Geographical distribution of Burkholderia pseudomallei in Taiwanese croplands and the influence of bacterial community interactions on its incubation viability.

Burkholderia pseudomallei is a soil-borne pathogen responsible for melioidosis, a potentially fatal disease. While endemic melioidosis in Taiwan is marked by both clinical cases and environmental detection, a comprehensive environmental survey has been lacking. A nationwide cropland survey using B. pseudomallei-specific orf2-PCR revealed regional positivity rates of 2.1% in northern, 8.2% in central, 15.1% in southern, and 9.8% in eastern Taiwan, with the highest PCR positivity and cumulative melioidosis incidence (12.14 cases per 100,000 people from 2003 to 2024) observed in the south. Vertical profiling showed a higher DNA detection rate at a depth of 60 cm, with increased surface-level detection during rainy periods and a decline after sunny conditions, particularly in the southern area. Identical molecular sequence types across layers suggested upward movement from deeper soil. However, viable bacteria were not consistently recovered from PCR-positive samples, indicating that bacterial dynamics during incubation may influence B. pseudomallei viability. To investigate this, full-length 16S rDNA sequencing and community analysis revealed inverse abundance patterns between B. pseudomallei and B. multivorans, B. cenocepacia, and B. vietnamiensis during incubation. In vitro assays confirmed strong antagonism by B. multivorans filtered supernatants against the growth of B. pseudomallei, while B. cenocepacia and B. vietnamiensis had weaker or no effects. These findings reveal distinct regional and vertical patterns of B. pseudomallei DNA in croplands and highlight the potential influence of bacterial competition on its viability during incubation.