Isolation and whole-genome analysis of a multifunctional strain zafu-111 for phosphate-solubilizing in the rhizosphere of <i>Phyllostachys edulis</i>.

The deficiency of soil available phosphorus (P) is a key factor restricting the productivity and ecological function of Moso bamboo (<i>Phyllostachys edulis</i>) forest. It is thus important to explore the resources of rhizosphere P-solubilizing bacteria (PSB) and their solubilizing mechanisms for green and efficient cultivation of Moso bamboo forest. In this study, we isolated PSB from the rhizosphere using high-throughput screening method, and investigated its P-solubilizing activity under various carbon sources. We analyzed the genes involved in P cycling by whole-genome sequencing technology. An inoculation experiment was conducted to explore the P-solubilizing ability of the strain in soils with long-term P addition (100 kg P·hm^-2·a^-1). The highly efficient P-solubilizing bacterium, zafu-111, isolated from the rhizosphere, was identified as <i>Burkholderia cepacia</i>. The strain mainly utilized four kinds of carbon sources, such as glucose and citric acid to dissolve three inorganic P (Ca₃(PO₄)₂, FePO₄, AlPO₄) and two organic P (lecithin and calcium phytate), with a maximum activity of 54.55 mg·L^-1·d^-1. The strain zafu-111 possessed four categories of functional genes involved in soil P cycling, such as inorganic P solubilization, organic P mineralization, P transportation, and P starvation regulation. The strain contained 41 coding genes for organic acid metabolism (such as <i>gltA</i> and <i>ppa</i>) and 45 genes regulating phosphatase synthesis (including <i>phoA</i> and <i>phoD</i>). Additionally, strain zafu-111 could produce IAA, secrete siderophores, decompose lignin and calcium silicate. After 30 d inoculation, strain zafu-111 increased acid phosphatase activity by 34.4% and elevated available P content by 21.6% in the control, but decreased both by 5.9% and 6.8% in the P addition group. After 90 d inoculation, soil pH in the control increased by 0.03 units with no significant change in available P content; P addition increased pH by 0.06 units and available P by 35.4%. Overall, strain zafu-111 improved the dissolution of insoluble P through utilizing various carbon sources, and possessed abundant functional genes and traits associated with plant growth-promoting. These characteristics of strain provide significant potential for alleviating P stress in Moso bamboo forests and developing microbial fertilizers.