Distribution and Generic Composition of Denitrifying Bacteria in Coastal and Oceanic Bottom Sediments

Abstract

Distribution and generic composition of denitrifying bacteria in the bottom sediments of Ise Bay, Kumano Nada, Nansei Shoto and the surrounding area were investigated from 1983 to 1986.Denitrifying bacteria were enumerated by the M.P.N. method. Their number in the surface layer (0-3cm) of the bottom sediments ranged from less than 2.0×101 to 7.9×104cells/g(wet). The average percentage of the occurrence of denitrifying bacteria to that of heterotrophic ones was about 1.64% in Ise Bay, Kumano Nada, Nansei Shoto and the surrounding area, and about only 0.67% in the sand beach of Machiya Ura, Mie Prefecture.Most of the denitrifying bacteria were gram negative, asporogenous motile rods with polar, lateral or peritrichous flagella. About 64.8% of the denitrifiers required NaCl for growth and 86.9% were able to grow on the medium containing inorganic nitrogenous compounds (NO3- or NH4+) as a nitrogen source. Pseudomonas (40.1%) was the most dominant denitrifying bacterial genus. Pseudomonas, Alcaligenes and Bacillus comprised 77.8% of the denitrifying bacteria isolated from coastal and oceanic bottom sediments.