Authors:P. Bhatia, C. Bansal, R. Prakash, and T.P. Nagaraja
The present study was carried out to examine the antioxidant activity in oyster mushroom cultivated on selenium (Se) rich substrate. Pleurotus fossulatus was cultivated on Se-rich wheat straw collected from the seleniferous belt of Punjab (India) and its potential to accumulate Se from substrate was examined. Using different assay systems the modulations in the anti-oxidant profile of Se enriched mushroom was studied in comparison to the mushrooms cultivated on normal straw. The oyster mushrooms were observed to potentially mobilize Se from Se-rich substrates to fruiting bodies, resulting in significantly high uptake (37.2±0.6 μg g−1) as compared to control (3.57±0.53 mg g−1). The antioxidant activity, as determined by various assays, such as reducing power, 2,2-diphenyl-1-picrylhydrazyl free radical scavenging, and metal chelating activity, was higher in the experimental mushrooms when compared to control. The results obtained demonstrate that Se-fortified mushrooms through cultivation on straw containing organic forms of Se can be considered as natural and effective dietary supplements of organic Se for humans. The present study proposes the use of Se-rich agricultural residues as substrates for mushroom cultivation for human and livestock supplementation.
Authors:Y. S. Mostafa, E. László, and F. I. El-hawary
Factors affecting the cellulase production of Aspergillus niger using sugar cane bagasse as carbon source were investigated. The highest enzyme activities were obtained, when the culture medium was supplemented with 0.133% tryptone as nitrogen source. The rate of cellulase production was considerably increased when 0.5% Tween 60 was added to the production medium. For FPA and b-glucosidase production pH 5.0, while for CMC-ase pH 5.5 was found to be optimal. The highest cellulase activities were obtained at 30 °C and 300 r.p.m. The highest saccharification degree was achieved, when alkali treated rice straw was used as substrate. The main objective of the present study was to examine the possibilities of lactic acid production from alkali treated rice straw using simultaneous saccharification and fermentation technique with T. koningii cellulases and L. delbrueckii. The highest conversion of cellulose was obtained using 6% alkaline treated rice straw supplemented with 1.2 mg enzyme/g substrate at pH 4.8 and 45 °C.
Authors:E. Kovács, P. Merész, Z. Kristóf, and E. Németh-Szerdahelyi
Colour, texture, pectin autolysis, membrane permeability and microstructure (SEM, TEM), β-galactosidase and polygalacturonase were studied in apricots (cv. Magyar kajszi) harvested in mature green, straw yellow, bright orange and deep orange stages. The L* increased from mature green to straw yellow then decreased from straw yellow to deep orange state. The a* values increased with ripening. The bright and deep orange apricots were significantly softer than the mature green and straw yellow ones and the membrane permeability increased with ripening. The presence of β-galactosidase enzyme was proved by immunoblotting analysis using monoclonal anti-β-galactosidase clone GAL-13 (Sigma) in all ripening stages. The enzyme activity was very low in mature green stage and increased significantly (P>95%) with increasing ripeness and during storage. The PG activity was very low in the mature green apricot. A significant (P>95%) increase was observed in the straw yellow apricot and in the riper fruits. The mature green apricot showed a regular, the straw yellow and bright orange samples showed a moderately regular tissue structure, while the tissue of the deep orange apricot collapsed (SEM). The cell wall and the middle lamella of the green apricot (TEM) were intact. Generally, there were intact cytoplasm membranes with some damaged parts. In the straw yellow apricot, the cell wall started to loosen, the middle lamella lost pectic polysaccharides. The structure of the cytoplasm was not recognisable, the tonoplast and the cytoplasm membrane were injured. The cell wall of the bright orange apricot was similar to that of the straw yellow ones. The middle lamella dissolved and hairy, fibrillar structure of cell wall was found in the deep orange samples.
Authors:H. Morais, C. Ramos, E. Forgács, T. Cserháti, and J. Oliviera
The activity of lignin peroxidase (LiP) and laccase produced by Pleurotus ostreatus in culture media composed of agro-residues was measured by spectrophotometry. The overall enzyme activity and its dependence on the composition of culture media were determined by using spectral mapping technique followed by non-linear mapping. The relationships between the parameters of enzyme production and the composition of culture media and fermentation time were assessed by stepwise regression analysis. It was established that P. ostreatus did not produce LiP. The lowest enzyme production was observed in culture media containing extract of wheat straw. This finding indicates that the use of other agro-residues as substitutes for wheat straw is justified. It was further established that the enzyme production was also influenced by the pH of the culture media. It was found that enzyme activity quadratically depended on the fermentation time.
Microbiology and International Conference on Applied Biology and Biotechnology. August 1988, Hong Kong, pp. 565-569.
Tsang, L.J., Reid, I.D. & Coxworth, E.C. (1987): Delignification of wheat straw by Pleurotus spp. under
Because of the need for renewable energy resources, cellulose, which can be enzymatically hydrolyzed to glucose, has drawn lot of attention during the past decade. However, the process of cellulose conversion using cellulase is not yet economically feasible because of the high cost of enzymes. Factors influencing the cellulase production of Trichoderma koningii using both acid and steam treated sugar cane bagasse and rice straw as carbon sources were investigated. The highest levels of cellulase activities were obtained using a culture medium containing urea and (NH4)2SO4 together as nitrogen sources at 0.217% and 0.241% for both carbon sources. When the culture medium was supplemented either with 0.5% Tween 60 or Tween 80, the rate of cellulase production was increased considerably. Maximum levels of both filter paper and CMC-ase activities produced on both media were obtained at 25 °C and 100 r.p.m., while the highest level of â -glucosidase production was obtained at 30 °C and 200 r.p.m.
Authors:T. Lošák, J. Vollmann, J. Hlušek, J. Peterka, R. Filipčík, and L. Prášková
The influence of joint applications of N and S on false flax (Camelina sativa L.) growing was studied in a pot experiment. Nitrogen was applied as NH4NO3 at rates of 0.6 (N1)–0.9 (N2)–1.2 (N3) g per pot. Sulphur was applied as (NH4)2SO4 to achieve levels of 35 ppm (S1) and 55 ppm (S2) S-SO
. The number of branches per plant increased with the nitrogen doses (10.62–12.41–15.38). The N2 and N3 rates (4.91 g and 4.79 g, respectively) significantly increased the seed yields (g/plant) as compared to N1 (3.77 g). Straw yields (g/plant) and thousand-seed weight (g) increased significantly only with the highest level of nitrogen N3 (18.23 and 1.17, respectively) compared to N1 (16.52 and 1.06, respectively). Increasing levels of nitrogen (N1–N2–N3) reduced the oil content of seeds (40.79–38.40–37.66%), but increased the protein content (23.93–25.63–28.19%). The level of sulphur S2 significantly stimulated only the oil content to 39.36% compared to 38.54% with S1. At the same time a negative correlation was discovered between the oil and protein content in the seeds (r= −0.8164). The applied doses of nitrogen N2 and N3 significantly increased the total oil yields (1.88–1.80 g/plant) as well as the total protein yields (1.25–1.35 g/plant) compared to N1 (1.53 and 0.90 g/plant, respectively).