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.

Cultivation of freshwater microalga Scenedesmus sp. using a low-cost inorganic fertilizer for enhanced biomass and lipid yield.

The potential of an inorganic fertilizer as an alternative nutrient source for the cultivation of Scenedesmus sp. IMMTCC-6 was investigated. With a preliminary study at a shake-flask scale, the microalgae cultivation was scaled up in a photobioreactor containing an inorganic fertilizer medium. Microalgae cultured in a shake flask containing 0.1 g L(-1) of urea and 1.0 g L(-1) of NPK (Nitrogen: Phosphorus: Potassium) fertilizers showed a promising result in biomass productivity. During the scale-up study in a photobioreactor the specific growth rate (µ d(-1)), biomass yield (g L(-1)), and total biomass productivity (mg L(-1) d(-1)), was found to be 0.265, 1.19 and 66.1, respectively. The lipid yield (%) as per dry cell weight (DCW) and lipid productivity (mg L(-1) d(-1)) was found to be a maximum of 28.55 and 18.87, respectively, in a stationary phase of the microalgae growth. The fatty acids methyl ester profile was proven to be desirable for biodiesel production.

High-performance liquid chromatographic quantification of plumbagin from transformed rhizoclones of Plumbago zeylanica L.: inter-clonal variation in biomass growth and plumbagin production.

An optimized protocol for induction and establishment of Agrobacterium rhizogenes-mediated hairy root cultures of Plumbago zeylanica L. was developed through selection of suitable explant type and the bacterial strain. The infection of internodal explants from an in vivo plant and leaves of in vitro origin with the A4 strain resulted in the emergence of hairy roots at a transformation frequency of 86.33 and 42.33 %, respectively. Independent transformed root somaclones (rhizoclones) capable of sustained growth were maintained under a low illumination in auxin-free agar-solidified Murashige and Skoog (MS) medium through subcultures at periodic intervals. The presence of pRi T L-DNA rolB or rolC genes and pRi T R-DNA mas2 gene in the transformed rhizoclone genome was ascertained by PCR amplification. Concentrations and type of carbon source, auxin and media strength were optimized for root biomass growth. Five independent rhizoclones each from A4- and LBA9402-transformed root lines were studied for their plumbagin accumulation at different growth phases, using HPLC analysis. The potential for plumbagin biosynthesis was expressed in all the tested rhizoclones, although distinct inter-clonal variations were noted. It was evident that maturation of hairy roots was more important for plumbagin accumulation; slow-growing and early-maturing rhizoclones accumulated more plumbagin compared to fast-growing and late-maturing rhizoclones. A4-induced rhizoclone HRA2B5 was identified as the most superior clone with a higher plumbagin yield potential in comparison with other tested hairy root clones, in vitro-grown non-transformed roots and in vivo roots of naturally occurring P. zeylanica.

Maximizing biomass productivity and CO2 biofixation of microalga, Scenedesmus sp. by using sodium hydroxide.

A series of experiments were carried out with three native strains of microalgae to measure growth rates, biomass, and lipid productivities. Scenedesmus sp. IMMTCC-6 had better biomass growth rate and higher lipid production. The growth, lipid accumulation, and carbon dioxide (CO2) consumption rate of Scenedesmus sp. IMMTCC-6 were tested under different NaOH concentrations in modified BBM. The algal strain showed the maximum specific growth rate (0.474/day), biomass productivity (110.9 mg l(-1) d(-1)), and CO2 consumption rate (208.4 mg l(-1) d(-1)) with an NaOH concentration of 0.005 M on the 8(th) day of cultivation. These values were 2.03-, 6.89-, and 6.88-fold more than the algal cultures grown in control conditions (having no NaOH and CO2). The CO2 fixing efficiency of the microalga with other alternative carbon sources like Na2CO3 and NaHCO3 was also investigated and compared. The optimized experimental parameters at shake-flask scale were implemented for scaling up the process in a self-engineered photobioreactor. A significant increase in lipid accumulation (14.23% to 31.74%) by the algal strain from the logarithmic to stationary phases was obtained. The algal lipids were mainly composed of C16/C18 fatty acids, and are desirable for biodiesel production. The study suggests that microalga Scenedesmus sp. IMMTCC-6 is an efficient strain for biodiesel production and CO2 biofixation using stripping solution of NaOH in a cyclic process.