Microbial Occurrence and Distribution at Different Rhizosphere Depths of Musa sapientum var parasidiaca and Senna occidentalis

Abstract

In this study, we focussed on the isolation, enumeration, distribution and occurrence of rhizomicroflora of Musa sapientum var parasidiaca and Senna occidentalis. The population, occurrence and distribution of culturable bacteria, fungi and actinomycetes in 5, 10, 15, and 20 cm depths rhizosphere samples of Musa sapientum var parasidiaca and Senna occidentalis growing in the botanical garden of the University of Lagos, Akoka, Nigeria, were investigated using standard plate count and biochemical techniques. Bacteria were the most predominant in the rhizosphere of both plants, followed by fungi, then actinomycetes. The culturable microbial population was at its maximum for depths 10 and 15 cm in M. sapientum var parasidiaca. In S. occidentalis, bacterial population was highest at 5cm, fungi at 10cm and actinomycetes at 15cm depth of the rhizosphere. Bacillus cereus had 100% distribution in the rhizosphere of both plants and Staphylococcus aureus, Pseudomonas aeruginosa, Proteus mirabilis each had 75% distribution in both rhizospheres. Rhizosphere depth of 10 cm had 100% distribution of bacteria, and the least bacterial distribution was found at 20cm. Fungi were most distributed at 15cm rhizosphere of M. sapientum var parasidiaca and at 10 and 15 cm rhizosphere of S. occidentalis. Rhizopus stolonifer had 100% distribution and the highest % occurrence in the rhizosphere of both plants with Aspergillus niger having 100 and 75% distribution in the rhizosphere of M. sapientum and S. occidentalis respectively. Actinomycetes were most distributed at 10 cm (60 and 80% in rhizosphere of M. sapientum and S. occidentalis respectively). Streptomyces sp had the highest distribution in the rhizosphere of both plants and 58.33 and 55.17% occurrences in rhizosphere of M. sapientum and S. occidentalis respectively. Streptomyces alanosinicus and S. gancidicus were absent among the rhizosphere isolates of M. sapientum. Similarly, S. globosus and S. sampsonii were not found in the rhizosphere of S. occidentalis. The abundance of the microorganisms in these rhizospheres is typical of an environment with high species richness and functional diversity.