Culture on Nutritive Media and Characterization of Some Endophytic Bacteria Isolated from the Roots and Leaves of Mangrove Plants: Avicennia germinans, Acrostichum aureum and Rhizophora mangle

Abstract

Aim: The aim of this study was to isolate and characterize the culturable endophytic bacteria from the roots and leaves of three different mangrove plants found growing in same environment.
 Study Design: This study employs experimental design, statistical analysis of the data and interpretation.
 Place of Study: The roots and leaves of three mangrove plants; Rhizophora mangle, Avicennia germinans and Acrostichum aureum were gotten from a waterfront location in old Port Harcourt township of Rivers State, situated at Longitude 40 45’5.18’’N and Latitude 70 0’58.35” E.
 Methodology: Using standard Microbiological techniques, the roots and leaves were treated and endophytic bacteria isolated and subjected to morphological and biochemical tests.
 Results: From the roots, the hydrocarbon utilizing bacteria counts ranged from 7.0x103cfu/g – 1.6x104cfu/g, while the that of the leaves ranged from 3.0 x105cfu/g – 8.0 x105cfu/g. The nitrogen fixing bacteria counts for roots ranged from 4.5 x103cfu/g – 1.0 x104cfu/g and that of the leaves ranged from 3.0 x105cfu/g – 6.0 x105cfu/g. Nitrifying bacteria counts for the roots ranged from 5.0x103cfu/g – 7.0x103cfu/g, while the counts from the leaves ranged from 3.5 x 105cfu/g - 5.0 x105cfu/g. Out of the 24 isolates, 14 were from the roots, while 10 were from the leaves. Percentage of occurrence of the isolates was in this order Bacillus sp 33% > Staphylococcus sp 21%> Klebsiella sp 13%> Pseudomonas sp 9%> Micrococcus sp 8%> Nitrobacter sp 8%> Nitrosomonas sp 4%> Azotobacter sp 4%. This reveals that Bacillus sp occurred most in the plant samples. The result also revealed that the Red Mangrove Roots had the highest number of organisms. The endophytic bacteria isolated were further subjected to morphological and biochemical identification and they were identified as: Pseudomonas sp, Bacillus sp, Staphylococcus sp, Micrococcus sp, Klebsiella sp, Azotobacter sp, Nitrobacter sp. and Nitrosomonas sp. Five of the isolates showed a high potential to degrade crude oil in the following order Pseudomonas sp (H2) > Bacillus sp (BA) > Klebsiella sp (SB)> Bacillus sp (TG) > Pseudomonas sp (H1).
 Conclusion: From the results, the mangrove roots and leaves contained high numbers of active indigenous bacteria most of which are known to use up crude oil as their carbon source. The mangrove roots had higher number of endopyhtic bacteria than the leaves.