Linear (n-hexadecane) and branched (pristane) alkanes were degraded by a mixed culture isolated from an oil-contaminated field. The degradation was accompanied by formation of biofloccules. The culture was composed of Rhodococcus strain NTU-1, Bacillus fusiformis L-1, and Ochrobactrum sp. Rhodococcus strain NTU-1 carried out the degradation of the alkane via a hydroxylase. Bacillus fusiformis L-1 and Ochrobactrum sp. did not degrade the alkanes but aided the flocculation by forming more rigid bacterial aggregates that enhanced the trapping of alkanes. In batch cultures, transformation and removal of the linear and branched alkanes was achieved within 66 h with more than 95% efficiency.