Production and Characterization of Cross-Linked Aggregates of Geobacillus thermoleovorans CCR11 Thermoalkaliphilic Recombinant Lipase.

Immobilization of enzymes has many advantages for their application in biotechnological processes. In particular, the cross-linked enzyme aggregates (CLEAs) allow the production of solid biocatalysts with a high enzymatic loading and the advantage of obtaining derivatives with high stability at low cost. The purpose of this study was to produce cross-linked enzymatic aggregates (CLEAs) of LipMatCCR11, a 43 kDa recombinant solvent-tolerant thermoalkaliphilic lipase from Geobacillus thermoleovorans CCR11. LipMatCCR11-CLEAs were prepared using (NH4)2SO4 (40% w/v) as precipitant agent and glutaraldehyde (40 mM) as cross-linker, at pH 9, 20 °C. A U10(56) uniform design was used to optimize CLEA production, varying protein concentration, ammonium sulfate %, pH, glutaraldehyde concentration, temperature, and incubation time. The synthesized CLEAs were also analyzed using scanning electron microscopy (SEM) that showed individual particles of <1 µm grouped to form a superstructure. The cross-linked aggregates showed a maximum mass activity of 7750 U/g at 40 °C and pH 8 and retained more than 20% activity at 100 °C. Greater thermostability, resistance to alkaline conditions and the presence of organic solvents, and better durability during storage were observed for LipMatCCR11-CLEAs in comparison with the soluble enzyme. LipMatCCR11-CLEAs presented good reusability by conserving 40% of their initial activity after 9 cycles of reuse.

Sorption of BTEX on a nanoporous composite of SBA-15 and a calcined hydrotalcite.

Benzene, toluene, ethylbenzene, and p-xylene (BTEX) are hazardous volatile organic compounds mostly released from fuel combustion, paint gas emissions, and biomass burning. In this work, it is studied the BTEX sorption influence on the surface reactivity of a new kind of nanoporous composite, prepared via an in situ functionalization of SBA-15 with a Mg-Al calcined hydrotalcite (HTC). During its preparation, Mg/Al mixed oxides are indeed formed and dispersed on the SBA-15 surface with non-blockage porosity. Furthermore, the physicochemical surface properties are exalted from its precursors and it is synergistically favorable for the BTEX sorption at low pressure and temperature.

Chemical, physical and sensory properties of Vienna sausages formulated with a starfruit dietary fiber concentrate.

The use of a starfruit dietary fiber concentrate (SDFC) as a novel ingredient in Vienna sausages was investigated. A constrained mixture design was followed to evaluate the effect of different proportions of SDFC (0-10%), pork meat (0-100%) and turkey meat (0-100%) on the shear force, shrinkage, color, residual nitrite, moisture and polyphenol contents of sausages. Moreover, a chemical, physical and sensory characterization of the optimized formulations was performed. The cubic model equations demonstrated that the SDFC in mixture with pork or turkey meat had a reducing effect on nitrites, moisture, shear force and shrinkage, while there was an increase on the polyphenol concentration as the increase of SDFC proportion in the formulations. The optimization resulted in Vienna-type sausages formulated with a ternary mixture of pork/turkey meat and high SDFC proportion (7.4-8.4%). These products had high total dietary fiber content (11.04-17.79%) and antioxidant polyphenols, low residual nitrite content, shrinkage and red color. They presented good taste, color and texture attributes, and were sensory acceptable. This study demonstrated that enrichment of Vienna-type sausages with SDFC in mixture with pork/turkey meat is a way to obtain potential functional meat products with high antioxidant dietary fiber content, reduced in nitrites, and good physical and sensory properties.

Improved expression and immobilization of Geobacillus thermoleovorans CCR11 thermostable recombinant lipase.

Production of recombinant thermo-alkali-stable lipase LipMatCCR11, expressed in Escherichia coli BL21 (DE3), was investigated via response surface methodology by using a face-centered design with three levels of each factor. Additionally, improvement of the catalytic performance of expressed lipase was assessed by immobilization on microporous polypropylene. Results showed that inducer (isopropyl ß-d-1-thiogalactopyranoside [IPTG]) concentration and temperature were found to be the significant factors (P < 0.05). The maximum lipase expression was obtained at IPTG 0.6 mM, 16 °C, and 18 H, with a specific lipase activity of 7.29 × 106  U/mg, which was 36.4 times higher (over 1,300-fold increase) than lipase activity measured under nonoptimized conditions. On the other hand, immobilized lipase showed a high biocatalytic activity, particularly in the synthesis of aroma esters.

Ultraviolet-C light effect on physicochemical, bioactive, microbiological, and sensorial characteristics of carrot (Daucus carota) beverages.

The aim of this research was to evaluate the effect of ultraviolet-C light on physicochemical, bioactive, microbial, and sensory characteristics of carrot beverages. Beverages were formulated with different concentrations of carrot juice (60, 80, and 100% [v/v]) and treated with ultraviolet-C light at different flow rates (0, 0.5, 3.9, and 7.9 mL s(-1)) and times (5, 10, 15, 20, and 30 min), equivalent to ultraviolet-C dosages of 13.2, 26.4, 39.6, 52.8, and 79.2 J cm(-2) Total soluble solids, pH, and titratable acidity were not affected by the ultraviolet-C light treatment. Ultraviolet-C light significantly affected (p < 0.05) color parameters of pure juice; however, at low concentration of juice, total color change was slightly affected (ΔE = 2.0 ± 0.7). Phenolic compounds (4.1 ± 0.1, 5.2 ± 0.2, and 8.6 ± 0.3 mg of GAE 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) and antioxidant capacity (6.1 ± 0.4, 8.5 ± 0.4, and 9.4 ± 0.3 mg of Trolox 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) of carrot beverages were not affected by ultraviolet-C light treatment. Microbial kinetics showed that mesophiles were mostly reduced at high flow rates in carrot beverages with 60% of juice. Maximum logarithmic reductions for mesophiles and total coliforms were 3.2 ± 0.1 and 2.6 ± 0.1, respectively, after 30 min of ultraviolet-C light processing. Beverages were well accepted (6-7) by judges who did not perceive the difference between untreated and Ultraviolet-C light treated beverages.

Significant improvement of Geobacillus thermoleovorans CCR11 thermoalkalophilic lipase production using response surface methodology.

The medium optimization for the production of the Geobacillus thermoleovorans CCR11 thermoalkalophilic lipase was carried out in shake flask cultures using safflower high oleic oil. In the first step of optimization, a two level fractional factorial design allowed the identification of the concentration of nutrient broth and temperature as the main variables significantly affecting lipase production (P<0.05). In a second step, a D-optimal design was applied to determine the variables optimal values, defined as those yielding maximal lipase production in shaken flasks, thus demonstrating that the optimal concentration of nutrient broth was 3.8 g/l and the optimal culture temperature was 39.5°C. The model was experimentally validated, yielding a lipase production of 2283.70 ± 118.36 U/mL which represents a 6.7-fold increase in comparison to the non-optimized medium.