Oxygen and Nitrogen Nanobubbles for Plant Microbiome

https://www.sciencedirect.com/science/article/pii/S245221982500148X?via%3Dihub

• O₂ and N₂ nanobubbles (NBs) altered the tomato rhizosphere microbiome structure.

• High-concentration NBs had more pronounced impacts on the rhizosphere microbiome than low-concentration NBs.

• NBs enriched beneficial microbial taxa that are involved in soil nutrient turnover.

• NBs promoted interactions between diverse microbial groups in the rhizosphere.

Nanobubbles (NBs) in water have shown promise in promoting plant

growth and seed germination, potentially reducing the need for water

and fertilizer inputs. To elucidate the mechanisms underlying these benefits,

this study investigated the effects of oxygen nanobubbles (ONBs) and nitrogen

nanobubbles (NNBs) on the tomato rhizosphere microbiome over a 34-day

irrigation period. Treatments included varying NB types, dissolved oxygen (DO)

levels (9.30 and 26.73 mg·L^-1 for ONBs; 2.69 and 8.84 mg·L^-1 for NNBs), and

irrigation frequencies. Multivariate analysis of 16S rRNA gene sequencing revealed

that both ONBs and NNBs significantly altered rhizosphere microbial community

composition compared to controls. NB concentration and irrigation frequency further

influenced microbiome structure. High-concentration NB treatments increased the

relative abundance of multiple beneficial rhizobacteria involved in nutrient cycling,

including Bacteroidota, Chitinophagales, Gemmatimonadota, and Ureibacillus, while

low-concentration treatments had lower impacts on plant growth-promoting rhizobacteria.

Network analysis indicated enhanced microbial connectivity and reduced niche specialization

in NB-treated rhizosphere soils. Moreover, significant positive correlations were observed

between tomato agronomic traits and several rhizobacteria, including known plant

growth-promoting taxa like Comamonadaceae and other potentially beneficial microbes.

These findings demonstrate that NB type, concentration, and irrigation regime can

modulate rhizosphere microbial dynamics, offering insights for optimizing nanobubble

applications in sustainable precision agriculture.