Isolation and Identification of Endophytic Bacteria from Rumex nepalensis based on the Protein Profile and assay their Growth Conditions

Abstract

Rumex nepalensis Spreng (Amharic: Yewsha Tult) belongs to the Polygonaceae (buckwheat) family. It occurs as a weed of grassland, particularly in disturbed areas with high fertility and bushland. The current study aimed to isolate the endophytic bacteria from the root, stem and leaf parts of Rumex nepalensis plant. The R. nepalensis samples were collected and transported to the Applied Microbiology laboratory. Endophytic bacterial isolates were isolated from the root, stem, and leaf parts of R. nepalensis. Various biochemical tests, morphological characterization and enzymatic activities were performed. Phosphate and zinc solubilization were carried out for these Endophytic bacterial isolates. The secondary metabolites of isolates were extracted using ethyl acetate, and the antibacterial activities of the extracts were evaluated. The effect of various conditions like pH value, temperatures, salt concentration, and carbon and nitrogen sources were assessed against these endophytic bacterial isolates. Data analyses were conducted using multiple software. In this study, eight endophytic bacterial isolates were isolated from the plant’s leaf, stem, and root parts. Nearly all of these isolates were Gram-positive. These isolates were also identified as Cronobacter skazakii EIRS- 2, Cronobacter skazakii EIRS-3, Cronobacter skazakii EIRR-3, Proteus vulgaris EIRR-2, Psedomonas stutzeri EIRL-1, Serratia liquefaciens EIRL-2, and Serratia liquefaciens EIRS-1 based on growth condition from the root, stem, and leaf part of R. nepalensis. Some of these isolates can produce amylase, protease and cellulase enzymes. The recent isolate shows phosphates and zinc solubilization and is used for plant growth promotion. The ethyl acetate extract of the isolates also indicated inhibitory activity against test organisms. Considerable amounts of CDW (g/L) and OD600nm were obtained from these isolates. These growth conditions, such as pH values (7.5), temperatures (30&32oC), salt concentrations (1&0.05M), carbons (Mannitol and glucose) and nitrogen sources (Peptone and Yeast extract) were found to affect the growth of these plant growth-promoting bacterial isolates. In conclusion, these potential endophytic bacterial isolates can be employed for plant growth promotion at suitable environmental conditions by producing certain cellulolytic enzymes which may act as phytopathogens inhibitors.