Isolation and biochemical characterization of Plant Growth Promoting (PGP) bacteria colonizing the rhizosphere of Tef crop during the seedling stage

Abstract

The use of novel PGPR as bio inoculant is an alternative sustainable agricultural practice to improve soil health, grain quality, increase crop productivity, and conserve biodiversity. The aim of this study is to isolate, and characterized PGP bacteria colonizing tef rhizosphere during the seedling stage. For this concern, 426 samples of tef (Eragrostis tef) rhizosphere soils and roots were collected from East Shewa zone, Oromia regional state. 200 morphologically different bacterial pure colonies were isolated and screened for their PGP traits and biocontrol properties. Among these 40.5% isolates were positive for phosphate solubilization. 36% were positive for IAA production, 4.5% were positive for ammonia production, 19 % were positive for (EXPS), 15.5% were positive for protease production, 12.5% were positive for HCN productions, 9.5 % were positive for cellulase production, 4% were positive for amylase production, 3.5% were positive for chitinase production. For abiotic stress tolerance test, all of the isolates were grown well at 20 o c and 30 o c and neutral pH, 27% isolates were grown well at 4 o c, 25.5% grew at 40 o c, 25.5% were grown well on pH-9 and pH-11, 23.5% were tolerated pH-5, 3.5% grew at 50 o c and 60 o c, 13.5% were grown well on 5% NaCl (w/v), 3.5% were grown well on 10 and 15% NaCl (w/v), which indicated these isolates can survive in some extreme conditions. Totally 15 bacterial species having PGP traits, biocontrol properties, and abiotic stress tolerance ability were identifi ed using the Biolog bacterial identifi cation system. Among these, the majority of the identifi ed PGPR have utilized carbohydrate, carboxylic acid, and amino acid, which are the main components of plant root exudates. The above results indicated that thus PGPR can be used as biofertilizers as well as biocontrol agents to replace agrochemicals to improve crop productivity. Hence, these species can be further formulated and used for greenhouse and fi eld applications.

Use of termitarium soil as a viable source for biofertilizer and biocontrol

“…IAA promotes root development, uptakes nutrients (Carrillo et al 2002), coordinates demand and acquisition of nitrogen and enhances crop yields (Kiba et al 2011). Zerihun et al (2019) reported that IAA is one of the most important phytohormones which may function as an important signal molecule in the regulation of plant growth. IAA values recorded in this study disagree with the report of Devi and Thakur (2018) who recorded IAA potential of the bacterial isolates from their termite mound soil between 0.6 and 47.56 µg/mL.…”

Assessing the potential of phosphate solubilizing bacteria isolated from rhizospheres of Sorghum bicolor grown in Surat, south Gujarat

“…The most efficient rhizospheric PSB identified in the present study using morphological and biochemical characteristics are SB1 Serratia sp., SB3 Staphylococcus sp, SB4 Staphylococcus sp, SB10 Bacillus sp., and SB14 Klebsiella sp., SB17 Proteus sp. are regarded as the major group of plant growth promoting rhizobacteria (PGPR) [19] The rhizobacteria belonging to the genera Azotobacter, Acinetobacter, Klebsiella, Azatobacter, Azatospimillam, etc., have been qualified as good PGPR [20,21,22] . Bacterial treatments are used to assess the plant growth-promoting traits of the rhizobacteria for the selection of the optimal bacterial strains [23] .…”

Screening of Plant-Growth-Promoting Bacterial Isolates from Rhizosphere Soil of Prosopis cineraria from U.A.E.

“…All eleven purified isolates were spot-inoculated on the Pikovskaya's agar plates and incubated at 30 • C overnight. Plates were observed for bacterial growth and development of a zone of clearance [7].…”