Activity of Lignin-Modifying Enzyme of Selected Medicinal Mushrooms in Submerged Fermentation of Lignocellulosic Materials.

In the present study, wide diversity in the set and activity of lignin-modifying enzymes (LME) was revealed during submerged fermentation of mandarin peel with 15 strains of white rot Basidiomycetes. Among them, Trametes pubescens BCC153 was distinguished by the simultaneous production of laccase, manganese peroxidase (MnP), and lignin peroxidase (LiP). Supplementation of CuSO4 at a concentration of 1 mM in the media for the cultivation of four Trametes species manifold increased the production of laccase. The diverse effects of chemically different lignocellulosic growth substrates and nitrogen sources on the production of individual LME have been established. The maximum laccase activity of T. pubescens was observed when the fungus was cultivated on media containing mandarin peel and wheat bran, whereas the highest MnP and LiP activities were detected in the submerged fermentation of tobacco residue. Peptone and casein hydrolysate appeared to be the best sources of nitrogen to produce laccase and both peroxidases by T. pubescens BCC153 whereas KNO3 was the worst nitrogen-containing compound for the production of all enzymes.

Copper increases laccase gene transcription and extracellular laccase activity in Pleurotus eryngii KS004.

The white-rot fungus Pleurotus eryngii secretes various laccases involved in the degradation of a wide range of chemical compounds. Since the laccase production is relatively low in fungi, many efforts have been focused on finding ways to increase it, so in this study, we investigated the effect of copper on the transcription of the pel3 laccase gene and extracellular laccase activity. The results indicate that adding 0.5 to 2 mM copper to liquid cultures of P. eryngii KS004 increased both pel3 gene transcription and extracellular laccase activity in a concentration-dependent manner. The most significant increase in enzyme activity occurred at 1 mM Cu2+, where the peak activity was 4.6 times higher than in control flasks. Copper also induced the transcription of the laccase gene pel3. The addition of 1.5 and 2 mM Cu2+ to fungal culture media elevated pel3 transcript levels to more than 13-fold, although the rate of induction slowed down at Cu2+ concentrations higher than 1.5 mM. Our findings suggest that copper acts as an inducer in the regulation of laccase gene expression in P. eryngii KS004. Despite its inhibitory effect on fungal growth, supplementing cultures with copper can lead to an increased extracellular laccase production in P. eryngii.

Application of Miscanthus substrates in the cultivation of Ganoderma lingzhi.

Ganoderma lingzhi is a traditional Chinese medicine that has been used to improve health and longevity for thousands of years. It is usually cultivated on hardwood log- or sawdust-based formulations. Conversely, in this study, we used Miscanthus sacchariflorus (MSF), M. floridulus, and M. sinensis (MSS), fast-growing perennial grasses widely distributed in China, for G. lingzhi cultivation. Mycelial growth rate, activities of lignin-degrading enzymes on colonized mushroom substrates, and expression levels of CAZymes and laccase genes based on different substrates were analyzed. Total triterpenoids, sterols, and polysaccharides content of fruiting bodies obtained from different substrates were investigated. The activities of laccase and manganese peroxidase in mycelia increased in the MSF- and MSS-based formulations compared with that in the sawdust-based formulation. The results of mycelial growth- and cultivation-related experiments showed that the Miscanthus substrates could be used as the substrates for cultivating G. lingzhi. The content of active ingredients, namely triterpenoids, sterols, and polysaccharides, in fruiting bodies cultivated on the Miscanthus substrates did not decrease compared with those in substrate obtained from the sawdust-based formulation. Therefore, the present study provides alternative substrates for the cultivation of G. lingzhi, and a reference for better utilization of inexpensive substrate in future.

Characterization of white rot fungi from wood decayed for lignin degradation.

The present study was conducted to isolate and identify white rot fungi (WRF) from wood decayed and to determine their ability to produce lignin-modifying enzymes (LMEs), specifically laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP), on solid and liquid media supplemented with synthetic dyes namely 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), azure B, and phenol red. A total of 23 isolates of WRF were isolated from decayed wood and identified as eight different species namely Phanerochaete australis, Perenniporia tephropora, Lentinus squarrosulus, Ganoderma australe, Trametes polyzona, Lentinus sajor-caju, Gymnopilus dilepis, and Fomitopsis palustris based on morphological characteristics, DNA sequences of the internal transcribed spacer (ITS) region, and phylogenetic inference. The fungal isolates can be divided into four groups based on the type of LMEs produced, namely A (Lac-LiP-MnP) with 16 isolates, B (Lac-MnP) (three isolates), C (Lac) (three isolates), and D (MnP) (one isolate). This study highlights P. australis (BJ38) as the best producer of Lac and LiP, while L. squarrosulus (IPS72) is the best producer of MnP. The present study is the first reported P. australis as an efficient lignin degrader by demonstrating the highest activity of two important LMEs.

Ability of marine-derived fungi isolated from polluted saline environment for enzymatic hydrocarbon remediation.

Marine-derived fungi have attracted much attention due to their ability to present a new biosynthetic diversity. About 50 fungal isolates were obtained from Tunisian Mediterranean seawater and then screened for the presence of lignin-peroxidase (LiP), manganese-dependent peroxidase (MnP), and laccase (Lac) activities. The results obtained from both qualitative and quantitative assays showed that four of marine fungi isolates had a high potential to produce lignin-degrading enzymes. They were characterized taxonomically by a molecular method, based on international spacer (ITS) rDNA sequence analysis, as Chaetomium jodhpurense (MH667651.1), Chaetomium maderasense (MH665977.1), Paraconiothyrium variabile (MH667653.1), and Phoma betae (MH667655.1) which have been reported as producers of ligninolytic enzyme in the literature. The enzymatic activities and culture conditions were optimized using a Fractional Factorial design (2 7- 4). Then, fungal strains were incubated with the addition of 1% of crude oil in 50% of seawater for 25 days to evaluate their abilities to simultaneously degrade hydrocarbon compounds and to produce ligninolytic enzymes. The strain P. variabile exhibited the highest crude oil degradation rate (48.3%). Significant production of ligninolytic enzymes was recorded during the degradation process, which reached 2730 U/L for the MnP, 410 U/L for LiP, and 168.5 U/L for Lac. The FTIR and GC-MS analysis confirmed that the isolates rapidly biodegrade crude oil under ecological and economic conditions.

LACC1: A critical involvement in macrophage immunometabolism.

Laccase domain-containing 1 (LACC1) protein is an enzyme highly expressed in inflammatory macrophages, and studies have shown that it has a key role in diseases such as inflammatory bowel disease, arthritis, and microbial infections. Therefore, in this review, we focus on LACC1-mediated catalysis. In detail, LACC1 converts l-CITrulline (l-CIT) to l-ORNithine (l-ORN) and isocyanic acid in mice and humans and acts as a bridge between proinflammatory nitric oxide synthase (NOS2) and polyamine immunometabolism, thus exerting anti-inflammatory and antibacterial effects. Considering the actions of LACC1, targeting LACC1 may be a potent therapeutic avenue for inflammation-related diseases and microbial infection diseases.

Secretory expression of recombinant small laccase genes in Gram-positive bacteria.

BACKGROUND: Laccases are multicopper enzymes that oxidize a wide range of aromatic and non-aromatic compounds in the presence of oxygen. The majority of industrially relevant laccases are derived from fungi and are produced in eukaryotic expression systems such as Pichia pastoris and Saccharomyces cerevisiae. Bacterial laccases for research purposes are mostly produced intracellularly in Escherichia coli, but secretory expression systems are needed for future applications. Bacterial laccases from Streptomyces spp. are of interest for potential industrial applications because of their lignin degrading activities. RESULTS: In this study, we expressed small laccases genes from Streptomyces coelicolor, Streptomyces viridosporus and Amycolatopsis 75iv2 with their native signal sequences in Gram-positive Bacillus subtilis and Streptomyces lividans host organisms. The extracellular activities of ScLac, SvLac and AmLac expressed in S. lividans reached 1950 ± 99 U/l, 812 ± 57 U/l and 12 ± 1 U/l in the presence of copper supplementation. The secretion of the small laccases was irrespective of the copper supplementation; however, activities upon reconstitution with copper after expression were significantly lower, indicating the importance of copper during laccase production. The production of small laccases in B. subtilis resulted in extracellular activity that was significantly lower than in S. lividans. Unexpectedly, AmLac and ScLac were secreted without their native signal sequences in B. subtilis, indicating that B. subtilis secretes some heterologous proteins via an unknown pathway. CONCLUSIONS: Small laccases from S. coelicolor, S. viridosporus and Amycolatopsis 75iv2 were secreted in both Gram-positive expression hosts B. subtilis and S. lividans, but the extracellular activities were significantly higher in the latter.

Agro-industrial wastes revalorization as feedstock: production of lignin-modifying enzymes extracts by solid-state fermentation using white rot fungi.

The purpose of the study was to evaluate the production of lignin-modifying enzyme extracts and delignified biomass from agro-industrial wastes using white rot fungi (Inonotus sp. Sp2, Stereum hirsutum Ru-104, Bjerkandera sp. BOS55, Pleurotus eryngii IJFM 169 and Phanerochaete chrysosporium BKM-F-1767). These were screened based on their adaptability and colonization ability on different substrates, as well as by the Laccase, Manganese peroxidase, and Lignin peroxidase enzymatic production. Native strains (Inonotus sp. Sp2 and S. hirsutum Ru-104) showed the highest growth kinetics under the solid-substrate fermentation conditions and the growth rate parameters of the kinetic logistic model for the different substrates were between 0.39-0.81 (1/d) and 0.42-0.83 (1/d), respectively; the determination coefficients were ≥0.99. Inonotus sp. Sp2 was subsequently cultured in static flasks to produce crude enzyme extracts, obtaining manganese peroxidase activity levels of 18.5 and 31.3 (U/g) when growing in corn cob husk and spent tea leaves, respectively. Besides, it was to establish that the best conditions for lignin-modifying enzymes production using corn cob husk are 70% of initial moisture and 2.12 mm of particle size; reaching after 30 incubation days a manganese peroxidase activity of 21 ± 6 (U/g) under these conditions; enzyme that showed a suitable thermostability.

Pulsed Light Mutagenesis of the Willow Bracket Mushroom, Phellinus igniarius (Agaricomycetes), for Enhanced Production of Flavonoids, Laccase, and Fermentation Biomass.

Phellinus igniarius is a medicinal fungus possessing potent therapeutic activity due to the polysaccharides, polyphenols, flavonoids, and other secondary metabolites they contain. Laccases are crucial enzymes involved in lignin degradation in Ph. igniarius and offer great potential to accomplish several bioprocesses. To generate Ph. igniarius strains with high biomass, flavonoid, and laccase activity, we used pulsed light (PL) technology for mutagenesis of Ph. igniarius protoplasts and screened for mutants with high biomass, flavonoid, and laccase activity. At the irradiation power of 100 J, treated distance 8.5 cm, irradiation frequency was 0.5 s/time, three times treatments, after five generations of selection, three mutants were obtained with higher biomass production. Compared with control, the mycelium biomass and the flavonoid production of the screened mutant strain QB72 were increased 20.87% and 53.51%, respectively. The total amount of the accumulated extracellular laccase of the QB72 in the first 6 and 8 days increased 23.38% and 22.37% respectively, and over the total 16 days it increased 9.62%. In addition, RAPD analysis results indicated that the genetic materials of the mutant QB72 were altered. PL mutagenesis method has great potential for developing strains, especially Phellinus.

Microbial degradation and transformation of benzo[a]pyrene by using a white-rot fungus Pleurotus eryngii F032.

Polycyclic aromatic hydrocarbons (PAHs) are environmentally recalcitrant contaminants formed from naturally or incomplete combustion of organic materials and some of them are difficult to degrade due to their hydrophobicity and persistency. Benzo [a]pyrene (BaP), is one of PAHs that having five fused benzene and reported as mutagenic, carcinogenic and teratogenic compounds. Biodegradation is one of promising techniques due to its relatively low economic cost and microorganism is a natural capacity to consume hydrocarbons. In this investigation, Pleurotus eryngii F032 was grown in 20 mL of modified mineral salt broth (MSB) supplemented with BaP under static and agitated culture. Within 20 days, static culture removed 59% of BaP, whereas agitated culture removed the highest amount (73%). To expedite BaP elimination, the mechanism and behavior of BaP biosorption and biotransformation by Pleurotus eryngii F032 were additionally examined by gas chromatography-mass spectrometer (GC-MS). The optimal conditions for P. eryngii F032 to eliminate BaP were 25 °C, a C/N ratio of 8, pH 3 and 0.2% inoculum concentration. At an initial BaP content of 10 mg/L, more than 50% was effectively eliminated within 20 days under these conditions. Salinity, glucose, and rhamnolipids were the most important factors impacting BaP biodegradation. GC-MS found degradation products such as BaP-3,6-quinone, indicating plausible metabolic routes. Finally, it may be assumed that the primary mechanism by which white-rot fungi eliminate BaP is by the utilization of biotransformation enzymes such as laccase to mineralize the PAHs. Hence, Pleurotus eryngii F032 could be an ideal candidate to treat PAHs contaminated soils.

Laccase production by Pleurotus ostreatus using cassava waste and its application in remediation of phenolic and polycyclic aromatic hydrocarbon-contaminated lignocellulosic biorefinery wastewater.

The treatment of contaminants from lignocellulosic biorefinery effluent has recently been identified as a unique challenge. This study focuses on removing phenolic contaminants and polycyclic aromatic hydrocarbons (PAHs) from lignocellulosic biorefinery wastewater (BRW) applying a laccase-assisted approach. Cassava waste was used as a substrate to produce the maximum yield of laccase enzyme (3.9 U/g) from Pleurotus ostreatus. Among the different inducers supplemented, CuSO4 (0.5 mM) showed an eight-fold increase in enzyme production (30.8 U/g) after 240 h of incubation. The catalytic efficiency of laccase was observed as 128.7 ± 8.47 S-1mM-1 for syringaldazine oxidation at optimum pH 4.0 and 40 °C. Laccase activity was completely inhibited by lead (II) ion, mercury (II) ion, sodium dodecyl sulphate, sodium azide and 1,4 dithiothretiol and induced significantly by manganese (II) ion and rhamnolipid. After treating BRW with laccase, the concentrations of PAHs and phenolic contaminants of 1144 µg/L and 46160 µg/L were reduced to 96 µg/L and 16100 µg/L, respectively. The ability of laccase to effectively degrade PAHs in the presence of different phenolic compounds implies that phenolic contaminants may play a role in PAHs degradation. After 240 h, organic contaminants were removed from BRW in the following order: phenol >2,4-dinitrophenol > 2-methyl-4,6-dinitrophenol > 2,3,4,6-tetrachlorophenol > acenaphthene > fluorine > phenanthrene > fluoranthene > pyrene > anthracene > chrysene > naphthalene > benzo(a)anthracene > benzo(a)pyrene > benzo(b)fluoranthene > pentachlorophenol > indeno(1,2,3-cd)pyrene > benzo(j) fluoranthene > benzo[k]fluoranthène. The multiple contaminant remediation from the BRW by enzymatic method, clearly suggests that the laccase can be used as a bioremediation tool for the treatment of wastewater from various industries.

Diclofenac biotransformation and toxicity assessment of laccase from Pleurotus floridanus.

Laccase producing fungus Pleurotus floridanus was isolated from Siruvani forest, Tamil Nadu, India. The potential of P. floridanus to produce laccase by using various lignocellulosic substrates was screened under submerged fermentation. Laccase production in the presence of lignocellulosic substrates such as rice, wheat and maize bran as a sole source of carbon as well as an additional supplement was examined. Laccase activity of P. floridanus using varied substrates was observed in the order of rice bran > wheat bran > maize bran. The isolate showed maximum laccase activity of 13.29±0.01 U/mL using rice bran as a carbon source within 11 days. This was 18 fold higher than the control media that lacks lignocellulosic substrates. The diclofenac tolerance was assessed in solid media at various concentrations and the results showed that the mycelia growth is not significantly affected by the drug. Finally, the laccase mediated degradation of diclofenac at a concentration of 10 mg/L showed 98% degradation in 2 h. The phytotoxicity of the crude laccase treated diclofenac was lower than the untreated diclofenac. In conclusion, findings suggested direct application of crude laccase produced from P. floridanus using agro-residues as ideal substrate for environmental applications.

The potential role of betaine in enhancement of microbial-assisted phytoremediation of benzophenone-3 contaminated soil.

Benzophenone-3 (BP-3) is an emerging environmental pollutant used in personal care products, helping to reduce the risk of ultraviolet radiation to human skin. The BP-3 removal potential from soil by tobacco (Nicotiana tabacum) assisted with Methylophilus sp. FP-6 was explored in our previous study. However, the reduced BP-3 remediation efficiency by FP-6 in soil and the inhibited plant growth by BP-3 limited the application of this phytoremediation strategy. The aim of the present study was to reveal the potential roles of betaine, as the methyl donor of methylotrophic bacteria and plant regulator, in improving the strain FP-6-assisted phytoremediation capacity of BP-3 contaminated soil. The results revealed that strain FP-6 could use betaine as a co-metabolism substrate to enhance the BP-3 degradation activity. About 97.32% BP-3 in soil was effectively removed in the phytoremediation system using tobacco in combination with FP-6 and betaine for 40 d while the concentration of BP-3 in tobacco significantly reduced. Moreover, the biomass and photosynthetic efficiency of plants were remarkably improved through the combined treatment of betaine and strain FP-6. Simultaneously, inoculation of FP-6 in the presence of betaine stimulated the change of local microbial community structure, which might correlate with the production of a series of hydrolases and reductases involved in soil carbon, nitrogen and phosphorus cycling processes. Meantime, some of the dominant bacteria could secrete various multiple enzymes involved in degrading organic pollutants, such as laccase, to accelerate the demethylation and hydroxylation of BP-3. Overall, the results from this study proposed that the co-metabolic role of betaine could be utilized to strengthen microbial-assisted phytoremediation process by increasing the degradation ability of methylotrophic bacteria and enhancing plant tolerance to BP-3. The present results provide novel insights and perspectives for broadening the engineering application scope of microbial-assisted phytoremediation of organic pollutants without sacrificing economic crop safety.

Degradation of sulfonamides in aquaculture wastewater by laccase-syringaldehyde mediator system: Response surface optimization, degradation kinetics, and degradation pathway.

As a new type of environmental pollutant, environmental antibiotic residues have attracted widespread attention, and the degradation and removal of antibiotics has become an engaging topic for scholars. In this paper, Novozym 51003 industrialized laccase and syringaldehyde were combined to degrade sulfonamides in aquaculture wastewater. Design Expert10 software was used for multiple regression analysis, and a response surface regression model was established to obtain the optimal degradation parameters. In the actual application, the degradation system could maintain a stable performance within 9 h, and timely supplement of the mediator could achieve a better continuous degradation effect. Low concentrations of heavy metals and organic matter would not significantly affect the degradation performance of the laccase-mediator system, making the degradation system suitable for a wide range of water quality. Enzymatic reaction kinetics demonstrated a strong affinity of sulfadiazine to the substrate. Ten degradation products were speculated using high-resolution mass spectrum based on the mass/charge ratios and the publication results. Four types of possible degradation pathways of sulfadiazine were deduced. This work provides a practical method for the degradation and removal of sulfonamide antibiotics in actual sewage.

Production of Lignocellulolytic Enzymes and Phenolic Compounds by Lentinus strigosus from the Amazon Using Solid-State Fermentation (SSF) of Guarana (Paullinia cupana) Residue.

The Amazon rainforest has a rich biodiversity, and studies of Basidiomycete fungi that have biomolecules of biotechnological interest are relevant. The use of lignocellulosic biomass in biotechnological processes proposes an alternative use, and also adds value to the material when employed in the bioconversion of agro-industrial waste. In this context, this study evaluate the production of lignocellulolytic enzymes (carboxymethylcellulases (CMCase), xylanase, pectinase, laccase) as well as phenolic compounds and proteases by solid-state fermentation (SSF) using the fungus Lentinus strigosus isolated from Amazon. The guarana (Paullinia cupana) residue was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). SSF was carried out with 60% humidification of the residue, at 30 °C, for 10 days. The lignocellulosic biomass presented fragmented structures with irregular shapes and porosities, and was mainly constituted by cellulose (19.16%), hemicellulose (32.83%), and lignin (6.06%). During the SSF, significant values of CMCase (0.84 U/g) on the 8th day, xylanase (1.00 U/g) on the 7th day, pectinase (2.19 U/g) on the 6th day, laccase (176.23 U/mL) on the 5th day, phenolic compounds (10.27 µg/mL) on the 1st day, soluble proteins (0.08 mg/mL) on the 5th day, and protease (8.30 U/mL) on the 6th day were observed. In general, the agro-industrial residue used provided promising results as a viable alternative for use as a substrate in biotechnological processes.

Mycoremediation of oil contaminant by Pleurotus florida (P.Kumm) in liquid culture.

This study investigated the potential functions of Pleurotus florida (an edible mushroom) in the biodegradation of gas oil at concentrations of 0 (control), 2.5, 5, and 10% (V: V) for 30 days. The gas oil increased dry weight and protein concentration in all treatments (by an average of 19.5 and 108%, respectively). Moreover, the pH, surface tension (ST), and interfacial tension (IFT) were reduced by the mushroom supplementation. The lowest surface tension (31.9 mN m-1) and the highest biosurfactant production belonged to the 10% gas oil treatment (0.845 ± 0.03 mg mL-1). The results demonstrated that the adsorption isotherm agreed well with the Langmuir isotherm. The maximum Langmuir adsorption capacity was calculated at 0.743 mg g-1 wet biomass of P. florida. The fungal supplementation efficiently remedied the total petroleum hydrocarbons (TPHs) by an average of 55% after 30 days. Gas chromatography (GC) analysis revealed that P. florida effectively detoxified C13-C28 hydrocarbons, Pristane, and Phytane, implying its high mycoremediation function. The toxicity test showed that mycoremediation increased the germination by an average of 35.82% ± 8.89 after 30 days. Laccase activity increased significantly with increasing gas oil concentration in the treatments. The maximum laccase activity was obtained in the 10% gas oil treatment (142.25 ± 0.72 U L-1). The presence of pollutants was also associated with induction in the tyrosinase activity when compared to the control. These results underline the high mycoremediation capacity of P. florida through the involvement of biosurfactants, laccase, and tyrosinase.

Improved functional properties of meat analogs by laccase catalyzed protein and pectin crosslinks.

The gap between the current supply and future demand of meat has increased the need to produce plant-based meat analogs. Methylcellulose (MC) is used in most commercial products. Consumers and manufacturers require the development of other novel binding systems, as MC is not chemical-free. We aimed to develop a novel chemical-free binding system for meat analogs. First, we found that laccase (LC) synergistically crosslinks proteins and sugar beet pectin (SBP). To investigate the ability of these SBP-protein crosslinks, textured vegetable protein (TVP) was used. The presence of LC and SBP improved the moldability and binding ability of patties, regardless of the type, shape, and size of TVPs. The hardness of LC-treated patties with SBP reached 32.2 N, which was 1.7- and 7.9-fold higher than that of patties with MC and transglutaminase-treated patties. Additionally, the cooking loss and water/oil-holding capacity of LC-treated patties with SBP improved by up to 8.9-9.4% and 5.8-11.3%, compared with patties with MC. Moreover, after gastrointestinal digestion, free amino nitrogen released from LC-treated patties with SBP was 2.3-fold higher than that released from patties with MC. This is the first study to report protein-SBP crosslinks by LC as chemical-free novel binding systems for meat analogs.

Ferulated Pectins and Ferulated Arabinoxylans Mixed Gel for Saccharomyces boulardii Entrapment in Electrosprayed Microbeads.

Ferulated polysaccharides such as pectin and arabinoxylan form covalent gels which are attractive for drug delivery or cell immobilization. Saccharomyces boulardii is a probiotic yeast known for providing humans with health benefits; however, its application is limited by viability loss under environmental stress. In this study, ferulated pectin from sugar beet solid waste (SBWP) and ferulated arabinoxylan from maize bioethanol waste (AX) were used to form a covalent mixed gel, which was in turn used to entrap S. boulardii (2.08 × 108 cells/mL) in microbeads using electrospray. SBWP presented a low degree of esterification (30%), which allowed gelation through Ca2+, making it possible to reduce microbead aggregation and coalescence by curing the particles in a 2% CaCl2 cross-linking solution. SBWP/AX and SBWP/AX+ S. boulardii microbeads presented a diameter of 214 and 344 µm, respectively, and a covalent cross-linking content (dimers di-FA and trimer tri-FA of ferulic acid) of 1.15 mg/g polysaccharide. The 8-5', 8-O-4'and 5-5'di-FA isomers proportions were 79%, 18%, and 3%, respectively. Confocal laser scanning microscopy images of propidium iodide-stained yeasts confirmed cell viability before and after microbeads preparation by electrospray. SBWP/AX capability to entrap S. boulardii would represent an alternative for probiotic immobilization in tailored biomaterials and an opportunity for sustainable waste upcycling to value-added products.

Structural, gelation properties and microstructure of rice glutelin/sugar beet pectin composite gels: Effects of ionic strengths.

In this study, the rice glutelin (RG)/sugar beet pectin (SBP) composite gels were prepared by laccase induced cross-linking and subsequent heat treatment, and the effects of different calcium ion concentrations (0-400 mM) on the gelation, structural properties and microstructure of the RG/SBP composite gels were investigated. The results showed that the addition of 200 mM calcium ion could improve the rheological, textural properties and water holding capacity of the RG/SBP composite gels. The addition of SBP and calcium ions enhanced the hydrophobic interaction between RG molecules, thereby increased the gel properties of RG. The changes in Raman spectroscopy reflected the positive effect of the addition of SBP and calcium ions on the formation of a denser and more homogeneous protein gel, as evidenced by the results of scanning electron microscopy. Overall, SBP and calcium ions could be applied to the plant protein gel systems as gel-strengthening agents.

Laccase-catalyzed conjugation of potato protein (PPT) with selected pectic polysaccharides (PPS): Conjugation efficiency and emulsification properties.

The current study focused on the investigation of laccase-catalyzed conjugation of potato protein (PPT) with selected pectic polysaccharides (PPS) and modulation of the conjugation in order to obtain desired functional ingredients. PPS, including sugar beet pectin/arabinan, apple/citrus pectin and potato galactan, were evaluated as substrates in the conjugation reaction-catalyzed by laccases (Trametes versicolor-LacTv, Coriolus hirsutus-LacCh). LacCh exhibited a higher catalytic efficiency than LacTv. The reactivity of PPT/PPS and their ratio were determinants for their heteroconjugation. Both laccases exhibited the highest specificity towards the conjugation of PPT/sugar beet pectin. Predictive models were developed for conjugation efficiency and emulsification performance. The conjugation extent was negatively affected by the protein proportion and the protein proportion/enzyme concentration interaction; while the emulsification performance was positively correlated with the protein proportion and the protein proportion/reaction time interaction. This study contributed to the understanding of laccase-catalyzed conjugation reaction for the controlled synthesis of conjugated-PTT as functional ingredients.