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2014 AACC International Annual Meeting

Poster Presentation
Dietary Fiber


Exploring the relationship between corn arabinoxylan structure and gut bacterial growth behavior
X. NIE (1), E. Martens (2), B. Hamaker (1)
(1) Purdue University, West Lafayette, IN, U.S.A.; (2) University of Michigan, Medical School, Ann arbor, MI, U.S.A.

Investigation of the relationship between substrate structure and gut bacterial growth is critical to the attempt of manipulation of the growth of gut microbiota via diet, which is closely related to human chronic diseases. In this study, the correlation of different structures of hydrolyzed/modified arabinoxylan products (termed here DBH3, DBH4 and modified DBH4) and bacterial growth behavior, including relative response on gene expression, was investigated. Growth curves were obtained from single culture of B. ovatus 3-1-23 and B. cellulosilyticus DSM 14838 on the different substrates for 120 hours. Growth differences were shown between the two bacterial strains, particularly on the substrate modified by B. ovatus 3-1-23 in advance. B. cellulosilyticus DSM 14838 still grew although the digestion ability was lower on the modified substrate; B. ovatus 3-1-23 did not grow indicating that it lost its ability of digest the modified substrate. A transcriptional sensitivity assay was conducted on B. xylanisolvens XB1A. Three primers were chosen for xylan-utilization related to gene transcription. From the result we have obtained so far for the different substrates, gene response time was different up to 60 min, which could be part of the reason for the 600 min lag time difference of B. xylanisolvens XB1A's growth curves on the different substrates. Substrates were purified by phenol extraction, dialysis and HPSEC. Their structures were analyzed by Smith degradation, HPSEC, NMR, and GC/MS. The results showed structural similarity and difference between DBH3 and DBH4, and that the structure change from DBH4 to modified-DBH4 created different growth behaviors of the bacterial strains. The study implies a high fiber substrate specific of the colonic bacterial strain level, and suggest a path towards understanding how bacteria or bacterial groups in the colon can be manipulated.

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