Topic
Melibiose
About: Melibiose is a research topic. Over the lifetime, 1002 publications have been published within this topic receiving 27300 citations. The topic is also known as: Melibiose.
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TL;DR: Antibiotic susceptibility tests of Y.e.rh+ isolates should be incubated at both 37 C and at a lower temperature to allow the greatest expression of resistance of these organisms to the various antibiotics.
Abstract: Clinical isolates of rhamnose-positive Yersinia enterocolitica (Y.e.rh+) were compared with typical rhamnose-negative Y. enterocolitica (Y.e.rh-) and with Yersinia pseudotuberculosis. The Y.e.rh+ differed from the Y.e.rh- and Y. pseudotuberculosis in their ability to ferment raffinose and lactose, utilize citrate and in their inability to grow on Hektoen enteric agar at 22 or 37 C, on Salmonella-Shigella agar at 37 C, and scant on xylose-lysine-deoxycholate agar at 37 C. An extensive temperature-dependent profile of characteristics was established for the Y.e.rh+: motility, acetoin production, citrate utilization, growth on Salmonella-Shigella agar, and ampicillin resistance occurred at 22 C but not 37 C; fermentation of melibiose, raffinose, and cellobiose occurred within 24 h at 22 C, but not before 5 days at 37 C; fermentation of rhamnose and production of beta-galactosidase occurred within 24 h at 22 C, but not before 48 h at 37 C; greater resistance to ampicillin, chloramphenicol, streptomycin, kanamycin, carbenicillin, and gentamicin was observed at 22 than 37 C; and good growth on xylose-lysine-deoxycholate agar occurred at 22 but not 37 C. For optimal recovery of Y.e.rh+ from mixed culture, e.g., stools, two MacConkey plates should be inoculated and incubated, one at 37 C, and one at 22 C. Lactose-negative colonies appearing after 48 h on the 22 C MacConkey agar but not the 37 C MacConkey agar should be considered possible Y.e.rh+. Biochemicals should be tested in duplicate, one set incubated at 22 C, one set at 37 C. Antibiotic susceptibility tests of Y.e.rh+ isolates should be incubated at both 37 C and at a lower temperature to allow the greatest expression of resistance of these organisms to the various antibiotics.
27 citations
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TL;DR: The Saccharomyces carlsbergensis strain was found to be heterozygous for 2 unlinked MGL genes, in this paper indicated as MGLa, and MGLb, both indispensable for the fermentation of α-methylglucoside.
Abstract: 1.
Saccharomyces carlsbergensis N.C.Y.C.74 was shown to be diploid and heterothallic. On acetate medium four spored asci were produced with a spore viability of no more than 2%. However diploid hybrids from the viable spores yielded asci with a spore viability of 75%, thus making tetrad analysis and consequently a genetical study of sugar fermentation in this strain feasible.
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Auxotrophic mutants in a haploid derivative of this strain were obtained, some of which could be classified as ade1, ade2, ade4, ade5, ade6, ade7, ura2, ura3, lys1, trp2, trp5, his4 and his5.
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150 Random spores all fermented glucose, sucrose, mannose, galactose, melibiose, raffinose, and maltose, but only 28% fermented α-methylglucoside. The same fermentation pattern was found in petites of these 150 spores, except that 40% grew poorly on galactose; this gal phenotype could not be ascribed to a single gene.
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In crosses with mal strains the maltose fermenting ability of the spores from S. carlsbergensis appeared to be dependent upon 1 single gene, which could be identified as MAL6, one of the 7 known polymeric genes for maltose fermentation in Saccharomyces.
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Our strain was found to be heterozygous for 2 unlinked MGL genes, in this paper indicated as MGLa, and MGLb, both indispensable for the fermentation of α-methylglucoside.
6.
After mutagenesis of a haploid strain with genotype MGLaMGLb, one mgl mutant was found, which complemented a strain with genotype mglamglb. This third indispensable MGL gene, preliminarily called MGLc, is homozygously present in our strain and is not linked to either MGLa or MGLb.
27 citations
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TL;DR: The functional defect with DDM or UDM likely results from the relative instability of the sensitive MelB proteins, and stability, as well as galactoside binding, is retained in MNG-3 or GDN, indicating that the conformational dynamics of MelB is restricted in this detergent.
Abstract: The effect of various detergents on the stability and function of the melibiose permeases of Escherichia coli (MelBEc) and Salmonella typhimurium (MelBSt) was studied. In n-dodecyl-β-d-maltoside (DDM) or n-undecyl-β-d-maltoside (UDM), WT MelBSt binds melibiose with an affinity similar to that in the membrane. However, with WT MelBEc or MelBSt mutants (Arg141 → Cys, Arg295 → Cys, or Arg363 → Cys), galactoside binding is not detected in these detergents, but binding to the phosphotransferase protein IIA(Glc) is maintained. In the amphiphiles lauryl maltose neopentyl glycol (MNG-3) or glyco-diosgenin (GDN), galactoside binding with all of the MelB proteins is observed, with slightly reduced affinities. MelBSt is more thermostable than MelBEc, and the thermostability of either MelB is largely increased in MNG-3 or GDN. Therefore, the functional defect with DDM or UDM likely results from the relative instability of the sensitive MelB proteins, and stability, as well as galactoside binding, is retained in MNG-3 or GDN. Furthermore, isothermal titration calorimetry of melibiose binding with MelBSt shows that the favorable entropic contribution to the binding free energy is decreased in MNG-3, indicating that the conformational dynamics of MelB is restricted in this detergent.
27 citations
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TL;DR: The α-Galactosidase activity was commonly found in the basidiocarp materials of higher fungi as discussed by the authors, however, phenyl- and nitrophenyl-α-d -galactopyranosides were hydrolyzed much faster than naturally occurring α-galactosides.
27 citations
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TL;DR: The results suggest that the preferred cation couplings via K. pneumoniae melibiose carrier are H(+)-melibiose, Li( +)-lactose, and H+/Li(+-TMG, which is quite different from that of the E. coli melibioses carrier.
27 citations