Search

Soil salinity significantly impacts crop productivity. In response, plant growth-promoting rhizobacteria (PGPR) offer an innovative and eco-friendly solution to mitigate salinity stress. However, research on PGPR's effects on crop physiology under varying salinity levels is still emerging. This study evaluates the impact of five bacterial strains, isolated from compost, on the growth of maize (Zea mays) and tomato (Solanum lycopersicum) plants under different levels of salt stress. This study involved treating maize and tomato seeds with five bacterial strains, and then planting them in a greenhouse under varying salt stress conditions (43 mM, 86 mM, 172 mM, 207 mM NaCl) using a Randomized Complete Block Design. Results showed that bacterial inoculation improved plant growth under saline conditions. S2015-1, S2026-2, and S2027-2 (Bacillus cereus, Acinetobacter calcoaceticus, Bacillus subtilis) were particularly effective in promoting plant growth under salt stress, especially at ionic concentrations of 43 mM and 86 mM, leading to a substantial increase in fresh and dry weight, with strain S2015-1 boosting chlorophyll by 29% at 86 mM in both crops. These results highlight the potential of PGPR to enhance crop resilience and productivity under salinity stress, promoting climate-smart agricultural practices. [ABSTRACT FROM AUTHOR]

Natural amino acids (NAA) have been rarely investigated as chelators, despite their ability to chelate heavy metals (HMs). In the present research, the effects of extracted natural amino acids, as a natural and environmentally friendly chelate agent and the inoculation of Pseudomonas fluorescens (PF) and Micrococcus yunnanensis (MY) bacteria were investigated on some responses of quinoa in a soil polluted with Pb, Ni, Cd, and Zn. Inoculation of PGPR bacteria enhanced plant growth and phytoremediation efficiency. Pb and Cd were higher in quinoa roots, while Ni and Zn were higher in the shoots. The highest efficiencies were observed with NAA treatment and simultaneous inoculation of PF and MY bacteria for Ni, Cd, Pb, and Zn. The highest values of phytoremediation efficiency and uptake efficiency of Ni, Cd, Pb, and Zn were 21.28, 19.11, 14.96 and 18.99 μg g−1, and 31.52, 60.78, 51.89, and 25.33 μg g−1, respectively. Results of present study well demonstrated NAA extracted from blood powder acted as strong chelate agent due to their diversity in size, solubilizing ability, abundant functional groups, and potential in the formation of stable complexes with Ni, Cd, Pb, and Zn, increasing metal availability in soil and improving phytoremediation efficiency in quinoa. NOVELTY STATEMENT: This study focused on an underexplored topic, the potential of natural amino acids (NAA) and plant growth-promoting rhizobacteria (PGPRs) to enhance phytoremediation efficiency of quinoa in a multi-metal contaminated soil with the waste recycling approach. Despite their chelating abilities, NAA have been rarely studied in this context. In the present study, the effects of extracted NAA, acting as environmentally friendly chelating agents, and the inoculation of Pseudomonas fluorescens (PF) and Micrococcus yunnanensis (MY) bacteria were examined on the responses of quinoa in a soil contaminated with Pb, Ni, Cd, and Zn. HIGHLIGHTS: Three agricultural wastes were used to prepare natural amino acids. Natural amino acids caused satisfactory results in remediating HMs-polluted soil and amino acid extracted from blood powder gave the best results. Phytoremediation efficiency depends strongly on the type of metal. Pseudomonas fluorescens and Micrococcus yunnanensis improved remediation performance. [ABSTRACT FROM AUTHOR]

Background: Grass coverage (GC) under no-tillage systems in orchards significantly influences underground carbon (C) and nitrogen (N) sequestration, primarily through promoting mineral nutrient utilization by rhizospheric microorganisms. However, the comprehensive impact of GC on microbial communities and plant responses using soil metabolomics remains inadequately recognized. Methods: We investigated two rhizosphere types established since 2002: bristlegrass (Setaria viridis (L.) P. Beauv.) coverage (SC) and clean cultivation (CC) to assess their effects on soil parameters, enzyme activities, and key pear agronomic traits, including yield (single fruit weight (SFW)) and qualities (soluble solids content (SSC), and total soluble sugar (TSS)). We combined microbiological analysis (16S rRNA sequencing) and non-targeted metabolomics (UPLC-MS/MS and GC-MS) to explore how microbial communities influence fruit agronomic traits and soil nutrient dynamics in pear orchards under SC conditions. Results: Our findings indicate that SC significantly enhances soil organic carbon (SOC), soil organic nitrogen (SON), the C:N ratio, and available nitrogen (AN). Moreover, SC leads to pronounced increases in soil enzyme activities involved in the C cycle and storage, including soil sucrase, β-glucosidase, polyphenol oxidase and cellulase. Microbiome analysis revealed substantial differences in microbial community composition and diversity indices between SC and CC rhizosphere soils within the 0-40 cm depth. Metabolomic analysis demonstrated significant alterations in metabolite profiles across both the 0-20 cm and 20-40 cm layers under SC conditions. The identified metabolites primarily involve sugar and amino acid-related metabolic pathways, reflecting perturbations in C and N metabolism consistent with shifts in bacterial community structure. Several plant growth-promoting rhizobacteria (PGPRs) taxa (e.g., Haliangium, Bacteroides, mle1-7, Subgroup_22, Ellin6067, MND1, Flavobacterium, and Cellvibrio) were enriched under SC, associated with metabolites such as sucrose, N-acetyl-D-glucosamine, N-acetyl-L-glutamic acid, rhamnose, UDP-GlcNAc and D-maltose. These findings suggest their roles in promoting C and N sequestration processes through sucrose synthesis and glycolytic pathways in the soil, which was significantly correlated with the formation of agronomic traits such as fruit yield, SFW SSC and TSS (p<0.05), and SC treatments significantly increased yields by 35.40-62.72% and sucrose content in TSS by 2.43-3.96 times than CC treatments. Conclusion: This study provides valuable insights into the effects of SC on soil microbial communities and plant physiology, enhancing our understanding of their implications for sustainable orchard management. [ABSTRACT FROM AUTHOR]

Copyright of Arab Journal of Plant Protection is the property of Arab Society for Plant Protection and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Prosopis koelziana genus, a member of the Fabaceae family, is crucial to the ecology and economy of arid areas. It is commonly used to restore deserts, forests, and degraded soil with low fertility and high salt concentration. However, recent studies found that the seedlings of P. koelziana are highly susceptible to salinity stress despite having a high tolerance to it. To address this issue, an experiment was conducted to determine if plant growth-promoting rhizobacteria (PGPR) pretreatment and biochar application could enhance the seedlings' tolerance to saline conditions. The research showed that salinity stress decreased seedling growth but increased proline content, soluble sugar content, and antioxidant enzyme activity. Na+ ions increased in plants under salt stress, while K+ ions decreased. The results indicated that the pretreatment of plants with biochar and bacteria increased the fresh weight of seedlings by about 23%, 58%, and 50% in 200, 400, and 600 mM NaCl, respectively, compared with non-pretreated plants. Biochar and bacteria application also increased the proline content by about 62%, 46%, 32%, and 45% in 0, 200, 400, and 600 mM NaCl. This experiment showed that bacteria and biochar pretreatment of plants reduced oxidative stress and sodium uptake (20%, 28%, and 10% decrement of root Na uptake in 200, 400, and 600 mM NaCl). Therefore, these two bio stimulators should be used together for more significant effects on the salinity mitigation of P. Koelziana seedlings and the production of resistant seedlings that have a high ability to transfer to the field. [ABSTRACT FROM AUTHOR]

Zinc oxide nanoparticles (ZnO NPs) are one of the most studied metal oxide NPs (MONPs) owing to their unique physiochemical properties. The last few years have witnessed a growing interest among researchers in adopting the green chemistry approach to fabricate MONPs. We herein report the synthesis of ZnO NPs stabilized by carboxymethyl cellulose (CMC) derived from noxious aquatic weed, i.e., Eichhornia crassipes biomass (EC-CMC). The UV–Vis spectra showed maximum absorbance at ∼380 nm, and the XRD crystallite size of EC-CMC capped ZnO NPs (c-ZnO NPs) (∼26 nm) was smaller as compared to virgin ZnO NPs (v-ZnO NPs) (∼29 nm). The value of apparent strain (εA x 10−3), root mean square strain (E RMS x 10−3), stress (MPa), and energy density (KJm−3) for c-ZnO NPs obtained from the SSP plot was ∼0.893, ∼0.173, ∼116 and ∼51.83 respectively. The study also examined the differential effects of c-ZnO NPs treatment on the growth of two plant growth-promoting rhizobacteria (PGPR), i.e., Pseudomonas fluorescens (Gram -ve), and Bacillus subtilis (Gram +ve). The findings revealed that P. fluorescens (PFL) was more susceptible to c-ZnO NPs than B. subtilis (BST). Furthermore, R. sativus seeds treated with c-ZnO NPs (10–50 ppm) exhibited notable improvements in plumule length, radicle length, vigor index, and biomass content over other treatments and control. The biopriming of R. sativus seeds with PFL and BST showed synergistic effects with 10-ppm c-ZnO NPs treatment and promoted overall seedling growth. The bacterial kinetics and seed germination studies manifest that the c-ZnO NPs at lower doses have growth-promoting effects. The combination of PFL + BST+10-ppm c-ZnO NPs showed substantial improvements in the germination indices of R. sativus. The present work has demonstrated the potential of utilizing positive bipartite interaction of PGPRs and bio-stabilized ZnO NPs to develop nanoformulations promoting plant growth management. [Display omitted] [ABSTRACT FROM AUTHOR]

It is well known that plant-growth-promoting rhizobacteria (PGPRs) increase the tolerance of plants to abiotic stresses; however, the counteraction of Al toxicity has received little attention. The effects of specially selected Al-tolerant and Al-immobilizing microorganisms were investigated using pea cultivar Sparkle and its Al-sensitive mutant E107 (brz). The strain Cupriavidus sp. D39 was the most-efficient in the growth promotion of hydroponically grown peas treated with 80 µM AlCl3, increasing the plant biomass of Sparkle by 20% and of E107 (brz) by two-times. This strain immobilized Al in the nutrient solution and decreased its concentration in E107 (brz) roots. The mutant showed upregulated exudation of organic acids, amino acids, and sugars in the absence or presence of Al as compared with Sparkle, and in most cases, the Al treatment stimulated exudation. Bacteria utilized root exudates and more actively colonized the root surface of E107 (brz). The exudation of tryptophan and the production of IAA by Cupriavidus sp. D39 in the root zone of the Al-treated mutant were observed. Aluminum disturbed the concentrations of nutrients in plants, but inoculation with Cupriavidus sp. D39 partially restored such negative effects. Thus, the E107 (brz) mutant is a useful tool for studying the mechanisms of plant–microbe interactions, and PGPR plays an important role in protecting plants against Al toxicity. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during the two fall seasons 2017 and 2018 aimed to study the irrigation scheduling and the role of plant growth-promoting rhizobacteria (PGPRs) in increasing the availability of nutrient elements as well as some indicators of popcorn maize growth. The Randomized Complete Block Design (RCBD) within the order of split plots including three replicates was used. The experiment included three levels of irrigation applied after depleting 50, 60, and 70% of the available water symbolized by S1, S2 and S3 that represented the main plots, while the subplots included the treatment of bacterial vaccine: without vaccine (control), Azotobacter, Azospirillum and Azotobacter + Azospirillum symbolized by F0, F1, F2 and F3. Results showed the superiority of the irrigation after depleting 50% of the available water in producing the highest percentage of nitrogen and phosphorus that were 0.76 and 0.42 % on average respectively for both seasons, yet in the first season they did not differ significantly from the treatment S2 producing 0.68 and 27.66% of nitrogen and phosphorus, respectively. The depletion treatment S1 (irrigation after depleting 50% of the available water) produced the highest values of root dry weight (26.25 and 27.66 g.plant-1) and leaf area (3562 and 367 cm2) in the two seasons, respectively. Treating by the PGPRs achieved significant responses. The treatment F3 gave the highest percentages of nitrogen (0.72 and 0.81%) and phosphorus (0.38 and 0.43%) in the two seasons respectively and it participated in increasing the dry weight of the root system to be 23.00 and 35.62g in the two seasons respectively compared to the control treatment producing the lowest root dry weight 21.63 and 22.60 g in the two seasons respectively, in addition to the increment in the other studied vegetative traits. We conclude that the PGPR scontributed to limit the harmful effect of water stress through increasing the element availability and enhancing the vegetative growth indicators where the two treatments Azospirillum and Azotobacter + Azospirillum achieved the best contribution. [ABSTRACT FROM AUTHOR]

Abstract Short-term lead (Pb) uptake by plants is important to better understand the mechanisms of metal uptake, plant tolerance and detoxification strategy. Thus we examined the response of Lathyrus sativus to 1 mM Pb application in hydroponic sorption kinetics at 24, 48 and 72 h, and we investigated the contribution of two inocula I1 (R. leguminosarum (M5) + B. simplex + Luteibacter sp + Variovorax sp) and I5 (R. leguminosarum (M5) + P. fluorescens (K23) + Luteibacter sp + Variovorax sp) in plant mechanisms responses. Pb application induced its immediate uptake by L. sativus with highest concentrations, which increased gradually mostly for inoculated plants. The control plant shoots accumulated the highest concentration of lead at 24 h. However, at 48 and 72 h this potential uptake was significantly enhanced in plants inoculated with I5. Moreover, inoculation increased significantly root Pb-uptake with the maximum reached at 72 h. We observed a progressive decline in chlorophyll contents after Pb exposure in control plants that was higher than in PGPR-treated plants and the greatest improvement (152%) was recorded in I5 inoculated leaves. The PGPR also promoted significant elevation in the carotenoid content with the highest increases (188%) in plants inoculated with I5 at 72 h. Data illustrated remarkable augmentation in malondialdehyde, ion leakage level and decrease in membrane stability. Whereas, inoculation enhanced significantly cellular membrane integrity through increases in membrane stability index as compared to the control plants. In response to Pb, proline biosynthesis, as well as total soluble sugars concentration, immediately increased and the stimulatory effect was more pronounced in inoculated plants at 72 h. Lead considerably altered the activities of SOD, GPOX, CAT and APX enzymes in leaves and roots in a time- and inoculation- dependent manner. It is concluded that antioxidant enzymes, carotenoids, soluble sugars and proline were involved in the main defense mechanism and tolerance of Lathyrus sativus to Pb oxidative stress, as well lead accumulation, and are likely to operate in combination. Highlights • The Pb application induced its immediate uptake by L. sativus , which increased gradually for inoculated plants. • Inoculation enhanced cellular membrane integrity through increases in membrane stability and reduces in lipid peroxidation. • Proline, soluble sugars and antioxidant enzymes activities immediately increased after Pb application mainly in inoculated plants. • Antioxidant systems responses and the compatible solutes likely to operate in combination in the main defense mechanism. [ABSTRACT FROM AUTHOR]

Natural sources of water are limited in Egypt. The rapidly growing populations necessitate continuous expansion of the cultivated area. This means an increase of the gap between the demands of water for irrigation and the limited water supply. Looking for other sources such as low quality water like (industrial effluent, drainage and sewage) must be used in irrigation of some garden and wood plants. This investigation was conducted on agricultural drainage wastewater from El Mohete drain (Marioteya Canal) west of Cairo; the samples were collected from different places during (Summer and Winter seasons). The wastewater contaminated with pathogenic microorganisms, the excess of fertilizers (inorganic & organic), heavy metals, and the residuals of pesticides. Plant Growth Promoting Rhizobacteria (PGPR) could remediate the wastewater as biological bioremediation to remove some pollutants such as pathogenic microorganisms, heavy metals and pesticides. Chemical remediation was used as nitrification inhibitor to stop transformation of ammonia to nitrate. This work was conducted to study the ability of PGPR strains e.g. Bacillus megaterium, Bacillus subtillis, Bacillus circulans, Paenibacillus polymyxa, Pseudomonas floresense, Serratia sp. and Azotobacter chroococcum 5, 9 and 23 to treat the drainage water for irrigation the Mentha viridis cv. and Gladiolas grandiflorus cv. plants. Two pot experiments were conducted in greenhouse. The treatments were applied as follows; Natural water, treated water and drainage water to irrigate the plant. Use the PGPR as inoculants and thiourea as nitrification inhibitor, Heavy metal treated was (Copper, Cobalt, Zinc, Cadmium and Mercury) the result showed us heavy metals removal by PGPR from drainage water. The characterizations of PGPRs as shown in the obtained results are they could enhance plant growth by using their own metabolism (solublizing phosphate, producing hormones or fixing nitrogen) as well as correlation of them with the potenit of effects on the growth of plants in unfavorable conditions in order to improve the efficiency of phytoremdiation of contarinated soils. The removal of heavy metals and the elimination of pesticides residues were markedly noticed in this investigation. Results also confirmed the ability of PGPRs in suppressing the effect of pathogenic bacteria like Salmonellasp and E.coli. These abilities are of great importance in terms of plant and soil health. Consequently, the role of PGPRs bacteria associated with plant rhizosphere in remediation of water and soil contaminations due to its biochemical activity and thus, stimulate plant growth is a great important subject in phytoremediation process nowadays. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a toxic, biologically non-essential and highly mobile metal that has become an increasingly important environmental hazard to both wildlife and humans. In contrast to conventional remediation technologies, phytoremediation based on legume-rhizobia symbiosis has emerged as an inexpensive decontamination alternative which also revitalize contaminated soils due to the role of legumes in nitrogen cycling. In recent years, there is a growing interest in understanding symbiotic legume-rhizobia relationship and its interactions with Cd. The aim of the present review is to provide a comprehensive picture of the main effects of Cd in N2-fixing leguminous plants and the benefits of exploiting this symbiosis together with plant growth promoting rhizobacteria to boost an efficient reclamation of Cd-contaminated soils. [ABSTRACT FROM AUTHOR]

High performance liquid chromatographic (HPLC) analysis of culture filtrates of plant growth promoting rhizobacteria (PGPR) and medium of inhibitory zone of interaction of Sclerotium rolfsii with PGPR, viz. Pseudomonas aeruginosa, Pseudomonas fluorescens 4, Pseudomonas fluorescens 4 (new) and Pseudomonas sp. varied from sample to sample. In all the culture filtrates of PGPRs, P. aeruginosa had nine phenolic acids in which ferulic acid (14.52 μg/ml) was maximum followed by other phenolic acids. However, the culture filtrates of P. fluorescens 4 had six phenolic acids with maximum ferulic acid (20.54 μg/ml) followed by indole acetic acid (IAA), caffeic, salicylic, o-coumeric acid and cinnamic acids. However, P. fluorescens 4 culture filtrate had seven phenolic acids in which salicylic acid was maximum (18.03 μg) followed by IAA, caffeic, vanillic, ferulic, o-coumeric and cinnamic acids. Pseudomonas sp. also showed eight phenolic acids where caffeic acid (2.75 μg) was maximum followed by trace amounts of ferulic, salicylic, IAA, vanillic, cinnamic, o-coumeric and tannic acids. The analysis of antibiosis zone of PGPRs showed fairly rich phenolic acids. A total of nine phenolic acids were detected in which caffeic acid was maximum (29.14 μg/g) followed by gallic (17.64 μg/g) and vanillic (3.52 μg/g) acids but others were in traces. In P. aeruginosa, antibiosis zone had seven phenolic acids where IAA was maximum (3.48 μg/g) followed by o-coumeric acid (2.08 μg/g), others were in traces. The medium of antibiosis zone of P. fluorescens 4 and P. fluorescens 4 new had eight phenolic acids in which IAA was maximum with other phenolic acids in traces. [ABSTRACT FROM PUBLISHER]

The effect of two plant growth-promoting rhizobacteria (PGPRs) on the germination and growth of pepper seedlings was investigated in a culture chamber. The two strains showed metabolic capacities related to their potential PGPR action. Two different patterns of inoculation were carried out. In the first, strains were inoculated when seeds were sown, and in the second when seedlings showed fully developed cotyledons. In both cases the following parameters were measured: aerial and root surface, aerial and root length and aerial and root weight. In the first pattern of inoculation no aerial parameters were modified, probably because the bacteria did not colonize the root. In the second pattern of inoculation, all parameters were significantly modified by Chryseobacterium balustinum, except root surface, which indicated that this bacterium was able to colonize the root. Serratia fonticola did not modify any parameter. In both inoculation patterns root length was reduced by both bacteria probably due to a hormonal effect. C. balustinum enhanced aerial surface, aerial length and also the dry aerial and root weight. This resulted in stronger and more robust plants with a higher adaptative capacity and a greater resistance against pathogens. [ABSTRACT FROM AUTHOR]

Biodegradable chelant (S,S)–N,N′ -ethylenediaminedisuccinic acid (EDDS) has the more advantages of enhanced metal mobility, rapid degradation, environmental friendliness, and ammonium release. However, the risk of metal and/or nitrate residues and leaching within EDDS biodegradation remains as the bottleneck for the widespread application of EDDS-induced phytoremediation. This study aims to explore if the inoculation of plant growth-promoting rhizobacteria (PGPRs) can eliminate the risk associated with the short-term application of EDDS by investigating Cu phytoextraction and soil nitrate content. Results showed that EDDS application significantly increased the copper (Cu) concentration in shoots, soil total Cu, NH 4 +-N and NO 3 −-N content, but decreased plant biomass. The inoculation of PGPRs in the soil showed a strong ability to increase plant biomass, Cu phytoextraction and soil NH 4 +-N content, and decrease soil Cu and NO 3 −-N content. Moreover, bacterial dominant taxa were found to be the largest contributors to soil NH 4 +-N and NO 3 −-N variation, and the abundance of denitrifying bacteria (Bacteroidetes and Stenotrophomonas) decreased in the treatment with PGPRs. The risk of residual Cu and nitrate leaching was reduced by the inoculation of PGPRs without significantly changing the stability of the bacterial community. These new findings indicate that the exogenous application of beneficial rhizobacteria can provide an effective strategy to reduce the risk in metal-contaminated soils of chelant-assisted phytoextraction. [Display omitted] • Short-term addition of EDDS increased Cu uptake but inhibited plant growth. • The leaching risk of Cu and/or nitrate was exposed in the EDDS biodegradation. • Soil Cu and NO 3 −-N concentrations were reduced in the presence of PGPRs. • Bacterial dominant taxa were the main contributors to NO 3 −-N variation. • Chelant-PGPRs system minimized environmental risks with enhanced phytoextraction. [ABSTRACT FROM AUTHOR]

• PGPR Consortium to suppress phytopathogens and promote plant growth was developed. • The PGPR consortiums G1 and G2 were plant growth promoters and pathogen suppressors. • From Pot culture, G2 was more effective against phytopathogens and beneficial to plants. • Results indicates Successful pathogen suppression and promotion of plant growth. In this study, we have attempted to develop a plant growth promoting rhizobacteria (PGPR) consortia against early-stage diseases in Arachis hypogaea (Groundnut crop) plantation of Andhra Pradesh, India. The dominant PGPRs were selected by considering the various plant growth and protection qualities, followed by characterisation and grouping based on compatibility to form a consortium of PGPRs [ Group-1 includes EX-1 (Acinetobacter baumannii stain HAMBI 1846); EX-3 (Pseudomonas aeruginosa strain A1K319); EX-5 (Bacillus subterraneus strain CF1.9); KNL-1 (Bacillus subtilis strain JMP-B); CTR-4 (Enterobacter cloacae strain VITKJ1); ANT-4 (Bacillus subtilis strain SBMP4) and Group-2 includes EX-4 (Pseudomonas otitidis strain SLC8); KDP-4 (Pseudomonas aeruginosa strain Kasamber 11); NLR-4 (Bacillus species ADMK68); ANT-6 (Bacillus subtilis subsp. inaquosorum strain KCTC 13429)]. In addition to resistance to early stage pathogens, in both in vitro and pot experiments the PGPR consortium showed significantly higher germination rate and root induction (Aspergillus niger ; A. flavus ; Fusarium oxysporum) when compared to control and fertilizer treated groups. In addition, Group 2 was more successful in stimulating and protecting plant growth among the two groups of PGPRs developed. The PGPR consortia developed showed multiple plant growth characteristics, including phosphate solubilization, production of HCN and Indole acetic acid along with broad antagonism against the tested phytopathogens. [ABSTRACT FROM AUTHOR]

Plant growth-promoting rhizobacteria (PGPR), which include isolates from genera Paraburkholderia, Burkholderia and Serratia, have received attention due to their numerous plant growth-promoting mechanisms such as their ability to solubilize insoluble phosphates and nitrogen-fixation. However, there is a dearth of information on the potential plant growth-promoting effects of these three groups of bacteria on non-legumes such as maize. This study determined the influences of the aforementioned strains on soil properties, maize growth, nutrient uptake and nutrient use efficiency. A pot trial using maize as a test crop was done using a randomized complete block design with 7 treatments each replicated 7 times. The treatments used in this study were: Control (no fertilizer), chemical fertilizer (CF), organic-chemical fertilizers combination without inoculum (OCF) and with inocula consisting of single strains [cellulolytic bacteria (TC), organic fertilizer and chemical fertilizer with N-fixing bacteria (TN), organic fertilizer and chemical fertilizer with P-solubilizing bacteria (TP)) and three-strain inocula (TCNP), respectively. The variables measured included plant growth and nutrient content, soil nutrient content and functional rhizospheric bacterial populations. Paraburkholderia nodosa NB1 and Burkholderia cepacia PB3 showed comparable effects on maize biomass and also improved N and P use efficiencies when compared to full chemical fertilization. Nitrogen-fixing rhizobacteria had a positive effect on above-ground biomass of maize. Paraburkholderia nodosa NB1 improved soil total C and organic matter contents, besides being the only bacterial treatment that improved K use efficiency compared to OCF. The results suggest that P. nodosa NB1 and B. cepacia PB3 have potential usage in bio-fertilizers. In contrast, treatments with Serratia nematodiphila C46d and consortium strains showed poorer maize nutrient uptake and use efficiency than the other single strain treatments. Bacterial treatments generally showed comparable or higher overall N and P use efficiencies than full chemical fertilization. These findings suggest that at least half the amounts of N and P fertilizers could be reduced through the use of combined fertilization together with beneficial bacteria. [ABSTRACT FROM AUTHOR]