Abstract.
The Algerian coastline is exposed to several types of pollutions, including Hydrocarbons. The
aim of this work was to study the degradation abilities of bacteria isolated from a
contaminated area of the Algerian coast (Sidi Fredj harbour). A collection of 119 strains,
capable to grow on mineral medium supplemented with hydrocarbons as the sole source of
carbone and energy, was obtained. 23 strains were selected for further studies. Sequencing of
the 16S rRNA gene showed that most isolates belong to genera of hydrocarbonoclastic
bacteria (Alcanivorax), generalist hydrocarbons degraders (Marinobacter, Pseudomonas,
Gordonia, Halomonas, Erythrobacter and Brevibacterium) and other bacteria not known as
hydrocarbon degraders (Xanthomarina) but were able to degrade Hydrocarbons. Culture
independent approach (DGGE) showed that Higher diversity and variability among stations
was detected in seawater than in sediment samples
Strains related to Marinobacter and Alcanivorax were the most effective in degrading crude
oil with 61% and 57% of oil degraded after one week of incubation, while strains related to
Halomonas and Labrenzia were the less effective with only 8% and 12% of crude oil
degraded respectively. Screening of catabolic genes alkB and xylA, revealed the presence
of alkB gene in several bacterial strains, one isolate harboured both catabolic genes while
some isolates carried none of the studied genes. However, they grew in the presence of crude
oil implying the existence of other biodegradation pathways.
Most of isolates revealed a significant production of biosurfactants with important
emulsification activities useful in bioremediation. The highest emulsification activity was
detected in Alcanivorax borkumensis with 52 % of emulsification. Our results showed that
Strains producing high levels of biosurfactant can better degrade crude oil.
Our overall results suggest that the obtained bacterial isolates may constitute potential
candidates for bioremediation and can be useful for biotechnological applications.
Keywords : Crude oil - Marine bacteria – Bioremediation – Biodegradation – alkB –
Biodiversity – DGGE - Biosurfactant.
The Algerian coastline is exposed to several types of pollutions, including Hydrocarbons. The
aim of this work was to study the degradation abilities of bacteria isolated from a
contaminated area of the Algerian coast (Sidi Fredj harbour). A collection of 119 strains,
capable to grow on mineral medium supplemented with hydrocarbons as the sole source of
carbone and energy, was obtained. 23 strains were selected for further studies. Sequencing of
the 16S rRNA gene showed that most isolates belong to genera of hydrocarbonoclastic
bacteria (Alcanivorax), generalist hydrocarbons degraders (Marinobacter, Pseudomonas,
Gordonia, Halomonas, Erythrobacter and Brevibacterium) and other bacteria not known as
hydrocarbon degraders (Xanthomarina) but were able to degrade Hydrocarbons. Culture
independent approach (DGGE) showed that Higher diversity and variability among stations
was detected in seawater than in sediment samples
Strains related to Marinobacter and Alcanivorax were the most effective in degrading crude
oil with 61% and 57% of oil degraded after one week of incubation, while strains related to
Halomonas and Labrenzia were the less effective with only 8% and 12% of crude oil
degraded respectively. Screening of catabolic genes alkB and xylA, revealed the presence
of alkB gene in several bacterial strains, one isolate harboured both catabolic genes while
some isolates carried none of the studied genes. However, they grew in the presence of crude
oil implying the existence of other biodegradation pathways.
Most of isolates revealed a significant production of biosurfactants with important
emulsification activities useful in bioremediation. The highest emulsification activity was
detected in Alcanivorax borkumensis with 52 % of emulsification. Our results showed that
Strains producing high levels of biosurfactant can better degrade crude oil.
Our overall results suggest that the obtained bacterial isolates may constitute potential
candidates for bioremediation and can be useful for biotechnological applications.
Keywords : Crude oil - Marine bacteria – Bioremediation – Biodegradation – alkB –
Biodiversity – DGGE - Biosurfactant.