Insights into the Occurrence, Adaptation, and Links to Sediment Chemistry of Hydrocarbon-Degrading Bacteria in Polluted Mangrove Forests

Polluted mangroves are ecologically sensitive habitats that provide ecosystem services. In a selected polluted forest of Simaisma, viable aerobic, halophilic, and heterotrophic hydrocarbon-degrading bacterial strains were isolated from both rhizosphere and non-rhizosphere regions. The chemical composition of sediment showed a clear distinction between the rhizosphere and non-rhizosphere sites, as well as coastal and non-coastal sediments, as per Principal Component Analysis (PCA) clustering. Anthracene, an indicator of oil pollution, was present along with vanadium, another marker of oil pollution. Through selective enrichment cultures, a total of 25 hydrocarbon-degrading bacterial strains were isolated, including Lysinibacillus xylanilyticus, Bacillus cereus, Lysinibacillus sphaericus, Pseudomonas stutzeri, Acinetobacter calcoaceticus, and Staphylococcus warneri. To link the adaptation of bacteria to sediment chemistry, nine B. cereus strains were investigated using their MALDI-TOF MS protein profiles combined with their dendrogram. The relationship between protein profiles of B. cereus strains with their biosurfactant production capabilities was explained by a tanglogram. The tanglegram suggests that biosurfactant production is an important functional trait in B. cereus, but it is not consistently reflected in the overall protein profile. This suggests that bacterial adaptation in the polluted mangrove sediments may involve changes at multiple cellular levels, including metabolic activity and variation in protein expression profiles. These findings confirm the involvement of mangrove-associated bacteria in the sustainability of mangrove forests by promoting bioremediation of oil pollution, thereby protecting coastal ecosystems and their environmental and socio-economic aspects.