A deep-sea bacterium with unique nitrifying property

Sediment cores collected from the Central Indian Basin (10 degrees1 ' -10 d egrees2 'S, 75 degrees 59 ' -76 degrees2 'E) harboured a high population of nitrifying bacteria which ranged from 10(3) to 10(7) cfu per gram dry weig ht. This high density could,contribute to the high nitrate concentration ob served in these sediments. We report for the first time the unusual propert y of having both the phases of nitrification, i.e. NH4+ --> NO2- (Phase I) and NO2- --> NO3- (Phase II) under normal and high pressure conditions in a n autotrophic nitrifying bacterium isolated from the deep sediments cores a t 5000 m depth (15-20 cm below the sea floor).