Isolation and identification of endophytic bacteria of bananas (Musa spp.) in Kenya and their potential as biofertilizers for sustainable banana production

Abstract

This study was conducted with the aim of isolating and identifying endophytic bacteria associated with bananas in Kenya and assessing their functional potentiality as biological fertilizers. Banana material was collected from two different banana cultivars in five different geographical regions and bacteria were isolated using five different isolation media. Whole-cell matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) analysis was used for microorganism profiling. Protein from the living cells were extracted using the ethanol/formic acid extraction procedure and intact molecular weights of the ionized proteins directly measured and the pattern of the protein molecular weights used as fingerprints. Forty three isolates were selected for partial 16S rRNA gene sequencing. Isolates were characterized on the basis of their in-vitro plant growth-promoting activities that included abilities to fix free nitrogen, solubilize phosphates and produce siderophores. The isolates were identified as Serratia, Pseudomonas, Rahnella, Enterobacter, Raoultella, Yokenella, Bacillus, Klebsiella, Yersinia and Ewingella species. Siderophore production activity was detected with all the Pseudomonas isolates as determined on blue Chrome Azurol S (CAS) agar plates. Twenty seven isolates were observed to solubilize phosphates, with Rahnella isolates showing the highest potential as determined on NBRIP growth medium. All the isolates grew on solid nitrogen-source free medium, suggesting their ability to fix nitrogen. In conclusion, endophytic bacteria of bananas in Kenya were isolated and identified, and Rahnella and Pseudomonas isolates proposed as potential microbial biofertilizers for sustainable banana production in Kenya.