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1.
Summary
Bifidobacterium adolescentis ATCC 15703, B. longum ATCC 15707, and B. thermophilum ATCC 25525 were examined for the ability to grow with fructo-oligosaccharides (FOS) as carbohydrate sources. The three species produced cell-associated -fructosidases (inulinases) capable of hydrolysing FOS. Maximum activity was obtained with short-chain FOS with degrees of polymerization (DP) of between three and five (neosugars). The B. thermophilum inulinase was induced by inulin, a long-chain FOS with DP=35, while the enzymes from the other two strains were constitutive. Production of inulinase by all three strains was regulated by catabolite repression. Inulinase activity of the three Bifidobacterium spp. was similar when grown with 0.5% inulin as the carbohydrate source; however, B. thermophilum grew much more rapidly. All three strains utilized crude Jerusalem artichoke flour (JAF) as a carbohydrate source, suggesting that JAF might have commercial application as a food or feed additive to stimulate bifidobacteria in the gut.Contribution no. 802 from the Food Research Centre 相似文献
2.
Hyalomma anatolicum anatolicum ticks infected with Theileria annulata were partially fed on rabbits and then ground up with tissue culture medium. The ground up ticks were treated by centrifugation at 100 g, filtration through membranes of 8 μm pore diameter and centrifugation on a discontinuous density gradient of Percoll. Counts of sporozoites and tick debris were made from Giemsa stained slides of samples at each stage of the separation. Debris was removed during light centrifugation and filtration at a greater rate than sporozoites. After filtration approximately 41% of the original sporozoites remained in the suspension. After density gradient centrifugation most sporozoites were found in a distinct zone, at approx. 1·08 g/cm3 density, separate from most dense debris and light debris and soluble contaminants. After this final centrifugation approximately 24% of the original sporozoites remained in the recovered suspension. 相似文献
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4.
Identification of the Listeria monocytogenes virulence factors involved in the CAMP reaction 总被引:1,自引:1,他引:0
R.C. McKellar 《Letters in applied microbiology》1994,18(2):79-81
There is a need to identify the virulence factors involved in the synergistic lysis of erythrocytes (CAMP reaction) by Listeria monocytogenes and either Staphylococcus aureus or Corynebacterium equi , in order to assess the relationship between the CAMP reaction and virulence of L. monocytogenes . The ability of various L. monocytogenes mutants to secrete listeriolysin O and phospholipases, and to produce lysis of sheep blood agar was determined. The results suggest that the CAMP reaction with Coryne. equi involves listeriolysin O and Coryne. equi cholesterol oxidase, and that the reaction with Staph. aureus involves either of the phospholipases C produced by L. monocytogenes . A modified CAMP test, which incorporates cholesterol oxidase into sheep blood agar, is proposed for the rapid (4–6 h) identification of L. monocytogenes. 相似文献
5.
The metabolic response to L-lysine of Escherichia coli ATCC 13002, a lysine-histidine double auxotroph, has been examined in a synthetic medium containing sucrose. In shaken cultures largest amounts of extracellular DAP were produced with an initial lysine concentration of 7·5 mg/1 and in static cultures of 2·5 mg/1. Considerably smaller amounts of DAP accumulated under stationary conditions. In cultures shaken for 20 and 43 h there was an overall decrease in the yields of DAP, expressed in terms of cell biomass and of sucrose consumed, as the initial concentration of lysine was increased from 0·75 mg/1 in steps up to 25 mg/1. The regulatory effect of lysine on DAP production was also observed when lysine was supplied to cultures at a constant rate employing diffusion capsules. 相似文献
6.
Isolation and characterization of a FAD-dependent NADH diaphorase from Methanospirillum hungatei strain GP1 总被引:3,自引:0,他引:3
Crude extracts of Methanospirillum hungatei strain GP1 contained NADH and NADPH diaphorase activities. After a 483-fold purification of the NADH diaphorase the enzyme was further separated from contaminating proteins by polyacrylamide disc gel electrophoresis. Two distinct activity bands were extracted from the acrylamide, each one having oxygen, 2,6-dichlorophenolindophenol, and cytochrome c linked activities. In these preparations NADPH could not replace NADH as electron donor. During the initial purification steps all activity was lost due to the removal of a readily released cofactor. Enzyme activity was restored by either FAD or a FAD fraction isolated from M. hungatei. Oxidase activity exhibited a broad pH optimum from 7.0 to 8.5 and apparent Km values of 26 microM for NADH and 0.2 microM for FAD. Superoxide anion, formed in the presence of oxygen, accounted for all of the NADH consumed in the reaction. The molecular weight of the diaphorase was about 117 500 by sodium dodecyl sulfate gel electrophoresis. Sulfhydryl reagents and chelating agents were inhibitory. Inactivation, which occurred during storage in phosphate buffer at 4 degrees C, was delayed by dithiothreitol. The isolated NADH diaphorase lacked NADPH:NAD transhydrogenase and NAD reductase activities. 相似文献
7.
G D Sprott R C McKellar K M Shaw J Giroux W G Martin 《Canadian journal of microbiology》1979,25(2):192-200
A NADH-linked oxygen-tolerant malate dehydrogenase was purified 270-fold from cell extracts of Methanospirillum hungatii. Inhibitors of the enzyme included ADP, alpha-ketoglutarate, and excess NADH. Inhibition patterns for ADP were competitive with respect to NADH and non-competitive with respect to oxalacetate. Inhibition by alpha-ketoglutarate was non-competitive with oxalacetate as variable substrate and uncompetitive with respect to NADH. alpha-Ketoglutarate is surmised to function as an end-product inhibitor of the enzyme in reactions converting oxalacetate to alpha-ketoglutarate. No enzyme activity was detected in the direction of malate conversion to oxalacetate, in keeping with a strictly biosynthetic function of the enzyme. An analysis of variance of intial rate data fit to sequential and ping-pong equations showed that a sequential mechanism was perferred. The malate dehydrogenase of M. hungatii resembles those of many other bacteria and eucaryotic cells respect to molecular weight (61,700) and reaction mechanism, but may be regulated differently. 相似文献
8.
Nonsurgical recoveries and transfers of embryos were performed at the McKellar Embryo Transplant Center from 122 superovulated Brahman cows. FSH-P (Armour) was used to superovulate all cows at dose levels ranging from 36 to 48 mg total FSH-P. Luteal regression was induced by use of 40 mg PGF(2(alpha)) in all 122 cows. Embryos were transferred into recipients 6, 7 or 8 days after observed estrus. Embryos were successfully collected from 82% of the FSH-P treated cows. The dose level of FSH-P affected numbers of embryos collected (P<.05). Numbers of embryos collected from cows superovulated with 36-38, 40, 42, 43, 44, 45, 46 and 47-48 mg FSH-P were 2.8 +/- 1.0, 6.8 +/- 1.1, 9.4 +/- 1.4, 10.0 +/- 2.7, 7.1 +/- 1.6, 6.8 +/- 2.0, 5.0 +/- 1.7 and 4.6 +/- 2.0 embryos, respectively. The dose level of FSH-P also affected numbers of embryos transferred (P<.10). Number of embryos transferred from cows superovulated with 36-38, 40, 42, 43, 44, 45, 46 and 47-48 mg FSH-P were 2.8 +/- 1.9, 5.2 +/- 0.9, 6.9 +/- 1.2, 6.7 +/- 2.1, 4.8 +/- 1.3, 5.1 +/- 1.4, 3.4 +/- 1.2 and 3.2 +/- 2.1 embryos, respectively. The developmental stage (D) of the embryo was also a factor in pregnancy rate of recipients (morula = 13.8%, blastocyst = 22.1% and expanded blastocyst = 29.9%; P<.005). The skill of the technician (T) transferring the embryo had a dramatic effect upon subsequent pregnancy rate of the recipients (T 1 = 46.0% vs T 2 = 22.6% pregnancy rate; P<.005). Pregnancy rate of recipients was also affected by the stage postestrus (S) at which the embryo was transferred (day 6 = 23.5%, day 7 = 25.5% and day 8 = 42.3% pregnancy rate; P<.05). Interactions were found between T x S, T x D, S x D and T x S x D (P<.05). These data indicate that use of 40, 42, or 43 mg total doses of FSH-P were quite effective in superovulating the Brahman cow. Recipients transferred on day 8 postestrus achieved higher pregnancy rates than recipients transferred on days 6 or 7 postestrus. Embryos transferred in the expanded blastocyst stage of development proved to yield the highest pregnancy rates in recipients. 相似文献
9.
10.
SH Chew 《Biotechnic & histochemistry》2013,88(5-6):177-183
The phagocytic activity of neuroglial cells in adult feline degenerating optic nerve was investigated by immunocytochemistry at both light and electron microscopy levels. Degeneration was initiated by unilateral eye enucleation and the segment distal to the transection showing true Wallerian degeneration was examined. Following enucleation, twelve adult domestic cats were examined over a period of seven to 215 days. All cases showed slow clearance of myelin debris and absence of proliferating monocytes throughout the post-enucleation period. All phagocytic cells present were neuroglial cells, and many of these cells expressed oligodendroglial antigens. These findings demonstrate the persistence of an active population of oligodendrocytes that might play an additional functional role during Wallerian degeneration of feline optic nerve. 相似文献