A laccase from the medicinal mushroom Ganoderma lucidum

Natural Products with Inhibitory Activity against Human Immunodeficiency Virus Type 1

Infections caused by human immunodeficiency virus (HIV) are considered one of the main public health problems worldwide. Antiretroviral therapy (ART) is the current modality of treatment for HIV-1 infection. It comprises the combined use of several drugs and can decrease the viral load and increase the CD4+ T cell count in patients with HIV-1 infection, thereby proving to be an effective modality. This therapy significantly decreases the rate of morbidity and mortality owing to acquired immunodeficiency syndrome (AIDS) and prolongs and improves the quality of life of infected patients. However, nonadherence to ART may increase viral resistance to antiretroviral drugs and transmission of drug-resistant strains of HIV. Therefore, it is necessary to continue research for compounds with anti-HIV-1 activity, exhibiting a potential for the development of an alternative or complementary therapy to ART with low cost and fewer side effects. Natural products and their derivatives represent an excellent option owing to their therapeutic potential against HIV. Currently, the derivatives of natural products available as anti-HIV-1 agents include zidovudine, an arabinonucleoside derivative of the Caribbean marine sponge (Tectitethya crypta), which inhibits the reverse transcriptase of the virus. This was the first antiviral agent approved for treatment of HIV infection. Additionally, bevirimat (isolated from Syzygium claviflorum) and calanolide A (isolated from Calophyllum sp.) are inhibitors of viral maturation and reverse transcription process, respectively. In the present review, we aimed to describe the wide repertoire of natural compounds exhibiting anti-HIV-1 activity that can be considered for designing new therapeutic strategies to curb the HIV pandemic.

Anti-HIV-1 reverse transcriptase property of some edible mushrooms in Asia

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS), which is a serious health threat worldwide. One of its core enzymes, reverse transcriptase (RT), is a target for HIV inhibition. A number of bioactive compounds have been successfully used for HIV treatment. However, HIV rapidly mutates, and long-term treatment can cause drug-resistant strains. Therefore, new inhibitors are required to overcome this problem. In this study, the aqueous, ethanolic and hexane crude extracts of 19 edible and medicinal mushrooms, which are widely grown and available commercially in Thailand, were screened against HIV-1 RT. The results showed that the water extracts of A. blazei and I. obliquus, the ethanol extracts of I. obliquus and P. igniarius and the hexane extract of I. obliquus exhibited strong anti-HIV-1 RT activity with IC₅₀ values of 1.92 ± 0.15, 4.39 ± 0.79, 6.17 ± 0.76 and 7.75 ± 246 µg/ml, respectively. These mushrooms have the potential for HIV treatment, and further study on identification of the bioactive compounds against HIV-1 RT should be performed.

Importance of a Laccase Gene (Lcc1) in the Development of Ganoderma tsugae

In this study, a novel laccase gene (Lcc1) from Ganoderma tsugae was isolated and its functions were characterized in detail. The results showed that Lcc1 has the highest expression activity during mycelium development and fruit body maturation based on the analysis of Lcc1 RNA transcripts at different developmental stages of G. tsugae. To investigate the exact contribution of Lcc1 to mycelium and fruit body development in G. tsugae, Lcc1 transgenic strains were constructed by targeted gene replacement and over-expression approaches. The results showed that the lignin degradation rate in Lcc1 deletion mutant was much lower than the degradation efficiency of the wild-type (WT), over-expression and rescue strains. The lignin degradation activity of G. tsugae is dependent on Lcc1 and the deletion of Lcc1 exerted detrimental influences on the development of mycelium branch. Furthermore, the study uncovered that Lcc1 deletion mutants generated much shorter pale grey fruit bodies, suggesting that Lcc1 contributes directly to pigmentation and stipe elongation during fruit body development in G. tsugae. The information obtained in this study provides a novel and mechanistic insight into the specific role of Lcc1 during growth and development of G. tsugae.

Purification and characterization of laccase from Marasmius species BBKAV79 and effective decolorization of selected textile dyes

A novel laccase-producing white-rot fungus, Marasmius sp. BBKAV79 (Genbank Accession Number-KP455496, KP455497), was isolated and subjected to purification, characterization and dye decolorization study. The purified enzyme was obtained with a specific activity of 0.226 U mg-1 protein and a final yield of 13.5 %. The enzyme was found to be a monomeric protein with a molecular mass of ~75 kDa as estimated by non-denaturing polyacrylamide gel electrophoresis (PAGE) and further confirmed with zymogram analysis. The optimal pH and temperature of the laccase was recorded to be 5.5 and 40 °C, respectively. The metal ions Hg2+ and Ag+ were found to drastically inhibit the activity of laccase at the rate of 96.6 and 96.5 %, respectively. Nevertheless, Fe3+ was found to inhibit laccase activity at 40 %. Phenylmethanesulfonyl fluoride (PMSF) strongly inhibited the laccase activity, and additives viz, sodium dodecyl sulfate (SDS), hydrogen peroxide (H2O2) and sodium chloride (NaCl) were known to follow the earlier pattern of enzyme inhibition. The values of kinetic parameters K m and V max for purified laccase were noted at 3.03 mM and 5 μmol min-1, respectively, for guaiacol as substrate. The textile dyes were decolorized at a range of 72-76 % and 88-93 % when treated with Marasmius sp. BBKAV79 and purified laccase, respectively. Based on the outcome of the present investigation, it could be, therefore, inferred that laccase isolated from Marasmius sp. BBKAV79 effectively decolorizes the textile dyes; however, the metal ions Hg2+, Ag+ and Fe3+ and agents like PMSF, SDS, H2O2 and NaCl pose an effective inhibitory potential under specified physicochemical conditions.

Bioactivities and Health Benefits of Mushrooms Mainly from China

Many mushrooms have been used as foods and medicines for a long time. Mushrooms contain polyphenols, polysaccharides, vitamins and minerals. Studies show that mushrooms possess various bioactivities, such as antioxidant, anti-inflammatory, anticancer, immunomodulatory, antimicrobial, hepatoprotective, and antidiabetic properties, therefore, mushrooms have attracted increasing attention in recent years, and could be developed into functional food or medicines for prevention and treatment of several chronic diseases, such as cancer, cardiovascular diseases, diabetes mellitus and neurodegenerative diseases. The present review summarizes the bioactivities and health benefits of mushrooms, and could be useful for full utilization of mushrooms.

Recent Developments in Using Advanced Sequencing Technologies for the Genomic Studies of Lignin and Cellulose Degrading Microorganisms

Lignin is a complex polyphenyl aromatic compound which exists in tight associations with cellulose and hemicellulose to form plant primary and secondary cell wall. Lignocellulose is an abundant renewable biomaterial present on the earth. It has gained much attention in the scientific community in recent years because of its potential applications in bio-based industries. Microbial degradation of lignocellulose polymers was well studied in wood decaying fungi. Based on the plant materials they degrade these fungi were classified as white rot, brown rot and soft rot. However, some groups of bacteria belonging to the actinomycetes, α-proteobacteria and β-proteobacteria were also found to be efficient in degrading lignocellulosic biomass but not well understood unlike the fungi. In this review we focus on recent advancements deployed for finding and understanding the lignocellulose degradation by microorganisms. Conventional molecular methods like sequencing 16s rRNA and Inter Transcribed Spacer (ITS) regions were used for identification and classification of microbes. Recent progression in genomics mainly next generation sequencing technologies made the whole genome sequencing of microbes possible in a great ease. The whole genome sequence studies reveals high quality information about genes and canonical pathways involved in the lignin and other cell wall components degradation.

From 2000years of Ganoderma lucidum to recent developments in nutraceuticals

Medicinal mushrooms have been used for centuries as nutraceuticals to improve health and to treat numerous chronic and infectious diseases. One such mushroom is Ganoderma lucidum, commonly known as Lingzhi, a species revered as a medicinal mushroom for treating assorted diseases and prolonging life. The fungus is found in diverse locations, and this may have contributed to confusion regarding the correct taxonomic classification of the genus Ganoderma. G. lucidum was first used to name a specimen found in England and thereafter was naively applied to a different Ganoderma species found in Asia, commonly known as Chinese Lingzhi. Despite the taxonomic confusion, which has largely been uncorrected, the popularity of Lingzhi has escalated across the globe. The current taxonomic situation is now discussed accurately in this Special Issue on Ganoderma. Today it is a multi-billion dollar industry wherein Lingzhi is cultivated or collected from the wild and consumed as a tea, in alcoholic beverages, and as a nutraceutical to confer numerous health benefits. Consumption of nutraceuticals has grown in popularity, and it is becoming increasingly important that active ingredients be identified and that suppliers make substantiated health claims about their products. The objective of this article is to present a review of G. lucidum over the past 2000 years from prized ancient "herbal" remedy to its use in nutraceuticals and to the establishment of a 2.5 billion $ (US) industry.

Identification of a laccase Glac15 from Ganoderma lucidum 77002 and its application in bioethanol production

BACKGROUND

Laccases have potential applications in detoxification of lignocellulosic biomass after thermochemical pretreatment and production of value-added products or biofuels from renewable biomass. However, their application in large-scale industrial and environmental processes has been severely thwarted by the high cost of commercial laccases. Therefore, it is necessary to identify new laccases with lower cost but higher activity to detoxify lignocellulosic hydrolysates and better efficiency to produce biofuels such as bioethanol. Laccases from Ganoderma lucidum represent proper candidates in processing of lignocellulosic biomass.

RESULTS

G. lucidum 77002 produces three laccase isoenzymes with a total laccase activity of 141.1 U/mL within 6 days when using wheat bran and peanut powder as energy sources in liquid culture medium. A new isoenzyme named Glac15 was identified, purified, and characterized. Glac15 possesses an optimum pH of 4.5 to 5.0 and a temperature range of 45°C to 55°C for the substrates tested. It was stable at pH values ranging from 5.0 to 7.0 and temperatures lower than 55°C, with more than 80% activity retained after incubation for 2 h. When used in bioethanol production process, 0.05 U/mL Glac15 removed 84% of the phenolic compounds in prehydrolysate, and the yeast biomass reached 11.81 (optimal density at 600 nm (OD600)), compared to no growth in the untreated one. Addition of Glac15 before cellulase hydrolysis had no significant effect on glucose recovery. However, ethanol yield were improved in samples treated with laccases compared to that in control samples. The final ethanol concentration of 9.74, 10.05, 10.11, and 10.81 g/L were obtained from samples containing only solid content, solid content treated with Glac15, solid content containing 50% prehydrolysate, and solid content containing 50% prehydrolysate treated with Glac15, respectively.

CONCLUSIONS

The G. lucidum laccase Glac15 has potentials in bioethanol production industry.

A laccase with antiproliferative and HIV-I reverse transcriptase inhibitory activities from the mycorrhizal fungus Agaricus placomyces

A novel 68 kDa laccase was purified from the mycorrhizal fungus Agaricus placomyces by utilizing a procedure that comprised three successive steps of ion exchange chromatography and gel filtration as the final step. The monomeric enzyme exhibited the N-terminal amino acid sequence of DVIGPQAQVTLANQD, which showed only a low extent of homology to sequences of other fungal laccases. The optimal temperature for A. placomyces laccase was 30°C, and optimal pH values for laccase activity towards the substrates 2,7′-azinobis[3-ethylbenzothiazolone-6-sulfonic acid] diammonium salt (ABTS) and hydroquinone were 5.2 and 6.8, respectively. The laccase displayed, at 30°C and pH 5.2, K_m values of 0.392 mM towards hydroquinone and 0.775 mM towards ABTS. It potently suppressed proliferation of MCF 7 human breast cancer cells and Hep G2 hepatoma cells and inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity with an IC₅₀ of 1.8 μM, 1.7 μM, and 1.25 μM, respectively, signifying that it is an antipathogenic protein.

Deep insight into the Ganoderma lucidum by comprehensive analysis of its transcriptome

BACKGROUND

Ganoderma lucidum is a basidiomycete white rot fungus and is of medicinal importance in China, Japan and other countries in the Asiatic region. To date, much research has been performed in identifying the medicinal ingredients in Ganoderma lucidum. Despite its important therapeutic effects in disease, little is known about Ganoderma lucidum at the genomic level. In order to gain a molecular understanding of this fungus, we utilized Illumina high-throughput technology to sequence and analyze the transcriptome of Ganoderma lucidum.

METHODOLOGY/PRINCIPAL FINDINGS

We obtained 6,439,690 and 6,416,670 high-quality reads from the mycelium and fruiting body of Ganoderma lucidum, and these were assembled to form 18,892 and 27,408 unigenes, respectively. A similarity search was performed against the NCBI non-redundant nucleotide database and a customized database composed of five fungal genomes. 11,098 and 8, 775 unigenes were matched to the NCBI non-redundant nucleotide database and our customized database, respectively. All unigenes were subjected to annotation by Gene Ontology, Eukaryotic Orthologous Group terms and Kyoto Encyclopedia of Genes and Genomes. Differentially expressed genes from the Ganoderma lucidum mycelium and fruiting body stage were analyzed, resulting in the identification of 13 unigenes which are involved in the terpenoid backbone biosynthesis pathway. Quantitative real-time PCR was used to confirm the expression levels of these unigenes. Ganoderma lucidum was also studied for wood degrading activity and a total of 22 putative FOLymes (fungal oxidative lignin enzymes) and 120 CAZymes (carbohydrate-active enzymes) were predicted from our Ganoderma lucidum transcriptome.

CONCLUSIONS

Our study provides comprehensive gene expression information on Ganoderma lucidum at the transcriptional level, which will form the foundation for functional genomics studies in this fungus. The use of Illumina sequencing technology has made de novo transcriptome assembly and gene expression analysis possible in species that lack full genome information.

The genome of Ganoderma lucidum provides insights into triterpenes biosynthesis and wood degradation [corrected]

Background

Ganoderma lucidum (Reishi or Ling Zhi) is one of the most famous Traditional Chinese Medicines and has been widely used in the treatment of various human diseases in Asia countries. It is also a fungus with strong wood degradation ability with potential in bioenergy production. However, genes, pathways and mechanisms of these functions are still unknown.

Methodology/Principal Findings

The genome of G. lucidum was sequenced and assembled into a 39.9 megabases (Mb) draft genome, which encoded 12,080 protein-coding genes and ∼83% of them were similar to public sequences. We performed comprehensive annotation for G. lucidum genes and made comparisons with genes in other fungi genomes. Genes in the biosynthesis of the main G. lucidum active ingredients, ganoderic acids (GAs), were characterized. Among the GAs synthases, we identified a fusion gene, the N and C terminal of which are homologous to two different enzymes. Moreover, the fusion gene was only found in basidiomycetes. As a white rot fungus with wood degradation ability, abundant carbohydrate-active enzymes and ligninolytic enzymes were identified in the G. lucidum genome and were compared with other fungi.

Conclusions/Significance

The genome sequence and well annotation of G. lucidum will provide new insights in function analyses including its medicinal mechanism. The characterization of genes in the triterpene biosynthesis and wood degradation will facilitate bio-engineering research in the production of its active ingredients and bioenergy.

A laccase with HIV-1 reverse transcriptase inhibitory activity from the broth of mycelial culture of the mushroom Lentinus tigrinus

A 59 kDa laccase with inhibitory activity against HIV-1 reverse transcriptase (IC₅₀ = 2.4 μM) was isolated from the broth of mycelial culture of the mushroom Lentinus tigrinus. The isolation procedure involved ion exchange chromatography on DEAE-cellulose and CM-cellulose, and gel filtration by fast protein liquid chromatography on Superdex 75. The laccase was adsorbed on both types of ion exchangers. About 95-fold purification was achieved with a 25.9% yield of the enzyme. The procedure resulted in a specific enzyme activity of 76.6 U/mg. Its N-terminal amino acid sequence was GIPDLHDLTV, which showed little similarity to other mushroom laccase and other Lentinus tigrinus strain laccase. Its characteristics were different from previously reported laccase of other Lentinus tigrinus strain. Maximal laccase activity was observed at a pH of 4 and at a temperature of 60°C, respectively. This study yielded the information about the potentially exploitable activities of Lentinus tigrinus laccase.

A laccase with antiproliferative activity against tumor cells from an edible mushroom, white common Agrocybe cylindracea

A laccase, with HIV-1 reverse transcriptase inhibitory activity (IC(50)=12.7 μM) and antiproliferative activity against HepG2 cells (IC(50)=5.6 μM) and MCF7 cells (IC(50)=6.5 μM), was purified from fresh fruiting bodies of the edible white common Agrocybe cylindracea mushroom. The laccase, which had a novel N-terminal sequence, displayed a molecular mass of 58 kDa within the range reported for most other mushroom laccases. The purification protocol entailed ion exchange chromatography on DEAE-cellulose, SP-Sepharose, and Q-Sepharose and gel filtration on Superdex 75. The laccase was adsorbed on DEAE-cellulose and Q-Sepharose, but unadsorbed on SP-Sepharose. Its optimum pH was pH 3-4 and its optimum temperature was 50°C. The activity of the isolated laccase differed from one substrate to another. The ranking was ABTS>N,N-dimethyl-1,4-phenylenediamine>hydroquinone>catechol>2-methylcatechol>pyrogallol.

Effects on tyrosinase activity by the extracts of Ganoderma lucidum and related mushrooms

The inhibitory effects on tyrosinase activity by extracts of several mushrooms belonging to Basidiomycetes were evaluated. Among the tested mushrooms (Ganoderma lucidum, Antrodia camphorata, Agaricus brasiliensis, and Cordyceps militaris), G. lucidum exhibited significant inhibition of tyrosinase activity (IC(50) value 0.32 mg/ml), compared to those prepared from other Basidiomycetes. Tyrosinase inhibitors are effective components of skin-lightening compounds and other cosmetics; currently many of the facial mask cosmetics in the market contain Ganoderma extracts in their ingredients. The finding that mushroom extracts contain tyrosinase activity inhibition will contribute to better understanding of how their 'healing' properties in various Chinese traditional herbal on skin care products.