Isolation and characterization of acetoin-producing <i>Bacillus</i> species from <i>Salicornia europaea</i> rhizosphere with evaluation of their saline-alkaline adaptation

Yao Li; Hanwen Cui; Enbiao Wang; Tianwen Cao; Yao Meng; Mai Du; Tingting Li; Nan Gao; Yao Li; Hanwen Cui; Enbiao Wang; Tianwen Cao; Yao Meng; Mai Du; Tingting Li; Nan Gao

doi:10.3934/microbiol.2026012

AIMS Microbiology

2026, Volume 12, Issue 2: 282-297. doi: 10.3934/microbiol.2026012

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Research article

Isolation and characterization of acetoin-producing Bacillus species from Salicornia europaea rhizosphere with evaluation of their saline-alkaline adaptation

1.
School of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211816, China
2.
Shenyang Research Institute of Chemical Industry, Shenyang 110021, China

Received: 10 March 2026 Revised: 29 April 2026 Accepted: 06 May 2026 Published: 12 May 2026

Soil salinization is a major constraint on global agricultural productivity, and the application of plant growth‑promoting rhizobacteria offers an important solution for the management and utilization of saline-alkali land. In this study, we aimed to isolate and characterize beneficial rhizobacteria from the halophyte Salicornia europaea growing in coastal saline‑alkali soils, and to evaluate their potential in promoting plant growth under stressful conditions. Among 57 purified bacterial isolates, 3 acetoin‑producing strains, identified as Bacillus sp. HPZ‑9, HPZ‑47, and HPZ‑50, were selected. They produced acetoin at concentrations of 2.30 g·L⁻¹, 2.73 g·L⁻¹, and 2.77 g·L⁻¹, respectively. All strains exhibited broad environmental adaptability, sustaining growth and acetoin production across a pH range of 5–11, NaCl concentrations of 0.3–1.2 mol·L⁻¹, and under moderate drought stress simulated with 20% polyethylene glycol 6000. Notably, HPZ‑9 tolerated NaCl levels up to 2.4 mol·L⁻¹. In pot experiments with maize seedlings, inoculation with these strains significantly increased plant height, stem diameter, leaf length, and fresh and dry biomass of shoots and roots compared to the uninoculated controls (p < 0.05). The most notable improvement was observed in dry biomass, which increased by 49% to 60%. In conclusion, the selected Bacillus strains show strong plant growth‑promoting traits and high tolerance to saline‑alkaline stress. These findings highlight their potential as effective microbial inoculants for promoting crop health and improving saline-alkali soils.
- Salicornia sp.,
- acetoin-producing bacteria,
- Bacillus,
- PGPR,
- saline‑alkali soil
Citation: Yao Li, Hanwen Cui, Enbiao Wang, Tianwen Cao, Yao Meng, Mai Du, Tingting Li, Nan Gao. Isolation and characterization of acetoin-producing Bacillus species from Salicornia europaea rhizosphere with evaluation of their saline-alkaline adaptation[J]. AIMS Microbiology, 2026, 12(2): 282-297. doi: 10.3934/microbiol.2026012

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Abstract

Soil salinization is a major constraint on global agricultural productivity, and the application of plant growth‑promoting rhizobacteria offers an important solution for the management and utilization of saline-alkali land. In this study, we aimed to isolate and characterize beneficial rhizobacteria from the halophyte Salicornia europaea growing in coastal saline‑alkali soils, and to evaluate their potential in promoting plant growth under stressful conditions. Among 57 purified bacterial isolates, 3 acetoin‑producing strains, identified as Bacillus sp. HPZ‑9, HPZ‑47, and HPZ‑50, were selected. They produced acetoin at concentrations of 2.30 g·L⁻¹, 2.73 g·L⁻¹, and 2.77 g·L⁻¹, respectively. All strains exhibited broad environmental adaptability, sustaining growth and acetoin production across a pH range of 5–11, NaCl concentrations of 0.3–1.2 mol·L⁻¹, and under moderate drought stress simulated with 20% polyethylene glycol 6000. Notably, HPZ‑9 tolerated NaCl levels up to 2.4 mol·L⁻¹. In pot experiments with maize seedlings, inoculation with these strains significantly increased plant height, stem diameter, leaf length, and fresh and dry biomass of shoots and roots compared to the uninoculated controls (p < 0.05). The most notable improvement was observed in dry biomass, which increased by 49% to 60%. In conclusion, the selected Bacillus strains show strong plant growth‑promoting traits and high tolerance to saline‑alkaline stress. These findings highlight their potential as effective microbial inoculants for promoting crop health and improving saline-alkali soils.

Acknowledgments

This study was supported by the National Natural Science Foundation of China (32172673), and the Chinese Academy of Sciences.

Conflict of interest

There are no conflicts of interest.

Author contributions

Yao Li (Writing original draft, Methodology, Data curation, Investigation, Writing review & editing); Hanwen Cui (Data curation, Formal analysis, Investigation, Writing review & editing); Enbiao Wang (Data curation, Investigation, Methodology); Tianwen Cao (Data curation, Investigation, Methodology); Yao Meng (Investigation, Data curation, Software); Mai Du (Investigation, Data curation, Software); Tingting Li (Conceptualization, Funding acquisition, Supervision); Nan Gao (Conceptualization, Funding acquisition, Resources, Supervision, Writing review & editing).

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