Biology subjects

Bell, T. H.

Publications and source records attributed to Bell, T. H..

4 recordsLinked to original sources

bioRxiv2026

Resident soil microbial diversity and urea amendment legacy interact to shape the composition and expression of a surface film-forming soil inoculant

Soil microbial inoculants have the potential to improve crop yield, enhance agricultural sustainability, and support soil restoration, but they often display unpredictable in-field performance across varied soil conditions. Cyanobacteria-dominated soil surface consortia (SSCs) offer a tractable model for studying inoculant-soil interactions because their visible surface growth enables direct observation and sampling after application. Here, we introduced the SSC "DG1," dominated by the diazotrophic cyanobacterium Nostoc linckia, into soil microcosms differing in resident microbiome diversity (low vs. high diversity) and urea fertilization history, (+urea vs. -urea). We used 16S rRNA gene sequencing and genome-resolved metatranscriptomics to assess inoculant establishment and functioning. Resident microbiome diversity did not affect total N. linckia gene expression, but heterotrophic DG1 members showed reduced expression in high-diversity soils. Soil diversity and urea history drove broad shifts in DG1 transcription and significantly affected transcription of key N. linckia carbon and nitrogen metabolism genes. High-diversity soils with urea were associated with increased transcription of photosynthesis, CAZyme, and nitrogen cycling genes, whereas low-diversity soils without urea promoted increased nitrogenase transcription and reduced carbon and nitrogen metabolism transcription. These results show that inoculant outcomes depend not only on establishment, but also how soil conditions and biology shape post-establishment functioning.

microbiology↗

bioRxiv2024

An Autonomous Microbial Sensor Enables Long-term Detection of TNT Explosive in Natural Soil

Microbes can be engineered to detect target chemicals, but when they operate in real-world environments, it remains unclear how competition with natural microbes affect their performance over long time periods. We engineered sensors and memory-storing genetic circuits inside Bacillus subtilis to sense and respond to the TNT explosive, using predictive models for rational design. We characterized their ability to detect TNT in a natural soil system, measuring single-cell and population-level behavior over a 28-day period. The autonomous microbial sensor activated its response by 14-fold when exposed to low TNT concentrations and maintained stable activation for over 21 days, exhibiting exponential decay dynamics at the population-level with a half-life of about 5 days. Our results show that engineered soil bacteria can carry out long-term detection of an important chemical in natural soil with competitive growth dynamics serving as additional biocontainment.

synthetic biology↗

bioRxiv2024

Insects visit Fusarium xyrophilum pseudoflowers on the host Xyris surinamensis (Xyridaceae) and carry fungal DNA on their bodies

The fungus Fusarium xyrophilum produces flower-like structures (i.e., pseudoflowers) that were recently discovered on yellow-eyed grasses (Xyris spp.) in Guyana. It is unknown whether these pseudoflowers, which are composed entirely of fungal tissue, are true mimics that attract insects as a means of fungal dispersal. We evaluated the potential of F. xyrophilum to affect insect visitation patterns to flowers and pseudoflowers by 1) documenting insect visitation to X. surinamensis in Guyana, 2) measuring the presence of F. xyrophilum DNA on insects, and 3) evaluating fluorescence and volatile production on flowers and pseudoflowers. We report for the first time Vespidae, Formicidae, Salticidae, Acrididae, and Tetrigidae visiting Xyris. Diverse insects, including Conocephalini spp. (meadow katydids; Tettigoniidae), Camponotus spp. (carpenter ants; Formicidae), and a Geometridae sp. (geometer moths) were found to visit flowers and pseudoflowers. Fusarium xyrophilum DNA was detected on 3/12 (25%) of captured insect bodies using conventional and quantitative PCR. Volatiles produced in the field by pseudoflowers and flowers were similar, except for the presence of a sesquiterpene, putatively identified here as -gurjunene, which was detected both in F. xyrophilum pure cultures and field-collected pseudoflower samples, but not from flowers. The production of this sesquiterpene by F. xyrophilum and the fluorescence of X. surinamensis peduncles represent potential signals involved in insect attraction for this system. These observations, along with the overlap in insect visitors of flowers and pseudoflowers and the detection of F. xyrophilum DNA on insect bodies, are consistent with insect visitors being vectors of Xyris pollen and F. xyrophilum propagules between host plants.

ecology↗

bioRxiv2023

Bacterial assembly in the switchgrass rhizosphere is shaped by phylogeny, host genotype, and growing site.

O_LISince microbial traits are conserved at different taxonomic levels, plant hosts may influence microbiome composition differently at different levels to broadly promote or resist microbiota with traits that impact host fitness. We tested this hypothesis by assessing signals of host genetic influence on bacterial composition in the switchgrass rhizosphere using 128 genotypes in dissimilar growing sites. C_LIO_LIWe employed three common gardens, combined with host genetic mapping, 16S rRNA gene sequence analysis, hierarchical modeling, tests of phylogenetic conservation of host influence, and genome-wide association analyses to determine the contributions of host genetics in shaping rhizosphere bacterial composition at different taxonomic levels. C_LIO_LIModeling bacterial assembly showed that growing site was a strong factor shaping bacterial composition in the rhizosphere, though host genetic influence played a significant role. The heritability of bacterial abundance was strongest at the genus level. Phylogenetic signal for heritability was detected within the bacterial phylogeny but conserved clades differed between common gardens. We identified shared host genetic variants associated with bacterial abundance and host traits related to plant metabolism. C_LIO_LIOur results suggest further investigation is required regarding the genotype-by-environment-by-microbiome relationship to elucidate the factors shaping rhizosphere microbiome composition and the agroecological dynamics shaping plant phenotype. C_LI

plant biology↗