Isolation, Morphological and Molecular Characterisation of the Endophytic bacterium Burkholderia contaminans from leaves of Irvingia gabonensis

Abstract

Endophytic bacteria constitute an important component of plant-associated microbial communities and occur within healthy plant tissues without necessarily producing visible symptoms of disease. The diversity of culturable bacterial endophytes associated with Irvingia gabonensis, an economically and nutritionally important indigenous African tree, remains insufficiently documented. This study aimed to isolate and characterise an endophytic bacterium recovered from healthy Irvingia gabonensis leaves. Healthy leaves were subjected to sequential surface sterilisation using ethanol and sodium hypochlorite before internal tissues were aseptically cultured on Nutrient Agar. The recovered isolate, designated PC5, was characterised based on cultural, morphological and biochemical properties. Molecular identification was performed by amplifying and sequencing the bacterial 16S rRNA gene using universal primers 27F and 1492R, followed by sequence comparison using BLASTn against the National Centre for Biotechnology Information nucleotide database. PC5 produced yellow, circular colonies with a smooth-to-mucoid surface. The isolate was Gram-negative, rod-shaped and motile. Biochemical characterisation showed positive reactions for oxidase, catalase and citrate utilisation, while indole production and glucose fermentation were negative. The 16S rRNA sequence from PC5 showed 100% similarity to the closest reference sequence, identified as Burkholderia contaminans. The sequence was submitted to the NCBI GenBank database under accession number PV523554, as supplied from the sequence submission record. The findings provide a molecularly characterised record of a culturable endophytic B. contaminans isolate associated with healthy Irvingia gabonensis leaves collected in Edo State, Nigeria. The study establishes a basis for subsequent investigations of the ecological, physiological and biological characteristics of this isolate.