Screening for Biodegradation Potential of Endophytic Bacteria Isolated from the Roots and Leaves of Mangrove Plants (Avicennia germinans) (Black Mangrove), Acrostichum aureum (Golden Leather Fern) and Rhizophora mangle (Red Mangrove)

Aim: The aim of this study is to screen and determine the biodegradation potential of the endophytic bacteria isolated from roots and leaves of mangrove plants.

Methodology: In this work were isolated, identified and screened endophytic bacteria from roots of Rhizophora mangle, Avicennia germinans and Acrostichum aureum; the three major species of mangrove plants found in the Niger Delta. The roots were transported in a sterile bag to the Microbiology Laboratory and treated using standard Microbiological techniques. The organisms isolated include: Pseudomonas sp, Bacillus sp, Staphylococcus sp, Micrococcus sp, Klebsiella sp, Azotobacter sp, Nitrobacter sp. and Nitrosomonas sp. These organisms were screened for their ability to degrade crude oil by analyzing them using an ultra-violet spectrophotometer at a wavelength of 600nm and through a colorimetric test that involves the use of 2,6, Dichlorophenol-indophenol (DCPIP) as the metabolic activity indicator for a 14 days period.

Results: According to the colorimetric test, isolates that were positive hydrocarbon degraders were observed by a colour change from blue to colourless, which include: Pseudomonas sp, Staphylococcus sp, Bacillus sp, Klebsiella sp and Nitrobacter sp, while those that changed from blue to pink(an indication of a negative reaction) were: Nitrosomonas sp, Bacillus sp, Micrococcus sp, Staphylococcus sp, Azotobacter sp and Klebsiella sp. Amount degraded and percentage biodegradation ranged from Micrococcus sp 278.6 (6.2%) ˂ Azotobacter sp. 1242.8 (17.8%) ˂ Nitrosomonas sp 1392.9 (19.9%) ˂ Staphylococcus sp1543.0 (22.1%) ˂ Bacillus sp 17927.8 (25.6%) ˂ Nitrobacter sp 1935.7 (28%) ˂ Klebsiella sp 3392.9 (48.5%) ˂ Bacillus sp 3671.4 (52.5%) ˂ Pseudomonas sp 4942.8 (70%).

Conclusion: Pseudomonas and Bacillus species demonstrated the highest potential to degrade crude oil and can therefore be used in bioremediation of water ecosystem impacted by crude oil. Hence, the scientific contribution of this research is related to identifying several culturable groups of bacteria that might be directed to these further biotechnological approaches.