C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C24 FSAE 40 94.3 90.9 86.0 88.1 96.20 93.1 90.5 94.9 99.3 98.9 99.03 100 USAE 40 94.5 89.1 74.7 87.5 97.3 94.1 97.3 100 100 100 100 100 FSW 20-50 97.1 97.66 88.8 94.2 95.5 96.1 95.5 96.1 95.5 95.33 98.033 100 USW- 20-50 93.99 95.1 83.00 87.2 96.1 83.00 98.77 100 97.6 86.1 100 100 C12 - Dodecane, C13 - Tridecane, C14 - Tetradecane, C15 - Pentadecane, C16 - Hexadecane, C17 - Heptadecane, C18 - Otadecane, C19 - Nonadecane, C20 - Icosane, C21 - Heinecosane, C22 - Docosane, C24 - Tetracosane. Percentages degradation for respective n-alkanes were obtained by comparing peak area counts on the chromatograms obtained at day 0 with the values for day 21, as there is usually a linear relationship between peak area and amount of hydrocarbon present in injected samples. n-aliphatics were recognized on the basis of their initial peak intensity and retention time, which distinguished them from aromatics and iso-alkanes with the same number of carbon atoms.

Table 2: Percentage of n-alkane hydrocarbon fractions of fresh and used engine oils degraded by Pseudomonas aeruginosa LP5 after 21 days of incubation in mineral salt medium at room temperature.