raffinose and galactomannan

Due to their prebiotic potential indigestible oligosaccharides became a major focus of research interest. In this study the growth of selected probiotic strains including lactobacilli, bifidobacteria, Lactococcus lactis, Streptococcus salivarius ssp. thermophilus, Pediococcus ssp. and Enterococcus faecium with the, raffinose family oligosaccharides (RFOs) raffinose, stachyose and verbascose and galactomannan from guar bean Cyamopsis tetragonoloba (total guar carbohydrates, oligosaccharides (dp 2-4) and polysaccharides (dp > 5), obtained by size exclusion chromatography) were tested by means of turbidity measurements. RFOs were used by 75% of all strains, with some delay for the trisaccharide raffinose and the tetrasaccharide stachyose and a limited fermentation of the pentasaccharide verbascose. L. reuteri, P. pentosaceus and B. lactis HNO19™ were able to ferment not only raffinose and stachyose but also verbascose. Guar oligosaccharides were fermented by 15 out of 20 strains; P. acidilactici, L. acidophilus, L. rhamnosus GG and B. animalis ssp. lactis BB12 metabolized them comparably well as glucose or galactose. Isolated guar polysaccharides were not fermented whereas total guar carbohydrates were fermented by 7 strains, apparently caused by the oligosaccharide content. The findings of this study may be important for functional food products especially for indigestible oligosaccharides which may cause adverse effects in the gut when not cleaved.

Topics: Bacterial Proteins; beta-Galactosidase; Fermentation; Galactose; Lactobacillales; Mannans; Oligosaccharides; Prebiotics; Probiotics; Raffinose

The seed of Coffea arabica accumulates large amounts of cell wall storage polysaccharides (CWSPs) of the mannan family in the cell walls of the endosperm. The variability induced by the growing environment and extensive pairwise correlation analysis with stringent significance thresholds was used to investigate transcript-transcript and transcript-metabolite relationships among 26 sugar-related genes, and the amount of CWSPs and seven soluble low molecular weight carbohydrates in the developing coffee endosperm. A dense module of nine quantitatively co-expressed genes was detected at the mid-developmental stage when CWSPs accumulate. This module included the five genes of the core galactomannan synthetic machinery, namely genes coding for the enzymes needed to assemble the mannan backbone (mannan synthase, ManS), and genes that introduce the galactosyl side chains (galactosyltransferase, GMGT), modulate the post-depositional degree of galactose substitution (α-galactosidase), and produce the nucleotide sugar building blocks GDP-mannose and UDP-galactose (mannose-1P guanyltransferase and UDP-glucose 4'-epimerase, respectively). The amount of CWSPs stored in the endosperm at the onset of their accumulation was primarily and quantitatively modulated at the transcriptional level (i.e. positively correlated with the expression level of these key galactomannan biosynthetic genes). This analysis also suggests a role for sorbitol and raffinose family oligosaccharides as transient auxiliary sources of building blocks for galactomannan synthesis. Finally, a microarray-based analysis of the developing seed transcriptome revealed that all genes of the core galactomannan synthesis machinery grouped in a single cluster of 209 co-expressed genes. Analysis of the gene composition of this cluster revealed remarkable functional coherence and identified transcription factors that putatively control galactomannan biosynthesis in coffee.

Topics: Biosynthetic Pathways; Carbohydrate Metabolism; Cell Wall; Coffea; Endosperm; Galactose; Gene Expression Profiling; Gene Expression Regulation, Plant; Mannans; Multigene Family; Oligonucleotide Array Sequence Analysis; Plant Proteins; Raffinose; Regulon; Seeds; Sorbitol; Transcription Factors; Transcriptome

The substrate specificities of three Penicillium simplicissimum alpha-galactosidases, AGLI, AGLII, and AGLIII, were determined by using various isolated galactose-containing oligosaccharides and polymeric galacto(gluco)mannans. AGLI released galactose from melibiose and raffinose-family oligosaccharides but the amount of galactose released was decreased from 96% to 35% by the increasing chain length of the substrate from raffinose to verbascose. It was able to release galactose linked to the nonreducing end and less efficiently to the internal residues of the galactomanno-oligomers. AGLI was able to hydrolyze 60-92% of galactose from polymeric galacto(gluco)mannans alone but its action was facilitated by mannanase and beta-mannosidase. In addition, it was able to release about 10% of the galactose from softwood kraft pulp alone and about 22% in combination with mannanase. AGLII was highly specific toward small galactose-containing oligosaccharides in which the galactose is linked to the nonreducing end of the substrate. It released 90-100% of galactose present in melibiose, raffinose, stachyose, and verbascose; however, it was able to degrade polymeric substrates only in combination with mannanase and beta-mannosidase. AGLIII had only low activity toward the oligomeric substrates tested. It was able to release some galactose from the polymeric galacto(gluco)mannans alone, but its action was clearly enhanced by the backbone degrading enzymes.

Topics: alpha-Galactosidase; Aspergillus niger; beta-Mannosidase; Galactose; Isoenzymes; Mannans; Mannosidases; Melibiose; Oligosaccharides; Penicillium; Raffinose; Substrate Specificity; Wood