# A Herpetosiphon llansteffanensis Strain from Forest Soil Exhibits Biocontrol Activity Against Pear Fire Blight

## TL;DR

A soil bacterium from China shows strong potential as a natural treatment for pear fire blight, a destructive plant disease.

## Contribution

This study is the first to demonstrate the biocontrol potential of Herpetosiphon llansteffanensis against fire blight.

## Key findings

- H. llansteffanensis NSD29 inhibited lesion expansion on pear leaves and fruit with 75.2% and 72.0% efficacy.
- Pre-treatment with NSD29 reduced blossom blight incidence by 61.2%.
- The strain showed 86.8% protective and 75.6% curative efficacy on pear shoots.

## Abstract

Fire blight, a devastating bacterial disease caused by Erwinia amylovora, has posed significant challenges to apple and pear production for over a century. This study introduces a gliding filamentous bacterium, the strain NSD29, isolated from natural forest soil in Xinjiang, China, as a biological control agent for managing this disease. Comprehensive characterization based on morphological, physiological, biochemical, 16S rRNA gene, and whole-genome analyses identified the strain NSD29 as Herpetosiphon llansteffanensis. The train NSD29 demonstrated potent predatory activity against E. amylovora in vitro. Its biocontrol efficacy was subsequently evaluated on detached leaves, inflorescences, young fruit, and shoots of fragrant pear under controlled greenhouse conditions. Results indicated that applying H. llansteffanensis NSD29 significantly inhibited lesion expansion on pear leaves and young fruit, achieving protective efficacies of 75.2% and 72.0%, respectively. Furthermore, pre-treatment spraying with NSD29 effectively reduced the incidence of blossom blight, with a control efficacy of 61.2%. On detached pear shoots, the application of NSD29 fermentation broth suppressed lesion expansion, demonstrating substantial protective (86.8%) and curative (75.6%) efficacies. This research provides the first evidence for the potential of Herpetosiphon species in the biological control of plant diseases, highlighting H. llansteffanensis NSD29 as a promising candidate for developing strategies to combat fire blight.