Polycyclic aromatic hydrocarbons (PAHs) are pollutants that occur in mangrove sediments. Their removal by bacteria often depends on specific characteristics as the number of benzene rings they possess and their solubility. Their removal also depends on environmental factors, such as pH, temperature, oxygen, and the ability of the endogenous or exogenous microflora to metabolize hydrocarbons. With the aim of treating mangrove sediments polluted by hydrocarbons in a biological way, a biodegradation experiment was conducted using mangrove sediments artificially contaminated with a mixture of four PAHs. The study used Rhodococcus erythropolis as an exogenous bacterial strain in order to assess the biodegradation of the PAH mixture by natural attenuation, biostimulation, bioaugmentation, and a combination of biostimulation and bioaugmentation. The results showed that the last three treatments were more efficient than natural attenuation. The biostimulation/bioaugmentation combination proved to be the most effective PAH degradation treatment.

Hydrocarbons are ubiquitous and persistent organic pollutants in the environment. In wetlands and marine environments, particularly in mangrove ecosystems, their increase and significant accumulation result from human activities such as oil and gas exploration and exploitation operations. Remediation of these ecosystems requires the development of adequate and effective strategies. Natural attenuation, biostimulation, and bioaugmentation are all biological soil treatment techniques that can be adapted to mangroves. Our experiments were performed on samples of fresh mangrove sediments from the Cameroon estuary and mainly from the Wouri River in Cameroon. This study aims to assess the degradation potential of a bacterial consortium isolated from mangrove sediment. The principle of our bioremediation experiments is based on a series of tests designed to evaluate the potential of an active indigenous microflora and three exogenous pure strains, to degrade diesel with/without adding nutrients. The experiments were conducted in laboratory flasks and a greenhouse in microcosms. In one case, as in the other, the endogenous microflora showed that it was able to degrade diesel. Under stress of the pollutant, the endogenous microflora fits well enough in the middle to enable metabolism of the pollutant. However, the Rhodococcus strain was more effective over time. The degradation rate was 77 and 90 % in the vials containing the sterile sediments and non-sterile sediments, respectively. The results are comparable with those obtained in the microcosms in a greenhouse where only the endogenous microflora were used. The results of this study show that mangrove sediment contains an active microflora that can metabolize diesel. Indigenous and active microflora show an interesting potential for diesel degradation.

RESUMELes mangroves constituent un écosystème particulier. Leur développement est fortement lié à leur fonctionnement. La microflore y joue un rôle de premier plan. Grâce à son activité de dégradation de la matière organique, elle pourvoie, aux organismes supérieurs, les éléments nutritifs d'importance tels que l'azote et le phosphore indispensables à leurs cycles biologiques. Il existe une relation entre la composition globale des microorganismes et la demande en éléments nutritifs. Une simulation artificielle de la dégradation des hydrocarbures par les bactéries demande une addition d'azote et de phosphore. La biodégradation qui est un phénomène naturel de dégradation des molécules organiques par les microorganismes (bactéries et champignons, etc.), dont la croissance s'effectue par l'oxydation du carbone utilisé comme source d'énergie est une réaction qui met en jeu l'azote et le phosphore qui participent à la synthèse protéique. Lorsque l'oxydant est représenté par l'oxygène, on parle de condition d'aérobiose. Dans le cas d'anaérobiose, l'oxygène est remplacé par les nitrates, phosphates, sulfates ou le méthane. © 2016 International Formulae Group. All rights reserved.Mots clés : mangroves, microflore, pollution, biodégradation, réhabilitation. Microorganisms in maintaining balance and rehabilitation of polluted mangrove ecosystem by oil. A review ABSTRACTMangroves are a particular ecosystem. Their development is strongly linked to their operation. The microflora plays a prominent role. Through its degradation of organic matter of activity, it provides higher organisms, nutrients matter such as nitrogen and phosphorous essential for their biological cycles. There is a relationship between the overall composition of the microorganisms and the nutrient demand. An artificial simulation of hydrocarbon degradation by bacteria requires the addition of nitrogen and phosphorus. Biodegradation is a natural phenomenon of degradation of organic molecules by microorganisms (bacteria and F. SEMBOUNG LANG et al. / Int. J. Biol. Chem. Sci. 10(5): 2268-2284, 2016 2269 fungi, etc.), the growth is carried out by oxidation of the carbon used as an energy source is a reaction that involves the nitrogen and phosphorus involved in protein synthesis. When the oxidant is represented by oxygen, it is called aerobic condition. In the case of anaerobiosis, oxygen is replaced by nitrates, phosphates, sulphates or methane.