Jasmina Ćilerdžić

Lignin degradation by selected fungal species.

As biological decomposition of plant biomass represents a popular alternative environmental-friendly and economically justified process, screening of ligninolytic enzyme systems of various fungal species is a topical study area. The goal of the study was to obtain clear insight into the dynamics of laccase, Mn-dependent peroxidase, and Mn-independent peroxidase activity and levels of wheat straw lignin degradation in seven wood-rotting fungi. The best laccase producers were Pleurotus ostreatus and Pleurotus eryngii. Lenzites betulinus and Fomitopsis pinicola were the best Mn-dependent peroxidase producers, and P. ostreatus the weakest one. The peak of Mn-independent peroxidase was noted in Dichomytus squalens, and the minimum value in P. ostreatus. The profiles of the three enzymes, obtained by isoelectric focusing, were variable depending on the species and cultivation period. D. squalens was the best lignin degrader (34.1% of total lignin amount), and P. ostreatus and P. eryngii the weakest ones (7.1% and 14.5%, respectively).

Biological activity of Ganoderma lucidum basidiocarps cultivated on alternative and commercial substrate

ETHNOPHARMACOLOGICAL RELEVANCE Ganoderma lucidum (W. Curt.:Fr.) P. Karst. has been used for several thousand years in traditional medicine of the Far East for the treatment of a various diseases including: cancer, immunological disorders, hepatitis, arthritis, nephritis, bronchitis, asthma etc. Ganoderma species are natural sources of various antimicrobial, antioxidant and antitumor active compounds which can be alternative to commercial antibiotics, antimycotics, antioxidants and cytostatics. As the amount of wild Ganoderma lucidum basidiocarps is not sufficient, the aim of this study was to compare the bioactivity of basidiaocarps obtained on alternative substrate (wheat straw) with commercially cultivated ones. MATERIALS AND METHODS Antimicrobial potential of the tested Ganoderma lucidum extracts was studied by disc-diffusion and microdilution method. Cytotoxic effect of tested extracts on two cancer cell lines was determined by microculture tetrazolium test. DPPH scavenging ability, total phenols and flavonoids content were measured in order to determine the antioxidative potential of Ganoderma lucidum extracts. RESULTS Ganoderma lucidum BEOFB 434 extract was the most effective antibacterial agent, while commercial strain was the weakest. DPPH· scavenging activity of extracts of basidiocarps from alternative substrate was also significantly higher than that of commercially obtained basidiocarps. The extracts of Ganoderma lucidum BEOFB 431 exhibited the strongest cytotoxic activity significantly higher than those in commercial strain. CONCLUSION The study showed that fruiting bodies produced on one of the most accessible and cheapest crop residue, wheat straw, are better antimicrobial, antioxidant and cytotoxic agents than those obtained on conventional substrate, oak sawdust.

Induction of wheat straw delignification by Trametes species.

Wheat straw is the major crop residue in European countries which makes it the most promising material for bioconversion into biofuels. However, cellulose and hemicellulose are protected with lignin, so delignification is an inevitable phase in lignocellulose processing. The organisms predominantly responsible for its degradation are white-rot fungi and among them Trametes species represent promising degraders due to a well-developed ligninolytic enzyme system. Although numerous studies have confirmed that low molecular weight compounds can induce the production and activity of ligninolytic enzymes it is not clear how this reflects on the extent of delignification. The aim of the study was to assess the capacity of p-anisidine and veratryl alcohol to induce the production and activity of Mn-oxidizing peroxidases and laccases, and wheat straw delignification by six Trametes species. Significant inter- and intraspecific variations in activity and features of these enzymes were found, as well as differences in the potential of lignocellulose degradation in the presence or absence of inducers. Differences in the catalytic properties of synthesized enzyme isoforms strongly affected lignin degradation. Apart from enhanced lignin degradation, the addition of p-anisidine could significantly improve the selectivity of wheat straw ligninolysis, which was especially evident for T. hirsuta strains.

Role of Mushroom Mn-Oxidizing Peroxidases in Biomass Conversion

Intensive agricultural and industrial production followed by increased production of lignocellulosic wastes, disruption of environment, and depletion of natural resources are features of the modern society. However, these wastes present sustainable resources of fibers and energy and can be useful raw materials for many industries. Therefore, development of the optimal ways for their environmental and economical friendly biological pretreatment where the main participants will be fungi, owing to their ability to produce lignocellulolytic enzymes, preoccupies scientists. Mn-oxidizing peroxidases play crucial role in the process and based on the substrate specificity, this group is divided into Mn-dependent- and versatile peroxidases. However, delignification capacity depends on fungal species and strain, namely on their potential of lignocellulolytic enzyme production and degradation selectivity, type and composition of lignocellulosic wastes, and fermentation conditions. Species which predominantly degrade lignin and significantly weaker cellulose could have important role in processes of food, feed, paper, and biofuel production.

Neuroprotective Potential and Chemical Profile of Alternatively Cultivated Ganoderma lucidum Basidiocarps

Various neurodegenerative diseases are the main challenges to the modern medicine and there is a great need for novel, natural, neuroprotective agents. Ganoderma lucidum is a well‐known medicinal mushroom, which health benefits have been confirmed by numerous studies. As demand for its basidiocarps is increased and traditional cultivation on hardwoods is not environmentally friendly and economically justified, finding of alternative substrates is necessary. The aim of the study was to assess the effect of alternative cultivation substrates on the chemical profile of G. lucidum basidiocarps and their capacity to inhibit acetylcholinesterase and tyrosinase, which higher activity is directly associated with neurodegenerative processes. Extracts of basidiocarps cultivated on alternative substrates, especially on clear wheat straw, showed significantly higher inhibition capacities than extracts of commercially‐grown ones. These extracts were considerably different chemically from commercial basidiocarps extracts and even nine new compounds were isolated from them. Our results suggest that cultivation substrate greatly affect the chemical profile and neuroprotective capacity of obtained basidiocarps and wheat straw is a promising cultivation substrate.

Dynamics of ligninolytic enzyme production in Ganoderma applanatum depending on cultivation type

Ganoderma applanatum belongs to the group of white-rot fungi, due to a well-developed ligninolytic enzyme system. White-rot fungi have attracted great scientific attention in recent years, especially with respect to their enzymatic potential for the bioremediation of persistent pollutants. Contrary to G. lucidum, which medicinal properties, as well as ligninolytic enzyme system have been extensively studied, enzymatic system of G. applanatum has not been studied yet. Thus, the aim of this study was to analyze the dynamics of laccase, Mn-dependent peroxidase, and versatile peroxidase activity during submerged and solid state cultivation on two selected plant raw materials. Enzyme activity was determined spectrophotometrically after 7, 10 and 14 days of cultivation. The peak of laccase activity (220.14 Ul-1) was noted after 14 days of submerged wheat straw fermentation. Maximum level of Mn-dependent peroxidase (110.91 Ul-1) and versatile peroxidase (116.20 Ul-1) activity was obtained in the medium with oak sawdust after 14 days of submerged cultivation.