Wildfire Ashes from the Wildland-Urban Interface Alter Vibrio vulnificus Growth and Gene Expression

Climate change-induced stressors are contributing to
the emergence
of infectious diseases, including those caused by marine bacterial
pathogens such as Vibrio spp. These stressors alter Vibrio temporal and geographical distribution, resulting
in increased spread, exposure, and infection rates, thus facilitating
greater Vibrio−human interactions. Concurrently,
wildfires are increasing in size, severity, frequency, and spread
in the built environment due to climate change, resulting in the emission
of contaminants of emerging concern. This study aimed to understand
the potential effects of urban interface wildfire ashes on Vibrio vulnificus (V. vulnificus) growth and gene expression using transcriptomic approaches. V. vulnificus was exposed to structural and vegetation
ashes and analyzed to identify differentially expressed genes using
the HTSeq-DESeq2 strategy. Exposure to wildfire ash altered V. vulnificus growth and gene expression, depending
on the trace metal composition of the ash. The high Fe content of
the vegetation ash enhanced bacterial growth, while the high Cu, As,
and Cr content of the structural ash suppressed growth. Additionally,
the overall pattern of upregulated genes and pathways suggests increased
virulence potential due to the selection of metal- and antibiotic-resistant
strains. Therefore, mixed fire ashes transported and deposited into
coastal zones may lead to the selection of environmental reservoirs
of Vibrio strains with enhanced antibiotic resistance
profiles, increasing public health risk.