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1.
Denis Roy Pierre Chevalier Pierre Ward Luc Savoie 《Applied microbiology and biotechnology》1991,34(5):653-655
Summary The ability of Bifidobacterium infantis ATCC 27 920 to ferment glucose, galactose, lactose, melibiose and raffinose was investigated with respect to -galactosidase (-d-galactoside galactohydrolase, E.C. 3.2.1.22). The sugars were tested at three concentrations: 0.5, 1.0 and 2.0%. The growth of B. infantis was slower on glucose compared with the other sugars. The highest specific growth rate was observed on melibiose followed by lactose. High cell numbers could be rapidly obtained on galactose-containing sugars. For each carbohydrate, enzyme activity was maximal at the end of the exponential phase and the highest specific -galactosidase activities were recorded on the two -1,6 galactosaccharides (melibiose and raffinose: 3.0 and 4.5 nkat · 109 colony-forming units, respectively).Contribution no. 186 from the Food Research and Development Centre
Offprint requests to: D. Roy 相似文献
2.
Differential kinetics and sensitivity to chloroquine of receptor-mediated insulin and prolactin endocytosis in liver parenchymal cells 总被引:1,自引:0,他引:1
Systemically injected [125I]prolactin or [125I]insulin was accumulated and cleared from rat liver at different rates. Quantitative subcellular fractionation indicated a predominant accumulation of [125I]insulin in liver microsomes while [125I]prolactin was found in both the light-mitochondrial and microsomal fractions. The acidotropic agent chloroquine diminished the rate and extent of loss of each ligand from liver homogenates. In chloroquine treated rats, radiolabeled insulin accumulated in both the light-mitochondrial and the microsomal fractions. Subfraction of microsomes on discontinuous sucrose gradients revealed "early' endosomes in which ligand uptake was maximal at 2-5 min. In contrast, comparable subfraction of the of light mitochondrial fraction revealed "late' endosomes in which ligand uptake was maximal at 10-20 min. Chloroquine-treated rats showed a more marked enhancement of insulin compared to prolactin uptake in the "early' endosomes. It is suggested that "early' endosomes found in the Golgi-intermediate and -heavy fractions floated from parent microsomes may selectively degrade insulin but not prolactin. This could account for the apparently different kinetics of insulin and prolactin uptake into liver parenchyma. 相似文献
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Polysaccharidases adsorbed on commercial amylodextrins were added to environmentally controlled composts of straw plus poultry manure. After 5 days of composting at 48°C, microbial enzyme activities and numbers of bacteria were higher in the treated compost than in the control. During the next phase at 80°C, between days 5 and 6, more C and N were solubilized in the treated compost. After introducing a microbial inoculum on day 6, and maintaining the substrate at 48°C, colonization by bacteria was faster in the treated compost and consequently, more fibre was degraded. Differences between composts in yields of Agaricus bisporus after 5 weeks of cropping were not significant (P=0.05).The authors are with INRA, Station de Recherches sur les Champignons, BP 81, 33883 Villenave d'Ornon, France 相似文献
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The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
相似文献
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Laboratory-scale reactors were used to watch aspects of biodegradation of wheat straw when supplemented with polysaccharidases (Czym) to increase the enzyme production of microorganisms involved during a composting process for mushroom production. Biochemical and biological parameters were tested both under aerobic and O2-limited conditions to assess degradability. These were measurement of released CO2 and NH3, determination of neutral detergent fibre content and cellulase activities from compost extract. The addition of Czym to decomposing straw had three consequences: (i) it supplied and released low quantities of readily available sugars; (ii) it increased the cellulase activities in the substrates; (iii) it increased the number of bacteria under aerobic conditions. The three effects were linked and the small quantity of sugars released by the addition of Czym may have acted as an activator of bacterial activities through an inductive mechanism.
Correspondence to: S. Libmond 相似文献
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