Soil salinity has emerged as a major obstacle to meet world food demands. Halo-tolerant plant growth promoting rhizobacteria (PGPR) are potential bioinoculants to enhance crop productivity in saline agriculture. Current work was aimed at studying individual or synergetic impact of salt tolerant PGPR on wheat growth and yield under saline conditions. A pot experiment was conducted on two wheat genotypes (Aas-11; salt tolerant and Galaxy-13; salt sensitive) inoculated with Pseudomonas fluorescence, Bacillus pumilus , and Exiguobacterium aurantiacum alone and in consortium. The salt tolerant variety (Aas-11) exhibited maximum root fresh (665.2%) and dry biomass (865%), free proline (138.12%) and total soluble proteins (155.9%) contents, CAT (41.7%) activity and shoot potassium uptake (81.08%) upon inoculation with B. pumilus , while improved shoot dry weight (70.39%), water (23.49%) and osmotic (29.65%) potential, POD (60.51%) activity, enhanced root potassium (286.36%) and shoot calcium (400%) were manifested by E. aurantiacum. Highest shoot length (14.38%), fresh weight (72.73%), potassium (29.7%) and calcium (400%) acquisition as well as glycinebetaine (270.31%) content were found in plants treated with PGPR consortium. On the other hand, in the salt sensitive variety (Galaxy-13), P. fluorescens treated plants showed significantly improved leaf-water relations, glycinebetaine (10.78%) content, shoot potassium (23.07%), root calcium (50%) uptake, and yield parameters, respectively. Plant root length (71.72%) and potassium content (113.39%), root and shoot fresh and dry biomass, turgor potential (231.02%) and free proline (317.2%) content were maximum upon PGPR inoculation in consortium. Overall, Aas-11 (salt tolerant variety) showed significantly better performance than Galaxy-13 (salt sensitive variety). This study recommends B. pumilus and E. aurantiacum for the salt tolerant (Aas-11) and P. fluorescens for the salt sensitive (Galaxy-13) varieties, as potential bioinoculants to augment their growth and yield through modulation of morpho-physiological and biochemical attributes under saline conditions.

Chromium is a known heavy metal and recognized as a carcinogen to the biological systems. Previously isolated Cr (VI) resistant Exiguobacterium UE1 and UE4 were used in this study. These strains were analysed for exopolysaccharides (EPS) production for the remediation of Cr (VI) contaminated soils. Both the strains could tolerate about 250µg/ml of Cr (VI) stress. Strain UE1 showed 100% Cr (VI) removal whereas UE4 reduced 99.2% at an initial concentration of K2CrO4 100µgml-1. Optimum growth was observed at 37ºC and pH 7 for both strains. Strains exhibited significant EPS production under Cr (VI) stress and non-stress conditions. However, UE1 showed increased production of released as well as loosely bound EPS (0.36g/100ml and 0.152g/100ml respectively) under Cr (VI) supplemented condition. Thin Layer Chromatography (TLC) technique confirmed the presence of sugars in EPS samples after hydrolysis. Fourier Transforms Infrared Spectroscopy (FTIR) analysis showed the involvement of various functional groups such as hydroxyl group and aromatic compounds in the binding of Cr (VI) ions to the EPS. These findings suggest that strains UE1 and UE4 isolated from local tanneries of Pakistan can be used for remediation of Cr (VI) pollutes soils.

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Citrobacter braakii AN-PRR1 is a potential salt-tolerant, plant growth-promoting rice rhizobacterium isolated from Pakistani soil. The 4.9-Mb draft genome sequence contributes to its taxonomic classification and will reveal the genes putatively responsible for its osmoprotectant and plant growth-promoting activity.