title: Hydrocarbonoclastic bacteria isolated from petroleum contaminated sites in Tunisia: isolation, identification and characterization of the biotechnological potential.
abstract: Petroleum hydrocarbons are important energy resources used by industry and in our daily life, whose production contributes highly to environmental pollution. To control such risk, bioremediation constitutes an environmentally friendly alternative technology that has been established and applied. It constitutes the primary mechanism for the elimination of hydrocarbons from contaminated sites by natural existing populations of microorganisms. In this work, a collection of 125 strains, adapted to grow on minimal medium supplemented with crude oil, was obtained from contaminated sediments and seawater from a refinery harbor of the Bizerte coast in the North of Tunisia. The diversity of the bacterial collection was analyzed by amplification of the internal transcribed spacers between the 16S and the 23S rRNA genes (ITS-PCR) and by 16S rRNA sequencing. A total of 36 distinct ITS haplotypes were detected on agarose matrix. Partial 16S rRNA gene sequencing performed on 50 isolates showed high level of identity with known sequences. Strains were affiliated to Ochrabactrum, Sphingobium, Acinetobacter, Gordonia, Microbacterium, Brevundimonas, Novosphingobium, Stenotrophomonas, Luteibacter, Rhodococcus, Agrobacterium, Achromobacter, Bacilllus, Kocuria and Pseudomonas genera. Acinetobacter and Stenotrophomons were found to be the most abundant species characterized by a marked microdiversity as shown through ITS typing. Culture-independent approach (DGGE) showed high diversity in the microbial community in all the studied samples with a clear correlation with the hydrocarbon pollution rate. Sequencing of the DGGE bands revealed a high proportion of Proteobacteria represented by the Alpha and Gamma subclasses. The predominant bacterial detected by both dependent and independent approaches were the Proteobacteria. The biotechnological potential of the isolates revealed a significant production of biosurfactants with important emulsification activities useful in bioremediation. The highest emulsification activity was detected in Pseudomonas geniculata with 52.77% of emulsification. Our overall results suggest that the obtained bacterial isolates may constitute potential candidates for bioremediation and can be useful for biotechnological applications.
authors.affiliation: Laboratory of Microorganisms and Active Biomolecules, Faculty of Sciences of Tunis, University of Tunis El Manar, 2092 Tunis, Tunisia; LR Biotechnology and Bio-Geo Resources Valorization, Higher Institute for Biotechnology, University of Manouba, Sidi Thabet Biotechpole, 2020 Sidi Thabet, Ariana, Tunisia.
authors.forename: Mouna
authors.initials: M
authors.lastname: Mahjoubi
authors.forename: Atef
authors.initials: A
authors.lastname: Jaouani
authors.forename: Amel
authors.initials: A
authors.lastname: Guesmi
authors.forename: Sonia
authors.initials: S
authors.lastname: Ben Amor
authors.forename: Ahlem
authors.initials: A
authors.lastname: Jouini
authors.forename: Hanen
authors.initials: H
authors.lastname: Cherif
authors.forename: Afef
authors.initials: A
authors.lastname: Najjari
authors.forename: Abdellatif
authors.initials: A
authors.lastname: Boudabous
authors.forename: Nedra
authors.initials: N
authors.lastname: Koubaa
authors.forename: Ameur
authors.initials: A
authors.lastname: Cherif
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification; D001709:Biotechnology; D010578:Petroleum / Q000382:microbiology*; D012329:RNA, Bacterial / Q000235:genetics*; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012338:RNA, Ribosomal, 23S / Q000235:genetics*; D012988:Soil Microbiology; D012989:Soil Pollutants; D014416:Tunisia
chemical_list: D010578:Petroleum; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S; D012989:Soil Pollutants