The objective of the study is to determine the antibiotic resistance (AR) of bacteria in the presence of arsenic (As). AR profile was estimated by growth curve analysis and its morphological alterations were recorded using a field emission scanning electron microscope (FESEM). Preliminary screening of the isolates revealed that PS-6 showed the highest As resistances at 1,000 mg l−1 concentration which was identified as Bacillus licheniformis using 16S RNA analysis. In the bacteriumAsantibiotic interaction, the culture showed sensitivity toward antibiotics in the initial phase but after treatment with inorganic As (V) at 50 mg/l, the bacterium developed resistance toward antibiotics like ampicillin, erythromycin, and methicillin with 38%, 30%, and 91%, respectively. In case of Chloramphenicol (C) and Kanamycin (K), a non-significant difference in the zone of clearance was observed indicating a reduction in the bacterial growth in the presence of erythromycin, whereas in the presence of As it increased. FESEM analysis showed clumping and aggregation in As-treated and As erythromycin-treated cells denoting the AR. These results eventually state that the bacterium exhibit an adaptive mechanism to overcome antibiotic stress influenced by As, which opens a new window in understanding the role of metalloids in AR and its adaptive pathway.
Key words: Arsenic, Antibiotic resistance, Bacillus, FESEM, Heavy metal
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