Detection and molecular insights into the azurin gene expression post- gamma irradiation in P. aeruginosa

Azurin, a secondary metabolite from Pseudomonas aeruginosa, has attracted much attention owing to its valuable therapeutic and biological applications. This work aimed to study and chartly maximize the azurin production process using different doses of gamma irradiation (5-400 Gy) in P. aeruginosa isolates. Seventy-six P. aeruginosa isolates were sourced from 135 environmental samples and 35 clinical bacterial isolates with the following descending order: 35 isolates (46%) from clinical samples, 26 isolates (34%) from water samples, and 15 isolates (20%) from soil samples. The disc diffusion technique was used for antimicrobial susceptibility testing, revealing that the multidrug-resistant (MDR) rate among all collected isolates according to the criteria determined by Clinical and Laboratory Standards Institute (CLSI) was 54 (71%). The genomic experimental results revealed that only 37 MDR isolates tested positive for the azurin gene, as detected by the PCR product at 446 bp. These findings were further supported by FTIR analysis, which revealed peaks around 1636.96 cm^- 1, indicating a prominent α-helix secondary structure of azurin in these isolates. Related to their pathogenicity and antibiotic resistance, isolates from clinical origin exhibited the higher azurin gene expression level. Besides, this study confirmed the potency of gamma radiation exposure at 50 and 100 Gy significantly increased the azurin expression levels in three tested clinical isolates (P ≤ 0.05), with a maximum fold expression level of 63.55 compared to the non-irradiated samples. In conclusion, low doses of gamma irradiation effectively enhanced expression level of a secondary metabolite azurin, providing a considerable benefit for subsequent purification processes in both biological and medical applications.