Improving soil phosphorus availability in saline areas by marine bacterium Bacillus paramycoides.

The utilization of phosphate-solubilizing bacteria (PSB) in agriculture has long been proposed as an eco-friendly method to enhance soil phosphorus (P) availability, thereby reducing reliance on chemical P fertilizers. However, their application in saline soils is challenged by salt-induced stress on common PSB strains. In this study, we sourced bacterial strains from marine environments, aiming to identify robust PSB strains adaptable to saline conditions and assess their potential as P bio-fertilizers through a microcosm experiment. Our findings indicate that the inoculation of a selected marine PSB, Bacillus paramycoides 3-1a, increased soil available P content by 12.5% when applied alone and by 61.2% when combined with organic amendments. This enhancement results from improved inorganic P solubilization and organic P mineralization in soils. Additionally, these treatments raised soil nitrogen levels, reshaped microbial community structures, and significantly enhanced wheat (Triticum aestivum L.) growth, with P accumulation increasing by 24.2-40.9%. Our results underscore the potential of marine PSB in conjunction with organic amendments for the amelioration of saline agricultural soils.

Li Z ，Liu Z ，Wang Y ，Wang X ，Liu P ，Han M ，Zhou W ... -  《-》

Phosphate-solubilizing bacteria and silicon synergistically augment phosphorus (P) uptake by wheat (Triticum aestivum L.) plant fertilized with soluble or insoluble P source.

Phosphorus (P) deficiency is one of the major problems in agricultural soils for crop production around the world. Use of silicon (Si) and phosphate-solubilizing bacteria (PSB) is known as one of the most effective and economical ways for increasing P availability and improving P use efficiency under low P conditions. However, little is known about the alleviative role of Si and PSB together in mitigating P-deficiency stress and in improving P use efficiency in Triticum aestivum L. (wheat), as one of the most important crop plants worldwide. Consequently, aim of the research was to study the combined and single effects of Si (0, 150, 300, and 600 mg kg-1 added as silicic acid) and PSB (B0, Bacillus simplex UT1, and Pseudomonas sp. FA1) on P uptake by wheat plant fertilized with soluble or insoluble P (Esfordi rock phosphate, RP) in a completely randomized design with factorial arrangement through a perlite potted experiment. In addition, the effects of various treatments on wheat shoot and root dry weight, activity of catalase, superoxide dismutase, and peroxidase enzymes, and the uptake of Si and potassium (K) by this plant were also investigated. Both shoot and root biomass of wheat plants were markedly reduced when grown in RP-fertilized medium compared with those grown in soluble P-fertilized medium. The PSB strains and Si levels independently improved all the aforementioned parameters. Application of Si to wheat plants grown in soluble P or insoluble P medium markedly enhanced P use efficiency. According to the results of this study, Si not only increased the uptake of P from sparingly soluble-P source (RP), but also enhanced uptake of P from water-soluble P source. Both Pseudomonas sp. FA1 and B. simplex UT1 showed a considerable role in improvement of root and shoot biomass and uptake of P (and K and Si) under both soluble and insoluble P fertilization conditions with Pseudomonas sp. FA1 being more effective than B. simplex UT1. However, the combined application of the PSB with Si resulted in the greatest enhancement in wheat plant P uptake and other measured parameters. Addition of 600 mg Si kg-1 and Pseudomonas sp. FA1 significantly increased the P shoot concentration of wheat plant fertilized with RP to an adequate level (>0.3%) in the range of P-fertilized plants. Therefore, in addition to PSB application, Si should be considered as soil amendment in agricultural soils deficient in plant available Si as a means of sustainable agriculture with respect to possible savings of scarce P resources (P-fertilizers). The information on the availability of P following PSB and Si addition to plant growth medium may help in better management of P fertilization.

Rezakhani L ，Motesharezadeh B ，Tehrani MM ，Etesami H ，Mirseyed Hosseini H ... -  《-》

Screening of phosphate-solubilizing bacteria and their abilities of phosphorus solubilization and wheat growth promotion.

Phosphate-solubilizing bacteria (PSB) can enhance plant growth and phosphorus (P) solubilization, it also has been reported to reduce the negative effects of overused agricultural fertilizer in farmland and protect the soil environment. However, the mechanism behind this interaction has not been fully elucidated. In this study, we screened out Pseudomonas moraviensis, Bacillus safensis, and Falsibacillus pallidus which can both solubilize P efficiently and produce indole-3-acetic acid (IAA) from sandy fluvo-aquic soils. The yield of wheat (Triticum aestivum) under PSB inoculation significantly increased up to 14.42% (P < 0.05) compared with the control treatment in phosphate fertilizer-used farmland. Besides promoting wheat growth, we found the labile P fraction in soil was significantly increased by over 122.04% (P < 0.05) under PSB inoculation compared with it in soils without, in parallel, the stable P fraction was significantly reduced by over 46.89% (P < 0.05). Furthermore, PSB inoculation increased the soil microbial biomass and activity, indicating that PSB screened out in this work performed a remarkable ability to colonize the soils in the wheat field. PSB from sandy fluvo-aquic soil improve wheat growth and crop productivity by increasing the labile P fraction and IAA content in the greenhouse and wheat field. Our work provides an environment and economy-friendly bacterial resource that potentially promotes sustainable agricultural development in the long term.

Wang Z ，Zhang H ，Liu L ，Li S ，Xie J ，Xue X ，Jiang Y ... -  《BMC MICROBIOLOGY》

Comparative efficacy of phosphorous supplements with phosphate solubilizing bacteria for optimizing wheat yield in calcareous soils.

Phosphorus (P) deficiency is the main hurdle in achieving sustainable crop production ps especially in calcareous soils. Using bio-fertilizers like phosphate solubilizing bacteria (PSB) could be a useful approach for sustainable P management as they improve P availability in soil via dissolution, desorption and mineralization reactions. In addition, application of organic amendments with PSB could further ameliorate soil conditions for sustainable management of immobilized nutrients in calcarious soils. Therefore, we performed pot experiment to study the role of PSB in nullifying antagonistic effects of liming (4.78, 10, 15 and 20%) on P availability from poultry manure (PM), farm yard manure (FYM), single super phosphate (SSP) and rock phosphate (RP) in alkaline soils. PSB inoculation improved wheat growth, P availability and stimulated soil acidification over control regardless of P sources and lime levels. Soil calcification adversely affected plant growth, P nutrition, induced soil salinity and alkalinity, however, PSB and manures application potentially nullified such harmful effects over mentioned traits. Individually, organic sources were superior than mineral sources however, the performance of mineral fertilizers with PSB was at par to sole application of manures. Furthermore, application of RP with PSB proved as effective as sole SSP. Therefore, using PSB as bio-fertilizer has huge potential for improving P availability in calcareous soils.

Adnan M ，Fahad S ，Saleem MH ，Ali B ，Mussart M ，Ullah R ，Amanullah Jr ，Arif M ，Ahmad M ，Shah WA ，Romman M ，Wahid F ，Wang D ，Saud S ，Liu K ，Harrison MT ，Wu C ，Danish S ，Datta R ，Muresan CC ，Marc RA ... -  《Scientific Reports》

Integrated application of phosphorus-accumulating bacteria and phosphorus-solubilizing bacteria to achieve sustainable phosphorus management in saline soils.

The challenge of managing agricultural phosphorus (P) in saline regions entails both reducing leaching for environmental protection and maintaining soil available P levels for crop production, which could be achieved through functional microorganisms that can facilitate P transformation processes like P assimilation, inorganic P solubilization, and organic P mineralization. In this study, we proposed an integrated utilization of phosphorus-accumulating bacteria (PAB) and phosphorus-solubilizing bacteria (PSB) to reach the goal of alleviating P leaching while improving soil available P levels. The study conducted a microcosm experiment that combined a soil column test, soil incubation, and pot experiment to evaluate the effect of bacterial inoculants on soil P leaching, soil P availability, and plant P accumulation. The results showed that the application of PAB reduced 22.6 % of dissolved P leaching through the absorption of labile phosphate in the soil, and 17.3 % of particulate P leaching through the promoted soil aggregation. The integrated inoculation of PSB and PAB synergistically improved soil available P content by 18.3 % through the mineralization of soil organic P, and remarkably boosted wheat growth and its P accumulation. Microbial community analysis revealed that the integrated microbial treatment decreased the diversity of soil bacterial community and increased the abundance of native microbial species, i.g. Lysobacter and Ramlibacter, which were positively correlated with soil available P content and alkaline phosphatase level. In conclusion, the integrated microbial strategy based on halotolerant PAB and PSB has great potential for sustainable P management in saline areas and agricultural activities.

Li Z ，Wang Y ，Liu Z ，Han F ，Chen S ，Zhou W ... -  《-》