Genomic diversity and clade clustering of Burkholderia pseudomallei and B. thailandensis prophages with soil-derived phages

Most studies on bacteriophages (phages) of the Gram-negative bacterium <i>Burkholderia pseudomallei</i> rely on <i>in silico</i> predictions and thus underestimate the true diversity of phages. Analysis of the whole genome sequences of culturable prophages induced from <i>B. pseudomallei</i> and <i>B. thailandensis</i>, along with their free <i>Burkholderia</i> phages isolated from soils in Thailand, identified six novel groups of <i>Burkholderia</i> phages, surpassing <i>in silico</i> expectations. The analysis also indicated that soil-dwelling phages may have originated from lysogenic <i>B. pseudomallei</i> strains. Free phages isolated from soil showed high nucleotide similarity to prophage sequences in <i>B. pseudomallei</i>, including phages previously cultured from melioidosis patients' hemocultures, indicating that similar phage types occur in both environmental and clinical sources. Phylogenomic analysis also revealed close genomic relatedness between prophages from <i>B. thailandensis</i> and <i>B. pseudomallei</i>, although the biological significance remains unknown. Together, these findings refine our understanding of the genomic diversity and ecological patterns of <i>Burkholderia</i> phages.