Optimization of the Fermentation Process and Plant Growth-Promoting Effects of a Salt-tolerant Microbial Consortium from the Rhizosphere of Elaeagnus angustifolia

doi:10.13560/j.cnki.biotech.bull.1985.2025-1104

Abstract

Abstract:

Objective To investigate the fermentation process of salt-tolerant and plant growth-promoting microbial consortia and evaluate their growth-promoting effects on plants under salt stress, providing theoretical basis for plant cultivation and microbial product development in saline-alkali regions of Xinjiang. Method Two salt-tolerant PGPR (plant growth-promoting rhizobacteria) strains isolated from the rhizosphere of Elaeagnus angustifolia in saline-alkali soil were selected to construct a bacterial consortium. The fermentation medium and culture conditions were optimized using single-factor experiments and Box-Behnken response surface methodology. Biological traits (viable cell count, biomass, and growth kinetics) and plant growth-promoting traits (solubilization of organic, inorganic phosphorus, nitrogen fixation and indole-3-acetic acid (IAA) production) were analyzed before and after optimization. A pot experiment was conducted to assess the consortium's effects on plant height, root length, leaf number, stem diameter, and fresh weight under salt stress. Result The optimal fermentation medium consisted of 14 g/L molasses, 11 g/L peptone, 5 g/L yeast extract, and 5 g/L Na₂HPO₄. Optimal culture conditions were pH 7.0, inoculation volume 10%, incubation temperature 37 ℃, shaking speed 180 r/min, and filling volume 40 mL per 150 mL flask. Under these conditions, viable cell count reached 7.28×10⁹ CFU/mL, representing a 36.04-fold increase over the unoptimized medium, with a shorter lag phase (6 h). The optimized consortium showed enhanced plant growth-promoting activity, with organic phosphorus solubilization, inorganic phosphorus solubilization, nitrogen fixation, and IAA production increased by 56.21%, 44.38%, 69.70% and 64.57%, respectively. Under salt stress, compared with the sterile water control group (CK), the optimized microbial consortium treatment group (FYA) showed significant increases in growth parameters of Elaeagnus angustifolia, with plant height, root length, leaf number, stem diameter, and fresh weight increasing by 63.76%, 34.17%, 36.24%, 71.15%, and 73.68%, respectively. Compared to the unoptimized compound bacterial treatment group (FYB), the FYA group showed improvements of 19.32%, 5.96%, 15.58%, and 17.86% in plant height, root length, stem diameter, and fresh weight, respectively. Conclusion The optimized fermentation process significantly enhanced both the viability and growth-promoting traits of the salt-tolerant microbial consortium, contributing to improved plant growth under salt stress and offering potential for application in saline-affected agricultural systems.

Key words: Elaeagnus angustifolia, salt-tolerant and plant growth-promoting microbial consortium, fermentation medium formulation, culture conditions, response surface methodology, plant growth-promoting effect

DONG Yu-tao, BAO Hui-fang, He Miao, HOU Peng, LI Feng, WANG Zhi-xi, QIN Yao, LUO Qing-hong. Optimization of the Fermentation Process and Plant Growth-Promoting Effects of a Salt-tolerant Microbial Consortium from the Rhizosphere of Elaeagnus angustifolia[J]. Biotechnology Bulletin, 2026, 42(4): 297-309.

Figures/Tables 13

References 36

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菌株编号 Strain code	菌株学名 Strain scientific name	促生特性 Growth-promoting characteristic
SZ1^［9］ CGMCC No.32296	泛菌	固氮，产铁载体，产氨，溶磷，分泌吲哚乙酸
SZ1^［9］ CGMCC No.32296	Pantoea rodasii	Nitrogen fixation， siderophore production， ammonia synthesis， phosphorus solubilization， and indole-3-acetic acid secretion
NY8^［10］ CGMCC No.33699	嗜肉考克氏菌	固氮，产氨，分泌吲哚乙酸
NY8^［10］ CGMCC No.33699	Kocuria carniphila	Nitrogen fixation， ammonia synthesis， and indole-3-acetic acid secretion

菌株编号 Strain code	菌株学名 Strain scientific name	促生特性 Growth-promoting characteristic
SZ1^［9］ CGMCC No.32296	泛菌	固氮，产铁载体，产氨，溶磷，分泌吲哚乙酸
SZ1^［9］ CGMCC No.32296	Pantoea rodasii	Nitrogen fixation， siderophore production， ammonia synthesis， phosphorus solubilization， and indole-3-acetic acid secretion
NY8^［10］ CGMCC No.33699	嗜肉考克氏菌	固氮，产氨，分泌吲哚乙酸
NY8^［10］ CGMCC No.33699	Kocuria carniphila	Nitrogen fixation， ammonia synthesis， and indole-3-acetic acid secretion

因素 Factor	水平 Factor level
因素 Factor	-1	0	1
A：糖蜜 Glycerol （g/L）	5	10	15
B：蛋白胨 Peptone （g/L）	5	10	15
C：酵母粉 Yeastextract （g/L）	4	5	6
D：磷酸氢二钠 Na₂HPO₄ （g/L）	4	5	6

因素 Factor	水平 Factor level
因素 Factor	-1	0	1
A：糖蜜 Glycerol （g/L）	5	10	15
B：蛋白胨 Peptone （g/L）	5	10	15
C：酵母粉 Yeastextract （g/L）	4	5	6
D：磷酸氢二钠 Na₂HPO₄ （g/L）	4	5	6

方差来源 Sources of variance	平方和 Sum of squares	自由度 Degrees of freedom	均方 Mean square	F值 F-value	P值 P-value	显著性 Significance
模型	4.38	14	0.312 7	28.01	<0.000 1	**
A-糖蜜 Molasses	0.622 9	1	0.622 9	55.79	<0.000 1	**
B-蛋白陈 Peptone	0.085 3	1	0.085 3	7.64	0.015 2	*
C-酵母粉 Yease extract	0.165 7	1	0.165 7	14.84	0.001 8	**
D-磷酸氢二钠 Na₂HPO₄	0.053 3	1	0.053 3	4.78	0.046 3	*
AB	0.215 8	1	0.215 8	19.32	0.000 6	**
AC	0.003 8	1	0.003 8	0.344 3	0.566 7	-
AD	0.161 2	1	0.161 2	14.44	0.002 0	**
BC	0.067 3	1	0.067 3	6.03	0.027 7	*
BD	0.313 6	1	0.313 6	28.09	0.000 1	**
CD	0.146 3	1	0.146 3	13.10	0.002 8	**
A²	1.04	1	1.04	92.75	<0.000 1	**
B²	0.927 1	1	0.927 1	83.04	<0.000 1	**
C²	0.845 6	1	0.845 6	75.74	<0.000 1	**
D²	1.16	1	1.16	104.23	<0.000 1	**
残差	0.156 3	14	0.011 2
失拟项	0.145 5	10	0.014 5	5.37	0.059 7
纯误差	0.010 8	4	0.002 7
总和	4.53	28