Wilfredo L. Barraquio

Nitrogen Fixation by Pseudomonas saccharophila Doudoroff ATCC 15946

Summary: Pseudomonas saccharophila Doudoroff (ATCC 15946) reduced C2H2 and fixed 15N2 heterotrophically in N-free semi-solid medium supplemented with 100 mg yeast extract l−1. Nitrogenase activity was markedly stimulated by addition of sugars and organic acids and was expressed microaerobically. Autotrophically-grown cells showed nitrogenase activity. This is the first report of N2 fixation in a well-characterized Pseudomonas species capable of chemoautotrophic growth with H2 as the electron donor.

Effect of Hydrogen, Sucrose and Oxygen on Uptake Hydrogenase in Nitrogen-fixing and Ammonium-grown Pseudomonas saccharophila ATCC 15946

SUMMARY: Pseudomonas saccharophila, grown microaerobically in batch culture, showed much higher uptake hydrogenase activity in N2-fixing than in NH+ 4-grown cultures. Hydrogenase synthesis was induced by H2 under a low partial pressure of O2 and under air, in autotrophic as well as in heterotrophic conditions, provided that the sucrose concentration was relatively low. Sucrose at 15 mM repressed hydrogenase formation but did not inhibit preformed activity. Other utilizable carbon substrates repressed, while non-utilizable substrates did not repress, hydrogenase synthesis. The activity, unlike nitrogenase, was not sensitive to O2 but hydrogenase synthesis was partially repressed by O2.

Congo Red Decolorizing Bacteria from Paper Factory Effluent

Synthetic dyes usually consist of aromatic rings, methyl, methoxy, sulfo or nitro group. They are not readily degradable and can not be removed from water by conventional wastewater treatment systems (Anliker in Biodegradation of heterocyclic dyes by Phanerochaete chrysosporium 1990. Utah State University, Logan, 1979).