Enhancement of Short Chain Fatty Acid Production from Millet Fibres by Pure Cultures of Probiotic Fermentation

M Mohsin,H Zhang,U Farooq,X Liu

doi:10.4314/tjpr.v12i2.9

Abstract

Purpose: To enhance the in vitro synthesis of short chain fatty acids through millet dietary fibre fermentation by human faecal probiotic bacteria.Methods: The effect of millet dietary fibre fermentation on production of short chain fatty acids (SCFA) by four probiotics was studied. Dietary fibre was extracted from two millet varieties viz Pearl millet, Pennisetum glaucum (PM) and Foxtail millet (FxM, Setaria italica), and separated into total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble dietary fibre (SDF). Four probiotic bacteria (Lactobacillus rhamnosus, Lactobacillus acidophilus, Bifidobacterium longum and Bifidobacterium bifidus) were grown on specific medium containing IDF, SDF and TDF. SCFA production by the probiotics was measured at 0, 6, 24, and 48 h using gas liquid chromatography.Results: SCFA production in the fibre fractions followed the rank order, TDF > SDF > IDF, irrespective of millet variety, indicating that TDF is the best possible dietary fibre for SCFA production. Lactobacillus and Bifidobacteria spp. digested 60 – 80 and 75 – 85 % of the millet fibre fractions from both millet samples, respectively. The quantity of different SCFAs produced was in the rank order: acetate > propionate > butyrate.Conclusion: The results from this study suggest that millet dietary fibre has a potential for conversion into new nutraceuticals.Keywords: Probiotic, Millet, Short chain fatty acid, Prebiotic, Probiotic, Dietary fibre

Highlights

A synbiotic is a combination of prebiotics and probiotics in which the prebiotic substance favor growth of probiotic microbes or other beneficial bacteria in the host and sustain microbial balance in the gut which promote gastrointestinal functions [1,2]
Each probiotic strain produced short chain fatty acids (SCFA), mainly acetate, at more than twice the level from the negative control which consisted of only the growth media
It was found that soluble dietary fibre (SDF) was a more fermentable fibre and formed higher SCFA than insoluble dietary fibre (IDF) but less than total dietary fibre (TDF)

Summary

INTRODUCTION

A synbiotic is a combination of prebiotics and probiotics in which the prebiotic substance favor growth of probiotic microbes or other beneficial bacteria in the host and sustain microbial balance in the gut which promote gastrointestinal functions [1,2]. To understand the capability of probiotics to produce SCFAs on IDF, SDF and TDF from two millet varieties, the digestion of millet fibre and the formation of SFCA (acetate, propionate and butyrate) using pure cultures of Bifidobacterium spp.and Lactobacillus spp. were carried out in this study. Combined solution of filtrate and water washings were precipitated with 4 volumes of 95% ethanol (EtOH) for soluble dietary fibre (SDF) determination. The millet-isolated dietary fibre fractions (TDF, IDF and SDF) were used as the substrates for the fermentation process. 60 ml of culture medium and 0.6 mg substrate, viz, TDF, SDF and IDF from each of the millet varieties was separately added to each bottle, and sealed for 24 h for complete hydration of fibre before adding the inoculum. The difference between experimental groups and the control containing glucose were evaluated using Student’s t- test and one-way analysis of variance (ANOVA)

RESULTS

DISCUSSION

CONCLUSION