Hendrich, C. | Search bioRxiv

bioRxiv2025

Engineering the citrus phyllosphere microbiome for enhanced disease resistance to bacterial canker

Engineering phyllosphere microbiomes toward plant protection against pathogens on crops has shown promising effects. Here we tested the effect of application of beneficial bacteria individually and as a synthetic community (SynCom) on the phyllosphere microbiome and management of bacterial canker caused by Xanthomonas citri subsp. citri (Xcc). Foliar spray of a SynCom consisting of three citrus endophytic bacterial strains (Paenibacillus sp. ATY16, Bacillus megaterium PT6, and Bacillus subtilis PT26A, SynCom1) with mechanistically complemented plant-beneficial properties exerted a more profound effect on the leaf microbiota and suppression of citrus canker than single strains. Cultivation-dependent and bacterial 16S rRNA gene-sequence profiling analyses revealed that leaf endophytic Bradyrhizobium, Brevibacillus, Cellvibrio, Flavobacterium, and Pseudomonas were significantly enriched in the SynCom treated plants, in addition to Bacillus and Paenibacillus. The enriched Brevibacillus and Pseudomonas spp. were isolated, whole-genome sequenced, and confirmed to possess multiple beneficial traits including antimicrobial activity against Xcc, Moreover, the expression of citrus defense genes was induced by the SynCom1 inoculation. Foliar application of SynCom1 and a newly assembled SynCom (SynCom2; SynCom1 with representative Brevibacillus and Pseudomonas isolates) prior to Xcc inoculation significantly reduced the citrus canker disease severity in greenhouse assays, and SynCom2 had a better efficacy, comparable to a copper bactericide. Three-year field tests showed that both SynCom1 and SynCom2 effectively controlled citrus canker, with a 50% reduction of foliar and fruit canker incidence. Collectively, these findings provide novel insights and valuable clues for microbiome engineering to serve as a sustainable strategy for the control of phyllosphere pathogens on crops.

plant biology↗

bioRxiv2022

An approach to rapid distributed manufacturing of broad spectrum anti-viral griffithsin using cell-free systems to mitigate pandemics

This study describes the cell-free biomanufacturing of a broad-spectrum antiviral protein, griffithsin (GRFT) such that it can be produced with consistent purity and potency in less than 24 hours. We demonstrate GRFT production using two independent cell-free systems, one plant and one microbial. Griffithsin purity and quality were verified using standard regulatory metrics. Efficacy was demonstrated in vitro against SARS-CoV-2 and HIV-1 and was nearly identical to that of GRFT expressed in vivo. The proposed production process is efficient and can be readily scaled up and deployed anywhere in the world where a viral pathogen might emerge. The current emergence of viral variants has resulted in frequent updating of existing vaccines and loss of efficacy for front-line monoclonal antibody therapies. Proteins such as GRFT with its efficacious and broad virus neutralizing capability provide a compelling pandemic mitigation strategy to promptly suppress viral emergence at the source of an outbreak.

bioengineering↗