Despite being one of the most abundant elements in soil, phosphorus (P) often becomes a limiting macronutrient for plants due to its low bioavailability, primarily locked away in insoluble organic and inorganic forms. Phosphate solubilizing and mineralizing bacteria, also called phosphobacteria, isolated from P-deficient soils have emerged as a promising biofertilizer alternative, capable of converting these recalcitrant P forms into plant-available phosphates. Three such phosphobacteria strains - Serratia sp. RJAL6, Klebsiella sp. RCJ4, and Enterobacter sp. 198 - previously demonstrated their particular strength as plant growth promoters for wheat, ryegrass, or avocado under abiotic stresses and P deficiency. Comparative genomic analysis of their draft genomes revealed several genes encoding key functionalities, including alkaline phosphatases, isonitrile secondary metabolites, enterobactin biosynthesis and genes associated to the production of indole-3-acetic acid (IAA) and gluconic acid. Moreover, overall genome relatedness indexes (OGRIs) revealed substantial divergence between Serratia sp. RJAL6 and its closest phylogenetic neighbors, Serratia nematodiphila and Serratia bockelmanii. This compelling evidence suggests that RJAL6 merits classification as a novel species. This in silico genomic analysis provides vital insights into the plant growth-promoting capabilities and provenance of these promising PSRB strains. Notably, it paves the way for further characterization and potential application of the newly identified Serratia species as a powerful bioinoculant in future agricultural settings.

Application of native PGPR as bio inoculant is an alternative sustainable agricultural practice to enhance crop productivity, grain quality, and soil fertility. In this view, a study was to examine the effect of either individual or consortium PGPR inoculation on growth, yield, and grain nutrient uptake of two teff varieties. The pot experiment was carried out in (CRD) three replication and 10 treatments. The PGPR inoculants used in this study were Pseudomonas fluorescens biotype G, Enterobacter cloacae ss disolvens, and Serratia marcescens ss marcescen and their consortium. Dukem and Magna varieties were used in this study. The results of the analysis of variance showed significant differences (P ≤ 0.001) among the treatment and most of the agronomic traits except number of fertile tillers and also significant different (P ≤ 0.01) for grain P and N uptake. The variety was significantly affected grain Mg, Zn and Fe uptake at 5 % probability level and did not significantly influence all agronomic traits of the two varieties. Furthermore, interaction effects of two factors (TM*VT) were significant differences (P ≤ 0.05) for plant height and panicle length. Individual treatments mean comparison results showed that inoculation of native PGPR consortium significantly affected most of the PGP traits at (P ≤ 0.05). The maximum traits like plant height (189cm), panicle length (66.7cm), shoot dry biomass (9.98g), root dry biomass (2.90g) and grain yield per plant (4.55g) were observed from Dz-01-196. It could be concluded that the consortium of native PGPR inoculants for plant growth, yield and grain nutrient uptake improvement performed better than their individual strain.

The climate and its changes are major risk factors for agricultural activities because agricultural systems are highly affected by climatic factors such as temperature, rain, humidity, wind, and solar radiation. While some agricultural areas of the world are irrigated, the vast majority rely on natural rainfall patterns. Farmers will consume more water as a result of climate change and experience less water availability, resulting in a decrease in production capacity. As one of the most important natural phenomena affecting agricultural productivity, drought is a limiting environment for plant growth. The response of plants to water stress is complex and involves coordination between gene expression and its integration with hormones. It has been shown that bacteria have mechanisms to reduce water stress in these plant species and promote greater growth. The underlined mechanism involves root-to-shoot phenotypic changes in growth rate, architecture, hydraulic conductivity, water conservation, plant cell protection, and damage restoration through integrating phytohormones modulation, stress-induced enzymatic apparatus, and metabolites. This review demonstrates how plant growth-promoting bacteria can mitigate negative effects associated with water stress in plants and provide examples of technology conversion in agroecosystems.

Salinity is one of the major factors responsible for the deterioration of soils, making them unsuitable for agriculture. The application of halotolerant and halophilic plant growth promoting bacteria (PGPR: Plant Growth Promoting Rhizobacteria) with biological control activities as an inoculant of cultivated plants offers a biological alternative to the use of agrochemicals, particularly when subjected to salt stress. In this perspective, 70 bacterial strains were isolated from saline soils (sebkha) in arid and semi-arid areas of eastern Algeria. Three isolates were selected based on their ability to produce bioactive molecules allowing them to promote plant growth, such as hydrolytic enzymes, indole acetic acid, HCN, NH3, etc. Two of these isolates belong to the genus Serratia and the third is a halophilic Halomonas bacteria. These bacteria were identified based on the 16S rDNA sequence. Antagonism tests against phytopathogenic fungi were carried out. The identification of the antifungal molecules produced by these bacteria was done by high performance liquid chromatography. These bacteria are capable of inhibiting mycelial development against phytopathogenic fungi with rates reaching 80.67% against Botrytis cinerea, 76.22% against Aspergillus niger and 66.67% against Fusarium culmorum for Serratia sp. The strain Halomonas sp. inhibited mycelial growth by production of volatile substances of Aspergillus niger at 71.29%, Aspergillus flavus at 75.49% and Penicillium glabrum at a rate of 72.22%. The identification by HPLC of the antifungal molecules produced by these three bacteria reveals that they are polyphenols, which makes these strains the first rhizobacteria capable of producing phenolic compounds. Finally, pot tests to determine the effectiveness of these strains in promoting wheat growth under salinity stress (125 mM, 150 mM and 200 mM) were carried out. The results revealed that a consortium of two isolates (Serratia sp. and Halomonas sp.) performed best at 125 mM. But, at higher concentrations it was the halophilic bacteria Halomonas sp which gave the best result. In all cases, there was a significant improvement in the growth of wheat seedlings inoculated with the bacteria, compared to non-inoculated controls.