A Bacterium Isolated From Soil in a Karst Rocky Desertification Region Has Efficient Phosphate-Solubilizing and Plant Growth-Promoting Ability

Abstract

Phosphorus in the soil accessible to plants can easily be combined with calcium ion, the content of which is high in karst rocky desertification (KRD) regions, thereby resulting in a low utilization efficiency of phosphorus. The application of phosphate-solubilizing bacteria (PSB) from the KRD region would facilitate enhanced phosphate availability in the soil. In the present study, the strains belonging to Acinetobacter, Paraburkholderia, and Pseudomonas with efficient phosphate-solubilizing ability were isolated from fruit tree rhizosphere soils in KRD regions. Particularly, Acinetobacter sp. Ac-14 had a sustained and stable phosphate-solubilizing ability (439–448 mg/L, 48–120 h). Calcium carbonate decreased the phosphate-solubilizing ability in liquid medium; however, it did not affect the solubilization index in agar-solidified medium. When cocultivated with Arabidopsis thaliana seedling, Ac-14 increased the number of lateral roots, fresh weight, and chlorophyll content of the seedlings. Metabolomics analysis revealed that Ac-14 could produce 23 types of organic acids, majorly including gluconic acid and D-(-)-quinic acid. Expression of Ac-14 glucose dehydrogenase gene (gcd) conferred Pseudomonas sp. Ps-12 with a sustained and stable phosphate-solubilizing ability, suggesting that the production of gluconic acid is an important mechanism that confers phosphate solubilization in bacteria. Moreover, Ac-14 could also produce indole acetic acid and ammonia. Collectively, the isolated Ac-14 from KRD regions possess an efficient phosphate-solubilizing ability and plant growth-promoting effect which could be exploited for enhancing phosphorus availability in KRD regions. This study holds significance for the improvement of soil fertility and agricultural sustainable development in phosphorus-deficient KRD regions.

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

“…The inoculation of PSB can alter community function of soybean rhizosphere bacteria and increase P-cycling-related gene abundance and thus enhance vegetation properties ( 24 ). Previous reports have also reported that inorganic phosphate-solubilizing bacteria can release oxalic, lactic, malic, citric, succinic, and indole-3-acetic acid to enrich soluble P levels ( 9 , 23 , 53 , 57 ). The gcd -harboring bacteria can release gluconic acid via oxidizing gluconate by producing gluconate dehydrogenase ( 40 , 57 ).…”

“…Previous reports have also reported that inorganic phosphate-solubilizing bacteria can release oxalic, lactic, malic, citric, succinic, and indole-3-acetic acid to enrich soluble P levels ( 9 , 23 , 53 , 57 ). The gcd -harboring bacteria can release gluconic acid via oxidizing gluconate by producing gluconate dehydrogenase ( 40 , 57 ). Future studies will investigate the growth-promoting performances of Pseudomonas sp.…”

“…strain RS1 for chick pea ( 56 ), Acinetobacter sp. strain Ac-14 for Arabidopsis thaliana ( 57 ), and Pseudomonas monteilii PsF84 for geranium ( 58 ). The inoculation of PSB can alter community function of soybean rhizosphere bacteria and increase P-cycling-related gene abundance and thus enhance vegetation properties ( 24 ).…”

An Enterobacter cloacae strain NG-33 that can solubilize phosphate and promote maize growth

“…In addition, the inoculation of E. cloacae NG-33 strain into sandy soils dramatically increased the soluble phosphate could be mainly attributed to the more production of organic acids (i.e., tartaric acid, oxalic acid, acetic acid, and citric acid) into the rhizosphere to solubilize and release the available P from insoluble P pools. Microbes can solubilize inorganic phosphate compounds in the rhizosphere by releasing a variety of organic compounds into the environment ( Scervino et al, 2010 ; Xie et al, 2021 ). However, the inoculation of NG-33 strain also increased leaf P n and plant biomass in loamy soil without the supplemental TCP, likely due to the high production of IAA (20.4 μg ml −1 ) by NG-33.…”

Genomic Analysis of Pseudomonas asiatica JP233: An Efficient Phosphate-Solubilizing Bacterium

“…Microbial P-solubilization was first reported in the early 20th century, with observations that some bacterial strains isolated from soil were capable of liberating phosphate from bone meal and phosphate ore [ 9 , 10 ]. Subsequently, numerous highly efficient soil-borne phosphorus-solubilizing bacteria (PSB) have been isolated from a range of agricultural and natural environments including diverse rhizosphere soils [ 11 ] and karst rocky deserts [ 12 ]. Phosphate-solubilizing micro-organisms can convert insoluble P into soluble forms (primarily phosphate) that can be readily absorbed and utilized by plants [ 6 ].…”