Laccases have great potential for industrial applications due to their green catalytic properties and broad substrate specificities, and various studies have attempted to improve the catalytic ...performance of these enzymes. Here, to the best of our knowledge, we firstly report the directed evolution of a homodimeric laccase from
BBP6 fused with α-factor prepro-leader that was engineered through random mutagenesis followed by in vivo assembly in
. Three evolved fusion variants selected from ~3500 clones presented 31- to 37-fold increases in total laccase activity, with better thermostability and broader pH profiles. The evolved α-factor prepro-leader enhanced laccase expression levels by up to 2.4-fold. Protein model analysis of these variants reveals that the beneficial mutations have influences on protein pKa shift, subunit interaction, substrate entrance, and C-terminal function.
The removal of hazardous dyes has become a major economic and health concern to treat wastewater. In this study, efficient, low-cost, and eco-friendly spent mushroom waste (SMW) showed great ...potential for removing the anionic dyes, namely Direct Red 5B (DR5B), Direct Black 22 (DB22), Direct Black 71 (DB71), and Reactive Black 5 (RB5). The mechanisms of adsorption could be controlled by both physical and chemical adsorption. Scanning electron microscope analysis showed that SMW surface is porous and irregular. The kinetic study could be described well with the pseudo-second-order kinetic model, whereas the best representation of the equilibrium isotherm is the Langmuir model. The maximum adsorption capacities of SMW were found to be 18 mg g
−1
for DR5B, 15.46 mg g
−1
for DB22, 20.19 mg g
−1
for DB71, and 14.62 mg g
−1
for RB5. The analysis of thermodynamic study of Δ
G°
, Δ
H°
, and Δ
S°
proved that the adsorption of the tested dyes onto SMW was endothermic and spontaneous. Based on these results, SMW can be considered as high potential adsorbent for the removal of dyes from wastewater.
•Laccase was oriented immobilized on con A-activated Fe3O4 nanoparticles.•The oriented immobilized laccase showed higher removal rate of SAs than free laccase.•Syringic acid mediated almost complete ...removal of SAs after incubation for 5min.•Laccase mediated covalent cross-coupling of SAs and intermediate of S-type compounds.
A novel strategy was applied in the oriented immobilization of laccase from Echinodontium taxodii on concanavalin A-activated Fe3O4 nanoparticles (GAMNs-Con A) based on laccase surface analysis. These nanoparticles showed higher enzyme loading and activity recovery compared with conventional covalent binding. Along with the improvement in thermal and operational stabilities, the oriented immobilized laccase (GAMNs-Con A-L) exhibited higher substrate affinity than free laccase. Free laccase and GAMNs-Con A-L were then applied in the removal of sulfonamide antibiotics (SAs). Although both free and immobilized laccase resulted in the rapid removal of SAs, GAMNs-Con A-L showed a higher removal rate of SAs compared with the free counterpart in the presence of S-type compounds present in lignin structure. Syringic acid mediated the fastest removal efficiency of SAs among S-type compounds and resulted in an almost complete removal of these substances after incubation for 5min. The oxidation products of SAs were identified via LC–ESI+-MS. The results suggested the transformation of SAs and S-type compounds were catalyzed by laccase, resulting in the formation of cross-coupled products.
•Extracellular laccase activity was stimulated by metal ions or aromatic compounds.•Synergistic stimulation by metal ions and aromatic compounds on laccase was observed.•Transcript levels of laccase ...gene family under different stimulations were studied.•The crude extracellular laccase could efficiently degrade different synthetic dyes.
Promotion of laccase production has attracted much attention, because of its potential application in environment and industry areas. Metal ions and aromatic compounds are known to be effective in stimulating laccase production in many white-rot fungi. In this study, we examined the effect of several metal ions and aromatic compounds on extracellular laccase activity as well as on the transcription of laccase multi-gene family in Pleurotus ostreatus HAUCC 162. Extracellular laccase activity is enhanced by the addition of Cu2+ (3.86-fold), Fe2+ (1.85-fold), Mn2+ (1.65-fold), Cd2+ (1.45-fold), ferulic acid (1.83-fold), vanillic acid (1.62-fold), coumaric acid (2.16-fold), and cinnamic acid (1.95-fold) after 10-days induction, and the increased transcript level of laccase multi-gene family was also observed. Synergistic stimulation of metal ions (Fe2+, Cu2+) and aromatic compounds (vanillic acid, cinnamic acid, and ferulic acid) further improved the stimulatory effect, compared with single inducer. The results of decolorization test further indicated the laccase produced by P. ostreatus HAUCC 162 had a strong capacity to decolorize different synthetic dyes, which offers an opportunity to apply P. ostreatus HAUCC 162 laccase in the field of environmental biotechnology.
Ganoderma lucidum is a medicinal mushroom that is well known for its ability to enhance human health, and products made from this fungus have been highly profitable. The substrate-degrading ability ...of G. lucidum could be related to its growth. CAZy proteins were more abundant in its genome than in the other white rot fungi models. Among these CAZy proteins, changes in lignocellulolytic enzymes during growth have not been well studied. Using genomic, transcriptomic and secretomic analyses, this study focuses on the lignocellulolytic enzymes of G. lucidum strain G0119 to determine which of these degradative enzymes contribute to its growth. From the genome sequencing data, genes belonging to CAZy protein families, especially genes involved in lignocellulose degradation, were investigated. The gene expression, protein abundance and enzymatic activity of lignocellulolytic enzymes in mycelia over a growth cycle were analysed. The overall expression cellulase was higher than that of hemicellulase and lignin-modifying enzymes, particularly during the development of fruiting bodies. The cellulase and hemicellulase abundances and activities increased after the fruiting bodies matured, when basidiospores were produced in massive quantities till the end of the growth cycle. Additionally, the protein abundances of the lignin-modifying enzymes and the expression of their corresponding genes, including laccases and lignin-degrading heme peroxidases, were highest when the mycelia fully spread in the compost bag. Type I cellobiohydrolase was observed to be the most abundant extracellular lignocellulolytic enzyme produced by the G. lucidum strain G0119. The AA2 family haem peroxidases were the dominant lignin-modifying enzyme expressed during the mycelial growth phase, and several laccases might play roles during the formation of the primordium. This study provides insight into the changes in the lignocellulose degradation ability of G. lucidum during its growth and will facilitate the discovery of new approaches to accelerate the growth of G. lucidum in culture.
The feasibility of biological pretreatment for subsequent saccharification largely depends upon an effective pretreatment system. A significant enhancement of saccharification was discovered with ...corn stover pretreated by white rot fungus Irpex lacteus CD2. The highest saccharification ratio reached 66.4%, which was significantly higher than what was reported. Hemicellulose was first destroyed in the process and then lignin. Lignin and hemicellulose were selectively degraded over cellulose, respectively, resulting in increased crystallinity. Enhanced saccharification and the fluctuation in crystallinity together indicated the destruction of the cellulose crystalline structure. Additionally, further studies revealed the disruption of the cell wall and the vital increase of large pores in the pretreated samples, which might be caused by the selective degradation of amorphous components and fungal penetration. Results suggest that I. lacteus has a more efficient degradation system than other reported white rot fungi and can be further explored as an alternative to the existing thermochemical processes.
The mild acid pretreatment and the combination of biological pretreatment by a white rot fungus
Echinodontium taxodii or a brown rot fungus
Antrodia sp. 5898 with mild acid pretreatment were ...evaluated under different pretreatment conditions for enzymatic hydrolysis and ethanol production from water hyacinth. The combined pretreatment with
E. taxodii (10
days) and 0.25% H
2SO
4 was proved to be more effective than the sole acid pretreatment. The reducing sugar yield from enzymatic hydrolysis of co-treated water hyacinth increased 1.13–2.11 fold than that of acid-treated water hyacinth at the same conditions. The following study on separate hydrolysis and fermentation with
Saccharomyces cerevisiae indicated that the ethanol yield from co-treated water hyacinth achieved 0.192
g/g of dry matter, which increased 1.34-fold than that from acid-treated water hyacinth (0.146
g/g of dry matter). This suggested that the combination of biological and mild acid pretreatment is a promising method to improve enzymatic hydrolysis and ethanol production from water hyacinth with low lignin content.
► Fungal pretreatment can accelerate thermal degradation and slightly affect the shapes of TG and DTG curves. ► The temperature corresponding to maximum weight loss rate shows a lateral shift to ...higher temperature with the heating rate. ► The activation energies of coculture-pretreated corn stover were lower than that of monoculture pretreated.
Non-isothermal thermogravimetry/derivative thermogravimetry (TG/DTG) measurements are used to determine pyrolytic characteristics and kinetics of lignocellulose. TG/DTG experiments at different heating rates with corn stover pretreated with monocultures of Irpex lacteus CD2 and Auricularia polytricha AP and their cocultures were conducted. Heating rates had little effect on the pyrolysis process, but the peak of weight loss rate in the DTG curves shifted towards higher temperature with heating rate. The maximum weight loss of biopretreated samples was 1.25-fold higher than that of the control at the three heating rates, and the maximum weight loss rate of the co-culture pretreated samples was intermediate between that of the two mono-cultures. The activation energies of the co-culture pretreated samples were 16–72kJmol−1 lower than that of the mono-culture at the conversion rate range from 10% to 60%. This suggests that co-culture pretreatment can decrease activation energy and accelerate pyrolysis reaction thus reducing energy consumption.
Petroleum hydrocarbons (PHs) are a big group of chemicals that have caused a major concern because of their widespread distribution into the environment, bioaccumulation potential, harmful effects ...and biodegradation resistance. Soil and water pollution is mainly attributed to hydrocarbons from oil refineries, petrochemical industries, human activities and other sources. The mechanisms and factors that affect biodegradation should be further understood because the choice of bioremediation technique depends on them. This review described fungal PHs degradation, emphasized the relevant physicochemical and biological factors, and discussed the enzymatic systems influencing PHs biodegradation.
Developing methods for increasing the biomass and improving the plant architecture is important for crop improvement. We herein describe a gene belonging to the RING_Ubox (RING (Really Interesting ...New Gene) finger domain and U-box domain) superfamily,
(
), which regulates the number of grains per panicle, the plant height, and the number of tillers. We used the CRISPR/Cas9 system to introduce loss-of-function mutations to
. Compared with the control plants, the resulting
mutant plants had a higher grain yield because of increases in the plant height and in the number of tillers and grains per panicle. Thus,
may be useful for the genetic improvement of plant architecture and yield. An examination of evolutionary relationships revealed that
is highly conserved in rice. We demonstrated that OsPAGN1 can interact directly with OsCNR10 (CELL NUMBER REGULATOR10), which negatively regulates the number of rice grains per panicle. A transcriptome analysis indicated that silencing
affects the levels of active cytokinins in rice. Therefore, our findings have clarified the
functions related to rice growth and grain development.
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