Dr Adetunji Charles Oluwaseun and Julius Kola Oloke & Gandham Prasad & Oluwasesan Micheal Bello & Osarenkhoe Omorefosa Osemwegie & Mishra Pradeep & Ravinder Sing Jolly   (Published 2017)

Dr Charles Oluwaseun
See Profile Page


The consistent application of agrochemical herbicides has been reported to impact negatively on human health, environment, and food safety, and facilitated the emergence of weed resistances. Rhizosphere bacteria (RB) of different crops were screened for antagonism against Amaranthus hybridus L. (pigweed) and Echinochloa crusgalli (L.) Beauv. (barnyard grass) using necrosis assay technique. A total of eight rhizosphere bacterial isolates (B1–B8) produced different degrees of leaf necrosis on target weeds with isolate B2 manifesting the most significant necrotic activity. The rhizospheric bacterium (B2) with the highest necrotic activity was identified using 16S rRNA sequencing technique and further investigated. Molecular, morphological, and biochemical characterizations confirmed B2 isolate to be Pseudomonas aeruginosa. On isolation with ethyl acetate, separation, defatting, purification, and flash chromatography, seven different fractions (fraction 1–fraction 7) were obtained out of which fraction 4 showed the highest necrotic activity in necrosis assay experiment. Preparative HPLC of fraction 4 resulted in a pure compound that completely inhibited seed germination and seedling development of pigweed and barnyard grass but remained non-antagonistic to other tested soil fungi used in this study. The result obtained from this present study consequently confirmed the antagonistic behavior of rhizosphere-inhabiting P. aeruginosa to the target weeds and qualified the suitability of bacterium as good alternative source of bioherbicide. Potential herbicidal formulation from P. aeruginosa will help reduce crop loss due to weed challenges while offering a partial solution to the use of agrochemicals and food security.

Item Type: Journal article(non-copyrighted)
Format: PDF document,   1.2 MB
Copyright: Creative Commons LicenseCreative Commons license
Keywords: 16S rRNAgene, DNA sequencing, Deleterious rhizosphere bacteria, Phylogenetic tree, PHPLC and bioherbicide
Department: Natural Science
Field of Study: Biology
Uploaded By: Enoyoze Esosa
Date Added: 15 Feb 2019 3:38pm
Last Modified: 15 Feb 2019
Journal URL:

Google Docs     Print     Download