An investigation was carried out to compare the
ability of two bacteria
Pseudomonas aeruginosa
PSA5 and
Rhodococcus
sp. NJ2 isolated from petroleum sludge for
degradation of benzo(a)pyrene [B(a)P], a HMW PAH
compound in MSM. During 25 days of incubation, 50 ppm
B(a)P was degraded by 88 and 47 % by
P. aeruginosa
PSA5 and
Rhodococcus sp. NJ2, respectively. Besides,
involvement of different catabolic enzymes, that is, salicylate
hydroxylase, 2-carboxybenzaldehyde dehydrogenase,
catechol 1,2-dioxygenase and catechol 2,3-dioxygenase,
was also examined to identify their differential role in
B(a)P degradation. Among these enzymes, the highest
induction of 2-carboxybenzaldehyde dehydrogenase
(773.5 nmol mg
-1 protein) was recorded in
P. aeruginosa
PSA5, while salicylate hydroxylase was highly expressed
(839.6 nmol mg
-1 protein) in
Rhodococcus sp. NJ2. Both
the bacteria were found biosurfactant (glycolipid) producing,
and role of biosurfactant in PAH degradation was also
ascertained by reduced surface tension, higher emulsification
index and increased cell surface hydrophobicity.
