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1.
Summary The kinetics of straw solid-state fermentation (SSF) with Trametes versicolor and Pleurotus ostreatus was investigated to characterize the delignification processes by these white-rot fungi. Two successive phases could be defined during straw transformation, characterized by changes in respiratory activity, changes in lignin and polysaccharide content and composition, increase in in-vitro digestibility, and enzymatic activities produced by the fungi. Lignin composition was analysed after CuO alkaline degradation, and decreases in syringyl/guaiacyl and syringyl/p-hydroxyphenyl ratios and cinnamic acid content were observed during the fungal treatment. An increase in the phenolic acid yield, revealing fungal degradation of side-chains in lignin, was produced by P. ostreatus. The highest xylanase level was produced by P. ostreatus, and exocellulase activity was nearly absent from straw treated with this fungus. Lactase activity was found in straw treated with both fungi, but lignin peroxidase was only detected during the initial phase of straw transformation with T. versicolor. High levels of H2O2-producing aryl-alcohol oxidase occurred throughout the straw SSF with P. ostreatus. Offprint requests to: A. T. Martínez  相似文献   

2.
Five white-rot basidiomycetes were evaluated for their potential to improve ruminal degradation of wheat straw.Polyorus brumalis, Lyophyllum ulmarium III,Trametes gibbosa, Pleurotus ostreatus, and aPleurotus ostreatus mutant were incubated on wheat straw for 30 d at 28°C. Detergent fiber, crude protein andin vitro dry matter digestibility (IVDMD) were determined. The results showed increasing crude protein and ash contents in fungus-treated straw. IVDMD values were increased in straws treated withP. ostreatus, P. ostreatus mutant andT. gibbosa only. Relative to untreated wheat straw the detergent fiber content—neutral detergent fiber (NDF), and acid detergent fiber (ADF) was reduced in fungus-treated straw and out of three fractions—hemicellulose, cellulose and lignin, hemicellulose showed the largest proportionate loss whereas lignin the smallest one in all 5 samples of fungus treated straw.  相似文献   

3.
Aims: Selection of white‐rot fungi of bio‐conversion of mustard straw (MS) into feed for ruminants. Methods and Results: Mustard straw was cultured with Ganoderma applanatum, Coriolus versicolor and Phanerochaete chrysosporium for solid‐state fermentation at 35°C from 7 to 63 days for dilignification and for 21 days to study dry matter digestibility and protein enrichment. Lignin loss in fungus cultured straw varied between 100 and 470 g kg?1 lignin. Dilignification was higher between 7 and 28 days fermentation with C. versicolor. Among the three fungi P. chrysosporium was the most effective in degrading lignin for longer fermentation. In‐vitro dry matter digestibility (IVDMD) and crude protein content was higher in C. versicolor cultured straw. Large quantity of straw was cultured by C. versicolor for 21 days, for in vivo evaluation. Mean pH and metabolites of rumen fermentation were not different while, pH and volatile fatty acid increased at 6 h postfermentation on cultured straw feeding. Cultured straw fermentation increased (P = 0·001) small holotricks and reduced (P = 0·005) large holotricks population. Fungus cultures straw did not improve microbial enzyme concentration. Conclusions: Coriolus versicolor and P. chrysosporium were the promising fungus for MS bio‐dilignification. Significance and Impact of the Study: Coriolus versicolor treated MS improved dry matter digestibility and protein content.  相似文献   

4.
Cyathus stercoreus (Schw.) de Toni NRRL 6473, isolated from aged and fragmented cattle dung collected from a Michigan pasture, effected substantial losses in lignin (45%) from wheat straw during a 62-day fermentation (25°C). The basidiomycete also improved wheat straw digestibility by freeing α-cellulose for enzymatic hydrolysis to glucose (230 mg of glucose per 1,000 mg of fermented residue). The rationale for selecting C. stercoreus in attempting to biologically modify the lignin and cellulose components in wheat straw or other gramineous agricultural residues was based on the expectation that this organism is ecologically specialized to enzymatically attack the substructures of native lignins in grasses.  相似文献   

5.
Summary In laboratory and semi-industrial scale experiments the influence of the substrate water content, temperature, and incubation time on the progress of solid state fermentation of straw colonized by white rot fungi was investigated. The parameters used to evaluate the fermentation process were degradation of total organic matter and lignin, in vitro digestibility, the content of water soluble substances in the substrate and the pH.The degradation of total organic matter was species specific. Only Trametes hirsuta enhanced the degradation at elevated temperature (30 °C). With Abortiporus biennis, Ganoderma applanatum, and Pleurotus serotinus, elevated temperature had and adverse effect. Prolonged incubation only improved degradation of straw by the relatively slowgrowing fungi Ganoderma applanatum, Lenzites betulina, and Pleurotus sajor caju.Elevated temperature and prolonged incubation shifted the relative degradation rates in favour of total organic matter degradation. With Ganoderma applanatum, Pleurotus ostreatus, and Pleurotus serotinus lignin degradation, even on an absolute scale, was less at 30 °C than at 22 °C.In general, the in vitro digestibility also decreased, when the incubation time and temperature were raised. With Ganoderma applanatum the in vitro digestibility dropped below the value of the sterile straw control.Solid state fermentation of straw was at an optimum at a medium water content of 75 ml/25 g of substrate. However, most of the fungi tested could digest straw over a wide range of water content. At higher water contents (125–150 ml/25 g of substrate) an increased production of aerial mycelium was observed.In semi-industrial batch experiments (40 kg) with Abortiporus biennis the in vitro digestibility dropped below the reference value for sterile straw during the first 19 days of incubation. Later, the in vitro digestibility again rose and reached its optimum after about 60 days. The in vitro digestibility in the semi-industrial experiments was always lower than in the laboratory experiments (+9% and +25%, respectively).In long term experiments (2.5 kg batches, 8 months of incubation) very different values for the in vitro digestibility were found, and these depended on the fungus used (Abortiporus biennis, +16%; Pleurotus ostreatus, +4%; and Ganoderma applanatum, –27%).  相似文献   

6.
Summary In solid state fermentation,Stropharia rugosoannulata degrades lignin of wheat straw slightly better in the presence of oxygen than that in air. The sub-atmospheric partial pressure of oxygen (0.05 atm.) inhibits lignin and organic matter degradation. the increasing partial pressure of carbon dioxide (0.1–0.3 atm.) along with 0.2 atm. of oxygen does not have any effect on lignin degradation, but slightly decreases organic matter loss and increases thein vitro digestibility of fermented wheat straw, thereby making the process more efficient.  相似文献   

7.
The exploration of seven physiologically different white rot fungi potential to produce cellulase, xylanase, laccase, and manganese peroxidase (MnP) showed that the enzyme yield and their ratio in enzyme preparations significantly depends on the fungus species, lignocellulosic growth substrate, and cultivation method. The fruit residues were appropriate growth substrates for the production of hydrolytic enzymes and laccase. The highest endoglucanase (111 U ml−1) and xylanase (135 U ml−1) activities were revealed in submerged fermentation (SF) of banana peels by Pycnoporus coccineus. In the same cultivation conditions Cerrena maxima accumulated the highest level of laccase activity (7,620 U l−1). The lignified materials (wheat straw and tree leaves) appeared to be appropriate for the MnP secretion by majority basidiomycetes. With few exceptions, SF favored to hydrolases and laccase production by fungi tested whereas SSF was appropriate for the MnP accumulation. Thus, the Coriolopsis polyzona hydrolases activity increased more than threefold, while laccase yield increased 15-fold when tree leaves were undergone to SF instead SSF. The supplementation of nitrogen to the control medium seemed to have a negative effect on all enzyme production in SSF of wheat straw and tree leaves by Pleurotus ostreatus. In SF peptone and ammonium containing salts significantly increased C. polyzona and Trametes versicolor hydrolases and laccase yields. However, in most cases the supplementation of media with additional nitrogen lowered the fungi specific enzyme activities. Especially strong repression of T. versicolor MnP production was revealed.  相似文献   

8.
The potential of crude enzyme extracts, obtained from solid state cultivation of four white-rot fungi (Trametes versicolor, Bjerkandera adusta, Ganoderma applanatum and Phlebia rufa), was exploited to modify wheat straw cell wall. At different fermentation times, manganese-dependent peroxidase (MnP), lignin peroxidase (LiP), laccase, carboxymethylcellulase (CMCase), avicelase, xylanase and feruloyl esterase activities were screened and the content of lignin as well as hydroxycinnamic acids in fermented straw were determined. All fungi secreted feruloyl esterase while LiP was only detected in crude extracts from B. adusta. Since no significant differences (P > 0.05) were observed in remaining lignin content of fermented straw, LiP activity was not a limiting factor of enzymatic lignin removal process. The levels of esterified hydroxycinnamic acids degradation were considerably higher than previous reports with lignocellulosic biomass. The data show that P. rufa, may be considered for more specific studies as higher ferulic and p-coumaric acids degradation was observed for earlier incubation times.  相似文献   

9.
Summary The ability of 45 fungal strains to degrade wheat straw and beech wood was studied. Degradation patterns were defined in terms of chemical evolution of substrates and changes in lignin and polysaccharides. Trametes versicolor produced an important degradation of lignin and increased substrate digestibility, but it caused high weight losses and gave rise to similar decay patterns on both substrates. A preferential degradation of lignin was produced during straw transformation by Pleurotus eryngii. The increase of soluble lignin and decreases of lignin content and H/C ratio defined the degradation tendency after principal component analysis. The cation exchange capacity and water and alkali solubility presented the highest loading factors for the characterization of fungal transformation of beech wood. Offprint requests to: A. T. Martínez  相似文献   

10.
Various cereal straws are used as feed by supplementing the green forage or other feed stuffs. An experiment was designed to see the effect of different geographic locations and climatological conditions on biochemical constituents, fungal degradation and in vitro digestibility of paddy straw. Paddy straw (PS) obtained from three different geographic locations of India was subjected to solid state fermentation using four white rot fungi i.e. Phlebia brevispora, P. fascicularia, P. floridensis and P. radiata. Changes in the biochemical constituents like water soluble content, hemicellulose, cellulose, lignin, total organic matter, and in vitro digestibility of paddy straw was analyzed over a period of 60 days along with lignocellulolytic enzymes i.e. laccase, xylanase and carboxymethyl cellulase. All the fungi degraded the straw samples and enhanced the in vitro digestibility. The paddy straw, obtained from north western zone (NWZ) suffered a maximum loss (228 g/kg) of lignin by P. radiata, while a maximum enhancement of in vitro digestibility from 185 to 256 g/kg was achieved by P. brevispora, which also caused minimum loss in total organic matter (98 g/kg). In PS obtained from central eastern zone (CEZ) and north eastern zone (NEZ), a maximum amount of lignin (210 and 195 g/kg, respectively) was degraded by P. floridensis and resulted into a respective enhancement of in vitro digestibility from 172 to 246 g/kg and 188 to 264 g/kg. The study demonstrates that geographic locations not only affect the biochemical constituents of paddy straw but the fungal degradation of fibers, their in vitro digestibility and lignocellulolytic enzyme activity of the fungus may also vary.  相似文献   

11.
Wastewaters from the fruit packaging industry contain a high pesticide load and require treatment before their environmental discharge. We provide first evidence for the potential bioremediation of these wastewaters. Three white rot fungi (WRF) (Phanerochaete chrysosporium, Trametes versicolor, Pleurotus ostreatus) and an Aspergillus niger strain were tested in straw extract medium (StEM) and soil extract medium (SEM) for degrading the pesticides thiabendazole (TBZ), imazalil (IMZ), thiophanate methyl (TM), ortho-phenylphenol (OPP), diphenylamine (DPA) and chlorpyrifos (CHL). Peroxidase (LiP, MnP) and laccase (Lac) activity was also determined to investigate their involvement in pesticide degradation. T. versicolor and P. ostreatus were the most efficient degraders and degraded all pesticides (10 mg l−1) except TBZ, with maximum efficiency in StEM. The phenolic pesticides OPP and DPA were rapidly degraded by these two fungi with a concurrent increase in MnP and Lac activity. In contrast, these enzymes were not associated with the degradation of CHL, IMZ and TM implying the involvement of other enzymes. T. versicolor degraded spillage-level pesticide concentrations (50 mg l−1) either fully (DPA, OPP) or partially (TBZ, IMZ). The fungus was also able to rapidly degrade a mixture of TM/DPA (50 mg l−1), whereas it failed to degrade IMZ and TBZ when supplied in a mixture with OPP. Overall, T. versicolor and P. ostreatus showed great potential for the bioremediation of wastewaters from the fruit packaging industry. However, degradation of TBZ should be also achieved before further scaling up.  相似文献   

12.
Cyathus stercoreus (Schw.) de Toni NRRL 6473, isolated from aged and fragmented cattle dung collected from a Michigan pasture, effected substantial losses in lignin (45%) from wheat straw during a 62-day fermentation (25 degrees C). The basidiomycete also improved wheat straw digestibility by freeing alpha-cellulose for enzymatic hydrolysis to glucose (230 mg of glucose per 1,000 mg of fermented residue). The rationale for selecting C. stercoreus in attempting to biologically modify the lignin and cellulose components in wheat straw or other gramineous agricultural residues was based on the expectation that this organism is ecologically specialized to enzymatically attack the substructures of native lignins in grasses.  相似文献   

13.
Summary Lignin biodegradation, carbon loss and in vitro dry matter digestibility (IVDMD) have been investigated during the solid state fermentation of wheat straw by eight previously selected strains of white-rot fungi. A mathematical model of the degradation kinetics is presented. [The time period required to reach maximum rates of 14CO2 and unlabeled CO2 release from (14C)-lignin-labelled wheat straw and from whole wheat straw, respectively, was generally short (6–10 days).] High rates of 14C-lignin degradation were achieved by Pycnoporus cinnabarinus (2.9% 14CO2 evolved/day), an unidentified strain Nancon (3.0%/day), Sporotrichum pulverulentum Nov. (3.4%/day), Bjerkandera adusta (2.4%/day), and Dichomitus squalens (2.3%). However, only the latter two strains degraded whole wheat straw slowly and Bjerkandera adusta was not able to degrade more than 23% of the 14C-lignin. Cyathus stercoreus and Dichomitus squalens facilitated the highest improvement in IVDMD (68% against 38% for the sound straw) after 20 and 15 days of cultivation respectively, with low dry matter losses (15–20%). A study of the fate of 14C-lignin during fermentation using these two fungal strains showed that maximal levels of (14C)-water-soluble compounds are reached before peak levels of 14CO2 evolution suggesting that these compounds are intermediates in lignin degradation. A possible relationship between water-soluble lignins and IVDMD improvement is discussed.  相似文献   

14.
White rot fungi are good lignin degraders and have the potential to be used in industry. In the present work, Phellinus sp., Daedalea sp., Trametes versicolor and Pycnoporus coccineus were selected due to their relatively high ligninolytic enzyme activity, and grown on Acacia mangium wood chips under solid state fermentation. Results obtained showed that manganese peroxidase produced is far more compared to lignin peroxidase, suggesting that MnP might be the predominating enzymes causing lignin degradation in Acacia mangium wood chips. Cellulase enzyme assays showed that no significant cellulase activity was detected in the enzyme preparation of T. versicolor and Phellinus sp. This low cellulolytic activity further suggests that these two white rot strains are of more interest in lignin degradation. The results on lignin losses showed 20–30% of lignin breakdown at 60 days of biodegradation. The highest lignin loss was found in Acacia mangium biotreated with T. versicolor after 60 days and recorded 26.9%, corresponding to the percentage of their wood weight loss recorded followed by P. coccineus. In general, lignin degradation was only significant from 20 days onwards. The overall percentage of lignin weight loss was within the range of 1.02–26.90% over the biodegradation periods. Microscopic observations conducted using scanning electron microscope showed that T. versicolor, P. coccineus, Daedalea sp. and Phellinus sp. had caused lignin degradation in Acacia mangium wood chips.  相似文献   

15.
Summary 74 Basidiomycetes have been tested for ligninolytic capability on (14C)lignin-labelled wheat straw. Fifteen strains were selected and rested more accurately for ligninolytic activity and the capacity to degrade wheat straw. The asymptote, inflexion point and degradation rate were determined using a model approach. The fungi exhibited very different responses with respect to lignin biodegradation: high asymptote for Pleurotus ostreatus (77%), low inflexion points for Sporotrichum pulverulentum Nov. (6.1 days) and Pycnoporus spp. (2.7 to 4.7 days) with high and slow degradation rates, respectively (0.91% and 0.45% of 14CO2 release/day). Degradation values for (14C)whole-labelled wheat straw exhibited less variation. Finally, the strains Pleurotus ostreatus, Dichomitus squalens and Bjerkandera adusta showed the highest selectivity of lignin removal.  相似文献   

16.
The ability of three fungal strains (Pleurotus sajor-caju, Phanerochaete chrysosporium, Trametes versicolor) to decrease the lignin content and to enhance in vitro rumen digestibility of lignified spruce sawdust was assessed. In monoculture solid substrate fermentation (SSF) studies, a considerable length of time (6 weeks) elapsed before 4 to 14% lignin was degraded. In contrast, paired or multiple cultures of these fungi caused an 8 to 16% loss of native lignin within three weeks of incubation. There were also synergistic effects on total polysaccharide/hemicellulose degraded by mixed cultures. A similar observation was made for in vitro digestibility of fungal fermented samples: Total solubles (carbohydrate products) which accumulated in cultures were significantly higher in mixed cultures than in respective monocultures. In contrast, mixtures of cell free enzyme extracts of these fungi did not cause any marked reduction in lignin or cellulose content. Supplementation of wood sawdust with carbohydrate adjuncts prior to fungal treatment also led to substantial reduction in lignin content and increased substrate digestibility.F.O. Asiegbu is with the Department of Forest Mycology & Pathology, Swedish University of Agricultural Sciences, P.O. Box 7026, S-750 07 Uppsala, Sweden; A. Paterson and J.E. Smith are with the Department of Bioscience and Biotechnology, University of Strathclyde, Glasgow, G1 1XW, UK.  相似文献   

17.
A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P<0.05) and that TV1 had higher activity (P<0.05) towards cellulose. There was an increase in IVNDFD (P<0.05), resulting from treatment of wheat straw with enzyme extracts from BA, TV1 and TV2, reaching a difference of 13% for TV2 (P<0.05), versus the non-treated straw control. Treatment with enzyme extract from TV2 caused increased gas production (P<0.05) after the first 20 h of incubation, and also increased the maximum rate of gas production, thus enhancing fermentation kinetics. This study indicates that enzyme extracts from white-rot fungi can be used to develop new approaches to overcome low digestibility of some plant cell walls. Utilization of different substrates to produce enzyme extracts can lead to production of viable ligninolytic complexes which could improve the nutritive value of fibrous feeds.  相似文献   

18.
Bioconversion of wheat straw by solid-substrate fermentation (SSF) withCoriolus versicolor was optimized by varying its physiological parameters. Selective delignification (more lignin than holocellulose degradation) and increases in crude protein (CP) content andin vitro dry matter digestibility (IVDMD) were taken as the criteria to select optimum levels of these parameters. The fungus behaved optimally under the following set of cultural and nutritional conditions: pH 5.5, moisture level 55%, temperature 30 °C, duration of fermentation 21 d, form of inoculum—grain culture, turning frequency—once at mid-incubation, urea (nitrogen source) 1.5% (sterile) or 3.0% (nonsterile), single superphosphate (phosphorus+sulfur source) 1.0%, no addition of free polysaccharides (as whey or molasses). A maximum of 17.5% increase in IVDMD involving 4.3% degradation of lignin, was attained in the optimized SSF under laboratory conditions. The digestibility improvement could be further increased by using a substrate preteatment (physical/chemical/biological) in the following order of preference: NaOH treatment, urea or urine treatment, ensiling, steaming, grinding. For practical farm applications, urea treatment and ensiling appeared most feasible. The laboratory optimized process was also scaled up to 4 kg (sterile and unsterile) and 50 kg (unsterile) fermentations.  相似文献   

19.
Summary The solid-substrate fermentation of wheat straw with an alkaliphilic white-rot fungus (Coprinus sp.) was found to be influenced by the levels of nitrogen, phosphorus+sulphur and free carbohydrates, in terms of biodegradation of straw ingredients, microbial protein production and changes in in-vitro dry matter digestibility (IVDMD). Nitrogen and Phosphorus+Sulphur compounds favoured the bioconversion and their optimum levels were (g/100 g DM): urea (sterile): 1.5, urea (unsterile): 3.0; superphosphate: 1.0. The addition of free carbohydrates as molasses and whey had detrimental effect on biodegradation of lignin as also on organic matter degradation and digestibility. However, the protein production was enhanced in the supplemented straw. The optimized laboratory fermentation was also extended to 4 kg-(sterile and unsterile) and 50 kg-(unsterile) fermentation.  相似文献   

20.
Aims: To improve the digestibility of paddy straw to be used as animal feed by means of selective delignification using white rot fungi. Methods and Results: Solid state fermentation of paddy straw was carried out with some white rot fungi for 60 days. Different biochemical analyses, e.g. total organic matter (TOM) loss, hemicellulose loss, cellulose loss, lignin loss and in vitro digestibility, were carried out along with laccase, xylanase and carboxymethyl cellulase activity. The results were compared with that of a widely studied fungus Phanerochaete chrysosporium, which degraded 464 g kg?1 TOM and enhanced the in vitro digestibility from 185 to 254 g kg?1 after 60 days of incubation. Straw inoculated with Phlebia brevispora possessed maximum crude protein. Conclusions: All the tested white rot fungi efficiently degraded the lignin and enhanced the in vitro digestibility of paddy straw. Phlebia brevispora, Phlebia radiata and P. chrysosporium enhanced the in vitro digestibility almost to similar levels, while the loss in TOM was much lesser in P. brevispora and P. radiata when compared to P. chrysosporium. Significance and Impact of the Study: The study reflects the potential of P. brevispora and P. radiata as suitable choices for practical use in terms of availability of organic matter with higher protein value, selective ligninolysis and better digestibility.  相似文献   

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