title: Effect of haemin limitation on the cytochrome complement and glucose metabolism of non-typable Haemophilus influenzae.
abstract: 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.
authors.affiliation: Pharma Research, CIBA-GEIGY Limited, Basel, Switzerland.
authors.forename: T
authors.initials: T
authors.lastname: O'Reilly
authors.forename: I
authors.initials: I
authors.lastname: MacIver
authors.forename: R K
authors.initials: RK
authors.lastname: Poole
authors.forename: D F
authors.initials: DF
authors.lastname: Niven
authors.forename: P G
authors.initials: PG
authors.lastname: Martin
authors.forename: M R
authors.initials: MR
authors.lastname: Brown
mesh_terms: D001987:Bronchiectasis / Q000382:microbiology; D003470:Culture Media; D003580:Cytochromes / Q000096:biosynthesis*; D005561:Formates / Q000032:analysis; D005947:Glucose / Q000378:metabolism; D006193:Haemophilus influenzae / Q000145:classification / Q000378:metabolism*; D006427:Hemin / Q000378:metabolism*; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D007773:Lactates / Q000032:analysis; D010101:Oxygen Consumption; D010641:Phenotype; D013183:Sputum / Q000382:microbiology
chemical_list: D003470:Culture Media; D003580:Cytochromes; D005561:Formates; D007773:Lactates; D006427:Hemin; D007770:L-Lactate Dehydrogenase; D005947:Glucose