16S rRNA gene sequencing reveals bacterial diversity in Khewra Salt Mine walls.

The Khewra Salt Mine, also known as the source of Himalayan Pink Salt, is the second largest salt mine in the world and a significant site for salt export. The mine's salt exhibits both amorphous and crystalline textures, with colours ranging from white to deep red, contributing to its distinctive pink hue. While previous research has extensively explored the mine's soil, plants and brine samples, little attention has been given to the salt walls, which are a major tourist attraction. This study aimed to investigate the bacterial diversity within the salt walls from four distinct locations, including an under-construction area sampled for the first time. From these four collection points, 7 samples were gathered, yielding 19 isolates cultured on 2% NaCl nutrient agar. Bacterial isolates from the under-construction area (US1-1, US1-2, US2-1 and US2-2) and the museum walls (MS1-1 and MS1-2) underwent further biochemical, antibiotic sensitivity and salt requirement testing, followed by 16S rRNA sequencing. Biochemical assays identified these isolates as Gram-positive, catalase- and oxidase-positive rods. All isolates were sensitive to chloramphenicol (30 µg ml