Exploring Amino Acid Auxotrophy in Bifidobacterium bifidum PRL2010

Abstract

The acquisition and assimilation strategies followed by members of the infant gut microbiota to retrieve nitrogen from the gut lumen are still largely unknown. In particular, no information on these metabolic processes is available regarding bifidobacteria, which are among the first microbial colonizers of the human intestine. Here, evaluation of amino acid auxotrophy and prototrophy of Bifidobacterium bifidum, with particular emphasis on B. bifidum strain PRL2010 (LMG S-28692), revealed a putative auxotrophy for cysteine. In addition, we hypothesized that cysteine plays a role in the oxidative stress response in B. bifidum. The use of glutathione as an alternative reduced sulfur compound did not alleviate cysteine auxotrophy of this strain, though it was shown to stimulate expression of the genes involved in cysteine biosynthesis, reminiscent of oxidative stress response. When PRL2010 was grown on a medium containing complex substrates, such as whey proteins or casein hydrolysate, we noticed a distinct growth-promoting effect of these compounds. Transcriptional analysis involving B. bifidum PRL2010 cultivated on whey proteins or casein hydrolysate revealed that the biosynthetic pathways for cysteine and methionine are modulated by the presence of casein hydrolysate. Such findings support the notion that certain complex substrates may act as potential prebiotics for bifidobacteria in their ecological niche.

Deciphering the metabolic capabilities of Bifidobacteria using genome-scale metabolic models

“…We observed that the model did not demonstrate growth on fructose as the sole carbon source; to address these, we added additional transport reactions for fructose and glucose, expanding the model. Finally, our simulations were consistent with reported experiments, confirming the accuracy of the model in utilising different carbon sources 42 .…”

Taxonomic and Functional Compositions of the Small Intestinal Microbiome in Neonatal Calves Provide a Framework for Understanding Early Life Gut Health

“…The luminal microbiomes of functional cluster 1 had a higher abundance (69-fold) of Bifidobacterium than those in functional cluster 2, while those of functional cluster 2 had a higher abundance of sulfur-reducing bacteria (SRB) than functional cluster 1. A recent study has shown that Bifidobacterium utilizes milk protein effectively and requires cysteine, a sulfide amino acid, for growth (37). SRB also utilize cysteine as an energy source (38).…”

Protein‐oligosaccharide conjugates as novel prebiotics

“…In the LFH‐GOS conjugates sample, at the end of digestion, the protein fraction was mainly composed of (conjugated) peptides, whereas the protein fraction in the unconjugated components sample underwent complete proteolysis and was composed of mainly amino acids, in accordance with the results of Wang et al for pure LF. Peptides are the preferred substrates for many colonic bacteria because of kinetic advantages of peptide‐uptake systems in comparison with those for free amino acids, partially explaining the superior growth rate of L. casei on the conjugates. A more exciting possible explanation is that transporters on the cell surface of lactobacilli, which are involved in GOS uptake, had bound the GOS fraction and started its uptake.…”

“…Moreover, probiotic bacteria are auxotrophic for some amino acids and require their presence to grow. 9,10 For example, leucine, phenylalanine, glutamic acid, valine, cysteine, tryptophan, and tyrosine are essential for the growth of Lactobacillus casei, 11,12 and certain bifidobacteria require cysteine. 10,13 Here, we propose the next generation of prebiotics: proteincontaining prebiotics.…”

“…9,10 For example, leucine, phenylalanine, glutamic acid, valine, cysteine, tryptophan, and tyrosine are essential for the growth of Lactobacillus casei, 11,12 and certain bifidobacteria require cysteine. 10,13 Here, we propose the next generation of prebiotics: proteincontaining prebiotics. The approach is inspired by active targeting of anticancer drugs, achieved by conjugating them to ligands, which selectively bind to specific proteins uniquely expressed on the target cancer cells.…”