Pre-treatment of corn stover, Cynara cardunculus L. stems and wheat straw by ethanol-water and diluted sulfuric acid: Comparison under different energy input conditions.

Ethanol-water (EW) and diluted sulfuric acid (DSA) pre-treatment have been studied for lignocellulosic biomass (corn stover, Cynara cardunculus L. stems and wheat straw). Both pre-treatments have been compared taken into account: solids recovery, glucans recovery, xylans removed, delignification and glucose yield. In all cases, the amount of energy involved has been taken as a criterion for sustainability. In general terms, EW is more efficient to remove lignin and DSA more appropriate to hydrolysate xylans. The combined effect of delignification and xylans removal is responsible for the improvement in the enzymatic cellulose hydrolysis. Under conditions of moderate-low energy inputs, EW pre-treatment yields better results than DSA with glucose yields in the range of 50-60% for EW pre-treated corn stover and cardoon stems; while wheat straw pulps reach up to 80%. So, multiple raw materials biorefinery needs a previous study to fit the type and conditions of the pre-treatment to each feedstock.

Performance of three cardoon cultivars in an industrial heavy metal-contaminated soil: Effects on morphology, cytology and photosynthesis.

In the present work the cytomorphological and physiological effects on three cardoon cultivars - Sardo, Siciliano, Spagnolo - grown in a metal-polluted soil, were investigated, to assess the traits concurring to the high tolerance to metal stress observed in cv. Spagnolo compared to the other two cultivars. The plants were grown for one month on a real polluted soil collected at a dismantling battery plant, highly enriched by heavy metals, especially Cd and Pb, and their leaves were analyzed by a multidisciplinary approach. TEM observations highlighted severe ultrastructural damage in Sardo and Siciliano, and preserved cytological traits in Spagnolo. Both pigment content and photochemistry indicated a decline in photosynthesis in Sardo and Sicilano and a substantial stability of the same parameters in Spagnolo. Protein analysis indicated a decrease in D1 level in all cultivars; in Spagnolo the D1 decrease was more pronounced and associated to a significant increase in Rubisco, a pattern likely preserving photosynthetic efficiency and high biomass production. In conclusion, Spagnolo cardoon was able to face metal stress through a prompt, multiple response balancing structural and functional traits.

Ultrastructural, protein and photosynthetic alterations induced by Pb and Cd in Cynara cardunculus L., and its potential for phytoremediation.

The effects of cadmium and lead were investigated in Cynara cardunculus L. Plant uptake by root and shoot, changes in cell ultrastructure and photosynthetic efficiency, photosynthetic key protein levels, as well as regulation of stress-induced Hsp70 were examined. Cynara cardunculus accumulated Cd and Pb in their tissue, with a different trend for the two metals. The prompt translocation of Cd to the shoot may justify the ultrastructural injuries, especially observed in chloroplasts. However, Cd- treated plants did not show any decline in photochemistry; it is likely that Cd in shoot tissue triggers defense mechanisms, increasing the level of proteins involved in photosynthesis (i.e., Rubisco and D1 increased 7 and 4.5 fold respectively) as a compensatory response to neutralize chloroplast damage. The accumulation of Pb mainly in root, can explain the increase in Hsp70 level (23 folds) in this tissue. Pb reached the shoots, even at low amounts, causing an overall significant change in some photochemical parameters (QY and NPQ decreases and increases of 25%, respectively). The results suggest a higher sensitivity of C. cardunculus to Pb than Cd, although maximal photochemical efficiency suggests that this species seems to tolerate Pb and Cd and hence, it is a suitable candidate for phytoremediation.

Cyclopentyl methyl ether: a green co-solvent for the selective dehydration of lignocellulosic pentoses to furfural.

The effects of cyclopentyl methyl ether (CPME) addition during the aqueous xylose dehydration reaction to furfural are reported here. These investigations were conducted by using pure xylose and Cynara cardunculus (cardoon) lignocellulose as sugar source and H(2)SO(4) as catalyst. The research was also applied to aqueous solutions containing NaCl, since it has been previously demonstrated that NaCl incorporation to these reaction mixtures remarkably increases the furfural formation rate. It has been found that CPME incorporation inhibits the formation of undesired products (resins, condensation products and humins). Thus, cardoon lignocellulosic pentoses were selectively transformed into furfural (near 100%) at the following reaction conditions: 1 wt.% H(2)SO(4), 4 wt.% biomass referred to aqueous solution, 30 min reaction, 443 K, CPME/aqueous phase mass ratio equals to 2.33, and NaCl/aqueous solution mass ratio of 0.4. In contrast, no effect was observed for cellulosic glucose transformation into hydroxymethylfurfural and levulinic acid at identical reaction conditions.

Responses of Cynara cardunculus L. to single and combined cadmium and nickel treatment conditions.

A greenhouse pot experiment was carried out to study the responses of Cynara cardunculus L. (cardoon) to cadmium and nickel. Three groups of 12 pots each were planted with cardoon plants and spiked with single and combined cadmium and nickel aqueous solutions. The bioavailable metal concentrations, measured in soil, ranged widely and were up to 246.7 mg kg⁻¹ for Cd and 61.1 mg kg⁻¹ for Ni. Under Cd treatment, cardoon growth remained unaffected, while increased Ni soil concentrations inhibited plant growth and were lethal to the highly treated plants. In the combined Cd and Ni treatments, an antagonistic effect was observed between the two metals. Cadmium and nickel concentrations in cardoon tissues rose with increasing metal concentrations in the soil. Cadmium and nickel contents in shoots reached 169.3 and 342.3 mg kg⁻¹ in the single treatments while, under the combined Cd and Ni treatments, they were up to 235.0 and 440.7 mg kg⁻¹, respectively. Generally, mean contents of both metals in the shoots were higher than in the roots and the translocation factor was greater than 1. A possible enhancing effect of nickel on cadmium uptake was observed. Cardoon showed characteristics of a Cd accumulator.