Screening and Growth-promoting Characteristics of Multifunctional Exopolysaccharides-producing Bacteria

doi:10.13560/j.cnki.biotech.bull.1985.2023-0942

Abstract

Abstract:

【Objective】 To explore the effect of exopolysaccharides-producing strains in promoting plant growth and improving soil properties in saline soils, which may lay a foundation for the development of microbial bacterial agents applicable to saline soil remediation.【Method】 Strains with high-yield exopolysaccharide were isolated from the rhizosphere soil of saline-alkali grassland in Kashi, Xinjiang, and species identification was performed based on 16S rRNA gene sequence comparison and phylogenetic analysis. Moreover, the single factor and response surface method were used to optimize the medium components of the excellent strains to increase the yield of exopolysaccharides, and its effects on plant seedlings cultivated in saline-alkali soil and soil aggregate formation were verified by inoculation test.【Result】 A total of 19 exopolysaccharides-producing strains were screened, which were divided into 7 genera, of which Pseudomonas were the dominant. The exopolysaccharides yield was 236-1 544 mg/L, especially Pantoea sp. MQ A0. In addition, MQ A0 was capable of nitrogen fixation, indole-3-acetic acid（IAA）secretion, siderophores production and phosphorus solubilization. The optimal fermentation medium of MQ A0 was 12.5 mL/L glycerol, 9.0 g/L peptone, 5.5 g/L yeast exact and 5.1 g/L CaCO₃. Compared with the initial fermentation process, the exopolysaccharides yield reached 2 436 mg/L, which increased by 57.8%. Pot experiments showed that the inoculation of Zea mays with the fermentation broth of MQ A0 had a significant promoting effect on seedling in saline-alkali soil, including the development of plant height, fresh weight, stem diameter, root number and total root length, which increased by 41.2%, 203.0%, 42.7%, 30.4%, 99.7%, respectively. And the formation of soil aggregate was significantly promoted by the EPS（P<0.05）.【Conclusion】 The high-yield exopolysaccharide strain MQ A0 had various growth-promoting properties, and showed positive effects on plant growth and soil improvement in saline-alkali soil.

Key words: exopolysaccharides-producing strains, saline-alkali grassland, response surface method, saline-alkali soil, soil aggregate

CHANG Hai-xia, LI Ming-yuan, MAIRIYANGU·Yasheng , ZHOU Qian, WANG Ji-lian. Screening and Growth-promoting Characteristics of Multifunctional Exopolysaccharides-producing Bacteria[J]. Biotechnology Bulletin, 2024, 40(3): 273-285.

Figures/Tables 10

References 41

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编号 Strain No.	多糖产量Exopolysaccharides yield/（mg·L^-1）	固氮Nitrogen fixation	IAA分泌量 IAA concentration/ （µg·mL^-1）	产铁载体Siderophore	无机磷含量Inorganic phosphate solubility /（mg·L^-1）	有机磷含量 Organic phosphate solubility/ （mg·L^-1）
A1	302±2.83	-	7.77±2.39	+	2.61±1.63	1.26±0.55
B2	241±1.92	+	7.62±1.67	+	1.54±0.56	0.84±0.01
D1	256±0.87	+	8.38±2.26	+	2.24±1.01	0.60±0.03
MQ A0	1544±3.21	+	7.15±2.83	+	9.39±2.34	12.33±3.24
MQ 2-1-1	443±1.44	-	7.00±3.64	-	-	-
MQ 2-1-2	236±2.59	+	5.77±2.11	+	8.92±2.46	11.82±0.94
MQ 2-2	386±4.13	+	6.54±3.39	+	8.59±1.16	6.63±1.64
MQ 2-3	464±0.91	+	3.62±2.71	-	1.63±0.29	0.84±0.22
MQ 2-4	442±1.67	+	10.08±0.84	+	8.59±0.06	14.11±3.51
MQ 5-1	513±4.11	+	7.92±1.94	+	7.33±2.21	7.14±1.61
MQ 5-2	462±3.82	+	11.15±5.36	+	1.91±0.66	6.49±0.34
MQ 5-3	507±4.92	+	7.00±4.15	+	1.49±0.59	7.75±0.93
MQ 5-4	513±5.14	+	5.62±2.89	+	0.65±0.11	7.33±0.36
MQ 5-5	331±3.33	+	5.31±2.14	+	0.44±0.21	8.27±1.24
MQ 5-6	572±1.49	+	5.92±1.27	+	4.06±1.11	8.59±0.94
MQ 5-7	459±3.08	+	5.92±2.98	+	1.82±0.04	10.88±1.07
MQ 7-1	623±3.42	-	4.85±0.13	+	0.33±0.02	2.43±0.04
MQ 7-5	369±1.53	-	10.23±3.64	+	-	2.66±0.26
MQ 7-6	1342±2.67	-	7.31±1.69	+	-	-

编号 Strain No.	多糖产量Exopolysaccharides yield/（mg·L^-1）	固氮Nitrogen fixation	IAA分泌量 IAA concentration/ （µg·mL^-1）	产铁载体Siderophore	无机磷含量Inorganic phosphate solubility /（mg·L^-1）	有机磷含量 Organic phosphate solubility/ （mg·L^-1）
A1	302±2.83	-	7.77±2.39	+	2.61±1.63	1.26±0.55
B2	241±1.92	+	7.62±1.67	+	1.54±0.56	0.84±0.01
D1	256±0.87	+	8.38±2.26	+	2.24±1.01	0.60±0.03
MQ A0	1544±3.21	+	7.15±2.83	+	9.39±2.34	12.33±3.24
MQ 2-1-1	443±1.44	-	7.00±3.64	-	-	-
MQ 2-1-2	236±2.59	+	5.77±2.11	+	8.92±2.46	11.82±0.94
MQ 2-2	386±4.13	+	6.54±3.39	+	8.59±1.16	6.63±1.64
MQ 2-3	464±0.91	+	3.62±2.71	-	1.63±0.29	0.84±0.22
MQ 2-4	442±1.67	+	10.08±0.84	+	8.59±0.06	14.11±3.51
MQ 5-1	513±4.11	+	7.92±1.94	+	7.33±2.21	7.14±1.61
MQ 5-2	462±3.82	+	11.15±5.36	+	1.91±0.66	6.49±0.34
MQ 5-3	507±4.92	+	7.00±4.15	+	1.49±0.59	7.75±0.93
MQ 5-4	513±5.14	+	5.62±2.89	+	0.65±0.11	7.33±0.36
MQ 5-5	331±3.33	+	5.31±2.14	+	0.44±0.21	8.27±1.24
MQ 5-6	572±1.49	+	5.92±1.27	+	4.06±1.11	8.59±0.94
MQ 5-7	459±3.08	+	5.92±2.98	+	1.82±0.04	10.88±1.07
MQ 7-1	623±3.42	-	4.85±0.13	+	0.33±0.02	2.43±0.04
MQ 7-5	369±1.53	-	10.23±3.64	+	-	2.66±0.26
MQ 7-6	1342±2.67	-	7.31±1.69	+	-	-

方差来源Source	平方和Sum of squares	自由度Degree of freedom	均方Mean square	F	P	显著性Significant
Model	4230000	14	302000	41.5	< 0.0001	**
A	1000000	1	1000000	137.23	< 0.0001	**
B	0.75	1	0.75	0.000103	0.992
C	125000	1	125000	17.11	0.001	**
D	4961.33	1	4961.33	0.68	0.4231
AB	421000	1	421000	57.8	< 0.0001	**
AC	15129	1	15129	2.08	0.1716
AD	36	1	36	0.00494	0.945
BC	729	1	729	0.1	0.7564
BD	71022.25	1	71022.25	9.75	0.0075	**
CD	45582.25	1	45582.25	6.26	0.0254	*
A²	790000	1	790000	108.36	< 0.0001	**
B²	1150000	1	1150000	157.42	< 0.0001	**
C²	1200000	1	1200000	164.04	< 0.0001	**
D²	836000	1	836000	114.66	< 0.0001	**

方差来源Source	平方和Sum of squares	自由度Degree of freedom	均方Mean square	F	P	显著性Significant
Model	4230000	14	302000	41.5	< 0.0001	**
A	1000000	1	1000000	137.23	< 0.0001	**
B	0.75	1	0.75	0.000103	0.992
C	125000	1	125000	17.11	0.001	**
D	4961.33	1	4961.33	0.68	0.4231
AB	421000	1	421000	57.8	< 0.0001	**
AC	15129	1	15129	2.08	0.1716
AD	36	1	36	0.00494	0.945
BC	729	1	729	0.1	0.7564
BD	71022.25	1	71022.25	9.75	0.0075	**
CD	45582.25	1	45582.25	6.26	0.0254	*
A²	790000	1	790000	108.36	< 0.0001	**
B²	1150000	1	1150000	157.42	< 0.0001	**
C²	1200000	1	1200000	164.04	< 0.0001	**
D²	836000	1	836000	114.66	< 0.0001	**

处理 Treatment group	株高 Plant height/cm	根长 Root length/cm	须根数 Lateral root number	茎粗 Stem diameter/mm	鲜重 Fresh weight/g	叶绿素含量 Chlorophyll content/（mg·g^-1）
发酵液Fermentation broth	56.60±6.076a	52.78±5.926a	7.50±1.732a	6.25±0.311a	5.03±0.471a	20.80±0.901a
粗多糖 EPS	54.88±5.393a	45.88±2.732b	7.25±1.500a	6.28±0.359a	4.16±0.334a	22.10±1.105a
对照 Control check	40.10±3.340b	26.43±4.378c	5.75±0.957b	4.38±0.427b	1.66±0.236b	13.20±2.150b