DEGRADATION OF CRUDE-OIL BY ACINETOBACTER-CALCOACETICUS AND ALCALIGENES ODORANS

Two types of Indian crude oil (Bombay High and Gujarat) were tested fo r their biodegradability by Acinetobacter calcoaceticus and Alcaligene s odorans. Acinetobacter calcoaceticus S30 and Ale. odorans P20 degrad ed Bombay High crude oil by 50% and 45%, while only 29% and 37% of Guj arat crude oil (heavy crude oil) was degraded by these isolates, respe ctively. Acinetobacter calcoaceticus and Ale. odorans in combination d egraded 58% and 40% of Bombay High and Gujarat crude oils, respectivel y, which were significantly higher than that of by individual cultures . Acinetobacter calcoaceticus S30 degraded more of the alkanes fractio n than the aromatics fraction of both crude oils. GC fingerprinting of alkane fraction showed major degradation of heptadecane (C-17), octad ecane (C-18), nonadecane (C-19), eicosane (C-20), docosane (C-22), tri cosane (C-23) and tetracosane (C-24) of crude oil, while the Ale. odor ans P20 degraded alkanes and aromatics equally. The asphaltenic compon ent increased in both types of crude oil after biodegradation. The two strains grew very well on n-alkane up to C-33 as well as on pristane (branched-chain alkane) but could not grow on cycloalkanes. Acinetobac ter calcoaceticus S30 could not grow on pure polycyclic aromatic hydro carbon (PAH) compounds except naphthalene but Alc. odorans P20 could g row on anthracene, phenanthrene, dibenzothiophene, fluorene, fluoranth ene, pyrene and chrysene.