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Background and Objectives: Pseudomonas aeruginosa is a ubiquitous opportunistic pathogen. The presence of several virulence factors such as exotoxin and exoenzyme genes and biofilm may contribute to its pathogenicity. The purpose of this study was to investigate the presence of toxA, exoU and exoS, the determination of biofilm production and antimicrobial susceptibility patterns among clinical isolates of P. aeruginosa. Materials and Methods: In this study, 75 isolates of P. aeruginosa were recovered from various clinical specimens. Antimi- crobial susceptibility pattern of isolates were identified. Virulence genes toxA, exoU and exoS were determined using PCR. The ability of biofilm production was assessed. Results: Antimicrobial susceptibility test showed that 12 strains were resistant to more than 8 antibiotics (17.14%). The most effective antibiotic was colistin as 98.6% of isolates were sensitive. The frequencies of exoU and exoS genes were detected as 36.6% and 55.7%, respectively. In addition, 98.6% of the isolates were biofilm producers. Exotoxin A was detected in sixty-eight isolates (95.7%). Conclusion: The findings of this study showed that, the presence of P. aeruginosa exotoxin and exoenzyme genes, particu- larly, the exoU gene is the most common virulence factors in the bacterial isolates from urine samples. Biofilm is a serious challenge in the treatment of P. aeruginosa infection.

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Background:L-asparaginase has been used as a chemotherapeutic agent in treatment of lymphoblastic leukemia. In the present investigation, Bacillus sp. PG03 and Bacillus sp. PG04 were studied.Methods:L- asparaginases were produced using different culture media and were purified using ion exchange chromatography.Results:Maximum productivity was obtained when asparagine was used as the nitrogen source at pH 7 and 48 h after cultivation. New intracellular L-asparaginases showed an apparent molecular weight of 25 kDa and 30 kDa by SDS-PAGE respectively. These enzymes were active in a wide pH range (3-9) with maximum activity at pH 6 for Bacillus PG03 and pH 7 for Bacillus PG04 L-asparaginase. Bacillus PG03 enzyme was optimally active at 37 ˚C and Bacillus PG04 maximum activity was observed at 40˚C. Kinetic parameters km and Vmax of both enzymes were studied using L-asparagine as the substrate. Thermal inactivation studies of Bacillus PG03 and Bacillus PG04 L-asparaginase exhibited t1/2 of 69.3 min and 34.6 min in 37 ˚C respectively. Also T50 and ∆G of inactivation were measured for both enzymes.Conclusion: The results revealed that both enzymes had appropriate characteristics and thus could be a potential candidate for medical applications.

Bacterial L-asparaginases are amidohydrolases that act on Lasparagine and produce L-aspartate and ammonia. These enzymes have been used in treatment of lymphoblastic leukemia. In the present study, a novel strain, Bacillus sp. PG02 was explored for the production of intracellular L-asparaginase enzyme. The nitrogen source for L-asparaginase production was L-asparagine. New intracellular L-asparaginase was purified using ion exchange chromatography and the purity was assessed using SDS-PAGE. Kinetic parameters k m and V max and thermal properties were studied using L-asparagine as the substrate. SDS-PAGE analysis showed apparent molecular weight of approximately 38 kDa. The enzyme was active in a wide pH ranges (5-10) and it was maximally active at pH 7.5. Bacillus PG02 L-asparaginase was optimally active at 40°C. Thermal inactivation studies exhibited t 1/2 of 32.5 min in 37°C. Also T 50 and ∆G of inactivation were measured. The results revealed that the enzyme had appropriate characteristics and thus could be a potential candidate for medical and basic investigations.