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 ... -  《-》

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 ... -  《-》

Distribution of Culturable Phosphate-Solubilizing Bacteria in Soil Aggregates and Their Potential for Phosphorus Acquisition.

He D ，Wan W 《Microbiology Spectrum》

Identification of the Phosphorus-Solubilizing Bacteria Strain JP233 and Its Effects on Soil Phosphorus Leaching Loss and Crop Growth.

Phosphorus (P) is one of the most limiting nutrients in global agricultural ecosystems, and phosphorus-solubilizing bacteria (PSB) can convert insoluble P into soluble P, thereby improving the absorption and use of soil P by plants. Increasing leaching loss of soil P due to PSB that could lead to water eutrophication is a major concern, although no direct experimental evidence is available to evaluate these effects. In this study, a highly efficient PSB strain, Pseudomonas sp. JP233, was isolated from soil and its P-solubilizing agent was identified by metabolomics and HPLC analyses. The effects of JP233 on P contents in soil leachates were also analyzed by microcosm leaching experiments in the absence and presence of maize. JP233 could solubilize insoluble P into soluble forms, and the molybdate reactive phosphorus (MRP) content reached 258.07 mg/L in NBRIP medium containing 5 g/L Ca3(PO4)2 within 48 h. Metabolomics analysis demonstrated that the organic acid involved in JP233 P solubilization was primarily 2-keto gluconic acid (2KGA). Further, HPLC analysis revealed that 2KGA contents rapidly accumulated to 19.33 mg/mL within 48 h. Microcosm leaching experiments showed that MRP and total phosphorus (TP) contents in soil leaching solutions were not significantly higher after JP233 inoculation. However, inoculation with JP233 into maize plant soils significantly decreased MRP and TP contents in the soil leaching solutions on days 14 (P < 0.01), 21 (P < 0.01), and 28 (P < 0.05). Inoculation with strain JP233 also significantly increased the biomass of maize aerial components and that of whole plants (P < 0.05). Thus, strain JP233 exhibited a significant plant-growth-promoting effect on maize development. In conclusion, the application of PSB into soils does not significantly increase P leachate loss. Rather, the application of PSB can help reduce P leachate loss, while significantly promoting plant absorption and use of soil P.

Yu H ，Wu X ，Zhang G ，Zhou F ，Harvey PR ，Wang L ，Fan S ，Xie X ，Li F ，Zhou H ，Zhao X ，Zhang X ... -  《Frontiers in Microbiology》

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》