Biotransformation of xenobiotics by hairy roots

Co-cultures from Plants and Cyanobacteria: A New Way for Production Systems in Agriculture and Bioprocess Engineering

Due to the global increase in the world population, it is not possible to ensure a sufficient food supply without additional nitrogen input into the soil. About 30-50% of agricultural yields are due to the use of chemical fertilizers in modern times. However, overfertilization threatens biodiversity, such as nitrogen-loving, fast-growing species overgrow others. The production of artificial fertilizers produces nitrogen oxides, which act as greenhouse gases. In addition, overfertilization of fields also releases ammonia, which damages surface waters through acidification and eutrophication. Diazotrophic cyanobacteria, which usually form a natural, stable biofilm, can fix nitrogen from the atmosphere and release it into the environment. Thus, they could provide an alternative to artificial fertilizers. In addition to this, biofilms stabilize soils and thus protect against soil erosion and desiccation. This chapter deals with the potential of cyanobacteria as the use of natural fertilizer is described. Possible partners such as plants and callus cells and the advantages of artificial co-cultivation will be discussed later. In addition, different cultivation systems for studying artificial co-cultures will be presented. Finally, the potential of artificial co-cultures in the agar industry will be discussed.

Adsorption of Selenium and Lanthanum by Agrobacterium-mediated Hairy Roots of Hybanthus Enneaspermus (L.) F. Muell: A Greener Phytoremediation Strategy

In this study, phytoremediation potential of toxic metals like selenium (Se) and lanthanum (La) by transformed hairy roots was investigated and compared with plantlets under in-vitro conditions. Agrobacterium rhizogenes A4RS could induce hairy roots with higher biomass in 5-7 days of infection on in-vitro leaves of Hybanthus enneaspermus. The ICP-OES data indicated that the hairy roots were able to accumulate both selenium and lanthanum efficiently compared to plantlets. The hairy roots and plantlets show optimum absorption at 50 ppm under both individual and combined metal supply. The metal accumulation performances increased by 13.6% (La) and 10.9% (Se) in hairy roots with combined metal supply (La and Se) compared to individual supply (La or Se) conditions. The Se accumulated more than La, but the La accumulation percentage was found to increase substantially under combined metal supply conditions, shows the suitability and potential of hairy roots for phytoremediation of La and Se.

Hairy Root Cultures as a Source of Polyphenolic Antioxidants: Flavonoids, Stilbenoids and Hydrolyzable Tannins

Due to their chemical properties and biological activity, antioxidants of plant origin have gained interest as valuable components of the human diet, potential food preservatives and additives, ingredients of cosmetics and factors implicated in tolerance mechanisms against environmental stress. Plant polyphenols are the most prominent and extensively studied, albeit not only group of, secondary plant (specialized) metabolites manifesting antioxidative activity. Because of their potential economic importance, the productive and renewable sources of the compounds are desirable. Over thirty years of research on hairy root cultures, as both producers of secondary plant metabolites and experimental systems to investigate plant biosynthetic pathways, brought about several spectacular achievements. The present review focuses on the Rhizobium rhizogenes-transformed roots that either may be efficient sources of plant-derived antioxidants or were used to elucidate some regulatory mechanisms responsible for the enhanced accumulation of antioxidants in plant tissues.

Remediation of endosulfan-contaminated water by hairy roots: removal and phytometabolization assessment

Although many countries banned the insecticide endosulfan, it is still an environmental pollutant. Plants metabolize the two diastereomers of the formulations known as technical grade endosulfan (TGE) by two phase I pathways: hydrolysis leading to less toxic derivatives and oxidation giving endosulfan sulfate which is as toxic as endosulfan itself. We assessed the removal, bioaccumulation and phase I metabolization of TGE from water matrices using hairy root clones (HRs) of three edible species, Brassica napus, Raphanus sativus and Capsicum annuum. B. napus and C. annuum HRs removed 86% of TGE from the bioreaction media in 2 and 96 h, respectively, whereas R. sativus HRs removed 91% of TGE within 6 h of biotreatment. In the experiments with B. napus, only endosulfan sulfate was detected in both biomass and medium, whereas R. sativus and C. annuum accumulated endosulfan sulfate and endosulfan alcohol. Besides, endosulfan lactone was detected in C. annuum reaction medium. Acute ichthyotoxicity assays toward Poecilia reticulata showed that media contaminated with TGE lethal levels did not produce mortality after the phytotreatments. This research highlights the feasibility of using HRs to evaluate plant enzymatic abilities toward xenobiotics and their potential for the design of ex situ decontamination processes.

Kinetic Evaluation for Removal of an Anionic Diazo Direct Red 28 by Using Phytoremediation Potential of Salvinia molesta Mitchell

The dye removal using phytoremediation has demonstrated its potential to degrade many recalcitrant dyes. The kinetic investigations for phytoremediation ability of Salvinia molesta Mitchell (S. molesta) were evaluated for Direct Red 28 (DR28) dye in the present research work. The potential of S. molesta was analysed at different pH and different initial dye concentrations. About 90 % of dye decolorization was achieved for 50 mg L^-1 dye solution with 4 g of S. molesta plant at pH 6.5. The experimental results were evaluated with pseudo-first, pseudo-second and Elovich kinetic models. The validation indicated the most suitable curve with Pseudo-second order having the correlation value R² ≥ 0.99. FTIR studies supported the phytoextraction of DR28 through functional group interaction between plant hairy roots and dye molecules. The results of the present studies suggests that S. molesta can be utilized for remediation of water bodies and wetlands contaminated with dye wastewater in natural conditions.

Role of different earthworm species in nullifying the toxicity of Ipomea carnea and enhancing its utility as a phytoremediator

The dreaded weed ipomea (Ipomea carnea), has shown promise as a versatile phytoremediator. But I. carnea plants exude several alkaloids and phenols which are harmful to plants as well as animals. Due to this, the weed imparts as much or more toxicity to the soil as it remediates. These authors have earlier found that upon being vermicomposted by Eisenia fetida ipomea loses its toxicity and becomes a benign organic fertilizer with pest repellant attributes. These findings open up the possibility of using earthworms in those segments of land which are sought to be phytoremediated by ipomea so that the earthworms can keep converting the dead ipomea plants and the debris of live plants to fertilizer. The present work has aimed to determine whether the extent and nature of earthworm impact differs from species to species or is similar across different species. It has revealed that the action of each of the four different earthworm species deployed by the authors caused the C:N ratio of ipomea to change drastically ̶ from 28.20 to 15.95 ± 0.75, bringing the vermicomposts to the category of fertilizers fit for horticulture. The Fourier transform infrared (FTIR) spectra revealed that all the species caused a breakdown of the alkaloids and the phenolic compounds present in ipomea, resulting in the weed's detoxification. The earthworms also effected partial degradation of the lignocellulosic content of ipomea to simpler and more soil-friendly constituents like humic acids. Thermogravimetry, differential scanning calorimetry and scanning electron microscopy corroborated these findings. The influence exerted by the four species of earthworms was similarly beneficial in nature and extent.

Selected Aspects Related to Medicinal and Aromatic Plants as Alternative Sources of Bioactive Compounds

Natural compounds obtained from different medicinal and aromatic plants have gained respect as alternative treatments to synthetic drugs, as well as raw materials for different applications (cosmetic, food and feed industries, environment protection, and many others). Based on a literature survey on dedicated databases, the aim of the present work is to be a critical discussion of aspects regarding classical extraction versus modern extraction techniques; possibilities to scale up (advantages and disadvantages of different extraction methods usually applied and the influence of extraction parameters); and different medicinal and aromatic plants' different applications (medical and industrial applications, as well as the potential use in nanotechnology). As nowadays, research studies are directed toward the development of modern, innovative applications of the medicinal and aromatic plants, aspects regarding future perspectives are also discussed.