Beneficial Effects of Nickel on Pseudomonas saccharophila under Nitrogen-Limited Chemolithotrophic Conditions
AUTOR(ES)
Barraquio, Wilfredo L.
RESUMO
Addition of nickel stimulated growth and nitrogenase activity of Pseudomonas saccharophila under nitrogen-limited chemolithotrophic conditions, apparently because of a significant increase in expression of uptake hydrogenase activity. Inhibition of hydrogenase expression by 50 μM EDTA was relieved by nickel over a wide concentration range (1 to 200 μM). Co2+, Zn2+, Mn2+, and Cu2+ stimulated expression of hydrogenase activity, but to a much lesser degree than nickel, and Fe2+, Mg2+, SeO42−, and SeO32− did not increase expression. Nickel in individual combination with Mg2+, Fe2+, SeO32−, and SeO42− resulted in activities that were essentially the same as that with nickel alone. Hydrogenase synthesis required the presence of nickel, and repression by O2 was alleviated by increasing the concentration of added nickel. Cells placed under hydrogenase derepression conditions showed progressive incorporation of radioactive nickel to a much greater extent than did cells which were not derepressed.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=203246Documentos Relacionados
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