Abstract
(1) Background: Overuse of chemical nitrogen fertilizers drives the need for biological alternatives. Azotobacter chroococcum is a promising free-living nitrogen-fixing bacterium, but its efficiency needs improvement. This study investigated how Fe3O4 nanoparticles (Fe3O4 NPs) and molybdenum trioxide nanoparticles (n-MoO3) affect A. chroococcum growth and nitrogen fixation, and tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume); (2) Methods: In vitro tests measured bacterial growth, viable counts (CFU), nitrogenase activity, and nitrogen metabolites (total N, NO3−-N, NH4+-N) under 0–100 ng·mL−1 Fe3O4 NPs or n-MoO3. Pot experiments then tested modified inoculants on Glycine max and N. benthamiana for biomass and N, P, K uptake; (3) Results: Both nanomaterials showed low-dose stimulation and high-dose inhibition. At 10 ng·mL−1, bacterial growth (OD600 up ~1.2×) and nitrogenase activity (up >90%) rose significantly (p < 0.05–0.001), along with higher total N, NO3−-N, and NH4+-N. In pots, 10 ng·mL−1 modified inoculant improved all Glycine max traits and nutrient uptake (p < 0.05). For N. benthamiana, biomass peaked at 20 ng·mL−1, while stem and root growth did best at 10 ng·mL−1. At 100 ng·mL−1, effects weakened or vanished. A “metabolic remodeling–rhizosphere transformation–systemic response” mechanism is proposed; (4) Conclusions: Low concentrations (10–20 ng·mL−1) of Fe3O4 NPs and n-MoO3 can effectively boost the nitrogen-fixing function and growth-promoting effect of A. chroococcum inoculant, showing good potential for use on both legume and non-legume crops. This study provides a theoretical basis and technical reference for developing efficient, broad-spectrum nanomaterial-microbe composite inoculants.
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Claims 10
Claim · model-written summary
Low-dose nanomaterials stimulate Azotobacter chroococcum growth in vitro.
- Taxon
- Glycine max
Glycine maxe1 - Treatment
- nanomaterialse2
- Outcome
- low-dose stimulatione2
- Direction
- stimulatione2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e2“Both nanomaterials showed low-dose stimulation and high-dose inhibition”
Claim · model-written summary
High-dose nanomaterials inhibit Azotobacter chroococcum growth in vitro.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- nanomaterialse2
- Outcome
- high-dose inhibitione2
- Direction
- inhibitione2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e2“Both nanomaterials showed low-dose stimulation and high-dose inhibition”
Claim · model-written summary
At 10 ng·mL−1, bacterial growth rose significantly.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- 10 ng·mL−1e3
- Outcome
- bacterial growthe3
- Direction
- rosee3
- Value
- ~1.2×e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e3“At 10 ng·mL−1, bacterial growth (OD600 up ~1.2×) and nitrogenase activity (up >90%) rose significantly (p < 0.05–0.001), along with higher total N, NO3−-N, and NH4+-N”
Claim · model-written summary
At 10 ng·mL−1, nitrogenase activity rose significantly.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- 10 ng·mL−1e3
- Outcome
- nitrogenase activitye3
- Direction
- rosee3
- Value
- >90%e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e3“At 10 ng·mL−1, bacterial growth (OD600 up ~1.2×) and nitrogenase activity (up >90%) rose significantly (p < 0.05–0.001), along with higher total N, NO3−-N, and NH4+-N”
Claim · model-written summary
At 10 ng·mL−1, total N, NO3−-N and NH4+-N were higher.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- 10 ng·mL−1e3
- Outcome
- total N, NO3−-N, and NH4+-Ne3
- Direction
- highere3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e3“At 10 ng·mL−1, bacterial growth (OD600 up ~1.2×) and nitrogenase activity (up >90%) rose significantly (p < 0.05–0.001), along with higher total N, NO3−-N, and NH4+-N”
Claim · model-written summary
In pots, the 10 ng·mL−1 modified inoculant improved Glycine max traits and nutrient uptake.
- Taxon
- Glycine maxGlycine maxe4
- Treatment
- 10 ng·mL−1 modified inoculante4
- Interactor
- A. chroococcumAzotobacter chroococcume5symbiont
- Outcome
- Glycine max traits and nutrient uptakee4
- Direction
- improvede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“In pots, 10 ng·mL−1 modified inoculant improved all Glycine max traits and nutrient uptake (p < 0.05)”
e5“Low concentrations (10–20 ng·mL−1) of Fe3O4 NPs and n-MoO3 can effectively boost the nitrogen-fixing function and growth-promoting effect of A. chroococcum inoculant”
Claim · model-written summary
Biomass of Nicotiana benthamiana peaked at 20 ng·mL−1.
- Taxon
- N. benthamiana
Nicotiana benthamianae6 - Treatment
- 20 ng·mL−1e6
- Outcome
- biomasse6
- Direction
- peakede6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“For N. benthamiana, biomass peaked at 20 ng·mL−1, while stem and root growth did best at 10 ng·mL−1”
Claim · model-written summary
Stem and root growth of Nicotiana benthamiana did best at 10 ng·mL−1.
- Taxon
- N. benthamianaNicotiana benthamianae6
- Treatment
- 10 ng·mL−1e6
- Outcome
- stem and root growthe6
- Direction
- did beste6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e6“For N. benthamiana, biomass peaked at 20 ng·mL−1, while stem and root growth did best at 10 ng·mL−1”
Claim · model-written summary
At 100 ng·mL−1, the effects of nanomaterials on Nicotiana benthamiana weakened or vanished.
- Taxon
- Nicotiana benthamianaNicotiana benthamianae1
- Treatment
- 100 ng·mL−1e7
- Outcome
- effectse7
- Direction
- weakened or vanishede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e7“At 100 ng·mL−1, effects weakened or vanished”
Claim · model-written summary
Low concentrations of Fe3O4 NPs and n-MoO3 can boost the nitrogen-fixing function and growth-promoting effect of the inoculant, with potential for legume and non-legume crops.
- Taxon
- Glycine maxGlycine maxe1
- Outcome
- nitrogen-fixing function and growth-promoting effecte5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“tested the modified inoculants on Glycine max (legume) and Nicotiana benthamiana (non-legume)”
e5“Low concentrations (10–20 ng·mL−1) of Fe3O4 NPs and n-MoO3 can effectively boost the nitrogen-fixing function and growth-promoting effect of A. chroococcum inoculant”
The same questions in other papers
nanoparticle · disease · Glycine max (soybean)Positive and negative results
2 papers in the same direction as this paper · 9 in the opposite direction
- positive
- positive
- positive
8 papers more in this group
See all 12 papers →inoculation · Azotobacter chroococcum · Glycine max (soybean)Results agree
1 paper in the same direction as this paper
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.