Chromium (III) removal by perennial emerging macrophytes in floating treatment wetlands.

Floating treatment wetlands (FTWs) are a sustainable solution to treat polluted water, but their role in chromium (Cr(III)) removal under neutral pH conditions remains poorly understood. This study evaluated the potential of FTWs planted with two perennial emergent macrophytes, Phragmites australis and Iris pseudacorus, to remove Cr(III) and nutrients (N and PO4-P) from water containing 7.5 mg/L TN, 1.8 mg/L PO4-P, and Cr(III) (500, 1000, and 2000 µg/L). Within 1 h of exposure, up to 96-99% of Cr was removed from the solution, indicating rapid precipitation. After 50 days, Phragmites bound 9-19% of added Cr, while Iris bound 5-22%. Both species accumulated Cr primarily in the roots (BCF > 1). Biomass production and growth development were inhibited in Cr treatments, but microscopic examination of plant roots revealed no histological changes at 500 and 1000 µg/L Cr, suggesting high resistance of the tested species. At 2000 µg/L Cr, both species exhibited disruptions in the arrangement of vessel elements in the stele and increased aerenchyma spaces in Phragmites. At the end of the experiment, 70-86% of TN and 54-90% of PO4-P were removed.

Cadmium accumulation by Phragmites australis and Iris pseudacorus from stormwater in floating treatment wetlands microcosms: Insights into plant tolerance and utility for phytoremediation.

Environmentally sustainable remediation is needed to protect freshwater resources which are deteriorating due to severe industrial, mining, and agricultural activities. Treatment by floating wetlands could be a sustainable solution to remediate water bodies. The study aimed to examine the effects of Cd on Phragmites australis and Iris pseudacorus growth (height, biomass, root length and chlorophyll contents), anatomy, Cd accumulation in their biomass and their ability to remove Cd, N and P. Seedlings of both plants were grown in a greenhouse for 50 days in artificially prepared stormwater amended with Cd, N, and P. The treatments were: control (Cd _0), Cd_1, Cd_2, and Cd_4 mg L-1. N and P contents were 4 mg L-1 and 1.8 mg L-1, respectively. In the case of P. australis, the maximum plant height, root length, and total dry biomass production was increased in medium dose (Cd_2) treatment while the chlorophyll index (CCI) increased in high dose (Cd_4) treatment as compared to all treatments. For I. pseudacorus, the maximum plant height and total dry biomass production, root length and CCI values were improved in low dose (Cd_1) and high dose (Cd_4) treatments, respectively among all treatments. Results showed that P. australis accumulated 10.94-1821.59 µg · (0.05 m2)-1 in roots and 2.45-334.65 µg · (0.05 m2)-1 in shoots under Cd_0, Cd_1 and Cd_4 treatments. I. pseudacorus accumulated the highest Cd in roots up to 5.84-4900 µg · (0.05 m2)-1 and 3.40-609 µg · (0.05 m2)-1 in shoots under Cd_0, Cd_1 and Cd_4 treatments. The translocation factor was observed as <1 and the bioconcentration factor >1 for both species, which indicates their phytostabilization potential. Results demonstrate that P. australis and I. pseudacorus are suitable for use in floating wetlands to remediate contaminated sites.

Effect of solvent mixture pretreatment on sugar release from short-rotation coppice Salix schwerinii for biobutanol production.

This study investigated the effects of pretreatment using an acetone-butanol-ethanol (ABE) mixture with and without H2SO4 (H+) as a catalyst on sugar recovery from Salix schwerinii biomass. The sugar recovery was susceptible to both the temperature and the catalyst. Moreover, the relatively higher concentration of ABE (H+ABE4) at 200 °C yielded glucose recovery of 85.5% from the pretreated solid, higher than the recovery under other conditions. This result was mainly attributed to the compositional changes in the biomass, as the xylan and lignin were removed in large quantities by ABE pretreatment at 200 °C. Correspondingly, xylose recovery of 53.8% and glucose recovery of 12.1% were obtained from the liquid in which more sugar degradation products were formed. Ultimately, a fermentation broth containing a low concentration of ABE was successfully employed for pretreatment and showed great potential in producing fermentable sugars from S. schwerinii for biobutanol production.

Phytoextraction and recovery of rare earth elements using willow (Salix spp.).

Soil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix cultivars (Klara and Karin) were hydroponically exposed to different concentrations of six-REE for 4 weeks. The treatments were: T1 (Control: tap water), T2 (La: 50 mg/L) and T3 (La 11.50 + Y 11 + Nd 10.50 + Dy 10 + Ce 12 and Tb 11.50 in mg L-1). The effects of the REE on Salix growth indicators (height, biomass, shoot diameter and root length), concentrations of REE in the produced biomass, and accumulation of REE in different parts of the Salix (stem, root, and leaf) tissues, were determined. In addition, the retention of REE in ashes following Salix combustion (800 and 1000 °C) was determined. The result indicates that with La and REE exposure, the height growth, dry biomass, shoot diameter and root length of all Salix remained equivalent to the control treatment excluding Klara, which displayed relatively higher growth in all parameters. Further, among the REE studied, the highest La concentration (8404 µg g-1 DW) and La accumulation (10,548 µg plant-1) were observed in Karin and Klara root respectively. Translocations and bioconcentration factors were discovered at <1 for all Salix, which indicates their phytostabilization potential. The total REE concentrations in bottom ashes varied between 7 and 8% with retention rates between 85 and 89%. This study demonstrates that Salix are suitable candidates for REE phytostabilization and the remediation of wastewater sites to limit metals percolating to the water layers in the ecosystem.

Whole-genome sequencing of two Streptomyces strains isolated from the sand dunes of Sahara.

BACKGROUND: Sahara is one of the largest deserts in the world. The harsh climatic conditions, especially high temperature and aridity lead to unique adaptation of organisms, which could be a potential source of new metabolites. In this respect, two Saharan soils from El Oued Souf and Beni Abbes in Algeria were collected. The bacterial isolates were selected by screening for antibacterial, antifungal, and enzymatic activities. The whole genomes of the two native Saharan strains were sequenced to study desert Streptomyces microbiology and ecology from a genomic perspective. RESULTS: Strains Babs14 (from Beni Abbes, Algeria) and Osf17 (from El Oued Souf, Algeria) were initially identified by 16S rRNA sequencing as belonging to the Streptomyces genus. The whole genome sequencing of the two strains was performed using Pacific Biosciences Sequel II technology (PacBio), which showed that Babs14 and Osf17 have a linear chromosome of 8.00 Mb and 7.97 Mb, respectively. The number of identified protein coding genes was 6910 in Babs14 and 6894 in Osf17. No plasmids were found in Babs14, whereas three plasmids were detected in Osf17. Although the strains have different phenotypes and are from different regions, they showed very high similarities at the DNA level. The two strains are more similar to each other than either is to the closest database strain. The search for potential secondary metabolites was performed using antiSMASH and predicted 29 biosynthetic gene clusters (BGCs). Several BGCs and proteins were related to the biosynthesis of factors needed in response to environmental stress in temperature, UV light and osmolarity. CONCLUSION: The genome sequencing of Saharan Streptomyces strains revealed factors that are related to their adaptation to an extreme environment and stress conditions. The genome information provides tools to study ecological adaptation in a desert environment and to explore the bioactive compounds of these microorganisms. The two whole genome sequences are among the first to be sequenced for the Streptomyces genus of Algerian Sahara. The present research was undertaken as a first step to more profoundly explore the desert microbiome.

Biomass growth variation and phytoextraction potential of four Salix varieties grown in contaminated soil amended with lime and wood ash.

In a greenhouse experiment, plant growth and copper (Cu) and zinc (Zn) uptake by four Salix cultivars grown in Cu and Zn contaminated soils collected from a mining area in Finland were tested to assess their suitability for phytoextraction. The cultivars displayed tolerance to heavily contaminated soils throughout the experiment. After uptake, total mean Cu concentrations in the leaves, shoots and roots in all cultivars and treatments ranged from 163 to 474 mg kg-1 and mean Zn concentrations ranged from 776 to 1823 mg kg-1. Lime and wood ash addition increased dry biomass growth (25-43%), chlorophyll fluorescence (Fv/Fm) values (3-6%), the translocation factor (TF) (15-60% for Cu; 10-25% for Zn), the bio-concentration factor (BCF) (40-85% for Cu; 70-120% for Zn), and metal uptake (55-70% for Cu; 50-65% for Zn) compared to unamended treatment across all cultivars. The results revealed that Salix cultivars have the potential to take up and accumulate significant amounts of Cu and Zn. Cultivar Klara (Salix viminalis × S. schwerinii × S. dasyclados) was found to be the most effective cultivar for phytoextraction since it displayed greater dry biomass production, Fv/Fm, TF, BCF values and uptake percentage rates of Cu and Zn compared to the other three cultivars. This study indicates that further research is needed to clarify the wider phytoextraction capabilities of different Salix cultivars.

Amino acid-functionalized carbon nanotube framework as a biomimetic catalyst for cleavage of glycosidic bonds.

In this work, carbon nanotubes (CNTs) functionalized by acidic amino acids were used as a framework, which aims to form a mimetic structure of an active site of the glycoside hydrolases. It was demonstrated that the glycosidic bonds of the disaccharides were cleaved by the fabricated biofunctionalized CNTs. It was implied that the number of carboxyl groups and their individual pKa values in the amino acids, and the distance between the NH2 and the side chain carboxyl groups of the amino acid are predominant factors for determining the reaction efficiency and the optimum pH. It was suggested that glutamic acid functionalized CNTs framework showed the highest efficiency in the cleavage of glycosidic bond of cellobiose than other acidic biomolecules. It was also suggested that the glutamic acid functionalized CNT framework showed preference to the types of glycosidic bonds in the following order: ß-1,2-glycoside > ß-1,4-glycoside > α-1,4-glycoside [Formula: see text] α-1,1-glycoside bond.

Effect of salts formed by neutralization for the enzymatic hydrolysis of cellulose and acetone-butanol-ethanol fermentation.

Neutralization is essential to maintain the pH for enzymatic hydrolysis of cellulose followed by fermentation of biofuels. This study investigated the effect of salts formed during the neutralization on the enzymatic hydrolysis of cellulosic materials and acetone-butanol-ethanol (ABE) fermentation. The results showed that the formed Ca-citrate salt considerably decreased the glucose release by 26.9% and 26.1% from Avicel and sulfuric acid-pretreated hybrid Pennisetum, respectively, which was probably due to the unproductive adsorption of cellulases by Ca-citrate solids. On the other hand, the formed soluble Na and Ca salts severely inhibited ABE fermentation, thereby decreasing the ABE concentration from 12.8 g L-1 to 0-10.7 g L-1 in different degrees, but no or slight inhibition was observed when the Ca salts formed as precipitates. In particular, Ca-sulfate did not show apparent inhibition of both hydrolysis and fermentation. Therefore, the selection of suitable pretreatment and neutralizing reagents is an alternative way to avoid process inhibition in biofuel production from lignocellulosic materials.

Influence of size reduction treatments on sugar recovery from Norway spruce for butanol production.

This study investigated whether the effectiveness of pretreatment is limited by a size reduction of Norway spruce wood in biobutanol production. The spruce was milled, chipped, and mashed for hydrogen peroxide-acetic acid (HPAC) and dilute acid (DA) pretreatment. Sugar recoveries from chipped and mashed spruce after enzymatic hydrolysis were higher than from milled spruce, and the recoveries were not correlated with the spruce fiber length. HPAC pretreatment resulted in almost 100% glucose and 88% total reducing sugars recoveries from chipped spruce, which were apparently higher than DA pretreatment, demonstrating greater effectiveness of HPAC pretreatment on sugar production. The butanol and ABE yield from chipped spruce were 126.5 and 201.2 g/kg pretreated spruce, respectively. The yields decreased with decreasing particle size due to biomass loss in the pretreatment. The results suggested that Norway spruce chipped to a 20 mm length is applicable to the production of platform sugars for butanol fermentation.

Enhanced acetone-butanol-ethanol production from lignocellulosic hydrolysates by using starchy slurry as supplement.

This study aims to improve acetone-butanol-ethanol production from the hydrolysates of lignocellulosic material by supplementing starchy slurry as nutrients. In the fermentations of glucose, xylose and the hydrolysates of Salix schwerinii, the normal supplements such as buffer, minerals, and vitamins solutions were replaced with the barley starchy slurry. The ABE production was increased from 0.86 to 14.7g/L by supplementation of starchy slurry in the fermentation of xylose and the utilization of xylose increased from 29% to 81%. In the fermentations of hemicellulosic and enzymatic hydrolysates from S. schwerinii, the ABE yields were increased from 0 and 0.26 to 0.35 and 0.33g/g sugars, respectively. The results suggested that the starchy slurry supplied the essential nutrients for ABE fermentation. The starchy slurry as supplement could improve the ABE production from both hemicellulosic and cellulosic hydrolysate of lignocelluloses, and it is particularly helpful for enhancing the utilization of xylose from hemicelluloses.

Effects of contaminated soil on the growth performance of young Salix (Salix schwerinii E. L. Wolf) and the potential for phytoremediation of heavy metals.

Salix schwerinii was tested in a pot experiment to assess plant growth performance i.e., relative height and dry biomass and the potential for heavy metal uptake in soils polluted with chromium, zinc, copper, nickel and total petroleum hydrocarbons. The soil used in the pot experiment was collected from a landfill area in Finland. Peat soil was added at different quantities to the polluted soil to stimulate plant growth. The plants were irrigated with tap water or processed water (municipal waste water) to further investigate the effects of nutrient loading on plant biomass growth. The soil was treated at two pH levels (4 and 6). The results showed that the addition of 40-70% peat soil at pH 6 to a polluted soil, and irrigation with processed water accelerated plant growth and phytoextraction efficiency. In the pot experiment, Salix grown in chromium, zinc, copper, nickel and total petroleum hydrocarbons -contaminated field soil for 141 days were unaffected by the contaminated soil and took up excess nutrients from the soil and water. Total mean chromium concentration in the plant organs ranged from 17.05 to 250.45 mg kg-1, mean zinc concentration ranged from 142.32 to 1616.59 mg kg-1, mean copper concentration ranged from 12.11 to 223.74 mg kg-1 and mean nickel concentration ranged from 10.11 to 75.90 mg kg-1. Mean chromium concentration in the plant organs ranged from 46 to 94%, mean zinc concentration ranged from 44 to 76%, mean copper concentration ranged from 19 to 54% and mean nickel concentration ranged from 8 to 21% across all treatments. Under the different treatments, chromium was taken up by Salix in the largest quantities, followed by zinc, copper and nickel respectively. Salix also produced a moderate reduction in total petroleum total petroleum hydrocarbons in the polluted soil. The results from the pot experiment suggest that Salix schwerinii has the potential to accumulate significant amounts of chromium, zinc, copper and nickel. However, long term research is needed to verify the phytoextraction abilities of Salix observed in the pot experiment.

Enhanced sugar production from pretreated barley straw by additive xylanase and surfactants in enzymatic hydrolysis for acetone-butanol-ethanol fermentation.

This study aims to improve enzymatic sugar production from dilute sulfuric acid-pretreated barley straw for acetone-butanol-ethanol (ABE) fermentation. The effects of additive xylanase and surfactants (polyethylene glycol [PEG] and Tween) in an enzymatic reaction system on straw hydrolysis yields were investigated. By combined application of 2g/100g dry-matter (DM) xylanase and PEG 4000, the glucose yield was increased from 53.2% to 86.9% and the xylose yield was increased from 36.2% to 70.2%, which were considerably higher than results obtained with xylanase or surfactant alone. The ABE fermentation of enzymatic hydrolysate produced 10.8 g/L ABE, in which 7.9 g/L was butanol. The enhanced sugar production increased the ABE yield from 93.8 to 135.0 g/kg pretreated straw. The combined application of xylanase and surfactants has a large potential to improve sugar production from barley straw pretreated with a mild acid and that the hydrolysate showed good fermentability in ABE production.

Co-fermentation of hemicellulose and starch from barley straw and grain for efficient pentoses utilization in acetone-butanol-ethanol production.

This study aims to efficiently use hemicellulose-based biomass for ABE (acetone-butanol-ethanol) production by co-fermentation with starch-based biomass. Two processes were investigated: (I) co-fermentation of sugars derived from hemicellulose and starch in a mixture of barley straw and grain that was pretreated with dilute acid; (II) co-fermentation of straw hemicellulosic hydrolysate and gelatinized grain slurry in which the straw was pretreated with dilute acid. The two processes produced 11.3 and 13.5 g/L ABE that contains 7.4 and 7.8 g/L butanol, respectively. In process I, pretreatment with 1.0% H2SO4 resulted in better ABE fermentability than with 1.5% H2SO4, but only 19% of pentoses were consumed. In process II, 95% of pentoses were utilized even in the hemicellulosic hydrolysate pretreated with more severe condition (1.5% H2SO4). The results suggest that process II is more favorable for hemicellulosic biomass utilization, and it is also attractive for sustainable biofuel production due to great biomass availability.

Effect of dilute acid pretreatment on the conversion of barley straw with grains to fermentable sugars.

This study investigated the effects of pretreatment conditions, dilute sulfuric acid concentration and treatment time, on the carbohydrate solubility of a mixture of barley straw and grain. The conditions were expressed as combined severity (CS) to evaluate sugar recovery from pretreated samples. Enzymatic hydrolysates from the lignocellulose pretreatment residues were also included to the results. CS was positively correlating with glucose recovery in all conditions, but in higher acid concentrations CS did not predict xylose recovery. It appeared that the residual xylan better indicate the xylose release. An optimal fermentable sugar yield from the mixture of barley straw and grain was obtained by maintaining the CS at around 1.38, corresponding to an overall glucose yield of 96% and a xylose yield of 57%.