Abstract: Six bacterial Genera were identified based on their morphological, biochemical and physiological characteristics for the mangrove swamp soils supporting tall mangrove, short mangrove and Nypa palms in the Cross River estuary, South-East Nigeria. The six genera of bacteria were Stsp., Micrococcus sp., Bacillus sp., Pseudomonas sp., Staphylococcus sp. and Streptococcus sp. The percentage distributions of the isolates were as follows: Streptomyces sp. (33-50%), Micrococcus sp. (17%), Bacillus sp. (17-33%), Pseudomonas sp. (17%), Straphylococcus sp. (17%) and Streptococcus sp. (17%). Streptomyces sp., Micrococcus sp., Bacillus sp. and Pseudomonas sp. were classified as indigenous (authochthonous) bacteria responsible for the decomposition of leaf litter in the mangrove swamp soils. The bacterial isolates, Staphylococcus sp. and Streptococcus sp. were regarded as foreign (allochthonous) and such bacteria lack potentials to degrade leaf litter and are contaminants introduced by human activities in the mangrove swamp forest area.