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Substrate Structure‐dependent Growth of Bacteroides Xylanisolvens XB1A on Corn Arabinoxylan Fragments in Pure and Mixed Culture Environments
Author(s) -
Nie Xin,
Martens Eric,
Xiao Yao,
Reuhs Brad,
Hamaker Bruce
Publication year - 2016
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.30.1_supplement.683.7
Subject(s) - arabinoxylan , bacteroides , chemistry , food science , fiber , microbiology and biotechnology , bacteria , biochemistry , biology , polysaccharide , genetics , organic chemistry
Dietary fiber has been shown to influence the gut microbiota community which is associated with chronic metabolic diseases such as inflammatory bowel disease, obesity and diabetes. It remains unclear, though, whether and how bacteria can be modulated via specific fiber substrates in a controlled manner. Here, we have addressed this question by using Bacteroides isolates to study subtle variations in structure of a common cereal bran fiber, corn arabinoxylan. Bacteroides xylanisolvens XB1A, Bacteroides ovatus 3‐1‐23 and Bacteroides cellulosilyticus DSM 14838 , were used to investigate six partially debranched hydrolyzates of corn arabinoxylan by an enzymatic method to understand the degree of specificity of dietary fiber molecular fine structure on the utilization of target strains. The growth curves of strains were monitored using Optical Density (OD) (for pure culture) and qPCR method (for mixed‐culture). Using a pure culture of Bacteroides xylanisolvens XB1A, a large lag phase shift was linked to change in a specific branch pattern involving the 2‐O position of arabinosyl moieties on the xylan backbone. Gene transcription of a putative outer membrane xylooligosaccharide transporter BXY_46550, suggesting bacterial utilization of arabinoxylan substrates, changed in a similar way with lag phase. In a multi‐strain environment, B. xylanisolvens XB1A showed the capacity to support the growth of B. ovatus 3‐1‐23, which poorly digested the complex fragments alone, apparently due to a cross‐feeding interaction which was fiber structure‐dependent. The support of B. ovatus 3‐1‐23 by B. xylanisolvens XB1A was notably changed by the arabinoxylan substrates. In addition, B. xylanisolvens XB1A was apparently suppressed by other strains when it was fed on a structure that induced the longer lag phase, indicating that the length of the lag phase ( i.e ., response time to a new nutrient) is important to a strain's ability to compete for specific fiber substrates. This study shows a clear connection between subtle fiber structural features and utilization of target colonic bacteria. A high dependence of strains on specific fiber structural features for growth was observed, and implies the potential to deliberately change target strains within the competitive environment of the human colonic microbiota using proper dietary fibers. Support or Funding Information This research was supported by Whistler Center for Carbohydrate Research, Purdue University.