Purification and characterization of a thermo- and organic solvent-tolerant alkaline protease from Bacillus sp. JER02

Unveiling antibiofilm potential: proteins from Priestia sp. targeting Staphylococcus aureus biofilm formation

Staphylococcus aureus is the etiologic agent of many nosocomial infections, and its biofilm is frequently isolated from medical devices. Moreover, the dissemination of multidrug-resistant (MDR) strains from this pathogen, such as methicillin-resistant S. aureus (MRSA) strains, is a worldwide public health issue. The inhibition of biofilm formation can be used as a strategy to weaken bacterial resistance. Taking that into account, we analysed the ability of marine sponge-associated bacteria to produce antibiofilm molecules, and we found that marine Priestia sp., isolated from marine sponge Scopalina sp. collected on the Brazilian coast, secretes proteins that impair biofilm development from S. aureus. Partially purified proteins (PPP) secreted after 24 hours of bacterial growth promoted a 92% biofilm mass reduction and 4.0 µg/dL was the minimum concentration to significantly inhibit biofilm formation. This reduction was visually confirmed by light microscopy and Scanning Electron Microscopy (SEM). Furthermore, biochemical assays showed that the antibiofilm activity of PPP was reduced by ethylenediaminetetraacetic acid (EDTA) and 1,10 phenanthroline (PHEN), while it was stimulated by zinc ions, suggesting an active metallopeptidase in PPP. This result agrees with mass spectrometry (MS) identification, which indicated the presence of a metallopeptidase from the M28 family. Additionally, whole-genome sequencing analysis of Priestia sp. shows that gene ywad, a metallopeptidase-encoding gene, was present. Therefore, the results presented herein indicate that PPP secreted by the marine Priestia sp. can be explored as a potential antibiofilm agent and help to treat chronic infections.

One-pot synthesis and biochemical characterization of a magnetic collagenase nanoflower and evaluation of its biotechnological applications

Recently, hierarchical magnetic enzyme nanoflowers have been found extensive attention for efficient enzyme immobilization due to high surface area, low mass transfer limitations, active site accessibility, promotion of the enzymatic performance, and facile reusing. Herein, we report the purification of the Bacillus collagenase and then synthesis of magnetic cross-linked collagenase-metal hybrid nanoflowers (mcCNFs). The catalytic efficiency (k_cat/K_m) value of the immobilized collagenase was 2.2 times more than that of the free collagenase. The collagenase activity of mcCNFs enhanced about 2.9 and 4.6 at 85 and 90 °C, respectively, compared to free collagenase. Thermal stability of mcCNFs increased about 31% and 24% after 3 h of incubation at 50 and 60 °C, respectively. After 10 cycles of reusing, the mCNFs collagenase showed 83% of its initial activity. Results showed that the mcCNFs revealed 1.4 times more activity than the free collagenase in 0.16% protein waste. Furthermore, the hydrolysis value of chicken pie protein wastes by the immobilized enzyme obtained 4 times more than the free collagenase after 240 min incubation at 40 °C. Finally, our results showed that the construction of mcCNFs is an efficient method to increase the enzymatic performance and has excessive potential for the hydrolysis of protein wastes in the food industry.

Lipase immobilization on a novel class of Zr-MOF/electrospun nanofibrous polymers: Biochemical characterization and efficient biodiesel production

In this study, due to the favorable properties of MOF compounds and fibrous materials, new nanostructures of Zr-MOF/PVP nanofibrous composites were synthesized by electrospinning procedure. The related features of these samples were characterized by relevant analyzes, including SEM, BET surface area analysis, XRD, and FTIR spectroscopy. The final product showed significant properties such as small particle size distribution, large surface area, and high crystallinity. This strategy for producing these nanostructures could lead to new compounds as novel alternative materials for biological applications. Lipase MG10 was successfully immobilized on the mentioned nanofibrous composites and biochemically characterized. The lipase activity of free and immobilized lipases was considered by measuring the absorbance of pNPP (500 μM in 40 mM Tris/HCl buffer, pH 7.8, and 0.01% Triton X100) at 37 °C for 30 min. Different concentrations of glutaraldehyde, different crosslinking times, different times of immobilization, different enzyme loading, and different pH values have been optimized. Results showed that the optimized immobilization condition was achieved in 2.5% glutaraldehyde, after 2 h of crosslinking time, after 6 h immobilization time, using 180 mg protein/g support at pH 9.0. The immobilized enzyme was also totally stable after 180 min incubation at 60 °C. The free enzyme showed the maximum activity at pH 9.0, but the optimal pH of the immobilized lipase was shifted about 1.5 pH units to the alkaline area. The immobilized lipase showed about 2.7 folds (78%) higher stability than the free enzyme at 50 °C. Some divalent metal ions, including Cu²⁺ (22%), Co²⁺ (37%), Mg²⁺ (12%), Hg²⁺ (11%), and Mn²⁺ (17%) enhanced the enzyme activity of immobilized enzyme. The maximum biodiesel production (27%) from R. communis oil was obtained after 18 h of incubation by lipase MG10. The immobilized lipase displayed high potency in biodiesel production, about 83% after 12 h of incubation. These results indicated the high potency of Zr-MOF/PVP nanofibrous composites for efficient lipase immobilization.

Lipase immobilization on glutaraldehyde activated graphene oxide/chitosan/cellulose acetate electrospun nanofibrous membranes and its application on the synthesis of benzyl acetate

In this research, lipase Km12 was immobilized on the glutaraldehyde-activated graphene oxide/chitosan/cellulose acetate nanofibers (GO/Chit/CA NFs) prepared by the electrospinning method. This immobilized lipase exhibited a higher activity value than the free lipase in the acidic pH region. This enzyme showed a 10 °C shift in the maximum temperature activity. Results displayed that the Vmax value of NFs-lipase was 0.64 µmol/min, while it was gained 0.405 µmol/min for the free lipase. The activity of NFs-lipase was reserved 100% after 10 min maintaining at 60 °C, in which the free lipase only kept 75% of its original activity. Moreover, a 20% enhancement in the lipase activity was observed for NFs-lipase after 180 min of incubation at 60 °C, compared to the free enzyme. Reusability studies exhibited that the immobilized lipase well-kept 80% of its original activity after 10 cycles of reusing. Results displayed that 14% of the protein was leaked from NFs-lipase at the same condition. Transesterification results indicated that the free lipase exhibited 65% and 85% conversation level of benzyl acetate after 12 and 24 h of incubation. Besides, the immobilized lipase showed 80% and 95% conversation level at the same condition. These results indicated the high performance of free and immobilized lipase in the production of benzyl acetate for applications in the perfume and cosmetic industries.

Cross-linked Enzyme Aggregates of Fibrinolytic Protease BC1 Immobilized on Magnetic Chitosan Nanoparticles (CLEAs-Fib-mChi): Synthesis, Purification, and Characterization

Bacterial fibrinolytic proteases achieved more attention in the prevention and treatment of cardiovascular diseases, so purification, characterization, and activity enhancement are of prime importance. In this study, a fibrinolytic serine metalloprotease was purified from the culture supernatant from Bacillus sp. BC1. It was purified to homogeneity by a two-step procedure with a 24-fold increase in specific activity and a 33.1% yield. It showed 28 kDa molecular weight, while its optimal pH and temperature were obtained 8 and 50-60 °C. The cross-link enzyme aggregates of this fibrinolytic BC1 successfully immobilized on magnetic chitosan nanoparticles. A 52% activity enhancement was obtained by immobilized enzyme at pH 6.0, compared to free protease. K_m values of the free and immobilized proteases were obtained about 0.638 and 0.61 mg/ml, respectively. The free and immobilized enzymes did not show any activity concerning transferrin, γ-globulins, and hemoglobin, as blood plasma proteins. The in vitro blood clot lysis test of the free and immobilized proteases showed a maximum of 42 and 50% clot lysis, which was comparatively higher than that revealed by streptokinase and heparin at the same condition. These results indicated that the free and immobilized proteases have the potential to be effective fibrinolytic agents.

Production and Characterization of a Nitrilase from Pseudomonas aeruginosa RZ44 and its Potential for Nitrile Biotransformation

BACKGROUND

The conversion of nitriles into amides or carboxylic acids by nitrilase has taken its application into consideration, as the scope of its applications has recently been extended.

OBJECTIVES

In this study, P. aeruginosa RZ44 was isolated from sewage in the Kerman which has Nitrile-degradation activity. In order to improve the nitrilase production, several optimization were done on environmental condition. Nitrilase activity was characterized against different pHs, temperatures, ions, and substrates.

MATERIALS AND METHODS

Enzyme activity was evaluated by determining the production of ammonia following to the modification of the phenol/hypochlorite method. Different factors that affect production of the enzyme by P. aeruginosa RZ44 were optimized and evaluated in the culture mediums.

RESULTS

The results showed that degradation of the acetonitrile by P. aeruginosa RZ44 increased the pH of the growth medium from the initial pH 7.0 to 9.37. Optimizing the medium for P. aeruginosa RZ44, it was found that glucose and starch (5 g.L-1) have strongly supported nitrilase production, compared to the control. As well, urea (5 g.L-1) and yeast extract (15 g.L-1) have favored an increased biomass and nitrilase production, as the nitrogen sources. These results show that nitrilase production increases in the pH range 5.0 to 7.0 and then start decreasing. Addition of the Mg2+, Fe2+ and Na+ has supported the biomass and nitrilase production. Co2+, Mn2+ and Cu2+ were confirmed to inhibit cell growth and enzyme production. Enzyme characterization results show that, P. aeruginosa RZ44 nitrilase exhibits comparatively high activity and stability at pH 7.0 and 40°C. Nitrilase was completely inhibited by CoCl2 and CaCl2, whereas, the inhibition in the presence of MnSO4 and CuSO4 was about 60%. Time course analysis of the nitrile conversion by the resting P. aeruginosa RZ44 cells showed that nitrile substrates (i.e. acetonitrile) was hydrolyzed within 8 h.

CONCLUSIONS

these results indicate that P. aeruginosa RZ44 has the potential to be applied in the biotransformation of nitrile compounds.