# Diversity and Plant Growth‐Promoting Potential of Duckweed‐Associated Bacteria on Wolffia globosa Biomass Production and Nutritional Quality

## TL;DR

This study identifies bacteria that significantly boost the growth and nutritional quality of Wolffia, a superfood, suggesting their use as natural biofertilizers.

## Contribution

The study discovers and evaluates duckweed-associated bacteria that enhance Wolffia growth and quality, identifying specific strains like Pseudomonas toyotomiensis.

## Key findings

- 108 bacterial isolates from duckweed showed high diversity, with Pseudomonadota being the dominant phylum.
- Six PGPB strains increased Wolffia globosa biomass by 54.67%–77.75%, with Pseudomonas toyotomiensis W5–11 showing the highest improvement.
- Selected PGPB produced IAA, siderophores, and solubilized phosphate, linking IAA production to protein accumulation.

## Abstract

Wolffia (Lemnoideae) is recognised as a nutritional superfood with increasing interest in commercial cultivation. Its growth and biomass quality are influenced by abiotic factors and duckweed‐associated bacteria (DAB) that support nutrient cycling, stress tolerance and metabolism. This study assessed DAB diversity and their effects on Wolffia growth to select effective plant growth‐promoting bacteria (PGPB) and elucidated beneficial plant‐microbe interactions. A total of 108 isolates, representing 66 species from 41 genera across four phyla, were obtained from duckweeds collected in six provinces of Thailand. The culturable DAB community showed high taxonomic diversity, dominated by the phylum Pseudomonadota, particularly Alphaproteobacteria. The isolates, along with the known PGPB of
Spirodela polyrhiza
, were evaluated for growth promotion in axenic
Wolffia globosa
using co‐cultivation. Six PGPB enhanced growth by 54.67%–77.75% without reported pathogenicity. Several PGPB originally isolated from
S. polyrhiza
also showed growth‐promoting effects on Wolffia. Large‐scale co‐cultivation demonstrated that
Pseudomonas toyotomiensis
W5–11 most effectively increased dry weight and chlorophyll content (3.18‐ and 2.75‐fold, respectively). All selected isolates produced indole‐3‐acetic acid (IAA), siderophores and solubilised phosphate. Correlation analysis revealed that IAA production was associated with protein accumulation. These findings suggested that PGPB represent promising biofertilisers that enhance Wolffia productivity and nutritional quality through various mechanisms.

Co‐cultivation screening of 116 duckweed‐associated bacteria revealed isolates that enhanced
Wolffia globosa
biomass up to 77.75%, with
Pseudomonas toyotomiensis
W5–11 increasing dry weight 3.18‐fold and chlorophyll content 2.75‐fold, demonstrating their potential as biofertilisers for sustainable duckweed production.