Purification and identification of a growth-stimulating peptide for Bifidobacterium bifidum from natural rubber serum powder

Natural rubber serum powder, which is a by-product obtained in the production of latex rubber, has a strong growth-stimulating activity for Bifidobacterium bifidum JCM 1254. The retained fraction obtained by ultrafiltration (molecular weight cutoff 1000) showed a growth- stimulating activity in a dose-dependent manner on B 12 assay medium with ammonium sulfate. One of the growth stimulators was purified from the retained fraction by acetone precipitation, solid-phase extraction with a hydrophobic pretreatment column, and multi-stage reversed-phase HPLC. An increase of 53-fold in the specific activity, and a recovery of 1.3% were obtained. The amino acid composition and N-terminal sequence analysis of this growth stimulator provided the structure of Ala-Thr-Pro-Glu-Lys-Glu-Glu-Pro-Thr-Ala. The molecular mass was 1075 by MALDI-TOF MS analysis. These results showed that this growth stimulator was a decapeptide with the sequence shown above. This is the first report that clarified the structure of an active peptide for the growth of Bifidobacterium.