Xylanases from marine microorganisms: A brief overview on scope, sources, features and potential applications.

Global economic growth often leads to depletion of raw materials and generation of greenhouse gases, as industry manufactures goods at ever increasing levels to keep up with the demand. The currently implemented production processes mostly rely on non-renewable resources, they suffer from high energy consumption, and generate waste that often has a negative environmental impact. Eco-friendly production methods are therefore intensely searched for. Among them, enzyme-based processes are appealing, because of their high substrate and reaction specificity and the relatively mild operation conditions required by these catalysts. In addition, renewable raw materials that allow sustainable production processes are also widely explored. Marine xylanases, which catalyze the hydrolysis of xylan, the major component of lignocellulose, are promising biocatalysts. Since they are produced by microorganisms that thrive in a wide variety of environmental conditions, the enzymes may be active at widely different ranges of pH, temperature, and salt concentrations. These properties are important for their successful application in various industrial processes, such as production of bioethanol, bleaching of paper and pulp, and in the food and feed sector. The present work gives a brief overview of marine sources of xylanases, their classification and features, and of the potential applications of these marine enzymes, especially in sustainable processes in the scope of circular economy.

Molecular detection of virulence factors and biofilm formation in Pseudomonas aeruginosa obtained from different clinical specimens in Bandar Abbas.

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. Antimicrobial 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, particularly, 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.

Purification, Characterization and Comparison between Two New L-asparaginases from Bacillus PG03 and Bacillus PG04.

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.