Ligninolytic Fungi Research Articles

Comparative Analysis of Ligninolytic Potential among Pleurotus ostreatus and Fusarium sp. with a Special Focus on Versatile Peroxidase

Lignocellulosic biomass is contemplated to be an inexpensive and copious feedstock that can be used for numerous industrial applications. However, lignin forms the lignin sheath and provides a physical barrier to enzymatic hydrolysis. In addition, lignin physically blocks cellulase, preventing it from being combined with the substrate in a process known as non-productive binding. Therefore, the depletion of lignin is a crucial method for obtaining fermentable sugars from the lignocellulosic biomass. Different white-rot fungi secrete different sets of lignin-mineralizing enzymes and each fungus secretes one or more of the three enzymes essential for lignin degradation. Among efficient redox enzymes, versatile peroxidase is extensively studied for its ability to degrade aromatics without the need for a mediator or polyvalent catalytic site. However, the presence of versatile peroxidase in F. spp. has not been studied. This study was planned with the objective of screening and comparing the production of versatile peroxidase enzymes from F. spp. and a standard culture of Pleurotus ostreatus MTCC-142. These fungal strains were first screened on solid media containing tannic acid, malachite green, or bromocresol green. The potency index for the tannic acid, malachite green, and bromocresol green on the 16th day of incubation was reported to be 1.28, 1.07, 1.09, and 1.10, respectively. Versatile peroxidase production patterns were investigated under solid state fermentation conditions for a period of 25 days at different temperatures ranging from 10 to 35 °C. The highest versatile peroxidase activity (592 UL−1) in F. sp. was observed at 30 °C after the 7th day of incubation. The molecular confirmation showed the presence of the vp gene in F. sp. along with Pleurotus ostreatus MTCC-142. The results determined that F. sp. possesses a versatile peroxidase enzyme and is able to degrade lignin efficiently, and thus it could be utilized as an alternative to other ligninolytic enzyme-producing fungi.

Tequila Vinasse Treatment in Two Types of Vertical Downflow Treatment Wetlands (with Emergent Vegetation and Ligninolytic Fungi)

The aim of this study was to evaluate and compare the efficiency of two types of vertical downflow wetlands (VDFWs) (with the presence of ligninolytic fungus Trametes versicolor and planted with Iris sibirica) for the treatment of tequila vinasses (TVs) as a secondary treatment; control systems with only a filter medium were also included. The systems operated with a 7-day run/resting mode of operation. Various water quality parameters were analyzed in both the influent and the effluents, namely total suspended solids (TSS), chemical oxygen demand (COD), biological oxygen demand (BOD5), total organic carbon (TOC), pH, electrical conductivity (EC), true color and turbidity, total phosphorus (TP), total nitrogen (TN), etc. The two types of VDFWs as well as the control treatment were effective in reducing the different pollutants (p < 0.05); however, planted systems showed a tendency toward higher efficiencies. With an influent concentration of 49,000 mg L−1 and an organic loading rate of 4942 g COD m−2d−1, the COD reduction was around 40% in the planted systems, while in the other two, the reduction was 35%. Furthermore, TSS removals were 36, 20 and 16% in the VDFWs with vegetation, ligninolytic fungus and control systems, respectively. These results suggest that the fungus Trametes versicolor did not develop the desirable enzymatic expression for pollutant removal, probably as a result of the absence of aerobic conditions in the systems. Therefore, more research is needed to achieve a better fungal performance in VDFWs.

Valorizing fungal diversity for the degradation of fluoroquinolones

Continued widespread use of antibiotics, especially fluoroquinolones, raises environmental concerns, as its driving bacterial resistance and disrupts microbial ecosystems. Here we investigate the biodegradation of ten fluoroquinolone antibiotics (six for medical use and four for veterinary use) by ligninolytic fungi, including Trametes versicolor, Bjerkandera adusta, Porosterum spadiceum, Irpex lacteus, Pleuroteus ostreatus, Phanerochaete chrysosporium, Pycnoporus cinnabarinus, Ganoderma lucidum, and Gloeophyllum trabeum. The results show significant variations between strains in the efficiency of antibiotic transformation. B. adusta and P. spadiceum were the fungi that most efficiently reduced antibiotic concentrations and were able to totally degrade eight and six antibiotics, respectively, within a 15-day period. T. versicolor and P. ostreatus also showed the ability to effectively degrade antibiotics. Specifically, T. versicolor degraded six out of the ten fluoroquinolone antibiotics by more than 70 %, while P. ostreatus degraded the tested antibiotics between 43 % and 100 %. The remaining antibiotic activity did not always correlate with a reduction in antibiotic concentrations, which points to the presence of post-transformation antimicrobial metabolites. This study also explores the potential mechanisms used by these fungi to remove selected models of fluroquinolones via enzymatic routes, such as oxidation by laccases, heme-peroxidases, and cytochrome P450, or via adsorption on fungal biomass.

Diversity of ligninolytic ascomycete fungi associated with the bleached leaf litter in subtropical and temperate forests

<p>Little is known regarding the diversity patterns of Xylariaceae and Hypoxylaceae (Ascomycota) fungi taking part in the lignin decomposition of leaf litter from different tree species and under different climatic regions. The alpha and beta diversity of Xylariaceae and Hypoxylaceae fungi was investigated on bleached leaf litter from nine subtropical and cool temperate tree species in Japan. A total of 248 fungal isolates, obtained from 480 leaves from the nine tree species, were classified into 43 operational taxonomic units (OTUs) with a 97% similarity threshold and were assigned to nine genera of Xylariaceae and Hypoxylaceae. There was no overlap of fungal OTUs between subtropical and cool temperate trees. The mean number of fungal OTUs was generally higher in subtropical than cool temperate trees, whereas rarefaction curves depicting the numbers of OTU with respect to the number of leaves from which fungi were isolated were less steep in subtropical trees than in cool temperate trees, reflecting the dominance of major OTUs in the subtropical trees and indicating a higher species richness in cool temperate regions. Nonmetric multidimensional scaling showed general overlaps of fungal OTU compositions among tree species in the respective climatic regions, and one-way permutational multivariate analysis of variance indicated that the OTU composition was not significantly different between the tree species. These results suggest a wide host range and some geographic and climatic structures of distribution of these ligninolytic fungi.</p>

Evaluation of White Rot Fungus to Control Growth of Escherichia coli in Cattle Manure

Biological soil amendments of animal origin, such as aqueous dairy manure, may be contaminated with microbial pathogens that can subsequently result in contaminated soil, water runoff, and crops. Multiple mitigation strategies are being evaluated to reduce these risks. Inclusion of filamentous fungus in a biofiltration system to inactivate pathogenic bacteria in aqueous dairy manure prior to land application is explored in this study as a preharvest preventative method. Of the microbes used to remediate biologically contaminated sites, ligninolytic white-rot fungi have been previously studied for their ability to degrade a wide variety of toxic or persistent environmental contaminants. Reduction of two E. coli strains (E. coli TVS355 and E. coli O157:H7 4407) was evaluated in aqueous dairy manure and PBS and in the presence of white-rot fungi Pleurotus ostreatus on three different nutrient sources (woodchips (WC), spent mushroom compost (SMC), and reticulated polyurethane foam (RPF)). Overall, E. coli TVS355 was more persistent in aqueous dairy manure and PBS, surviving for 50 days in the presence of P. ostreatus, with a final concentration of 4 log CFU/g in aqueous manure and 7 log CFU/g in PBS. However, greater (p < 0.0001) reduction of E. coli O157:H7 was observed, surviving for 50 days at an average of 4 log CFU/g in aqueous dairy manure and an average of 3 log CFU/g in PBS. Therefore, P. ostreatus has the potential to result in bacterial decay, with potential reduction observed in E. coli O157:H7. The RPF matrix showed positive results as a potential model for a nutrient limiting resource for P. ostreatus and could be the key to increased bacterial reductions if resulting in ligninolytic activity in order to seek other nutrient sources.

Depolymerisation of Kraft Lignin by Tailor-Made Alkaliphilic Fungal Laccases.

Lignins released in the black liquors of kraft pulp mills are an underutilised source of aromatics. Due to their phenol oxidase activity, laccases from ligninolytic fungi are suitable biocatalysts to depolymerise kraft lignins, which are characterised by their elevated phenolic content. However, the alkaline conditions necessary to solubilise kraft lignins make it difficult to use fungal laccases whose activity is inherently acidic. We recently developed through enzyme-directed evolution high-redox potential laccases active and stable at pH 10. Here, the ability of these tailor-made alkaliphilic fungal laccases to oxidise, demethylate, and depolymerise eucalyptus kraft lignin at pH 10 is evidenced by the increment in the content of phenolic hydroxyl and carbonyl groups, the methanol released, and the appearance of lower molecular weight moieties after laccase treatment. Nonetheless, in a second assay carried out with higher enzyme and lignin concentrations, these changes were accompanied by a strong increase in the molecular weight and content of β-O-4 and β-5 linkages of the main lignin fraction, indicating that repolymerisation of the oxidised products prevails in one-pot reactions. To prevent it, we finally conducted the enzymatic reaction in a bench-scale reactor coupled to a membrane separation system and were able to prove the depolymerisation of kraft lignin by high-redox alkaliphilic laccase.

Exploring the bioremediation capability of petroleum-contaminated soils for enhanced environmental sustainability and minimization of ecotoxicological concerns.

The bioremediation of soils contaminated with petroleum hydrocarbons (PHCs) has emerged as a promising approach, with its effectiveness contingent upon various types of PHCs, i.e., crude oil, diesel, gasoline, and other petroleum products. Strategies like genetically modified microorganisms, nanotechnology, and bioaugmentation hold potential for enhancing remediation of polycyclic aromatic hydrocarbon (PAH) contamination. The effectiveness of bioremediation relies on factors such as metabolite toxicity, microbial competition, and environmental conditions. Aerobic degradation involves enzymatic oxidative reactions, while bacterial anaerobic degradation employs reductive reactions with alternative electron acceptors. Algae employ monooxygenase and dioxygenase enzymes, breaking down PAHs through biodegradation and bioaccumulation, yielding hydroxylated and dihydroxylated intermediates. Fungi contribute via mycoremediation, using co-metabolism and monooxygenase enzymes to produce CO2 and oxidized products. Ligninolytic fungi transform PAHs into water-soluble compounds, while non-ligninolytic fungi oxidize PAHs into arene oxides and phenols. Certain fungi produce biosurfactants enhancing degradation of less soluble, high molecular-weight PAHs. Successful bioremediation offers sustainable solutions to mitigate petroleum spills and environmental impacts. Monitoring and assessing strategy effectiveness are vital for optimizing biodegradation in petroleum-contaminated soils. This review presents insights and challenges in bioremediation, focusing on arable land safety and ecotoxicological concerns.

Enhancement of methane production from livestock manure with pre-treatments based in fungi of genus Pleurotus

Livestock manure, traditionally used just as fertilizer, can be energetically valued to produce biogas as an attractive alternative, since nowadays, energy production and its cost stands for a pressing problem around the world. Nevertheless, the presence of lignin in manure hinders the production of methane. This could be improved by pre-treating the manure with ligninolytic fungi, able to break lignin and therefore facilitate the hydrolysis step for the hydrolytic bacteria, yielding higher volumes of biomethane. Three strategies of incubation with living fungi of genus Pleurotus were evaluated to enhance methane production from livestock manure mixed with bedding material: short term (two weeks 2L container) and long term (two months 400 L container) and 24 h (2 L container) with a crude water extraction of Pleurotus extracellular enzymes. The positive effect of the fungal treatment was observed in the three strategies obtaining an increase in methane production with respect to the control manure of 7% at short term, 111% at long term and 173% (crude enzymatic extract). Consequently, the strategy of using crude enzyme extracts from Pleurotus to improve hydrolysis step as pre-treatment of manure should be considered as a novel, easy, cheap and promising tool to optimize methane production.

The relationship between tree species and wood colonising fungi and fungal interactions influences wood degradation

Deadwood is one of the main terrestrial carbon (C) pools and its decomposition is fundamental in biogeochemical cycles. As fungi are the main wood degraders, a study was carried out on deadwood-colonising fungal community changes as a function of host plants and wood degradation. Deadwood fungal communities were investigated in adjacent woody plantations of hybrid poplar, willow and black locust established in the early 2000 s and abandoned for fifteen years. Lying deadwood was estimated in the three plantations and wood decay (WD) visually assessed using a 3-class scale. Fungal colonization of wood samples was assessed using culture-based methods and identified with morphological and molecular features. Wood colonising fungal communities differed in composition both between host plants and WD classes (P < 0.001). Ligninolytic white rot fungal species (Basidiomycota) prevailed in black locust and poplar, where they co-colonised all three wood decay classes in association with soft rot fungal agents. In willow, Daldinia chilidiae, a ligninolytic ascomycete, co-colonised deadwood with fungal species associated with tree dieback (Botryosphaeriaceae); whilst soft rot fungi principally colonised the highest wood degradation class. Results showed high fungal preference towards tree species that was most evident in ligninolytic fungi. Moreover, different wood decay paths were deduced from fungal changes across the three wood degrading classes and the necromass distribution in those classes. The co-habitation of white rot and soft rot fungi in all the wood decay classes of poplar and black locust indicated a continuum decay process; whilst the prevalence of soft rot fungi in the almost decomposed class in willow, suggested sequential succession of primary and secondary phases in deadwood degradation. Wood degradation is influenced by plant species and the native fungal microbiome and is mediated by multiple biotic interactions and environmental factors, which supports the use of wood colonising fungi as indicators of forest ecosystem health.

The Neolithic site "La Marmotta": DNA metabarcoding to identify the microbial deterioration of waterlogged archeological wood.

The evaluation of biological degradation of waterlogged archeological wood is crucial to choose the conservative and protective treatments to be applied to the wooden material. The waterlogged environmental conditions are characterized by oxygen scarcity, only allowing the growth of adapted microbes capable to degrade the organic wooden material, mainly erosion bacteria and soft-rot fungi. In this work, we characterized and evaluated the biodegradation state and the microbial communities of wooden fragments preserved in storage tanks. These were preserved by waterlogging within the Neolithic village "La Marmotta," currently found under the Bracciano Lake (Lazio, Italy). The waterlogged wood samples were first identified taxonomically with an optical microscope, also allowing an evaluation of their preservation state. The microbial community was then evaluated through the sequencing of Internal Transcribed Spacer sequences for fungi and 16S for bacteria with the Oxford Nanopore Technologies (ONT) MinION platform. The identified microbial community appears to be consistent with the waterlogged samples, as many bacteria attributable to the erosion of wood and ligninolytic fungi have been sequenced. The reported results highlight the first use of targeted metabarcoding by ONT applied to study the biodeterioration of waterlogged archeological wood.

Fungal community composition and genetic potential regulate fine root decay in northern temperate forests.

Understanding how genetic differences among soil microorganisms regulate spatial patterns in litter decay remains a persistent challenge in ecology. Despite fine root litter accounting for ~50% of total litter production in forest ecosystems, far less is known about the microbial decay of fine roots relative to aboveground litter. Here, we evaluated whether fine root decay occurred more rapidly where fungal communities have a greater genetic potential for litter decay. Additionally, we tested if linkages between decay and fungal genes can be adequately captured by delineating saprotrophic and ectomycorrhizal fungal functional groups based on whether they have genes encoding certain ligninolytic class II peroxidase enzymes, which oxidize lignin and polyphenolic compounds. To address these ideas, we used a litterbag study paired with fungal DNA barcoding to characterize fine root decay rates and fungal community composition at the landscape scale in northern temperate forests, and we estimated the genetic potential of fungal communities for litter decay using publicly available genomes. Fine root decay occurred more rapidly where fungal communities had a greater genetic potential for decay, especially of cellulose and hemicellulose. Fine root decay was positively correlated with ligninolytic saprotrophic fungi and negatively correlated with ECM fungi with ligninolytic peroxidases, likely because these saprotrophic and ectomycorrhizal functional groups had the highest and lowest genetic potentials for plant cell wall degradation, respectively. These fungal variables overwhelmed direct environmental controls, suggesting fungal community composition and genetic variation are primary controls over fine root decay in temperate forests at regional scales.

Interference of wood decay, growth, and infection ofGanoderma boninenseby ligninolytic fungi from herbaceous plants

Basal stem rot (BSR) disease caused byGanoderma boninenseis the most destructive disease in oil palm plantations. Herbaceous plants such as arrowroot, cocoyam, and canna were reported to interfere with theGanodermadisease of oil palm under mixed planting on non-sterilized soil. This study aimed to determine the role of the ligninolytic fungi isolated from herbaceous plants on wood decay, mycelial growth, and infection ofGanoderma boninense. A total of 24 ligninolytic fungal isolates were isolated from arrowroot, cocoyam, and canna plant and grouped into 6 types of wood decay interaction, namely (1) neutral, (2) negative interference to the herbaceous isolates, (3) negative interference to both fungi, (4) negative interference toGanoderma, (5) negative interference to the herbaceous isolates and positive forGanoderma, and (6) positive interference in both fungi. Ligninolytic fungi from cocoyam and canna plants were able to negatively interfere with theGanodermawood decay, inhibit the colony, and reduce the initial root infection of oil palm. Keywords: antagonistic in vitro,Ganoderma boninense, ligninolytic fungi, root necrosis, wood decay.

PECULIARITIES OF BISPHENOL А UTILISATION BY ENZYMES RHODOTORULA MINUTA, SACCHAROMYCES CEREVISIAE, CORYNEBACTERIUM GLUTAMICUM, MICROCOCCUS LUTEUS

One of the most serious problems today is environmental pollution by plastic and its derivatives. It is known that bisphenol A (BPA) is a widespread compound used in the production of various polymeric materials. When it gets into water, soil, air, food and beverages, it causes numerous toxic effects in the body. Bisphenol A disrupts the functioning of the endocrine, reproductive, immune, nervous, and respiratory systems (Kosior E., Crescenzi I., 2020). When ingested by the animal body through the diet, BPA can be absorbed by cells of the gastrointestinal tract and liver, where it undergoes biotransformation to form bisphenol A-glucuronide, and less commonly bisphenol A-sulfate (Durovcova I. et al., 2022). Little is known about the impact of BPA on the development of microorganisms; the possibility of converting the polutant by enzymes of a number of gram-negative bacteria and microscopic fungi has been reported (Ingale S. et al., 2021). Today, effective and cost-effective strategies are being actively sought to remove xenobiotics from the environment and prevent their entry into the human body through trophic chains. Biodegradation is one of the most advanced technologies available today. Due to the efficient extracellular enzyme systems of ligninolytic and non-ligninolytic microscopic fungi and bacteria, BPA can be biotransformed to form non-toxic products (Daassi D. et al., 2016). We have studied the possibility of biodegradation of bisphenol A by Rhodotorula minuta, Saccharomyces cerevisiae, Corynebacterium glutamicum, Micrococcus luteus. It was found that the cultivation of microorganisms on media containing bisphenol concentrations exceeding its MPC in the environment was characterised by a decrease in the accumulation of their biomass and colony formation. The introduction of 0.3, 0.4, 0.5, 3, 4, 5 mg/l of bisphenol A into the culture medium led to an increase in laccase, Mn-peroxidase and lignin peroxidase activities, most of all in R. minuta. The ability to utilise the polutant in the environment by the studied microorganisms is different. Studies indicating the indirect ability to convert bisphenol A by these gram-positive bacteria and fungi showed that the enzymatic systems of R. minuta utilised, on average, 13 % of the introduced xenobiotic, and M. luteus - about 6 % of BPA.

Plant species, nitrogen status and endophytes are drivers of soil microbial communities in grasslands

Context There is concern that the introduction of ‘novel’ plant germplasm/traits could outpace our capacity to measure and so assess their impacts on soil microbial communities and function. Aim This study aimed to investigate the effects of plant species/functional traits, nitrogen (N) fertilisation and endophyte infection on grassland soil microbial communities within a short time span of 2 years. Methods Two field experiments with monoculture plots were conducted in a common soil. Experiment 1 compared grasses and legumes, using two cultivars of perennial ryegrass (Lolium perenne) that varied in fructan content, along with the legumes white clover (Trifolium repens) and bird’s-foot trefoil (Lotus pedunculatus) that varied in tannin content. Grass treatments received high and low N application levels. Experiment 2 compared the presence/absence of Epichloë strains in ryegrass, tall fescue (Schedonorus phoenix) and meadow fescue (Schedonorus pratensis). Soil microbial communities were analysed by using high-throughput sequencing of DNA isolated from bulk soil cores. Key results Higher abundance of ligninolytic fungi was found in grass soils and pectinolytic fungi in legume soils. Levels of N fertilisation and fructan in ryegrass had only minor effects on soil fungal communities. By contrast, N fertilisation or fixation had a strong effect on bacterial communities, with higher abundance of nitrifiers and denitrifiers in high-N grass soils and in legume soils than in low-N grass soils. Epichloë affected soil microbiota by reducing the abundance of certain fungal phytopathogens, increasing mycorrhizal fungi and reducing N-fixing bacteria. Conclusions Chemical composition of plant cell walls, which differs between grasses and legumes, and presence of Epichloë in grasses were the main drivers of shifts in soil microbial communities. Implications Impacts of farming practices such as mono- or poly-culture, N fertilisation and presence of Epichloë in grasses on soil microbial communities should be considered in pasture management.

Valorization of leaf litter by ligninolytic fungi from termite garden

The present study was focused on three indigenous litter dwelling ligninolytic fungi viz., Termitomyces sp.,Streptomyces spp, and Xylaria sp. from the fungal comb of termite garden were selected to study theirefficiency in decomposing leaf litter. Three different leaf littersuch assapota, mango, and guava dried leavesfrom orchards were used as the solid substrates to determine the efficiency of selected potential ligninolyticfungal strains to decompose them.Under in vitroconditions, the culture grows at 30-320C, pH 7.1 after 48 h,a clear zone was observed by the Congo Red plate method. The compost pile was supplemented with anisolated microbial consortium with 50-60 % moisture levels for 90 days to get maturity. The activity ofligninolytic cellulose(110 -240 μg g-1day-1) was observed higher in Termitomyces, whereasamylase inStreptomycesspp (950- 1370 μg g-1 day-1) and dehydrogenase in Xylaria (540-880 μg g-1day-1).

Bisphenol A in the environment and recent advances in biodegradation by fungi.

Bisphenol A (BPA) is a compound used in the manufacture of a wide variety of everyday materials that, when released into the environment, causes multiple detrimental effects on humans and other organisms. The reason for this review is to provide an overview of the presence, distribution, and concentration of BPA in water, soil, sediment, and air, as well as the process of release and migration, biomagnification, and exposure mechanisms that cause various toxic effects in humans. Therefore, it is important to seek efficient and economic strategies that allow its removal from the environment and prevent it from reaching humans through food chains. Likewise, the main removal techniques are analyzed, focusing on biological treatments, particularly the most recent advances in the degradation of BPA in different environmental matrices through the use of ligninolytic fungi, non-ligninolytic fungi and yeasts, as well as the possible routes of metabolic processes that allow their biotransformation or biodegradation due to their efficient extracellular enzyme systems. This review supports the importance of the application of new biotechnological tools for the degradation of BPA.

A systematic overview on treatment towards endocrine disruptors

Endocrine disruptors, also known as EDCs are omnipresent, as their presence can be easily observed in our day-to-day life. Endless exposure to EDCs can cause adverse health effects in organisms such as type 2 diabetes, cardiovascular diseases, obesity, growth inhibition, morphological deformities, behavioral changes, and certain types of cancer. The objective of this review is to deliver an overview of the environmental aspects of endocrine-disrupting chemicals and their effects on animals and human health. Based on their origin, EDCs are divided into two types: (a) Synthetic or man-made such as bisphenol A (BPA), triclosan (TCS), and other chemicals, and (b) natural hormones namely estrone E1, 17β-estradiol (E2), and estriol (E3); both are prone to human and animal health. Emphasis is given to the treatment of EDCs by eliminating them from the wastewater through advanced oxidation processes. However, these processes are generally expensive with limited specificity and side effects. An alternate approach is used for the post-treatment of EDCs by high redox potential enzyme peroxidases which are produced only by specific strains of ligninolytic fungi, helping in minimizing endocrine-disrupting compounds.

Chitosan/carboxymethyl cellulose wound dressings supplemented with biologically synthesized silver nanoparticles from the ligninolytic fungus Anamorphous Bjerkandera sp. R1

Chitosan (CHI) and carboxymethyl cellulose (CMC) are naturally sourced materials with excellent physical, chemical, and biological properties, which make them a promising tool for the development of different medical devices. In this research, CHI-CMC wound dressings were manufactured, by using different colloidal suspensions of silver nanoparticles (AgNPs) synthesized from the ligninolytic fungus Anamorphous Bjerkandera sp. R1, called CS and SN. Transmission electron microscopy (TEM), UV-Vis spectroscopy, and dynamic light scattering (DLS) analysis were used to characterize AgNPs. The wound dressings were characterized, by scanning electron microscopy (SEM), optical microscopy and their mechanical, antimicrobial, and biological properties were evaluated. The results of the different characterizations revealed the formation of spherical AgNPs with a mean size between 10 and 70 nm for the different mixtures worked. The mechanical properties of CHI-CMS-AgNPs doped with CS and SN suspensions showed superior mechanical properties with respect to CHI-CMC wound dressings. Compared to the latter, CHI-CMC-AgNPs wound dressings yielded better antibacterial activity against the pathogen Escherichia coli. In biological assays, it was observed that manufactured CHI-CMC-AgNPs wound dressings were not toxic when in contact with human skin fibroblasts (Detroit). This study, then, suggests that this type of wound dressings with a chitosan matrix and carboxymethyl cellulose doped with biologically synthesized nanoparticles from the fungus Bjerkandera sp., may be an ideal alternative for the manufacture of new wound dressings.

Comparative study of diverse pretreatment approaches to degrade lignin from Bambusa balcooa

Bamboo biomass is a potential source of monomeric sugars containing a high cellulose content with a low amount of lignin. However, for efficient hydrolysis, an effective biomass pretreatment technique is required to minimize the lignin content and other barrier components. In the present study, bamboo biomass was treated with different physical, chemical, biological, and combined treatments to reduce the lignin content. Among all the pretreatments, the maximum lignin removal amount (14.5%) was obtained with the combined chemical and biological treatment under 2% NaOH + 1% H2O2 + WDP2 fungal culture (5 plugs) conditions. In addition, the ligninolytic fungus and NaOH pretreatment was primarily effective in removing lignins, whereas the H2O2 pretreatment efficiently minimized cellulose crystallinity. Scanning electron microscopy and Fourier-transform infrared spectroscopy was utilized to analyze the structural changes of the raw and treated biomass. The structural analysis indicated that all the treatments caused disruption in the biomass structure and reduced the compactness of the biomass, which facilitated the biomass conversion during the hydrolysis process. The findings of the present study indicated effective pretreatment methods in overcoming the recalcitrancy of potential lignocellulosic biomass for maximum hydrolysis.

Widespread Ability of Ligninolytic Fungi to Degrade Hazardous Organic Pollutants as the Basis for the Self-Purification Ability of Natural Ecosystems and for Mycoremediation Technologies

The ability of sixteen wood- and soil-inhabiting basidiomycete strains and four ascomycete strains to degrade the most hazardous, widespread, and persistent pollutants (polycyclic aromatic hydrocarbons, oxyethylated nonylphenol, alkylphenol, anthraquinone-type synthetic dyes, and oil) was found. The disappearance of the pollutants, their main metabolites, and some adaptive properties (activities of ligninolytic enzymes, the production of emulsifying compounds and exopolysaccharides) were evaluated. The toxicity of polycyclic aromatic hydrocarbons decreased during degradation. New data were obtained regarding (1) the dependence of the completeness of polycyclic aromatic hydrocarbon degradation on the composition of the ligninolytic enzyme complex; (2) the degradation of neonol AF9-12 by higher fungi (different accessibilities of the oxyethyl chain and the aromatic ring of the molecules to different fungal genera); and (3) the production of an emulsifying agent in response to the presence in the cultivation medium of hydrophobic pollutants as the common property of wood- and soil-inhabiting basidiomycetes and ascomycetes. Promise for use in mycoremediation was shown in the wood-inhabiting basidiomycetes Pleurotus ostreatus f. Florida, Schizophyllum commune, Trametes versicolor MUT 3403, and Trametes versicolor DSM11372; the litter-decomposing basidiomycete Stropharia rugosoannulata; and the ascomycete Cladosporium herbarum. These fungi degrade a wide range of pollutants without accumulation of toxic metabolites and produce ligninolytic enzymes and emulsifying compounds.