# Selection and characterization of salt-tolerant plant growth promoting bacteria associated with the endosphere and rhizosphere of perennial glasswort from the Apulia Region (Italy)

## TL;DR

Researchers identified salt-tolerant bacteria from a coastal plant in Italy that could help improve farming in salty soils.

## Contribution

The study introduces three novel halotolerant bacteria with plant growth-promoting traits suitable for biofertilizer development.

## Key findings

- 110 bacterial isolates were obtained from glasswort plants, with 50 showing salt tolerance above 10% NaCl.
- Three bacterial strains (Pseudomonas sp., Bacillus safensis, Peribacillus frigotolerans) were selected for their complementary plant growth-promoting traits.
- The isolates exhibited traits like phosphate solubilization, indole acetic acid production, and siderophore production.

## Abstract

Soil salinization threatens global agricultural productivity, making halotolerant plant growth promoting bacteria (PGPB) crucial for sustainable farming in marginal areas. This study isolated and characterized PGPB from perennial glasswort (Arthrocaulon macrostachyum) collected at two sites in Margherita di Savoia, Apulia (Italy), during spring 2023. From rhizosphere and endosphere samples, 110 bacterial isolates (100 rhizobacteria, 10 endophytes) were obtained and characterized. Functional screening revealed: 18 isolates (16%) capable of phosphate solubilization, 25 isolates (23%) for silicon solubilization, 20 isolates (18%) producing indole acetic acid, 34 isolates (31%) producing siderophores, and 50 isolates (45%) demonstrating salt tolerance above 10% NaCl, with 28 isolates (25%) tolerating concentrations up to 17.5%. Using RAPD-PCR differentiation and Principal Component Analysis of PGPB traits, three promising halotolerant candidates were selected: Pseudomonas sp. (105S), Bacillus safensis (80S), and Peribacillus frigotolerans (114S), each exhibiting complementary plant growth promoting characteristics. These isolates represent valuable candidates for future field validation as biofertilizers in salt-affected agricultural systems.