Hemicellulosic hydrolyzates from trimming wastes of vine shoots were proposed as a carbon source for lactic acid production by Lactobacillus pentosus CECT‐4023T (ATCC‐8041). These hydrolyzates are ...composed mainly of glucose (12.0 g/L), xylose (17.5 g/L) and arabinose (4.3 g/L). Acetic acid, the main subproduct, started to be produced after all of the glucose was completely depleted, showing that the acetic acid coproduction came only from the xylose and arabinose consumption. In the absence of glucose, the L. pentosus pathway shifts from homo to heterofermentative. Thus, L. pentosus can be considered a facultative heterofermentative organism, degrading hexoses (glucose) via the Embden‐Meyerhoff‐Parnas pathway and pentoses (xylose and arabinose) via the phosphoketolase pathway. Hydrolyzates were vacuum evaporated to increase the initial sugars concentration up to 35.4 g/L of glucose, 52.3 g/L of xylose, and 13.0 g/L of arabinose. Under these conditions the lactic acid concentration reached 46.0 g/L (QP = 0.933 g/L·h, YP/S = 0.78 g/g; YP/S theoretical = 91.7%) and a clear product inhibition was observed. Additional experiments with synthetic sugars, in the absence of inhibitory compounds, indicate that this inhibition must be attributed to the metabolic pathway but not to the inhibitory compounds present in the fermentation broth.
This paper, which illustrates some results of the project SO.L.E.AGRI. (“Wood-energy chain sustainability in agricultural sector”) funded by Provincia di Siena and of the PRIN 2005–2006 “Study of the ...biomass-energy chains in Italy” funded by the Italian Ministry of Instruction, University and Research, highlights that the use of agricultural residuals as renewable energy source is economically and environmentally convenient.
This work firstly looks at the energy use of agricultural residuals harvested, and then it considers their packaging and supply management. The main objective of the production of the solid bio-fuels originated from pruning residuals is the reduction of harvesting and transport costs; therefore, experimental tests have been carried out in different farms using an innovative shredding machine that simultaneously permits harvesting, shredding and packaging of pruning residuals. These trials have been undertaken in olive groves and vineyards, on stony and hilly terrain. The machine has obtained good results under different operative conditions: intensive mechanisation of harvesting implies lower costs and simultaneous packaging assures a better organisation of the whole energy chain.
In organic farming, maximising the amount of nitrogen (N) which is fixed and retained within the soil is of paramount importance for the yield of the following crop. The aim of this study was to ...establish the extent to which increased soil fertility, farmyard manure (FYM) applications and/or mulching, could adversely affect fixation. At two sites, situated in the South West (SW) and North East (NE) of England, N
2 fixation was estimated in ‘organically’ managed red clover/grass plots, both with and without green manure (i.e. surface mulched) and/or the addition of FYM. The FYM was incorporated into the seedbeds at both sites in autumn 2002 at the rate of 170
kg total N
ha
−1, as either well-composted (SW site), or not actively-composted (NE site) manures. The same FYM application rate was repeated as top-dressings to both sites in autumn 2003. The plots were cut three or four times each year over two growing seasons. In the first harvest year (2003), incorporation of FYM had beneficial effects of increasing dry matter and N yields significantly at the first cut, but there were no significant differences in subsequent cuts. The same pattern was found in the second harvest year (2004) after the top dressings of FYM, suggesting that most of the N in both types of FYM was in recalcitrant forms. Over the two growing seasons, mulching did not affect red clover/grass dry matter or N yields, but did reduce the proportion of N
2 fixed, by up to 60
kg
N
ha
−1 when compared with plots from which the clover/grass herbage was cut and removed. Thus, the gain in N from FYM or green manure tended to be offset by a similar reduction in N
2 fixation. These results demonstrate the close association between the availability of soil N and the feed-back system which operates on N
2 fixation by red clover.
Recently, regular oscillations in bacterial populations and growth rates of bacterial feeding nematodes (BFN) were shown to occur after addition of fresh organic matter to soil. This paper presents a ...model developed to investigate potential mechanisms of those oscillations, and whether they were initiated by bacteria–substrate interactions or by predatory regulation of bacteria. The model was also used to investigate mineral nitrogen release during short-term organic matter decomposition. Experimental data originated from several microcosm experiments with a sandy soil amended with clover–grass mixture. Numbers of bacteria and BFN, and nitrate and ammonium content in soil were measured daily during about a month, whereas protozoa were counted occasionally. A substrate-based food web model was constructed with 3 plant residue and 5 soil organic matter compartments, 3 trophic groups of bacteria (copiotrophic, oligotrophic and hydrolytic), and two predatory groups (BFN and protozoa). Both carbon and nitrogen flows between these compartments were modelled. Fluctuations in microbial populations in soil after plant residue incorporation could be reproduced with and without participation of predators. The first two peaks in bacterial numbers were mainly related to bacteria–substrate interactions, while predators (particularly protozoa) influenced bacterial dynamics during later stages of bacterial community development. Oligotrophic bacteria had a stabilizing effect on fluctuations of other trophic groups, and were the main source of nutrients for predators. A peak in soil ammonium occurred within 1 week after residue incorporation. Nitrate increased sigmoidally after a short lag phase. The final nitrate concentration was primarily determined by bacterial dynamics, and to a lesser extent by protozoa and nematodes. This model indicates the importance of substrate–consumer relations for regulation of populations at different trophic levels and nutrient release from fresh organic matter added to soil.
Data on the input of plant falloff and organic matter decomposition on the surface of the peaty podzolic-gleyic humus-illuvial (Gleyic Podzol) soil under a mature blueberry pine forest in the middle ...taiga are presented. The fractional composition of the falloff was determined, and constants of decomposition for its components were calculated. The carbon flux to the atmosphere due to the mineralization of plant residues is estimated at 251 g/m
2
. A close positive correlation (
r
= 0.71;
P
< 0.05) was found between the carbon dioxide emission measured using a gas analyzer and the soil temperature at the depth of 10 cm. The CO
2
emission for a growing period calculated from the data on its dependence on soil temperature in different years varied from 243 to 313 g C/m
2
and was related to weather conditions.
Biorefineries--A Path to Sustainability Hatti-Kaul, Rajini
CGIAR Science Forum 2009,Wageningen, Netherlands,2009-06-16 - 2009-06-17,
March 2010, Letnik:
50, Številka:
2
Journal Article, Conference Proceeding
Recenzirano
Odprti dostop
Biorefining of crops for production of power, transport fuels, and a diverse array of chemicals has potential for providing significant added economic value to biomass. A shift in the industrial ...resource base from fossil resources to biomass also requires a shift in the technology base for producing, handling, and processing of raw materials. Biotechnology will play an important role in providing tools for different stages ranging from biomass production, treatment, and valorization to various products. First generation refineries have raised some critical issues related to land use and insufficient environmental benefits due to energy-intensive cultivation of crops. The abundant residual lignocellulosic biomass will constitute an important feedstock for the future biorefineries so as to have a minimal impact on the food availability. Necessary investments in technological development will be needed to realize the benefits of the new bioeconomy in the long term.
Agricultural activity generates two types of waste: firstly, biodegradable organic effluents generally treated by biological processes and, secondly, phytosanitary effluents which contain residues of ...plant protection products. The latter are collected and treated. Current technological solutions are essentially based on concentration or physical–chemical processes. However, recent improvements in the biodegradability of pesticides open the way to the consideration of alternative, biological, treatment using mixed liquor from wastewater plant activated sludge. The feasibility of the biological treatment of viticultural effluents has been evaluated by the application of pesticides to activated sludge. The necessity for selection of a pesticide-resistant biomass has been highlighted. The elimination of the phytosanitary products shows the potential of a resistant biomass in the treatment of pesticides. The aerated biological storage ponds at three wineries, followed by a sand or reed-bed filter, were used for the treatment of the total annual volume of the viticulture effluents and validate the laboratory experiments. The results show that the biological purification of pesticides by activated sludge is possible by allowing approximately 8 days for biomass adaptation. Stability of purification occurs between 20 and 30 days.
Display omitted
► Selection of a biomass that resists to pesticides has been highlighted. ► Biodegradability of wine effluent was not affected from pesticides addition. ► Stability of purification intervenes as from a time from 20 to 30 days. ► Biodegradation of the toxic molecules exceeds 85% and the filtered effluent has a reduced toxicity (>98%).
In this study, we illustrated enhanced biodegradation enzyme activity and the strains growth using the plants residues as carriers during the biodegradation of phenol in petrochemical wastewater. The ...three phenol-degrading strains named as A1, A2 and A3 were selected for an immobilized microorganism technique. A1, A2 and A3 were identified as Penicillium oxalicum, Aspergillus sp. and Sphingobacterium sp. using detailed morphological, biochemical and molecular characterization. The growth and degradation rate of phenol in wastewater by strains A1, A2 and A3 pre-grown in the agricultural residues (peanut shell) were higher than the free strains. Compared with the free strains,the enzyme activity of strains A1,A2 and A3, using the residues for pre-grown, increased 29.01 U/L, 30.30 U/L and 38.07 U/L, respectively. Hence, the immobilized microorganism technique is conducive to the phenol degradation.
The effect of wood ash, sawdust, ground cocoa husk, spent grain and rice bran upon root development, ash content, pod yield and nutrient status and soil fertility for okra (
Abelmoschus esculentum L ...NHAe 47 variety) was studied. The five organic fertilizer treatments were compared to chemical fertilizer (400
kg/ha/crop NPK 15-15-15) and unfertilized controls in four field experiments replicated four times in a randomized complete block design. The results showed that the application of 6
t
ha
−1 of plant residues increased (
P
<
0.05) the soil N, P, K, Ca, Mg, pH, and SOM; pod N, P, K, Ca, Mg and ash; root length; and pod yield of okra in all four experiments relative to the control treatment. For instance, spent grain treatment increased the okra pod yield by 99%, 33%, 50%, 49%, 65% and 67% compared to control, NPK, wood ash, cocoa husk, rice bran and sawdust treatments respectively. In the stepwise regression, out of the total
R
2 value of 0.83 for the soil nutrients to the pod yield of okra; soil N accounted for 50% of the soil fertility improvement and yield of okra. Spent grain, wood ash and cocoa husk were the most effective in improving okra pod weight, pod nutrients, ash content, root length and soil fertility whereas the rice bran and sawdust were the least effective. This was because the spent grain, wood ash and cocoa husk had lower C/N ratio and higher nutrient composition than rice bran and sawdust, thus, the former enhanced an increase in pod nutrients, composition for better human dietary intake, increased the root length, pod weight of okra and improved soil fertility and plant nutrition crop. The significance of the increases in okra mineral nutrition concentration by plant residues is that consumers will consume more of these minerals in their meals and monetarily spend less for purchasing vitamins and mineral supplement drugs to meet health requirements. In addition, the increase in plant nutrition and soil fertility would help to reduce the high cost of buying synthetic inorganic fertilizers and maintain the long term productivity of soils for sustainable cultivation of okra.
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.
