Bioconversion of sugarcane bagasse with white rot fungi

Summary Four cultures of white rot fungi were screened for their ability to degrade lignin and carbohydrates of sugarcane bagasse and their effect on changes inin vitro digestibility.Polyporus hirsutus534 degraded maximum lignin and carbohydrates accompanied with the highest increase in digestibility, but increase in nutrient availability was maximum withPleurotus sajorcaju (Z-6) due to lower dry matter loss during the process of fungal treatment. All the fungi tested exceptPolyporus caperatus Berk. degraded lignin more selectively than the other components of sugarcane bagasse.     

Influence of oxygen and carbon dioxide on lignin degradation in solid state fermentation of wheat straw withStropharia rugosoannulata

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.     

Biodegradation of wheat straw lignocarbohydrate complexes (LCC)

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%).     

Solid state fermentation of oat straw by Polyporus sp A-336 and the effect of added sugars

Summary Supplementing oat straw in SSF by Polyporus sp A-336 with xylose, mannose, glucose and arabinogalactan at levels of 5 and 10% of straw weight stimulated lignin degradation and cellulose hydrolysis. Degradation of lignin, hemicellulose and cellulose was monitored for 30 days in plain straw, and straw plus xylose and showed that xylose shortened the lag in lignin breakdown and slowed hemicellulose utilization. At 24 days, similar polymer losses occurred in both systems and enzymatic cellulose hydrolysis had reached a maximum of 47% weight loss.     

Rapid Degradation of Isolated Lignins by Phanerochaete chrysosporium

Phanerochaete chrysosporium degraded purified Kraft lignin, alkali-extracted and dioxane-extracted straw lignin, and lignosulfonates at a similar rate, producing small-molecular-weight (~1,000) soluble products which comprised 25 to 35% of the original lignins. At concentrations of 1 g of lignin liter⁻¹, 90 to 100% of the acid-insoluble Kraft, alkali straw, and dioxane straw lignins were degraded by 1 g of fungal mycelium liter⁻¹ within an active ligninolytic period of 2 to 3 days. Cultures with biomass concentrations as low as 0.16 g liter⁻¹ could also completely degrade 1 g of lignin liter⁻¹ during an active period of 6 to 8 days. The absorbance at 280 nm of 2 g of lignosulfonate liter⁻¹ increased during the first 3 days of incubation and decreased to 35% of the original value during the next 7 days. The capacity of 1 g of cells to degrade alkali-extracted straw lignin under optimized conditions was estimated to be as high as 1.0 g day⁻¹. This degradation occurred with a simultaneous glucose consumption rate of 1.0 g day⁻¹. When glucose or cellular energy resources were depleted, lignin degradation ceased. The ability of P. chrysosporium to degrade the various lignins in a similar manner and at very low biomass concentrations indicates that the enzymes responsible for lignin degradation are nonspecific.     

Fungal Decomposition of Oat Straw during Liquid and Solid-State Fermentation

White rot fungi (Coriolus hirsutus, Coriolus zonatus, and Cerrena maxima from the collection of the Komarov Botanical Institute of the Russian Academy of Sciences) and filamentous fungi (Mycelia sterilia INBI 2-26 and Trichoderma reesei6/16) were grown on oat straw–based liquid and solid media, as well as in a bench-scale reactor, either individually or as cocultures. All fungi grew well on solid agar medium supplemented with powdered oat straw as the sole carbon source. Under these conditions, the mold Trichoderma reesei fully suppressed the growth of all basidiomycetes studied; conversely,Mycelia sterilia neither affected the development of any of the cultures, nor did it show any substantial susceptibility to suppression by their presence. Pure solid cultures of basidiomycetes, as well as the coculture of Coriolus hirsutus andCerrena maxima,caused a notable bleaching of the oat straw during its consumption. When grown on the surface of oat straw–based liquid medium, the basidiomycetes consumed up to 40% of the polysaccharides without measurable lignin degradation (a concomitant process). Under these conditions, Mycelia sterilia decomposed no more than 25% of the lignin in 60 days, but this was observed only after polysaccharide exhaustion and biomass accumulation. In contrast, during solid-state straw fermentation, white rot fungi consumed up to 75% of cellulose and 55% of lignin in 83 days (C. zonarus), whereas the corresponding consumption levels for cocultures ofMycelia sterilia and Trichoderma reesei equaled 70 and 45%, respectively (total loss of dry weight ranged from 55 to 60%). Carbon dioxide–monitored solid-state fermentation of oat straw by the coculture of filamentous fungi was successfully performed in an aerated bench-scale reactor.     

Changes in biochemical constituents of paddy straw during degradation by white rot fungi and its impact on in vitro digestibility

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.     

Removal of NH3-N from domestic waste water by fungi

Summary Nine species of fungi viz.,Aspergillus niger,A. flavus,A. terreus,Fusarium solani,Mucor sp.,Neurospora crassa,Penicillium janthinellum,Trichoderma harzianum andTrichothecium roseum were evaluated for their potential to remove NH₃–N from domestic waste water. Of the fungi tested,A. flavus was found to be the most effective in the removal of NH₃–N. Maximum reduction (92%) of NH₃–N by this organism was observed at pH 8.0 at 20°C.     

Biodelignification of wheat straw and its effect on in vitro digestibility and antioxidant properties

A variety of methods for feed development have been introduced during last few years. Bioprocessed agricultural residues may prove a better alternative to provide animal feed. For the purpose, some white rot fungi were allowed to degrade wheat straw up to 30 days under solid state conditions. Several parameters including loss in total organic matter, ligninolysis, in vitro digestibility of wheat straw and estimation of different antioxidant activities were studied. All the fungi were able to degrade lignin and enhance the in vitro digestibility. Among all the tested fungi, Phlebia brevispora degraded maximum lignin (30.6%) and enhanced the digestibility from 172 to 287 g/kg. Different antioxidant properties of fungal degraded wheat straw were higher as compared to the uninoculated control straw. Phlebia floridensis found to be more efficient organism in terms of higher antioxidant activity (70.8%) and total phenolic content (9.8 mg/ml). Thus, bioprocessing of the wheat straw with the help of these organisms seems to be a better approach for providing the animal feed in terms of enhanced digestibility, higher protein content, higher antioxidant activity and availability of biomass.     

Modification of wheat straw lignin by solid state fermentation with white-rot fungi

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.     

Biodegradation of paddy straw obtained from different geographic locations by means of <Emphasis Type="Italic">Phlebia</Emphasis> spp. for animal feed

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.     

Fungi of wheat and broad-bean straw composts II. Thermophilic fungi

Thirteen thermohilic genera and 19 species in addition to one variety of each of M. pulchella and H.grisea were collected from wheat and broad-bean straw composts at 45 °C. In wheat and broad-bean, all thermophilic fungi were completely checked between 4–9 days, and 1–8 days composting when the temperature ranged between 58 ° and 67 °C, and 58 ° and 70 °C respectively, and reappeared, represented by P. duponti, M. albomyces, T. lanuginosus and S. thermophile, after 9 or 10 days composting when the temperature decreased to 51.5 °–54 °C. Wheat and broad-bean straw composts were analyzed biochemically to follow the changes in ethanol and diastase soluble, hemicellulose, cellulose and lignin fractions during composting.     

Fungi of wheat and broad-bean straw composts

13 thermophilic genera and 19 species in addition to one variety of each of M. pulchella and H. grisea were collected from wheat and broad-bean straw composts at 45 °C. In wheat and broad-bean, all thermophilic fungi were completely checked between 4–9 days, and 1–8 days composting when the temperature ranged between 58° and 67 °C, and 58 ° and 70 °C respectively, and reappeared, represented by P. duponti, M. albomyces, T. lanuginosus and S. thermophile, after 9 or 10 days composting when the temperature decreased to 51.5° –54 ° C. Wheat and broad-bean straw composts were analysed biochemically to follow the changes in ethanol and diastase soluble, hemicellulose, cellulose and lignin fractions during composting.     

Biodelignification of Lemon Grass and Citronella Bagasse by White-Rot Fungi

Twelve white-rot fungi were grown in solid-state culture on lemon grass (Cymbopogon citratus) and citronella (Cymbopogon winterianus) bagasse. The two lignocellulosic substrates had 11% permanganate lignin and a holocellulose fraction of 58%. After 5 to 6 weeks at 20°C, nine fungi produced a solid residue from lemon grass with a higher in vitro dry matter enzyme digestibility than the original bagasse; seven did the same for citronella. The best fungus for both substrates was Bondarzewia berkeleyi; it increased the in vitro dry matter enzyme digestibility to 22 and 24% for lemon grass and citronella, respectively. The increases were correlated with weight loss and lignin loss. All fungi decreased lignin contents: 36% of the original value for lemon grass and 28% for citronella. Practically all fungi showed a preference for hemicellulose over cellulose.     

Solid state fermentation of lignocellulose containing plant residues withSporotrichum pulverulentum Nov. andDichomitus squalens (Karst.) Reid.

Summary The fermentation profiles ofSporotrichum pulverulentum andDichomitus squalens showed distinct differences.D. squalens digested the substrate more slowly thanSporotrichum pulverulentum. The relative degradation rates of total organic matter and lignin also differed considerably.Whereas withS. pulverulentum the ratio was about the same throughout the whole observation period, withDichomitus squalens it altered in favour of lignin degradation.WithSporotrichum pulverulentum an optimum digestion in vitro of 40%–50% was achieved after 20 days of incubation. WithDichomitus squalens the best value (about 60%) was reached after 30 days of incubation. Increasing incubation temperatures enhanced the degradation of the substrate.As found with wheat straw, all other substrates tested (straw of rape and barley, glumes of rice) were degraded more slowly byDichomitus squalens than bySporotrichum pulverulentum. The degradation rates for oak, spruce and beech sawdust were very low compared to those for straw.Small amounts of ammonium nitrate stimulated the degradation of straw byS. pulverulentum whereas higher concentrations had an inhibitory effect. The optimum water content of the substrate, measured by decomposition of total organic matter and lignin and by in vitro digestibility, was between 50 and 100 ml of water/25 g substrate. Higher and lower water contents had an unfavourable effect.Varying the pore size of the substrate by using milled straw of defined particle size had no influence on the 6 parameters tested under the given experimental conditions.The best method to supress potential competitors was to heat the substrate to 90°C for 24 h.     

Isolation,culture, and cell division in cotyledon protoplasts of cotton (Gossypium hirsutum and G. barbadense)

Protoplasts were isolated from cotyledons and foliage leaves of cotton (Gossypium hirsutum and G. barbadense). Cotyledon protoplasts were larger and responded to culture better than leaf protoplasts. Cotyledon derived protoplasts regenerated cell walls and formed microcolonies of 2–3 cells in G. hirsutum and 5–8 cells in G. barbadense. However, the microcolonies did not grow beyond this stage. Protoplast yield and viability, cell wall regeneration and cell division were influenced by several factors, e.g., genotype, age, tissue and growth condition of donor plant, enzyme mixture and concentration, preplasmolysis period, incubation period, and culture medium.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - BAP 6-benzylaminopurine - GA₃ gibberellic acid - p CPA p-chlorophenoxyacetic acid - MES 2[N-morpholino]ethanesulfonic acid     

Batch and membrane-assisted cell recycling in ethanol production byCandida shehatae

Summary During xylose fermentation byCandida shehatae ATCC 22984 with batch cell recycling, the volumetric ethanol fermentation rate increased two-fold, and the xylitol production rate increased three-fold as the cell density increased to ten-fold. In continuous fermentation with membrane-assisted cell recycle, the fermentation rates increased almost linearly with increasing agitation rates up to 300 rpm. The maximum continuous ethanol production rates obtained with 90 and 200 g L^–1 xylose were respectively 2.4 and 4.4 g L^–1h^–1. The cell density was 65–70 g (dry wt) L^–1. Ethanol yields ranged from 0.26 to 0.41 g g^–1.     

Brine organisms and the question of habitat-specific adaptation

Among the well-known ultrasaline terrestrial habitats, the Dead Sea in the Jordan Rift Valley and Don Juan Pond in the Upper Wright Valley represent two of the most extreme. The former is a saturated sodium chloride-magnesium sulfate brine in a hot desert, the latter a saturated calcium chloride brine in an Antarctic desert. Both Dead Sea and Don Juan water bodies themselves are limited in microflora, but the saline Don Juan algal mat and muds contain abundant nutrients and a rich and varied microbiota, includingOscillatoria,Gleocapsa,Chlorella, diatoms,Penicillium and bacteria.In such environments, the existence of an array of specific adaptations is a common, and highly reasonable, presumption, at least with respect to habitat-obligate forms. Nevertheless, many years of ongoing study in our laboratory have demonstrated that lichens (e.g.Cladonia), algae (e.g.Nostoc) and fungi (e.g.Penicillium,Aspergillus) from the humid tropics can sustain metabolism down to –40°C and growth down to –10°C in simulated Dead Sea or Don Juan (or similar) media without benefit of selection or gradual acclimation. Non-selection is suggested in fungi by higher growth rates from vegetative inocula than spores. The importance of nutrient parameters was also evident in responses to potassium and reduced nitrogen compounds.In view of the saline performance of tropicalNostoc, and its presence in the Antarctic dry valley soils, its complete absence in our Don Juan mat samples was and remains a puzzle.We suggest that adaptive capability is already resident in many terrestrial life forms not currently in extreme habitats, a possible reflection of evolutionary selection for wide spectrum environmental adaptability.     

Microbial reduction of ethyl acetoacetate using Sclerotium rolfsii

Summary A method for the quantitative enantioselective bioreduction of ethyl acetoacetate [1] to optically pure (+)-S-ethyl-3 hydroxybutyrate [II] usingSclerotium rolfsii mycelium is described. In a synthetic medium 1 g mycelium (dry weight) could convert 1 g of I to II within 2–3 days of fermentation (pH 5.8, 30°C). This is the first report demonstrating use ofS. rolfsii biomass for asymmetric reduction to get chiral building blocks.     

Graft formation in Solanum pennellii (Solanaceae)

Three phases of cohesion were observable during the development of compatible autografts in Solanum pennellii. Phase I cohesion 1) lasted 4–5 d after grafting, 2) was characterized by an average increase in tensile strength of 4 g breaking weight (BW) mm^–2 graft area (GA) d^–1, and 3) correlated positively with cellular interdigitation at the graft interface. The fresh weight of the scion increased by approximately 5% d^–1 during the first 2 d after grafting. Phase II cohesion occurred 5–15 d after grafting, during which time 1) the tensile strength of the graft union increased by 14 g BW mm^–2 GA d^–1, 2) vascular differentiation across the graft interface was completed, and 3) the fresh weight of the scion increased by 9% d^–1. Phase III cohesion occurred subsequent to 15 d after grafting, during which time 1) the tensile strength of the graft union leveled off at a value similar to that of an ungrafted internode, and 2) the fresh weight of the scion increased by 14% d^–1. These results are discussed relative to mechanisms underlying the formation of compatible grafts.