Abstract
Background The production of structurally complex multicellular communities or biofilms is a mode of growth that is believed to require and involves a differential gene expression as compared to their planktonic counterpart. There is a poor knowledge of biofilm formation and its molecular signaling function in a radiation resistance bacteria. Therefore, the aim of the present study was to investigate the genetic variations and gene expression levels of some critical genes involved in the biofilm formation and matrix production in an ionizing-radiation-resistant B. subtilis (RAM-04) isolated from Abe-Siah hot spring, Ramsar- Iran. Bacillus subtilis DSM-10 a non-ionizing-radiation-resistant and standard strain model considered as a negative control. Results Quantification of biofilms performed using crystal violet assay and Scanning Electron Microscopy that the results presented a significant difference of a high level of the biofilm formation in terms of quantity and structure by Bacillus subtilis (RAM-04) as compared to Bacillus subtilis DSM-10. At the Molecular level, a total of 13 genes including ( tapA ) yqxM-sipW-tasA (operon), sinR , sinI , ccpA , epsA-O , spoOB , spoOA , slrA , slrR , ymcA and abrB were selected to study the genetic variations and gene expression levels using direct sequencing method and quantitative PCR technique. Primary analysis revealed genetic variations in ( tapA ) yqxM-sipW-tasA (operon), sinR , sinI , epsA-O , and slrR in B. subtilis (RAM-04) as compared to the negative control. The result of gene expression revealed a significant difference between test and control bacteria. ( tapA ) yqxM-sipW-tasA operon was significantly over expressed ( p = 0.000 with expression folding of 13, 11, 8 respectively) and the expression level of ccpA and slrR were significantly down ( p = 0.000 with expression folding of 0.2 and 0.3 respectively). Conclusions These results support the hypothesis that the induction of biofilm formation is performed by ( tapA ) yqxM-sipW-tasA operon signaling pathway, which in turn indicate that this operon has a positive role in biofilm formation in ionizing-radiation-resistant B. subtilis (RAM-04) under natural radiation environment.