Overview of Mycelial Fungi - Lignin Destructors

In this work, the following genuses of mycelial fungi, capable of producing ligninolytic enzymes of various actions, were considered:Penicillium, Aspergillus, Fusariumand Altermaria. Fungi of the genus Aspergilluswere capable of producing laccase, manganese peroxidase and lignin peroxidase in the medium. Penicillium mostly produced laccase. Fusariumproduced laccase, aryl alcohol oxidase, manganesedependent peroxidase, manganese-independent peroxidase and lignin peroxidase. Alternariaproduced laccase, lignin peroxidase and manganese peroxidase. The results demonstrated the possibility of using specific substrates in the study of enzyme activity, as well as the influence of some factors introduced into the medium on the synthesis of enzymes. The auxiliary influence of these fungi on the synthesis of ligninolytic enzymes in symbiosis with otherswas considered. Keywords: mycelial fungi, ligninolytic enzymes, Penicillium, Aspergillus, Fusarium, Altermaria

Transcriptomic Analysis of the White-rot Basidiomycete Lentinus Squarrosulus to Provide Insights Into Its Lignocellulose Biodegradation Ability

BackgroundBasidiomycetes are of special interest in biotechnological research for their versatile potential in the degradation of lignocellulosic biomass, chiefly attributed to ligninolytic enzymes along with exo, endo β-glucanases, xylanases, esterases, pectinases, mannanases, cellobiohydrolases, polysaccharide monooxygenases. Relatively little is known about the metabolic process and the subsequent polysaccharide degradation. Transcriptomic analysis of lignicolous fungi grown on different substrates, although attempted by researchers, has focused on a fairly small group of species reporting the expression of fungal genes in response to lignocellulosic biomass as a substrate. This study accordingly reports analysis of transcriptome of a white-rot Basidiomycete L.squarrosulus grown in simple potato dextrose broth supplemented with aromatic compound, reactive black dye to gain an insight into the degradation ability of the fungus. RNA was sequenced using Illumina NextSeq 500 to obtain 6,679,162 high-quality paired-end reads that were assembled de novo using CLC assembly cells to generate 25,244 contigs. Putative functions were assigned for the 10,494 transcripts based on sequence similarities through BLAST2GO 5.2 and Function annotator.ResultsFunctional assignments revealed enhanced oxidoreductase activity through the expression of diverse biomass-degrading enzymes and their corresponding coregulators. CAZyme analysis through dbCAN and CUPP revealed the presence of 6 families of polysaccharide lyases, 51 families of glycoside hydrolases, 23 families of glycoside transferases, 7 families of carbohydrate esterases and 10 families of auxiliary activities. Genes encoding ligninolytic enzymes and auxiliary activities among the transcript sequences were identified through gene prediction by AUGUSTUS and FGENESH. Biochemical analysis of several biomass-degrading enzymes substantiated the functional predictions.ConclusionIn essence, L. squarrosulus grown in a simple medium devoid of lignocellulosic substrate demonstrated the presence of a repertoire of lignocellulose-degrading enzymes, simplying that a source of lignocellulose is not required for the expression of these biomass-degrading enzymes. This study on the transcriptome analysis of L. squarrosulus revealed significant facts on this front and will definitely enhance the knowledge about the biodegradative ability of this fungus, potentially paving the way for efficient biotechnological applications utilizing its potency in biomass degradation and its future functional exploitation in biomass conversion applications.

Evaluation of bamboo water-retting for fiber bundle extraction

Bamboo fiber bundles were successfully extracted from bamboo culms using water-retting, taking advantage of enzymes secreted by microorganisms in the retting liquid. The harvest year and place of origin of the bamboo and the source of water impacted the products of the retting process. One-month-old bamboo was decomposed completely, whereas the one-year-old sample was hardly changed after 24-day retting. Moisture regain and crystallinity varied with the different origins of the bamboo. However, all samples resulted in similar chemical structures and thermal properties. The best operational conditions for water-retting were 3-month-old bamboo from Wuxi incubated in deionized water. Enzyme activities, including cellulase, xylanase, pectinase, and ligninolytic enzymes (lignin peroxidase, manganese peroxidase, and laccase) were monitored during a 24-day retting. Manganese peroxidase was the primary enzyme used to degrade lignin, resulting in absorbance at 294 nm of UV-Vis spectra. In addition, xylanase played a leading role in hydrolyzing hemicellulose, which was consistent with the change in reducing sugar yield. In addition, variations in dissolved oxygen and pH values were also recorded, indicating the changes in bacterial strains and the enzymatic system. The wastewater from bamboo retting showed good biodegradability but a lack of nitrogen and phosphorus. Overall, a manganese peroxidase–xylanase combined enzyme-retting treatment would offer a more environmentally friendly approach for extracting bamboo fibers.

LIGNOCELLULOSE WASTE VALORIZATION BY AN ENZYMATIC COCKTAIL OF P. ERYNGII AND P. PULMONARIUS

The present study aimed to characterize Pleurotus eryngii and P. pulmonarius ligninolytic enzymes and to determine their potential for polymer degradation in common agroforestry residues. The peak of laccase activity (36052.33 U L-1) was observed after P. pulmonarius cultivation on oak sawdust. The maximal Mn-dependent peroxidase activity was reached by P. eryngii (2511.36 U L-1), while the highest level of versatile peroxidase activity was noted in P. pulmonarius (3053.03 U L-1), after fermentation of corn stalks. The highest level of lignin loss (46.28%) was achieved after cultivation of P. pulmonarius on corn stalks, but the most selective degradation of lignocellulose polymers was observed after P. eryngii cultivation on wheat straw. The obtained results lead to the conclusion that the studied P. eryngii and P. pulmonarius strains are good producers of ligninolytic enzymes and effective and selective depolymerizers of agroforestry residues, and therefore their use would be beneficial in numerous environmentally friendly technologies.

Decolourization of congo red synthetic dyes by dark septate endophytes

The use of fungi is known to be an eco-friendly and cost-competitive approach to degrade synthetic dyes such as Congo Red (CR) in industrial effluents. This research aimed to evaluate the potential of dark septate endophytes (DSE) fungi in decolourizing CR synthetic dyes. Two DSE strains, namely CPP and KSP, were studied to decolourize 50 mgL−1 CR based on the capability to produce the ligninolytic enzyme, dye decolourization efficiency, decolourization index, and fungal dry biomass weight after 7 and 14 days of incubation. CR decolourization was monitored spectrophotometry at 495 nm. The result indicated that CPP and KSP were successfully decolourized CR dye up to 97.00% and 85.00%, respectively, with decolourization index of 1.37 and 1.36 within 14 days. There is no significant difference in DSE growth with and without the addition of CR dye. In addition, these two DSE fungi (CPP and KSP) are able to produce ligninolytic enzymes. The results indicated that the DSE are potential to be used as decolourization agents for azo synthetic dyes. This is the first report on the ability of DSE to decolourize azo synthetic dyes.

Pretreated Sugarcane Bagasse Result in More Efficient Degradation by Streptomyces sp S2

Streptomyces genera plays important role in lignocellulose degradation. Many research founds Streptomyces has cellulolytic and ligninolytic enzymes that sufficient to degrade lignocellulosic materials. However, minimum lignocellulosic material condition that can efficiently degraded by Streptomyces sp. has not been fully understood. In this research, three pretreament conditions (physical, alkaline-hydrotermal, and hydrogen-peroxide chemical treatments) of sugarcane bagasse used as lignocellulosic material, to further degraded by Streptomyces sp. S2. Lignocellulose component measurement conclude that raw (physical treated only) bagasse wasn’t efficiently degraded by Streptomyces sp S2. Hydrogen-peroxide was effective on reducing both syringil and guaiacyl lignin, meanwhile alkaline-hydrotermal pretreatment was very effective on reducing syringil lignin. This study suggest that hydrogen-peroxide pretreatment can be used in many type of lignocellulosic material, which can be further degraded by Streptomyces sp. S2. Alkaline-hydrotermal preteatment on the other hand is best suited to degrade lignocellulosic material that have high percentage of syringil lignin.

Simultaneous Biological Pretreatment and Saccharification of Rice Straw by Ligninolytic Enzymes from Panus neostrigosus I9 and Commercial Cellulase

The utilization of rice straw for biofuel production is limited by its composition. The pretreatment process is required to improve the enzymatic accessibility of polysaccharides in the biomass prior to enzymatic saccharification. In this study, simultaneous biological pretreatment and saccharification (SPS) of rice straw starting from laccase production by Panus neostrigosus I9 was operated in a 2-L fermenter. It was found that fungal physiology was strongly influenced by the agitation, and that the highest laccase production was obtained at an agitation speed of 750 rpm (209.96 ± 0.34 U/L). The dilution rate of 0.05 h−1 was set in continuous fermentation which resulted in laccase activity of 678.49 ± 20.39 U/L, approximately three times higher than that in batch culture. Response surface methodology (RSM) was applied to achieve the condition for maximum percentage of delignification. The maximum percentage of delignification of 45.55% was accomplished after pretreatment of rice straw with laccase enzyme 39.40 U/g rice straw at 43.70 °C for 11.19 h. Reducing sugar of 3.85 ± 0.15 g/L was obtained from the digested rice straw in a SPS reactor, while non-pretreated rice straw gave only 1.13 ± 0.10 g/L within 12 h of incubation. The results indicated that simultaneous biological pretreatment and saccharification (SPS) of rice straw by laccase helped to improve the accessibility of cellulose by cellulolytic enzymes.

Seasonal Variation and Tissues Specificity of Endophytic Fungi of Dillenia Indica L. and their Extracellular Enzymatic Activity.

Endophytes are an unexplored group of microbes that live inside the living tissues of healthy plants without any visible symptoms of the disease. This study focused on the exploration and characterisation of culturable endophytic fungi inhabiting in different parts the medicinal plant Dillenia indica L during different seasons. A total of 2360 segments from different parts like leaves (820), stems (820) and fruits (720) were screened to isolate endophytic fungi from the plants growing in Botanical Gardens of Panjab University, Chandigarh (India), during different seasons i.e., Summer, Spring, Autumn and Winter of the years 2018 and 2019. A total of twenty-five (25) species of fungi belonging to twenty (20) genera were isolated from the selected plant during different seasons. The plant has the highest affinity for Lasiodiplodia theobromae followed by Colletotrichum gloeosporioides and Cladosporium cladosporides. The percentage frequency was found to be 96%, 64% and 20% for leaves, stems and fruits. The colonization rate for leaves, stems and fruits was 55.6%, 25.6% and 8.8%. The isolated fungi were identified by morphological, microscopic and molecular characteristics. Monsoon (Rainy season) had the highest number of isolates (312 isolates), followed by summer (208 isolates), Winter (164 isolates) and Autumn (114 isolates). Species diversity was highest during the rainy season (19 species) and lowest during the Winter (12 species). The isolated fungi also produce extracellular enzymes such as amylase, lipase, protease, asparaginase, cellulase and ligninolytic enzymes. The results indicate that Dillenia indica L. harbors novel endophytic fungi having agricultural, medical and industrial applications.