Inoculation of Bacillus spp. Modulate the soil bacterial communities and available nutrients in the rhizosphere of vetiver plant irrigated with acid mine drainage

The rhizosphere microbiota contributes immensely to nutrient sequestration, productivity and plant growth. Several studies have suggested that environmental factors and high nutrient composition of plant’s rhizosphere influence the structural diversity of proximal microorganisms. To verify this assertion, we compare the functional diversity of bacteria in maize rhizosphere and bulk soils using shotgun metagenomics and assess the influence of measured environmental variables on bacterial diversity. Our study showed that the bacterial community associated with each sampling site was distinct, with high community members shared among the samples. The bacterial community was dominated by Proteobacteria, Actinobacteria, Acidobacteria, Gemmatimonadetes, Bacteroidetes and Verrucomicrobia. In comparison, genera such as Gemmatimonas, Streptomyces, Conexibacter, Burkholderia, Bacillus, Gemmata, Mesorhizobium, Pseudomonas and Micromonospora were significantly (p ≤ 0.05) high in the rhizosphere soils compared to bulk soils. Diversity indices showed that the bacterial composition was significantly different across the sites. The forward selection of environmental factors predicted N-NO3 (p = 0.019) as the most influential factor controlling the variation in the bacterial community structure, while other factors such as pH (p = 1.00) and sulfate (p = 0.50) contributed insignificantly to the community structure of bacteria. Functional assessment of the sampling sites, considering important pathways viz. nitrogen metabolism, phosphorus metabolism, stress responses, and iron acquisition and metabolism could be represented as Ls > Rs > Rc > Lc. This revealed that functional hits are higher in the rhizosphere soil than their controls. Taken together, inference from this study shows that the sampling sites are hotspots for biotechnologically important microorganisms.

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“…Bacillus, Streptomyces, Pseudomonas and Mesorhizobium have been reported in several studies on maize, chicken pea etc. [ 17 , 50 , 51 , 52 ].…”

Section: Discussionmentioning

confidence: 99%

Metagenomic Insight into the Community Structure of Maize-Rhizosphere Bacteria as Predicted by Different Environmental Factors and Their Functioning within Plant Proximity

Akinola

Babalola

2021

Microorganisms

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“…Strain B2 produced significant amounts of IAA (42.7 μg ml –1 ), which might enhance root growth and enable the plant to uptake more nutrients from soil. Significant amounts of in vitro IAA production by B. amyloliquefaciens have also been documented by Abdallah et al (2018) and Daraz et al (2020) . The production of siderophores by strain B2 might play an important role in promoting plant growth by providing Fe to the plant and by limiting the Fe availability to pathogens.…”

Section: Discussionmentioning

confidence: 94%

Enhanced Biocontrol of Cucumber Fusarium Wilt by Combined Application of New Antagonistic Bacteria Bacillus amyloliquefaciens B2 and Phenolic Acid-Degrading Fungus Pleurotus ostreatus P5

Wang

Cai

et al. 2021

Front. Microbiol.

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Continuous monoculture of cucumber (Cucumis sativus L.) typically leads to the frequent incidence of Fusarium wilt caused by Fusarium oxysporum f. sp. cucumerinum (FOC). As potent allelochemicals, phenolic acids are believed to be associated with soilborne diseases. This study aimed to investigate the effect of single or co-inoculation of antagonistic bacteria Bacillus amyloliquefaciens B2 and phenolic acid-degrading fungus Pleurotus ostreatus P5 on the suppression of cucumber Fusarium wilt. The strain B2 was identified as B. amyloliquefaciens based on biochemical, physiological, and 16S rDNA and gyrB gene sequence analyses. Strain B2 showed indole-3-acetic acid (IAA) and siderophore production and phosphate solubilization in in vitro assays. Scanning electron microscope (SEM) imaging showed the ability of strain B2 to adhere to the root surface of cucumber. P. ostreatus P5 could effectively degrade mixed phenolic acids as its sole source of carbon and energy for growth in liquid medium. In a pot experiment, four treatments were established as follows: (1) CK, uninoculated control; (2) B2, inoculation of strain B2; (3) P5, inoculation of strain P5; and (4) B2 + P5, co-inoculation of strain B2 and strain P5. At the end of the 60-day pot experiment, the B2, P5, and B2 + P5 treatments significantly reduced disease incidence by 48.1, 22.2, and 63.0%, respectively, compared to the CK treatment (p < 0.05). All three inoculation treatments significantly increased the growth of cucumber seedlings and suppressed the FOC population compared to the control (p < 0.05). High-performance liquid chromatography (HPLC) analysis showed that total phenolic acids were decreased by 18.9, 35.9, and 63.2% in the B2, P5, and B2 + P5 treatments, respectively. The results from this study suggest that combined application of B. amyloliquefaciens B2 and P. ostreatus P5 could be a promising strategy for suppressing Fusarium wilt and improving plant growth of cucumber seedlings under continuous cropping conditions.

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“…A previous study by Azri et al [53] found that the positive effects of Bacillus on soil N absorption could be due to its N-fixing ability, and enhancement of the N level in soil and nutrient uptake was also recorded in Bacillus stains inoculation. Daraz et al [54] found that soil AP and AN fractions were positively correlated with inoculation of Bacillus strains, and Bacillus strains improved soil AP, total N, and AN, which was a benefit to promote plant adaptability under stress. These are consistent with our findings.…”

Section: Discussionmentioning

confidence: 99%

Bacillus Co-Inoculation Alleviated Salt Stress in Seedlings Cucumber

Lin

Gong

et al. 2021

Agronomy

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Soil salinity has become a serious threat to crop growth and productivity and has aggravated the gap between sustainable food supply and population growth. Application of plant growth-promoting rhizobacteria (PGPR) has emerged as a novel way of alleviating the harmful effects of salt stress and improving soil nutrients. The aim of this study was to study the effects of exposure cucumber seedlings at one co-inoculation of Bacillus licheniformis and B. subtilis, a mitigation of salt stress in cucumber seedlings. In this study, we isolated salt tolerant (NX-3 and NX-4) and growth-promoting (NX-48, NX-59, and NX-62) bacteria from the rhizosphere of cucumber. NX-3 and NX-59 were identified as B. licheniformis, and NX-4, NX-48 and NX-62 were identified as B. subtilis. Under salt stress, relative to non-inoculation, co-inoculation with B. licheniformis and B. subtilis increased stem diameter and plant fresh weight. Moreover, the concentration of substrate available phosphorus increased (except for NX4-59). The catalase and sucrase activities of NX4-62 were the highest. Meanwhile, NX3-62 and NX3-59 had the highest phosphorus content and NX3-59 had the highest urease activities. Comprehensive analysis indicated that NX4-62 and NX3-59 showed the best effect on promoting cucumber seedlings growth, activating substrate nutrients, and alleviate salt stress in seedlings of cucumber.

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Inoculation of Bacillus spp. Modulate the soil bacterial communities and available nutrients in the rhizosphere of vetiver plant irrigated with acid mine drainage

Cited by 32 publications

References 50 publications

Metagenomic Insight into the Community Structure of Maize-Rhizosphere Bacteria as Predicted by Different Environmental Factors and Their Functioning within Plant Proximity

Metagenomic Insight into the Community Structure of Maize-Rhizosphere Bacteria as Predicted by Different Environmental Factors and Their Functioning within Plant Proximity

Enhanced Biocontrol of Cucumber Fusarium Wilt by Combined Application of New Antagonistic Bacteria Bacillus amyloliquefaciens B2 and Phenolic Acid-Degrading Fungus Pleurotus ostreatus P5

Bacillus Co-Inoculation Alleviated Salt Stress in Seedlings Cucumber

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