Biochar-immobilised phosphate-solubilising bacteria enhance soil available phosphorus by affecting phosphorus fraction transformation and phosphorus-acquiring microbiota
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Updated: Oct 30, 2026

Measuring Phosphorus Release in Laboratory Microcosms for Water Quality Assessment
Published on: July 22, 2019
Liuyan Zhou1, Lu Peng2, Johannes Rousk3
1College of Resources and Environment, Southwest University, Chongqing 400715, China; Institute of Microbiology, Xinjiang Uygur Autonomous Region Academy of Agricultural Sciences, Urumqi 830000, China.
Abstract:
Phosphate-solubilising bacteria (PSB) play an important role in phosphorus (P) transformation and plant P uptake. However, their effectiveness is often limited by environmental instability and soil poor survival. Biochar has been proposed as a suitable carrier for microbial immobilisation; however, the effects of biochar-immobilised PSB on soil P fractions and the microbial mechanisms underlying P transformation remain unclear. In this study, we developed a biochar-immobilised PSB using Klebsiella sp. N107 and assessed its effects on soil P availability, P fraction transformation, and microbial processes regulating P cycling. A pot experiment was conducted: no fertilisation, conventional fertilisation (NPK), NPK + pristine biochar (NPKB), NPK + PSB (NPKP), and NPK + biochar-immobilised PSB (NPKBP). Soil properties, P fractions, organic acids, enzyme activities, and metagenomic characteristics were analysed. Compared with NPKB and NPKP, NPKBP enhanced plant P uptake and soil available P. It also increased labile P fractions, organic acid concentrations, and the activities of P acquiring enzymes. Genes associated with P transport (pit, ugpB, ugpQ, and ugpE), polyphosphate degradation (ppk1 and ppk2), organic P mineralisation (phoA and phoD), and inorganic P solubilisation (gcd, ppa, and ppx) were upregulated. P acquiring taxa, including Sphingomonas, Gaiella, and Bradyrhizobium, were enriched and contributed functionally to P cycling. Overall, biochar-immobilised PSB improved soil P availability by promoting P fraction transformation and restructuring microbial communities involved in P cycling. Soil pH, organic acids, and available nitrogen were identified as key drivers of these processes, highlighting the potential of biochar-immobilised PSB to improve soil P utilisation and management.
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