Mineralization kinetics of corn and clover residues in quartz sand, loam, sand + 15% bentonite, and sand + 30% kaolinite have been studied. A scheme has been proposed for the transformation of plant ...residues in mineral substrates. Kinetic parameters of mineralization have been calculated with the use of a first-order two-term exponential polynomial. It has been shown that the share of labile organic carbon pool in the clover biomass is higher (57–63%) than in the corn biomass (47–49%), which is related to the biochemical composition of plant residues. The mineralization constants of clover residues generally significantly exceed those of corn because of the stronger stabilization of the decomposition products of corn residues. The turnover time of the labile clover pool (4–9 days) in all substrates and that of the labile corn pool (8–10 days) in sands and substrates containing kaolinites and bentonite are typical for organic acids, amino acids, and simple sugars. In the loamy substrate, the turnover time of labile corn pool is about 46 days due to the stronger stabilization of components of the labile pool containing large amounts of organic acids. The turnover time of the stable clover pool (0.95 years) is significantly lower than that of the stable corn pool (1.60 years) and largely corresponds to the turnover time of plant biomass.
Species of the genus Trametes represent one of the most efficient
lignin-degraders which can be attributed to a well developed ligninolytic
enzyme system. Current trends are screening of ability of ...new species to
produce these enzymes, as well as the optimization of conditions for their
overproduction. Therefore, the aim of the study was to evaluate the potential
of T. suaveolens to synthesize laccase and Mn-oxidizing peroxidases during
fermentation of the selected plant raw materials. Level of enzyme activities
was measured on 7, 10 and 14th day of submersion, as well as the solid-state
fermentation of wheat straw and oak sawdust in the presence of NH4NO3 in
previously determined optimal nitrogen concentration of 25 mM. The enzyme
activity was determined spectrophotometrically using ABTS and phenol red as
the substrates. The highest level of laccase activity (1087.1 U/L) was noted
after 7 days of wheat straw solid-state fermentation, while during the
submerged cultivation the production of the enzyme was not noted. Submerged
cultivation in oak sawdust-enriched medium was the optimal for activity of
Mn-dependent peroxidase (1767.7 U/L on day 14) and Mn-independent peroxidase
(1113.7 U/L on day 7). Introduction of T. suaveolens to produce ligninolytic
enzyme represented the base for further study, as well as the determination
of relation between enzyme activity and rate of lignin degradation. It could
lead to greater possibility of fungal species selection with high
delignification capacity, which could take participation in sustainable
production of food, feed, fibres, and energy, environmentally friendly
pollution prevention, and bioremediation.
Vrste roda Trametes predstavljaju najefikasnije lignin-degradere zbog dobro
razvijenog ligninolitickog enzimskog sistema koji cine lakaza i Mn-zavisna
peroksidaza. Sadasnji trendovi su skrining sposobnosti novih vrsta da
produkuju ove enzime kao i optimizacija uslova za njihovu obimnu sintezu.
Zbog toga, cilj ovog istrazivanja je bio proucavanje potencijala T.
suaveolens da sintetise lakaze i Mn-oksidujuce peroksidaze tokom fermentacije
odabranog biljnog materijala. Nivo enzimske aktivnosti je meren 7-og, 10-og i
14-og dana tecne i cvrste fermentacije psenicne slame i piljevine hrasta u
prisustvu NH4NO3, u optimalnoj koncentraciji azota od 25 mM. Enzimska
aktivnost je odredjivana spektrofotometrijski koriscenjem ABTS i fenol crvenog
kao supstrata. Najvisi nivo aktivnosti lakaze (1087.1 U/L) zabelezen je nakon
7 dana cvrste fermentacije psenicne slame, dok u uslovima tecne fermentacije
ovaj enzim nije produkovan. Tecna kultivacija u medijumu sa piljevinom hrasta
je bila optimalna za aktivnost Mn-zavisne peroksidaze (1767.7 U/L 14-og dana)
i Mn-nezavisne peroksidaze (1113.7 U/L 7-og dana). Poznavanje potencijala T.
suaveolens da produkuje ligninoliticke enzime predstavlja osnovu za dalja
istrazivanja, odredjivanje odnosa izmedju enzimske aktivnosti i stepena
razgradnje lignina. To ce voditi vecoj mogucnosti selekcije vrsta sa visokim
kapacitetom delignifikacije, koje se mogu koristiti u proizvodnji hrane,
hraniva, papira i energije, kao i u zastiti zivotne sredine i
bioremedijaciji.
A very high level of alkalophilic and thermostable pectinase and xylanase has been produced from newly isolated strains of Bacillus subtilis and Bacillus pumilus respectively. Enzyme production for ...pectinase was carried out under SSF using combinations of cheap agricultural residues while xylanase was produced under submerged fermentation using wheat bran as substrate to minimize the cost of production of these enzymes Among the various substrates tested, the highest yield of pectinase production was observed by using combination of WB + CW (6592 U/g of dry substrate) supplemented with 4% yeast extract when incubated at 37 °C for 72 h using deionized water of pH 7.0 as moistening agent. The biobleaching effect of these cellulase free enzymes on kraft pulp was determined. Both xylanase and pectinase showed stability over a broad range of pH from 6 to 10 and temperature from 55 to 70 °C. The bleaching efficiency of the pectinase and xylanase on kraft pulp was maximum after 150 min at 60 °C using enzyme dosage of 5 IU/ml of each enzyme at 10% pulp consistency with about 16% reduction in kappa number and 84% reduction in permanganate number. Enzyme treated pulp when subjected to CDED₁D₂ steps, 25% reduction in chlorine consumption and upto 19% reduction in consumption of chlorine dioxide was observed for obtaining the same %ISO brightness. Also an increase of 22 and 84% in whiteness and fluorescence respectively and a decrease of approximately 19% in the yellowness of the biotreated pulp were observed by pretreatment of the pulp with our enzymatic mixture.
We conducted a study to investigate the role of aggregates in the stabilization of residue- and root-derived C in an illitic Mollisol and a kaolinitic Oxisol under the following treatments: (i) ...incorporated residue, (ii) growing plants, and (iii) both incorporated residue and growing plants. Residue-C dynamics were followed in soils incubated with ¹³C-labelled wheat residue with and without unlabelled growing wheat plants. Root-C was traced by growing wheat plants with and without unlabelled wheat residue in a ¹³CO₂-labelling chamber. After 46 and 76 incubation days, residue- and root-C were measured in four aggregate size classes and in microbial-C. Both soils had greater residue-derived than root-derived total aggregate-associated C at day 76, which we attributed to the larger residue-C than root-C inputs at the start of the experiment. On an aggregate basis, the ratio of residue-derived over root-derived C decreased in most size fractions over time, indicating a greater potential for longer-term root-C than residue-C stabilization by aggregates in both soils. At both sampling days, all aggregates > 53 μm had greater residue-C concentrations in the illitic soil than in the kaolinitic soil and this difference increased with increasing aggregate size. This suggested a greater affinity of illite clay than kaolinite clay to bind with fresh residue-derived compounds into larger aggregates and hence a greater importance of aggregates in stabilizing residue-C in illitic compared with kaolinitic soils. The stabilization of root-C by aggregates was less affected by clay mineralogy and thus less dependent on the affinity of clay minerals to bind with root-derived compounds.
New organic substrates have been introduced in hydroponic culture in order to substitute peat, because is a non-renewable resource, and in less rockwool or perlite due to their problematical ...recycling. The objective of this work is to evaluate the evolution of two renewable organic substrates, wood fibre (WF) and coconut fibre (CF) throughout one cultivation cycle. Two trials were set up, one with and a second one without crop. Volume, pH and EC of the input solution and the drainage solution were measured in both trials. In the trial without crop the content of NO
3
−, Cl
−, (SO
4)
2−,Ca
2+, Mg
2+, Na
+, P and K
+ was also determined. Physico-chemical characterization of the substrates was determined at the beginning and at the end of the trials. In order to know the loss of organic matter (OM), the dry matter content of the substrates was determined at the beginning and at the end of both trials. It has been observed that in both substrates retention of elements like NO
3
−, Ca
2+, P and Mg
2+ occurs. In the study of the physico-chemical properties, it has been observed that the air capacity decreases considerably in both substrates in the trial with crop, especially in the CF, as well as a greater reduction of the C/N rate and percentage of OM. The data of organic matter loosed shows that in the trial with crop both substrates have lost more OM and this loss is slightly superior in CF. Therefore it is important to consider the possible retention of nutrients in the organic substrates to optimise cultivation management, as well as their degradability, which influences on the physico-chemical properties throughout the crop cycle.
The decomposition of plant residues is a biological process mediated by soil fauna, but few studies have been done evaluating its dynamics in time during the process of disappearance of straw. This ...study was carried out in Chapecó, in southern Brazil, with the objective of monitoring modifications in soil fauna populations and the C content in the soil microbial biomass (C SMB) during the decomposition of winter cover crop residues in a no-till system. The following treatments were tested: 1) Black oat straw (Avena strigosa Schreb.); 2) Rye straw (Secale cereale L.); 3) Common vetch straw (Vicia sativa L.). The cover crops were grown until full flowering and then cut mechanically with a rolling stalk chopper. The soil fauna and C content in soil microbial biomass (C SMB) were assessed during the period of straw decomposition, from October 2006 to February 2007. To evaluate C SMB by the irradiation-extraction method, soil samples from the 0-10 cm layer were used, collected on eight dates, from before until 100 days after residue chopping. The soil fauna was collected with pitfall traps on seven dates up to 85 days after residue chopping. The phytomass decomposition of common vetch was faster than of black oat and rye residues. The C SMB decreased during the process of straw decomposition, fastest in the treatment with common vetch. In the common vetch treatment, the diversity of the soil fauna was reduced at the end of the decomposition process.
The effect of information on the health benefits of bio-active compounds on the acceptability of 5 tea infusions made from grape skins generated from wine processing waste (from Vitis vinifera var. ...Pinot Noir and Pinot Gris) was investigated. Samples of tea infusions with natural additives (PNHGT25 and PGGT50) and without additives (control PN, control PG, and PNPG50) were evaluated by 45 in-home consumer panels (30 female, 15 male) before and after information on the health benefits of grape skins were provided. Information significantly increased the overall acceptability, overall aroma, flavor, and aftertaste of the infusions. The results obtained showed a clear tendency toward increased purchase intention (by 29%) when information on the health benefits of the tea infusion samples was provided to consumers. Interactions existed between gender/infusion samples and stage of information on the purchase intention. Females recorded a significant increase (by 53%) in purchase intention, whereas no change in the males' purchase intention was found after information was provided.
Osmotic treatment (OT) is applied to obtain high quality intermediate moisture products impregnated with particular solutes, for instance phenolics from commercial grape seed extracts. To investigate ...how the nature of osmo-active solutes affects mass transfer of grape phenolics in a solid model food, sucrose, sodium chloride and glycerol were used as osmo-active solutes. Mass transfer of total and individual grape phenolics of low molecular weight were characterized by the diffusional approach and Peleg’s model. Of all the osmo-active solutes investigated, sodium chloride led to the highest phenolic infusion rate for each individual phenolic analyzed. With all the osmo-active solutes, the non esterified flavan-3-ol monomers showed a higher initial rate of phenolic mass transfer (1
/k
1) than their corresponding gallate esters and flavan-3-ol dimers. The phenolic content in the osmo-treated model food was similar or higher than that of the richest fruits and vegetables in all the conditions tested, thus increasing the antioxidant capacity of the product.
Ilex paraguariensis is known to contain compounds with antioxidant properties, such as phenolic acids, and its stimulant properties are attributed to methylxanthines, such as caffeine. The aims of ...this study were to evaluate the phenolic, methylxanthinic, and tannin composition of a mate residue (mate powder), to compare the quali-quantitative phenolic composition and the antioxidant potential of extracts obtained from distinct solvent systems. Among the extracts prepared with different solvents, the 80% methanol extract showed the highest total polyphenol content (11.51 g/100 g) and antioxidant activity. HPLC analysis showed that 4,5 dicaffeoylquinic acid is the major component of the phenolic fraction of mate powder. The caffeine, theobromine, and tannin contents in mate powder were 1.01, 0.10, and 0.29 g/100 g, respectively. Consumption of mate powder would significantly contribute to antioxidant and stimulant intake, providing high amounts of phenolic acids, tannins, and methylxanthines with biological effects potentially beneficial for human health. Practical Application: This article contributes to the minimization of residues in yerba-mate processing.
Fructosyl transferase (FTase) production by Aspergillus oryzae CFR 202 was carried out by solid-state fermentation (SSF), using various agricultural by-products like cereal bran, corn products, ...sugarcane bagasse,cassava bagasse (tippi) and by-products of coffee and tea processing. The FTase produced was used for the production of fructo-oligosaccharides (FOS), using 60% sucrose as substrate. Among the cereal bran used, rice bran and wheat bran were good substrates for FTase production by A. oryzae CFR 202. Among the various corn products used, corn germ supported maximum FTase production, whereas among the by-products of coffee and tea processing used, spent coffee and spent tea were good substrates, with supplementation of yeast extract and complete synthetic media. FTase had maximum activity at 60 degrees C and pH 6.0. FTase was stable up to 40 degrees C and in the pH range 5.0-7.0. Maximum FOS production was obtained with FTase after 8 h of reaction with 60% sucrose. FTase produced by SSF using wheat bran was purified 107-fold by ammonium sulphate precipitation (30-80%), DEAE cellulose chromatography and Sephadex G-200 chromatography. The molecular mass of the purified FTase was 116.3 kDa by SDS-PAGE. This study indicates the potential for the use of agricultural by-products for the efficient production of FTase enzyme by A. oryzae CFR 202 in SSF, thereby resulting in value addition of those by-products.
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