Showing papers on "Melibiose published in 1995"

Alcoholic beverage fermentations

Abstract: Most alcoholic beverage fermentations are carried out using strains of the yeast Saccharomyces cerevisiae. Although traditionally brewers distinguished between ale yeast S. cerevisiae and lager yeast S. carlsbergensis, or S. uvarum as it was later called, it is now recognized that these two species are completely interfertile and should be considered as one, namely S. cerevisiae ([Gilliland, 1981]). However, this is not to say that lager yeasts do not have some distinctive features, since the ability of the classical lager yeast to produce α-galactosidase and metabolize melibiose is well established. Similarly, strains defined as S. diastaticus have a well-established ability to metabolize low-molecular-weight dextrins, since they possess a glucoamylase gene. However, these strains are now considered to be strains of S. cerevisiae rather than distinct species.

Degradation of stachyose, raffinose, melibiose and sucrose by different tempe-producing Rhizopus fungi.

Abstract: Forty-six strains of tempe-forming Rhizopus species were screened for their ability to grow on raffinose as the sole carbon source. Six of the strains showed good growth and sporulation. These isolates were one Rhizopus oligosporus, one Rhizopus microsporus var. chinensis, three Rhizopus oryzae and one Rhizopus stolonifer. These six moulds and R. oligosporus strain NRRL 2710 were investigated for their metabolism of the raffinose family of α-galactoside carbohydrates. Degradation experiments were performed in submerged culture in a medium containing soybean α-protein, sodium phytate and either stachyose, raffinose or melibiose. R. oryzae and R. stolonifer completely consumed the tested carbohydrates as carbon source. R. microsporus var. chinensis failed to hydrolyse the α-galactosidic bonds of raffinose, stachyose or melibiose, whereas it was able to use sucrose and the fructose moiety of raffinose or stachyose for growth. R. oligosporus NRRL 2710 was unable to hydrolyse any of the tested carbohydrates. The results of the oligosaccharide degradation experiments could be verified during tempe production from soybeans with the selected fungal species.

Transgalactosylation Catalyzed by α-Galactosidase from Candida guilliermondii H-404

Abstract: The thermostable α-galactosidase from Candida guilliermondii H-404 synthesized self-transfer products in the absence of a suitable acceptor. The main self-transfer product, using melibiose as a donor substrate, was O-α-D-galactosyl-(1,6)-O-α-D-galactosyl-(1,6)-D-glucose. This enzyme had a wide acceptor specificity. D-Glucose, D-galactose, maltose, maltitol, and 1,4-butandiol were the most effective acceptors in the transgalactosylation catalyzed by this enzyme. The enzyme could also transfer α-galactosyl residues to pentoses (L-arabinose, D-xylose, and D-ribose) and methyl pentoses (D-fucose and L-rhamnose). The main transfer products to lactose, maltose, and sucrose as acceptors were identified as O-α-D-galactosyl-(1,6)-O-β-D-galactosyl-(1,4)-D-glucose, O-α-D-galactosyl-(1,6)-O-α-D-glucosyl-(1,4)-D-glucose, and O-α-D-galactosyl-(1,6)-O-α-D-glucosyl-(1,2)-β-D-fructoside (raffinose), respectively.

Identification and Genetic Characterisation of Melibiose-Negative Isolates of Streptococcus mutans

Abstract: Streptococcus mutans is frequently identified on the basis of phenotypic characteristics such as the ability to ferment carbohydrates. The usefulness of some of these identification tests may be limited in the case of isolates which are atypical with regard to their fermentation properties. We previously identified isolates of S. mutans which were unable to ferment melibiose, a characteristic which is included in some typing schemes. In all of these isolates there was a large chromosomal deletion which included the multiple sugar metabolism (msm) operon which encodes several genes involved in the uptake and metabolism of a number of sugars including melibiose. In the present study, sugar fermentation tests, ribotyping, colony hybridisation with DNA probes and polymerase chain reaction (PCR) were used to investigate the relatedness of these atypical isolates. The PCR and colony hybridisation procedures were based on amplification and detection of two genes: the wapA gene which encodes a surface protein found in all S. mutans strains and the gtfA gene which lies within the msm operon. The colony hybridisation and PCR results confirmed loss of the gtfA gene in the melibiose-negative isolates. Three new melibiose-negative isolates were also identified, but in only 2 of these was the gtfA gene absent, the third did not appear to have lost this region of the chromosome. Biotyping, as well as ribotyping based on an EcoRI digest of chromosomal DNA, revealed that the melibiose-negative isolates fell into a number of distinct groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of Genetically TransformedSaccharomyces cerevisiaeBaker's Yeasts Able To Metabolize Melibiose

Abstract: :SD 0.45 0.45 0.48 0.45 0.42 0.44 SS 0.40 0.39 0.41 0.40 0.39 0.39 SM 0.36 0.36 0.36 0.35 0.33 0.31 SR 0.29 0.30 0.10 0.12 0.11 0.11 SMeg 0 0.25 0 0.15 0 0.24

Characterization of genetically transformed Saccharomyces cerevisiae baker's yeasts able to metabolize melibiose

Abstract: Three transformant (Mel+) Saccharomyces cerevisiae baker's yeast strains, CT-Mel, VS-Mel, and DADI-Mel, have been characterized. The strains, which originally lacked alpha-galactosidase activity (Mel-), had been transformed with a DNA fragment which possessed an ILV1-SMR1 allele of the ILV2 gene and a MEL1 gene. The three transformed strains showed growth rates similar to those of the untransformed controls in both minimal and semi-industrial (molasses) media. The alpha-galactosidase specific activity of strain CT-Mel was twice that of VS-Mel and DADI-Mel. The yield, YX/S (milligrams of protein per milligram of substrate), in minimal medium with raffinose as the carbon source was 2.5 times higher in the transformed strains than in the controls and was 1.5 times higher in CT-Mel than in VS-Mel and DADI-Mel. When molasses was used, YX/S (milligrams of protein per milliliter of culture) increased 8% when the transformed strains CT-Mel and DADI-Mel were used instead of the controls. Whereas no viable spores were recovered from either DADI-Mel or VS-Mel tetrads, genetic analysis carried out with CT-Mel indicated that the MEL1 gene has been integrated in two of three homologous loci. Analysis of the DNA content by flow cytometry indicated that strain CT-Mel was 3n, whereas VS-Mel was 2n and DADI-Mel was 1.5n. Electrophoretic karyotype and Southern blot analyses of the transformed strains showed that the MEL1 gene has been integrated in the same chromosomic band, probably chromosome XIII, in the three strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Enzymatic Synthesis of α-Linked Galactooligosaccharides Using the Reverse Reaction of a Cell-bound α-Galactosidase from Candida guilliermondii H-404

Abstract: α-Linked galactooligosaccharides (α-GOS A from galactose, and α-GOS B from lactose hydrolyzates) were synthesized using the reverse reaction of α-galactosidase from Candida guilliermondii H-404. The α-GOS A and B were isolated and their structures were identified by methylation analysis. The main product of the disaccharides in α-GOS A and α-GOS B was the (1, 6)-isomer. The remaining disaccharides consisted of (1, 3)-, (1, 2)-, and (1, 1)-isomers. Conditions for synthesis of α-GOS B from lactose hydrolyzates were examined. The yield of α-GOS B was approximately 20% when the mixture of heat-treated cells containing a-galactosidase (60U/g galactose) and 85% lactose hydrolyzates was incubated for 90 h at pH 4.5 and 50°C. The α-GOS A and B were available as the donor substrates in transgalactosylation of α-galactosidase in the same manner as melibiose.

Physiological studies on the formation of alpha-galactosidase by fungi

Abstract: 38 fungal strains were screened for α-galactosidase (AGal) formation. Qualitative assay tests indicate that from the strains tested, only 5 strains produced appreciable amounts of enzyme. Penicillium janthinellum was the only strain which gave a high enzyme formation after 4 days in Dox-raffinose medium statically at 30 °C. Chromatographic identification of the products resulting from the enzymatic hydrolysis of melibiose and raffinose was used as a confirmatory test for the presence of AGal in the reaction mixture. Galactose was the best inducer for enzyme formation by P. janthinellum, followed by melibiose. The maximum AGal production was obtained when initial pH of the medium was adjusted at 5.0 and incubated for 4 days at 30 °C. The enzyme production was greatly affected by aeration ratio. Lupine seed powder was used instead of galactose as a carbon source in the medium. Results obtained indicate that soaked lupine did not seem to affect enzyme levels when compared to the unsoaked seeds. The effect of other factors influencing AGal formation was also studied

Carbohydrate composition of raw vegetable soybeans grown at the same location

Abstract: A series of 11 commercial vegetable soybean varieties, grown at the same location, was analyzed for their carbohydrate composition in the raw state. Carbohydrates identified and quantitated in all varieties included fructose, glucose, sucrose, cellobiose, galactobiose, melibiose, raffinose, stachyose and verbascose. In all but two of the varieties, sucrose was the major carbohydrate, with values of approximately 6–7 g/100g. The other two varieties had levels of 2.8–3.3 g/100g. Flatulence-inducing carbohydrates (raffinose, stachyose, verbascose) ranged from approximately 1–3 g/100g among all 11 varieties.

Isolation of a melibiose-binding protein from human spleen.

Abstract: A melibiose-binding protein was isolated from human spleen by serial affinity chromatography on lactose-, mannose-, and melibiose-Sepharose. The purified protein agglutinated rabbit erythrocytes and re-bound to melibiose, but did not bind to murine nor human laminin. The protein was composed of approximately 58 kDa and 26 kDa polypeptides. The polypeptides were detected in buffy coat cell extracts and they were synthesized in vitro by B lymphoblastoid cells. The polypeptides did not react with anti-galaptin, anti-C-reactive protein, anti-amyloid P, anti-keratin, and anti-rat lung lectin 29 sera. The 58 kDa polypeptide reacted very weakly with anti-core-specific lectin serum and reacted with anti-IgG serum. The data suggest that the major protein isolated is an anti-Ga1 alpha 1-->6 immunoglobulin.