ISSN:
1574-6968
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Abstract The effect of oxygen on the growth, metabolism, and leukotoxin production of Actinobacillus actinomycetemcomitans 301-b was examined using a chemostat equipped with a redox potential control system. Steady states were obtained with fructose-limited cultures grown at a dilution rate of 0.1 h−1 under strictly anaerobic (Eh=−460 mV) and microaerobic conditions (Eh≤ 150 mV) but not under highly aerated conditions (Eh≥ 100 mV). The optimum growth was recorded at Eh=−300 to − 200 mV and the recorded Yfructose value was about 1.3 times the Yfructose of anaerobic cultures. Although the organism contains a respiratory chain, the increased Yfructose under the microaerobic conditions might result from the increased substrate-level phosphorylation at the site of acetate kinase but not from electron transport phosphorylation. After passing threshold aeration (Eh=−100 mV), the culture yielded a variant with transparent colony morphology. Under anaerobic conditions, the Yfructose of the variant was about 1.6 times that of the original opaque colony-forming cells. The optimum growth of the variant was also recorded at Eh=− 300 to − 200 mV. In both types of cells, the production of leukotoxin reached a maximum at Eh=−350 to − 200 mV. These findings suggested the microaerophilic nature of A. actinomycetemcomitans.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1574-6968.1996.tb08155.x
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