Effects of [C₂mim][OAc] (1-ethyl-3-methyl-imidazolium acetate) on the growth of wheat seedlings under Cd²⁺ stress

Effects of [Cnpy]Br (n=3,5) on the growth and physiology of rape seedlings

1-Alkylpyridinium bromide [C_npy]Br is a common intermediate in chemical synthesis. With the discharge of industrial wastewater, it enters the environment and is toxic to plants. In this study, the impacts of two pyridine-based ionic liquids (ILs), [C₃py]Br and [C₅py]Br, on the growth and physiology of rape seedlings were investigated at concentrations of 10, 50, 100, 200, 300, and 400 mg/L. Within the concentration range (10-400 mg/L) of [C₃py]Br and [C₅py]Br treatment, the root length, plant height, activities of antioxidant enzymes (SOD, POD, and CAT), and the contents of Chla and Chlb showed an increase at low concentrations and a decrease at high concentrations. [C₃py]Br and [C₅py]Br increased MDA content in rape seedlings leaves in a concentration-dependent manner. It was also found that [C₅py]Br was more toxic to rape seedlings than [C₃py]Br. The toxicity of pyridine ILs such as [C₃py]Br and [C₅py]Br to plants should be highly concerned.

New Residue Analysis Method for Four Task-Specific Ionic Liquids in Water, Soil and Plants

With the extensive application of task-specific ionic liquids (TSILs), their environmental impact has attracted increasing attention. However, no studies involving residue analyses of TSILs have been reported in the literature thus far. In the present study, residues of four TSILs ([C₂NH₂MIm]BF₄, [HOEMIm]BF₄, [HOEMIm]NO₃, [MOEMIm]BF₄) were analyzed by high-performance liquid chromatography-tandem mass spectrometry. The limit of detection of instrument was approximately 10^-15 g. Residual TSILs were extracted from soil and plant samples by the accelerated solvent extraction method. In water, soil and plants, the coefficient of variation was 0.38%-4.43%, and the method detection limits of the four TSILs were lower than 1.40 ng g^-1. These results meet the standards of residue analysis. The present study can provide an analysis method for studying TSIL residues and toxicity in the environment.

Effects of imidazolium-based ionic liquids with different anions on wheat seedlings

The effects of five imidazolium ionic liquids with different anions were studied in hydroponically grown wheat seedlings at concentrations of 50, 100, 150, 200, 250, and 300 mg L^-1. The results showed that shoots and roots grew shorter and dry weight decreased with increasing concentrations of ionic liquids. Moreover, the antioxidant enzyme activities decreased and malondialdehyde (MDA) content was greater in the leaves of wheat seedlings subjected to ionic liquid (IL) treatments. The order of influence of ionic liquids on these indexes was [C₄mim][TfO]> [C₄mim][Cl]> [C₄mim][BF₄]> [C₄mim][Lact]> [C₄mim][Ala]. A transmission electron microscope (TEM) was used to observe leaf and root cellular structures, such as chloroplast, nucleus, mitochondria, and rough endoplasmic reticulum, in wheat exposed to ionic liquids at a concentration of 150 mg L^-1. The results showed that the cellular structures of wheat were affected, and the degree of the effect of five ILs was consistent with the general trend of the measured indexes in this study. Ionic liquids influence the growth of plants by impeding growth, disrupting metabolic physiology and changing cellular structures. The degree of toxicity of imidazolium-based ionic liquids with different anions varies.

Study on the growth of wheat seedlings under acetic acid ionic liquids [Cnmim][OAc] (n = 2, 4, 6)

A transmission electron microscope (TEM) was used to observe the cellular structure of wheat leaf under the effects of ionic liquids (ILs).

Study on the growth and photosynthetic characteristics of wheat seedlings under [C₄mim][OAc] (1-butyl-3-methyl-imidazolium acetate) with Cd²⁺ stress

In this paper, the joint effect of 0.5 mmol·L(-1) Cd(2+) and various concentrations (50-400 mg·L(-1)) of the ionic liquid 1-butyl-3-methyl-imidazolium acetate ([C4min][OAc]) on the growth and photosynthetic performance of wheat seedlings in hydroponic culture was investigated. Seedlings grown in presence of Cd(2+) and [C4min][OAc] showed significant (p < 0.05) improvement in growth (shoot and root lengths and dry weights) and photosynthetic performance (photosynthetic rate, stomatal conductance, transpiration rate, and chlorophyll a but not chlorophyll b) compared to seedlings grown in the presence of Cd(2+) but without [C4min][OAc]. However, this only happened under the lower range of [C4min][OAc] concentrations (50-200 mg·L(-1)). In addition, significant reduction in the level of Cd(2+) was also observed in the leaf tissue of wheat seedlings grown in the presence of 0.5 mmol·L(-1) Cd(2+) and 100 mg·L(-1) [C4min][OAc]. Overall, Cd(2+) exerted a stronger inhibition than [C4min][OAc] on the growth and photosynthetic performance of wheat seedlings. However, when both Cd(2+) and [C4min][OAc] were present in the culture, the toxicity of Cd(2+) could be mitigated by lower concentrations of [C4mim][OAc]. This phenomenon could be due to [C4mim][OAc] forming metal complexes with Cd(2+), thus reducing the toxicity of Cd(2+).

Impact of two ionic liquids, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium methylphosphonate, on Saccharomyces cerevisiae: metabolic, physiologic, and morphological investigations

BACKGROUND

Ionic liquids (ILs) are considered as suitable candidates for lignocellulosic biomass pretreatment prior enzymatic saccharification and, obviously, for second-generation bioethanol production. However, several reports showed toxic or inhibitory effects of residual ILs on microorganisms, plants, and animal cells which could affect a subsequent enzymatic saccharification and fermentation process.

RESULTS

In this context, the impact of two hydrophilic imidazolium-based ILs already used in lignocellulosic biomass pretreatment was investigated: 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and 1-ethyl-3-methylimidazolium methylphosphonate [Emim][MeO(H)PO2]. Their effects were assessed on the model yeast for ethanolic fermentation, Saccharomyces cerevisiae, grown in a culture medium containing glucose as carbon source and various IL concentrations. Classical fermentation parameters were followed: growth, glucose consumption and ethanol production, and two original factors: the respiratory status with the oxygen transfer rate (OTR) and carbon dioxide transfer rate (CTR) of yeasts which were monitored online by respiratory activity monitoring systems (RAMOS). In addition, yeast morphology was characterized by environmental scanning electron microscope (ESEM). The addition of ILs to the growth medium inhibited the OTR and switched the metabolism from respiration (conversion of glucose into biomass) to fermentation (conversion of glucose to ethanol). This behavior could be observed at low IL concentrations (≤5% IL) while above there is no significant growth or ethanol production. The presence of IL in the growth medium also induced changes of yeast morphology, which exhibited wrinkled, softened, and holed shapes. Both ILs showed the same effects, but [Emim][MeO(H)PO2] was more biocompatible than [Emim][OAc] and could be better tolerated by S. cerevisiae.

CONCLUSIONS

These two imidazolium-derived ILs were appropriate candidates for useful pretreatment of lignocellulosic biomass in the context of second-generation bioethanol production. This fundamental study provides additional information about the toxic effects of ILs. Indeed, the investigations highlighted the better tolerance by S. cerevisiae of [Emim][MeO(H)PO2] than [Emim][OAc].