Abstract
Polycyclic aromatic hydrocarbons (PAHs) biodegradation in contaminated sediment is an attractive remediation technique and its success depends on the optimal condition for the PAH-degrading isolates. The aims of the current study was to isolate and identify PAHs-degrading bacteria from surface sediments of Nayband Bay and to evaluate the efficiency of statistically based experimental design for the optimization of phenanthrene (Phe) and Fluorene (Flu) biodegradation performed by enriched consortium. PAHs degrading bacteria were isolated from surface sediments. Purified strains were then identified by 16S rDNA gene sequence analysis. Taguchi L16 (45) was employed to evaluate the optimum biodegradation of Phe and Flu by the enriched consortium. Total of six gram-negative bacterial strains including Marinobacter hydrocarbonoclasticus, Roseovarius pacificus, Pseudidiomarina sediminum and 3 unidentified strains were isolated from enrichment consortium, using Fluorene (Flu) and phenanthrene (Phe) as the sole carbon and energy source. The enriched consortium showed highest degradation abilities (64.0% Flu and 58.4% Phe degraded in 7 days) in comparison to a single strain cultures or mixtures. Maximum biodegradation efficiency was occur at temperature = 35°C; pH = 8; inoculum size = 0. 4 OD600nm; salinity = 40 ppt; C/N ratio = 100:10. In conclusion our results showed that, indigenous bacteria from mangrove surface sediments of Nayband Bay have high potential to degrade Flu and Phe with the best results achieved when enriched consortium was used.
Highlights
Mangrove forests are among the most productive coastal ecosystems along the coastline of tropical and subtropical regions
In conclusion our results showed that, indigenous bacteria from mangrove surface sediments of Nayband Bay have high potential to degrade Flu and Phe with the best results achieved when enriched consortium was used
Identification of microbial strains Six gram-negative bacterial strains were isolated from enrichment consortium (SBU) on nutrient agar plates
Summary
Mangrove forests are among the most productive coastal ecosystems along the coastline of tropical and subtropical regions. Due to their inherent physical and chemical properties (being rich in organic matter as well as anaerobic and reduced condition of soil) mangrove forests have an extraordinary capacity to accumulate materials discharged to the near shore marine environment [1]. The impact of that particular parameter on the process can be assessed. These procedures are time consuming, require more experimental data sets and cannot provide information about the mutual interactions of the parameters. The use of an orthogonal array approach called ‘Taguchi method’ has been successfully examined in the field microbiological optimization procedures [11,12] which enables one to examine many factors simultaneously and provides much quantitative information by doing few experimental trials
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