Research Article Isolation and Characterization of Plant Growth-Promoting Rhizobacteria from Coffee Plantation Soils and Its Influence on Maize Growth Yasin Ahmed Waday , 1 Ermias Girma Aklilu, 1 Mohammed Seid Bultum, 1 Venkata Ramayya Ancha, 2 and Dejene Beyene 3 1 School of Chemical Engineering, Jimma Institute of Technology, Jimma University, Jimma 378, Ethiopia 2 Faculty of Mechanical Engineering, Jimma Institute of Technology, Jimma University, Jimma 378, Ethiopia 3 Faculty of Civil and Environmental Engineering, Jimma Institute of Technology, Jimma University, Jimma, Po Box-378, Ethiopia Correspondence should be addressed to Yasin Ahmed Waday; yasinbiochem@gmail.com Received 26 January 2022; Revised 8 May 2022; Accepted 6 June 2022; Published 6 July 2022 Academic Editor: Balram Ambade Copyright © 2022 Yasin Ahmed Waday et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Plant growth-promoting rhizobacteria (PGPR) are an important bacterial resource as biofertilizers, which can promote plant growth and increase crop yields. In this study, isolation, characterization, and its effect on plant promotion were assessed by isolating PGPR using soil samples collected from Jimma, Ethiopia. Out of 10 isolates, three of them (JEC3, JEC4, and JEC7) exhibited PSB traits in Pikovskaya media by solubilizing phosphate and producing IAA. Of the three isolates, JEC4 recorded the maximum phosphate solubilization index (4.98), soluble phosphate (283 μg/ml), and IAA production (10.21 μg/ml). e findings of the isolates' mor- phological and biochemical tests showed that JEC3, JEC4, and JEC7 as Bacillus sp., Pseudomonas sp., and Enterobacter sp., re- spectively. e optimization of phosphate solubilization was done using different incubation times and sources of carbon and nitrogen. Furthermore, the isolate (JEC4) was tested for plant growth-promoting (PGP) activities and indicated the production of ammonia, hydrogen cyanide, and siderophore. JEC4 isolate showed a significant increase in sideways (%) seed germination, root and shoot length, fresh and dry weight of root, and shoot of maize in field experiments than the untreated ones. e results indicate that the JEC4 isolate can be developed as a biological fertilizer for promoting crop productivity and ecosystem dynamics. 1. Introduction Soil is the reservoir for a variety of microorganisms that have formed a complex interactive network [1]. Plant nutrient acquisition can be improved by soil microorganisms. ey are capable of solubilizing and altering insoluble soil phosphorus to soluble forms for improving the growth of plants [2]. Among others, the rhizosphere exists around or on the root surface of the plants that supports the growth of plants by increasing plant biomass, nutrient efficiency, and crop yields [1, 3]. e bacteria that support the plant growth are known as plant growth-promoting rhizobacteria (PGPR), and these also act as phosphate-solubilizing bac- teria (PSB) [4]. Phosphorus (P) is the second-most plant-essential macronutrient present in the soil after nitrogen and is found in organic and inorganic forms, which might be both in- soluble or very poorly soluble inorganic forms [5]. Most of the P occurs in insoluble form as iron and aluminum phosphates in acidic soils and calcium phosphates in alkaline soils. Some of them appear after the application of chemical fertilizers. Due to the formation of insoluble iron and alu- minum phosphates in acidic soils and calcium phosphates in alkaline soils, the deficiency of P occurs in soil [6]. To handle the P deficiency in different crops, chemical phosphate fertilizers are regularly added in various amount to the soil. However, this applied P is precipitated into an insoluble and stable form soon after the application and is available to Hindawi Applied and Environmental Soil Science Volume 2022, Article ID 5115875, 8 pages https://doi.org/10.1155/2022/5115875