

Identification of differentially expressed proteins.

<p>Identification of differentially expressed proteins.</p