Extracellular production of lipoxygenase from Anabaena sp. PCC 7120 in Bacillus subtilis and its effect on wheat protein

Production of recombinant intact and N-terminal truncated lipoxygenase isozyme III expressed in Saccharomyces cerevisiae and its influence on glutenin polypeptides

This study investigated the effects of wheat lipoxygenase isozyme III (LOX III) and its truncated form, Mini-LOX III, on flour dough properties using yeast-expressed recombinant enzymes and hypothesized their potential to enhance cereal-based food quality. These enzymes actively catalyze linoleic acid, which is crucial for dough formation. The addition of recombinant LOX III and Mini-LOX III to wheat flour significantly changed glutenin protein composition. An increase in the amount of soluble glutenin and a shift in polypeptide distribution were observed, marked by a decrease in the high-molecular-weight regions and an increase in the low-molecular-weight regions. This result reflects the role of enzymes in altering the hydrophobicity of glutenin surfaces, thereby affecting the protein solubility and dough properties. Thus, recombinant LOX III and Mini-LOX III offer new avenues for enhancing the texture and quality of cereal-based foods, providing valuable insights into the role of wheat LOX in flour processing and its potential industrial applications.

Characterization and Preliminary Application of a Novel Lipoxygenase from Enterovibrio norvegicus

Lipoxygenases have proven to be a potential biocatalyst for various industrial applications. However, low catalytic activity, low thermostability, and narrow range of pH stability largely limit its application. Here, a lipoxygenase (LOX) gene from Enterovibrio norvegicus DSM 15893 (EnLOX) was cloned and expressed in Escherichia coli BL21 (DE3). EnLOX showed the catalytic activity of 40.34 U mg-1 at 50 °C, pH 8.0. Notably, the enzyme showed superior thermostability, and wide pH range stability. EnLOX remained above 50% of its initial activity after heat treatment below 50 °C for 6 h, and its melting point temperature reached 78.7 °C. More than 70% of its activity was maintained after incubation at pH 5.0-9.5 and 4 °C for 10 h. In addition, EnLOX exhibited high substrate specificity towards linoleic acid, and its kinetic parameters of Vmax, Km, and Kcat values were 12.42 mmol min-1 mg-1, 3.49 μmol L-1, and 16.86 s-1, respectively. LC-MS/MS analysis indicated that EnLOX can be classified as 13-LOX, due to its ability to catalyze C18 polyunsaturated fatty acid to form 13-hydroxy fatty acid. Additionally, EnLOX could improve the farinograph characteristics and rheological properties of wheat dough. These results reveal the potential applications of EnLOX in the food industry.

Optimization of Hydroperoxide Lyase Production for Recombinant Lipoxygenase Pathway Cascade Application

Cis-3-hexenal and its more stable isomer, trans-2-hexenal, are highly valued chemicals used in the food and perfume industries. They are produced by the plant lipoxygenase pathway, where two enzymes, lipoxygenase (LOX) and hydroperoxide lyase (HPL), are involved. However, the application of this pathway is limited, especially due to the instability of HPL. This enzyme belongs to the cytochrome P450 enzyme family and needs heme as a prosthetic group. Its synthesis must be effectively performed by a host organism in order to produce an active protein. In this work, Pseudomonas aeruginosa LOX was expressed in Escherichia coli BL21(DE3), and whole cells were used for the synthesis of 13(S)-hydroperoxy-(Z,E,Z)-9,11,15-octadecatrienoic acid (13-HPOT) as a substrate for HPL. Expression of Psidium guajava HPL was carried out by recombinant E. coli JM109(DE3) in autoinduction media, and the influence of the addition of heme precursors δ-ALA and FeII+ was studied. Specific activity of whole cells expressing HPL was measured by the direct use of a synthesized 13-HPOT solution (2.94 mM of total hydroperoxides, 75.35% of 13-HPOT (2.22 mM)) and increased 2.6-fold (from 61.78 U·mg−1 to 159.95 U·mg−1) with the addition of 1 mM FeII+ to the autoinduction media. Productivity and activity were further enhanced by an increase in the expression temperature, and a total of 3.30·105 U·dm−3 of culture media was produced in the optimized process.

Effects of anabaena lipoxygenase on whole wheat dough properties and bread quality

The effects of the purified recombinant anabaena lipoxygenase (ana-rLOX) on the rheological characteristics of whole wheat dough and the quality of bread were investigated. The lightness of whole wheat dough supplemented with ana-rLOX was improved, which is superior to that of dough treated with benzoyl peroxide. The effect of ana-rLOX on the strength of dough was analyzed by farinograph, extensograph, and dynamic rheological tests. Compared with the control, the stability time of dough treated with 40 IU/g ana-rLOX increased by 35.4% and the farinograph quality number increased by 27.4%. In addition, the resistance to extension, as well as the elastic and viscous modulus, was improved by ana-rLOX in a dose-dependent manner. The height and specific volume of bread treated with ana-rLOX increased by 17.3 and 15.2%, respectively, compared with the control, and the lightless, whiteness, and other textural parameters, such as hardness, springiness, chewiness, resilience, and gumminess, were significantly improved. Overall, the results of this study suggest the promising application of ana-rLOX in enhancing quality of whole wheat flour.

Recombinant Lipoxygenases and Hydroperoxide Lyases for the Synthesis of Green Leaf Volatiles

Green leaf volatiles (GLVs) are mainly C₆- and in rare cases also C₉-aldehydes, -alcohols, and -esters, which are released by plants in response to biotic or abiotic stresses. These compounds are named for their characteristic smell reminiscent of freshly mowed grass. This review focuses on GLVs and the two major pathway enzymes responsible for their formation: lipoxygenases (LOXs) and fatty acid hydroperoxide lyases (HPLs). LOXs catalyze the peroxidation of unsaturated fatty acids, such as linoleic and α-linolenic acids. Hydroperoxy fatty acids are further converted by HPLs into aldehydes and oxo-acids. In many industrial applications, plant extracts have been used as LOX and HPL sources. However, these processes are limited by low enzyme concentration, stability, and specificity. Alternatively, recombinant enzymes can be used as biocatalysts for GLV synthesis. The increasing number of well-characterized enzymes efficiently expressed by microbial hosts will foster the development of innovative biocatalytic processes for GLV production.

ADJUSTING FLOUR QUALITY BY ENZYMES: CURRENT STATE, PROBLEM ANALYSIS, FUTURE DEVELOPMENT PROSPECTS

The article overviews the issue of wheat flour modification by enzymes. The role of enzymes in the dough formation process is considered. Modern ways of providing the desired dough parameters for flour products in conditions of Ukraine are shown. Recommendations and suggested directions for further research are given. Flour is a complex multicomponent product and have to correspond with a number of requirements for its composition and properties. Different conditions of grain cultivation and storage result in significant deviations of its quality indicators when it comes to flour mills. The modification of flour going through adding several technological additives, in particular by enzyme products. The action of enzymes to a large extent allows to adjust the properties of the dough and of flour end-products. In addition, enzymes further affect the nutritional values of flour, which makes it possible for the flour production to use low-quality grain, while maintaining the planned quality indicators of flour. The functional properties of flour fractions obtained on different technological passages depend on the content of various anatomical parts of the grain from which they derived from. Particle size, starch damage, protein content, fat content, ash content and intensity of enzyme activity vary significantly depending on the type of grinding equipment. All this gives reason for recommending the introduction of enzymes not while manufacturing bakery end-products but still at the stage of flour production. The damage to the grain with a corn bug, grain germination in Ukraine puts grain-processing plants the task of assessing the activity of own grain enzyme systems. Indirectly, this can be estimated using the gluten deformation index and the grain Falling Number. But the estimation of enzyme systems by such methods does not allow precisely to calculate the amount and composition of enzyme products necessary to achieve maximum effect when adjusting flour properties. The issue of removing anti-nutrient factors in flour, which is largely inhibitors of the action of both their own grain enzyme systems and additionally introduced enzyme preparations, is also relevant.

Microbial Synthesis of Linoleate 9 S-Lipoxygenase Derived Plant C18 Oxylipins from C18 Polyunsaturated Fatty Acids

Plant oxylipins, including hydroxy fatty acids, epoxy hydroxy fatty acids, and trihydroxy fatty acids, which are biosynthesized from C18 polyunsaturated fatty acids (PUFAs), are involved in pathogen-specific defense mechanisms against fungal infections. However, their quantitative biotransformation by plant enzymes has not been reported. A few bacteria produce C18 trihydroxy fatty acids, but the enzymes and pathways related to the biosynthesis of plant oxylipins in bacteria have not been reported. In this study, we first report the biotransformation of C18 PUFAs into plant C18 oxylipins by expressing linoleate 9 S-lipoxygenase with and without epoxide hydrolase from the proteobacterium Myxococcus xanthus in recombinant Escherichia coli. Among the nine types of plant oxylipins, 12,13-epoxy-14-hydroxy- cis, cis-9,15-octadecadienoic acid was identified as a new compound by NMR analysis, and 9,10,11-hydroxy- cis, cis-6,12-octadecadienoic acid and 12,13,14-trihydroxy- cis, cis-9,15-octadecadienoic were suggested as new compounds by LC-MS/MS analysis. This study shows that bioactive plant oxylipins can be produced by microbial enzymes.

Consensus design for improved thermostability of lipoxygenase from Anabaena sp. PCC 7120

Background

Lipoxygenase (LOX) from Anabaena sp. PCC 7120 (Ana-rLOX) offers important applications in the food industry, especially for improving aroma and dough rheological properties. However, industrial applications of LOXs have been limited by their poor thermostability. Herein, we report a bioinformatics-based consensus concept approach for the engineering of thermostable Ana-rLOX.

Results

A series of mutations (N130D, G260A, S437T, N130D/G260Q, N130D/S437Y) showed higher thermostability and activity than the wild-type enzyme. Thus, N130D/G260Q exhibited a 6.6-fold increase in half-life and 2.45 °C increase in unfolding temperature; N130D/S437Y showed a 10 °C increase in optimal temperature. The secondary structure did not change much that contributed to improved thermostability were investigated in detail using circular dichroism. Homology modeling suggested that enhanced thermostability and specific activity may result from favorable hydrophobic interactions.

Conclusions

A series of mutations were achieved, showing higher thermostability and activity than the wild-type enzyme by semi-rational mutagenesis with limited structure information. Our findings provide important new insights into molecular modifications aimed at improving Ana-rLOX thermostability and activity.

Electronic supplementary material

The online version of this article (10.1186/s12896-018-0468-4) contains supplementary material, which is available to authorized users.

Effects of recombinant lipoxygenase on the rheological properties of dough and the quality of noodles

BACKGROUND

The effects of purified recombinant lipoxygenase (ana-rLOX) on the rheological properties of dough and the quality of noodles made from wheat flour with low protein content (Yanmai 15) were studied.

RESULTS

The addition of ana-rLOX increased dough stability time, decreased the degree of softening within 12 min, enhanced the resistance to extension, and increased the extensibility with 135 min of resting time. The mechanical spectra of the dough showed an increase in both storage modulus (G') and loss modulus (G″) with increasing ana-rLOX levels. The L(*) values of the noodle sheets increased by 2.34 compared with the control after storing for 1 h at room temperature. The textural parameters of noodles improved after ana-rLOX addition, including hardness, gumminess, chewiness and springiness. The wheat flour treated with the ana-rLOX had a higher cooking yield and lower cooking loss for the resulting noodles. The scanning electron microscopy results revealed that gluten was formed in the noodle samples that were treated with ana-rLOX.

CONCLUSION

In this study, ana-rLOX was applied to noodles during the noodle-making process, and both dough rheological characteristics and noodle quality were improved. © 2015 Society of Chemical Industry.

Selective Production of 9R-Hydroxy-10E,12Z,15Z-Octadecatrienoic Acid from α-Linolenic Acid in Perilla Seed Oil Hydrolyzate by a Lipoxygenase from Nostoc Sp. SAG 25.82

Hydroxy fatty acids (HFAs) derived from omega-3 polyunsaturated fatty acids have been known as versatile bioactive molecules. However, its practical production from omega-3 or omega-3 rich oil has not been well established. In the present study, the stereo-selective enzymatic production of 9R-hydroxy-10E,12Z,15Z-octadecatrienoic acid (9R-HOTE) from α-linolenic acid (ALA) in perilla seed oil (PO) hydrolyzate was achieved using purified recombinant 9R-lipoxygenase (9R-LOX) from Nostoc sp. SAG 25.82. The specific activity of the enzyme followed the order linoleic acid (LA) > ALA > γ-linolenic acid (GLA). A total of 75% fatty acids (ALA and LA) were used as a substrate for 9R-LOX from commercial PO by hydrolysis of Candida rugosa lipase. The optimal reaction conditions for the production of 9R-HOTE from ALA using 9R-LOX were pH 8.5, 15°C, 5% (v/v) acetone, 0.2% (w/v) Tween 80, 40 g/L ALA, and 1 g/L enzyme. Under these conditions, 9R-LOX produced 37.6 g/L 9R-HOTE from 40 g/L ALA for 1 h, with a conversion yield of 94% and a productivity of 37.6 g/L/h; and the enzyme produced 34 g/L 9R-HOTE from 40 g/L ALA in PO hydrolyzate for 1 h, with a conversion yields of 85% and a productivity of 34 g/L/h. The enzyme also converted 9R-hydroxy-10E,12Z-octadecadienoic acid (9R-HODE) from 40 g/L LA for 1.0 h, with a conversion yield of 95% and a productivity of 38.4 g/L. This is the highest productivity of HFA from both ALA and ALA-rich vegetable oil using LOX ever reported. Therefore, our result suggests an efficient method for the production of 9R-HFAs from LA and ALA in vegetable oil using recombinant LOX in biotechnology.

Molecular engineering of secretory machinery components for high-level secretion of proteins in Bacillus species

Secretory expression of valuable enzymes by Bacillus subtilis and its related species has attracted intensive work over the past three decades. Although many proteins have been expressed and secreted, the titers of some recombinant enzymes are still low to meet the needs of practical applications. Signal peptides that located at the N-terminal of nascent peptide chains play crucial roles in the secretion process. In this mini-review, we summarize recent progress in secretory expression of recombinant proteins in Bacillus species. In particular, we highlighted and discussed the advances in molecular engineering of secretory machinery components, construction of signal sequence libraries and identification of functional signal peptides with high-throughput screening strategy. The prospects of future research are also proposed.

Effects of recombinated Anabaena sp. lipoxygenase on the protein component and dough property of wheat flour

The improvement effect of recombinated Anabaena sp. lipoxygenase (ana-rLOX) on the rheological property of dough was investigated with a farinograph and an extensograph. When 30 U/g ana-rLOX was added to wheat flour, the dough stability time extended from 7 to 9.5 min, the degree of softening increased about 31.1%, and the farinograph index also ascended. The dough with added ana-rLOX showed stronger resistance to extension throughout 135 min of resting time as compared to the dough without ana-rLOX. In addition, the protein component in the dough was varied with ana-rLOX. The glutenin in the dough was increased, whereas the gliadin, albumin, and globulin were decreased after the additino of ana-rLOX to the flours. Ana-rLOX could make globulin-3A, globulin 1a, and S48186 grain softness protein cross-link with gliadin and low-molecular-weight (LMW) glutenin, leading to the formation of the protein polymer. These results based on proteomic analysis might provide evidence that ana-rLOX could affect the gluten protein component and explain why it improved the farinograph and extensograph parameters of wheat flour.

Thermal inactivation of a recombinant lipoxygenase from Pseudomonas aeruginosa BBE in the absence and presence of additives

BACKGROUND

Bacterial lipoxygenase (EC 1.13.11.12, LOX) is an important enzyme used as a brightener and strengthening agent during breadmaking. In this study, thermal inactivation of a recombinant LOX of Pseudomonas aeruginosa BBE was characterized by kinetic and thermodynamic analysis in the absence and presence of additives.

RESULTS

As the heating temperature increased from 25 to 55 °C, the thermal inactivation rate (k) values for LOX without the additives ranged from 0.0407 to 0.2627 min(-1), while the half-life (t1/2) values were between 17.08 and 3.25 min. The activation energy (ΔE) values were increased with rise in heating temperatures from 13.26 to 108.9 kJ mol(-1) . Separate tests at 45 °C in the presence of additives (polyols, sugars and ions) at specific concentrations showed that xylitol (1 mol L(-1)) was the most effective stabilizer for recombinant LOX and increased the t1/2 value by 297%.

CONCLUSION

Recombinant LOX was sensitive to heat treatment, and addition of polyols, sugars and ions could enhance its thermal stability. Our findings may provide useful information for stabilizing emerging bacterial LOXs.

Peroxidation radical formation and regiospecificity of recombinated Anabaena sp. lipoxygenase and its effect on modifying wheat proteins

Peroxidation radical formation and the regiospecificity of recombinated lipoxygenase from Anabaena sp. PCC7120 (ana-rLOX) were characterized by using ESR and HPLC-MS. It was found that ana-rLOX oxygenated at the C-13 position of the substrate linoleic acid (LA); at C-13 and C-16 of α-linolenic acid (ALA); at C-9, C-12, and C-15 of arachidonic acid (AA); at C-12, C-15, and C-18 of eicosapentaenoic acid (EPA); and at C-14 and C-16 of docosahexaenoic acid (DHA), respectively. A total of 7, 14, 30, 28, and 18 radical adducts for LA, ALA, AA, EPA, and DHA were respectively identified by HPLC-MS. The functional characteristics of wheat protein, such as foaming capacity (FC), foam stability (FS), emulsifying activity index (EAI), emulsifying stability index (ESI), increased with enzymatic reactions. However, the average particle size of wheat proteins decreased with addition of ana-rLOX/LA. The ana-rLOX was also positivele effective in improving dough properties. These results provided clear evidence that ana-rLOX from Anabaena sp. could effectively improve the quality of wheat flour, which suggested that the enzyme could be applied as flour improver.

Purification and characterization of a temperature- and pH-stable laccase from the spores of Bacillus vallismortis fmb-103 and its application in the degradation of malachite green

Malachite green residue can affect aquaculture food safety. Bioremediation of contaminated water by enzyme treatment is an environmentally friendly and economical way to remove contaminating substances. In the present study, a temperature- and pH-stable laccase was purified from the spores of Bacillus ballismortis fmb-103 and was used to degrade malachite green. The laccase from fmb-103 (fmb-L103) was purified 15.2-fold to homogeneity (389.9 mU/mg protein with respect to ABTS as a substrate) by precipitation with 30-80% (NH4)2SO4, DEAE-Sephadex A-50 ion exchange chromatography, and Sephadex G-100 chromatography. fmb-L103 is a nonblue laccase with a molecular weight of 55.0 kDa and Cu content of 2.5 (mol:mol). fmb-L103 retained more than 50% activity after 10 h at 70 °C and demonstrated broad pH stability in both acidic and alkaline conditions. The effects of inhibitors and metal ions on fmb-L103 activity were also examined. A kinetic study revealed that ABTS was a suitable substrate with a Km of 22.7 μmol and a Vmax of 3.32 μmol/mL/min. fmb-L103 can efficiently degrade malachite green after a 48 h treatment period in combination with a mediator, without the appearance of leucomalachite green.

Bacterial lipoxygenases, a new subfamily of enzymes? A phylogenetic approach

Lipoxygenases (EC. 1.13.11.12) are a non-heme iron enzymes consisting of one polypeptide chain folded into two domains, the N-terminal domain and the catalytic moiety β-barrel domain. They catalyze the dioxygenation of 1Z,4Z-pentadiene moieties of polyunsaturated fatty acids obtaining hydroperoxy fatty acids. For years, the presence of lipoxygenases was considered a eukaryotic feature, present in mammals, plants, small marine invertebrates, and fungi, but now, some lipoxygenase sequences have been detected on prokaryotic organisms, changing the idea that lipoxygenases are exclusively a eukaryotic affair. Lipoxygenases are involved in different types of reactions on eukaryote organisms where the biological role and the structural characteristics of these enzymes are well studied. However, these aspects of the bacterial lipoxygenases have not yet been elucidated and are unknown. This revision discusses biochemical aspects, biological applications, and some characteristics of these enzymes and tries to determine the existence of a subfamily of bacterial lipoxygenases in the context of the phylogeny of prokaryotic lipoxygenases, supporting the results of phylogenetic analyzes with the comparison and discussion of structural information of the first prokaryotic lipoxygenase crystallized and other eukaryotic lipoxygenases structures.

Overproduction, purification, and characterization of extracellular lipoxygenase of Pseudomonas aeruginosa in Escherichia coli

Lipoxygenase (LOX; EC 1.13.11.12,) is an enzyme that is widely used in food industry to improve aroma, rheological, or baking properties of foods. In this study, we described the expression and characterization of Pseudomonas aeruginosa LOX in Escherichia coli. The recombinant LOX was successfully expressed and secreted by E. coli using its endogenous signal peptide. When induced with 1 mM isopropyl β-D-1-thiogalactopyranoside (final concentration) at 20 °C for 47 h, the titer of the recombinant enzyme reached 3.89 U/mL. In order to characterize the catalytic properties, the recombinant LOX was purified to homogeneity on Q High Performance and Mono Q5/50GL sequentially. The molecular weight of the LOX was estimated as 70 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The Km and Vmax of the recombinant enzyme were 48.9 μM and 0.226 μmol/min, respectively. The purified enzyme exhibited a maximum activity at 25 °C and pH 7.5. High-performance liquid chromatography analysis of the linoleic acid hydroperoxides produced by recombinant LOX revealed that the LOX from P. aeruginosa falls into linoleic acid 13(S)-LOX. To the best of our knowledge, this is the first report on the overexpression of extracellular LOX in microorganisms, and the achieved LOX yield is the highest ever reported.