Isolation and identification of endophytic bacteria and associated compound from Gloriosa superba and their antibacterial activities

Abstract

Gloriosa superba L., which belongs to the genus Gloriosa and family Colchicaceae, is a climbing annual herb and tuberous poisonous tropical medicinal plant. This study was aimed to isolate possible endophytic bacteria from leaves, stems and tubers of Gloriosa superba. Thirty pure endophytic bacteria were isolated and subjected to biochemical characterization. Bacterial identification was conducted by Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The structure of the isolated compound was characterized. The antibacterial activity was also evaluated. Majority (21, 70 %) of the isolates were Gram-positive. Certain of them are spore formers. Based on MALDI-TOF MS, 26 of the isolates were identified as Bacillus spp. (65.4 %), Escherichia spp. (30.8 %) and Providencia spp. (3.9 %). A 1-undecene was isolated from culture filtrate of E. coli (GST-5). The ethyl acetate extracts (1000 μg/mL) of GSL-5 and GST-2 culture filtrates recorded maximum inhibition zone against E. coli (9.4 ± 0.6 mm) and S. aurous ATCC 25923T (8.4 ± 0.8 mm), respectively. The Pseudomonas aeruginosa ATCC 27853T was prone to all ethyl acetate extracts. A 1-undecene showed a moderate activity against E. coli ATCC 25922Tand P. aeruginosa ATCC 27853T at 50 μg/mL. The present finding would be a breakthrough to studies of similar works in Ethiopia since it may be for the first time.