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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Haemophilus influenzae grown to exponential phase or stationary phase in medium with a low initial concentration of haemin (0.25 microgram/ml) was virtually devoid of cytochromes. Compared with bacteria grown in the presence of excess haemin (10 micrograms/ml), the haemin-limited organisms failed to respire formate and succinate and, generally, the respiratory rates with other substrates were reduced. However, growth rates were not affected by the haemin supply. Haemin-limited growth was associated with a reduced efficiency of glucose utilisation, in terms of glucose growth yields, and affected the net levels of excreted organic acids. Haemin limitation resulted in reduced acetate and increased succinate accumulation in the culture medium and the novel presence of D-lactate. These results indicate that, in contrast to the phenotype expressed in vitro during conventional cultivation of H. influenzae, the haemin-limited phenotype, which may be expressed in vivo, is characterised by a lack of cytochromes and a shift towards a more anaerobic type of metabolism.
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PMID:Effect of haemin limitation on the cytochrome complement and glucose metabolism of non-typable Haemophilus influenzae. 162 99

The mean generation time of Haemophilus influenzae in simulated blood cultures is 103 to 107 min. With 0.56 to 0.58 doublings per h, even large inocula of 256 cells per ml reach only 2 X 10(6) cells per ml and produce no visible evidence of growth after 24 h of incubation. Hemin and NAD added to simulated blood cultures triple the rate of growth of H. influenzae, so that even small inocula produce visible turbidity after overnight incubation. With a mean generation time of 36 min, a single cell of H. influenzae in simulated blood culture supplemented with hemin and NAD undergoes 30 doublings in 18 h, producing 2(30) (1.07 X 10(9] cells and visible turbidity.
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PMID:Growth of Haemophilus influenzae in simulated blood cultures supplemented with hemin and NAD. 660 36

White, D. C. (Rockefeller Institute, New York, N.Y.). Respiratory systems in hemin-requiring Haemophilus species. J. Bacteriol. 85:84-96. 1963.-If grown in Levinthal's medium or in proteose peptone medium with excess hemin, Haemophilus influenzae, H. aegyptius, and H. canis (H. haemoglobinophilus) form an electron-transport system consisting of six cytochromes and two respiratory flavoproteins. In proteose peptone, these species can greatly modify the composition of their electron-transport complex. With anaerobic incubation in the presence of nitrate, they produce increased amounts of cytochrome c(1) and the cytochrome oxidases a(1) and o. This anaerobic pattern is greatly exaggerated by growth under carbon monoxide, in which case large concentrations of cytochrome oxidase are produced. In the presence of the inhibitor secobarbital or of growth-limiting amounts of hemin, intermediate amounts of cytochromes and respiratory flavoproteins are formed. When only small amounts of hemin are present, these species grow but form no detectable cytochrome system. Catalase is the only hemoprotein found. Under these conditions, the addition of glucose induces the formation of a lactate oxidase flavoprotein if the system is incubated aerobically. This cytochromeless state also occurs when these species are grown in KCN or anaerobically without nitrate and with excess hemin. The ability of these species to modify the composition of the electron-transport system strongly suggests that this function unit is formed from individual components. Hemin-requiring Haemophilus species have a hemin-sparing compensatory mechanism that allows growth under conditions under which hemin-independent Haemophilus species will not grow.
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PMID:Respiratory systems in the hemin-requiring Haemophilus species. 1400 Feb 93

White, David C. (The Rockefeller Institute, New York, N.Y.) and S. Granick. Hemin biosynthesis in Haemophilus. J. Bacteriol. 85:842-850. 1963.-Hemin-independent Haemophilus species have been shown to form hemin by the classical hemin biosynthetic pathway. Three distinct species of Haemophilus [H. influenzae, H. aegyptius, and H. canis (H. haemoglobinophilus)] all lost the enzymatic capacities to convert delta-aminolevulinic acid to protoporphyrin, which accounts for their dependence on hemin for growth. The strain of H. aegyptus tested cannot form hemin from protoporphyrin, can be transformed with deoxyribonucleic acid (DNA) from H. influenzae, and the resultant progeny have the enzymatic activity to convert protoporphyrin to hemin. Attempts to transform these species to hemin independence with DNA from hemin-independent H. parainfluenzae are unsuccessful under conditions where streptomycin resistance is readily transformed.
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PMID:HEMIN BIOSYNTHESIS IN HAEMOPHILUS. 1404 53

Avian haemophili demonstrating in vitro satellitic growth, also referred to as the V-factor or NAD requirement, have mainly been classified with Avibacterium paragallinarum (Haemophilus paragallinarum), Avibacterium avium (Pasteurella avium), Avibacterium volantium (Pasteurella volantium) and Avibacterium sp. A (Pasteurella species A). The aim of the present study was to assess the taxonomic position of 18 V-factor-requiring isolates of unclassified Haemophilus-like organisms isolated from galliforme, anseriforme, columbiforme and gruiforme birds as well as kestrels and psittacine birds including budgerigars by conventional phenotypic tests and 16S rRNA gene sequencing. All isolates shared phenotypical characteristics which allowed classification with Pasteurellaceae. Haemolysis of bovine red blood cells was negative. Haemin (X-factor) was not required for growth. Maximum-likelihood phylogenetic analysis including bootstrap analysis showed that six isolates were related to the avian 16S rRNA group and were classified as Avibacterium according to 16S rRNA sequence analysis. Surprisingly, the other 12 isolates were unrelated to Avibacterium. Two isolates were unrelated to any of the known 16S rRNA groups of Pasteurellaceae. Two isolates were related to Volucribacter of the avian 16S rRNA group. Seven isolates belonged to the Testudinis 16S rRNA group and out of these, two isolates were closely related to taxa 14 and 32 of Bisgaard, whereas four other isolates were found to form a genus-like group distantly related to taxon 40 and one isolate remained distantly related to other members of the Testudinis group. One isolate was closely related to taxon 26 (a member of Actinobacillus sensu stricto). The study documented major genetic diversity among V-factor-requiring avian isolates beyond the traditional interpretation that they only belong to Avibacterium, underlining the limited value of satellitic growth for identification of avian members of Pasteurellaceae. Our study also emphasized that these organisms will never be isolated without the use of special media satisfying the V-factor requirement.
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PMID:Phylogenetic relationships of unclassified, satellitic Pasteurellaceae obtained from different species of birds as demonstrated by 16S rRNA gene sequence comparison. 1957 97

Hemin is one of the critical components of medium required for growth of Haemophilus influenzae type b (Hib) organisms. It is important to have different sources of critical components to ensure continuous supply for commercial production. Regulatory bodies also recommend having multiple sources for critical components. Hemin is produced from animal blood and the main sources are porcine and bovine origin. The approved Hib vaccine of SIIPL used for immunization is produced using hemin obtained from porcine origin. The present work focuses on the comparison of the growth of organisms on a large scale using hemin from bovine or porcine origin. Purified polysaccharide obtained using bovine source is tested with respect to the set WHO specifications as recommended by regulatory bodies and compared with commercial lots of PRP obtained from using hemin of porcine source. Identical product profile and quality attributes were obtained for PRP produced using bovine hemin and the regular commercial product suggests that there is no change in the product. Hemin from bovine source can be used as a replacement for hemin from porcine source in the fermentation medium for country specific requirement of Hib conjugate vaccine as long as it meets the guidelines on TSE/BSE risk.
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PMID:Comparability studies of hemin from two different origins porcine and bovine in the production of Haemophilus influenzae type b (Hib) polysaccharide. 3276 81