Unhydrolyzed and hydrolyzed konjac glucomannans modulated cecal and fecal microflora in Balb/c mice.
OBJECTIVE
The prebiotic role of intact konjac glucomannan (KGM) is contradictory. Short-chain glucomannan may cause a greater or faster effect on colonic microflora compared with KGM. Therefore, time-course and dose-dependent studies were conducted to examine and compare effects of unhydrolyzed KGM with those of acid-hydrolyzed glucomannan (KH) on cecal and fecal microflora. Short-chain fatty acid concentrations in cecal content were also determined.


METHODS
Seven-week-old male Balb/c mice were fed 5% (w/w) cellulose and KGM or KH diets for 2 or 4 wk in a time-course study. Cecal total anaerobes, bifidobacteria, Clostridium perfringens and Escherichia coli counts, and short-chain fatty acid concentrations were determined. In a subsequent dose-dependent study, Balb/c mice were fed AIN-93 fiber-free diets supplemented with 2.5%, 5%, or 7.5% of KGM or KH for 4 wk. Anaerobes, bifidobacteria, C. perfringens, and E. coli were enumerated in the cecal content and feces.


RESULTS
KGM and KH significantly increased cecal anaerobes and bifidobacteria counts at weeks 2 and 4, respectively, compared with cellulose. In contrast, KGM and KH significantly decreased cecal C. perfringens counts only at week 4. Acetate and propionate concentrations in cecal contents were increased by KGM and KH diets at weeks 2 and 4, respectively. In the dose-dependent study, KH increased cecal bifidobacteria counts only at the 2.5% level but increased fecal bifidobacteria count and suppressed C. perfringens counts at each dose level as compared with KGM.


CONCLUSIONS
Hydrolyzed glucomannan exerts a greater prebiotic effect than does KGM in Balb/c mice.
Chen
Hsiao-Ling
HL
School of Nutrition, Institute of Nutritional Science, Chung Shan Medical University, Taichung, Taiwan, Republic of China. hlchen@csmu.edu.tw
Fan
Ying-Hsin
YH
Chen
Mei-En
ME
Chan
You
Y
D000821:Animal Feed; D000818:Animals; D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000254:growth & development / Q000378:metabolism; D001644:Bifidobacterium / Q000254:growth & development / Q000378:metabolism; D002432:Cecum / Q000382:microbiology*; D003016:Clostridium perfringens / Q000254:growth & development / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis / Q000096:biosynthesis*; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D006868:Hydrolysis; D008297:Male; D008351:Mannans / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D019936:Probiotics; D011897:Random Allocation
D005232:Fatty Acids, Volatile; D008351:Mannans; C022901:(1-6)-alpha-glucomannan