COMPLEMENTARY DEGRADATION OF FUEL-OIL IN SUPERFICIAL WATERS AND IN AXENIC CULTURES OF AEROBIC GRAM-NEGATIVE BACTERIA ISOLATED FROM VENICE LAGOON

The percentages of bacteria degrading fuel oil (n-paraffins from C-12 to C-28) were determined in three stations in the northern part of Ven ice Lagoon. Concentrations of paraffin-degrading bacteria ranged from 8 to 70 bacteria per 100 mt in the least polluted station close to the sea, and from 33 to 345 bacteria per 100 mt in the most polluted stat ion near Porto Marghera. Biological oxygen demand with fuel oil additi ons was higher in this station, where oxygen was totally depleted in 7 and 5 days in November and June respectively. Twenty-five bacterial s trains were isolated from agar plates amended with fuel oil as the sol e carbon and energy source; only two were Acinetobacter spp. strains. Strain VE-C3 grew in the presence of n-paraffins. Growth was inducible with a generation time of 2.77 h and an oxygen consumption rate of 53 mu L h(-1) mg(-1) of cells (d.w). Five other strains thrived on inter mediate oxidation products of n-paraffin.