AEB Volume 13, Number 3
: March, 2019

Meta-Analysis of Heavy Metal Partitioning and Allocation Plasticity of Nicotiana glauca Graham (Solanaceae)

Salama Mohamed El-Darier, Ream Ibrahim Marzouk, Shimaa Abdel Razek Rashed

Abstract Background: Nicotiana glauca is an Egyptian invasive plant, with conflicted trend and it was difficult to judge its orientation respecting to the environmental pollution. Objective: The aim of the present study was the application of routine statistical as well as Meta-analyses (Box and Whisker plot and Pearson correlation coefficient) to investigate phytomass, heavy metal concentrations, molecular expression (RAPD) and heavy metal (HM) partitioning and allocation plasticity in N. glauca. Results: The maximum heavy metal partitioning was fluctuated from 1.15 for Mn to 9.03 for Cd and both BCF and TF were more than one. All metals showed 100% significant correlation in all sites except Ni in root and Cd in shoot. Copper attained a larger interquartile range with respect to BCF, TF and PEC. All sites were characterized by relatively high GTS%, site 10 exhibited the highest total number of bands and GTS %, and the lowest percentage of polymorphism. Reversely, the site 1 attained the highest values of percentage of polymorphism and specific bands. Conclusion: Meta-analysis revealed that Nicotiana glauca is hyperaccumulator species that can accumulate high levels of different heavy metals and adapted to polluted environments without severe changes in its genetic material.

[ FULL TEXT PDF 1-13 ] DOI: 10.22587/aeb.2019.13.3.1


Study of chromium uptake by three yeasts: Saccharomyces cerevisiae, Candida tropicalis, and Yarrowia lipolytica

Laila Trioui, Darouiche Bouchra, Errachidi Faouzi and Blaghen Mohammed

Abstract Heavy metal pollution is a topic that attracts a lot of environmental organization’s attention. Recognizing the capacity of microorganisms and biological materials to remove heavy metals from contaminated sites, and their advantage to be a cheaper method of heavy metal remediation, many researches have been dedicated to study and optimize this kind of process. The present work is an eco-physiologic study of hexavalent chromium uptake phenomena, by three species of yeast, in order to investigate some transformations that occur on yeast cell during exposure to chromium. The aim of this work is to optimize the chromium uptake by yeasts, by enlarging the knowledge about the fixation mechanism, in order to use this natural process for reducing the hexavalent chromium pollution from effluent contaminated by this dangerous heavy metal. The yeast growth was performed by kinetic evolution in liquid culture, the sucrose dosage was obtained by DNS protocol, the enzymatic dosage was done by Sinha colometric technique for catalase dosage, and by Nelson methodology for invertase dosage, the amount of chromium was determined by using atomic absorption spectrophotometry (AAS). Results demonstrate that chromium impact yeast growth in the cultivation medium even in low chromium concentration, a better resistance of Saccharomyces cerevisiae was observed, also this stain shows better performance in chromium bioaccumulation. The decrease of catalase in the yeast cells while exposure to chromium confirms the intra-cellular impact. As invertase exists in the soluble spaces of the cell membrane and in the vacuoles, its release during exposure to chromium suppose his complexation with chromium which enforce his passage through the membrane. Efficiency of chromium uptake by Saccharomyces cerevisiae attained 90% with a concentration of 0,5g/l of chromium. The promising yield given by Saccharomyces cerevisiae can be used in a natural chromium decontamination process. As perspective, this work can be used for further studies about the invertase-chromium complexation to profit from this capacity to extract invertase from yeast, for industrial use. The results obtained through this study indicate the possibility of treating a contaminated waste effluent with chromium, by using Saccharomyces cerevisiae.

[ FULL TEXT PDF 14-20 ] DOI: 10.22587/aeb.2019.13.3.2


Soil Burial, Hygrothermal and Morphology of Durian Skin Fiber Filled Polylactic Acid Biocomposites

Ming Meng Pang, Yesudian Aaron, Seong Chun Koay, Jiun Hor Low, Hui Leng Choo, Kim Yeow Tshai

Abstract In this work, the alkali (NaOH) treated and untreated durian skin fibers (DSF) were added into polylactic acid (PLA) to form biocomposites. The PLA/DSF biocomposite preparation was performed via melt blending method (180°C, 50 rpm and 10 mins retention time) at different loadings of DSF, i.e., 15, 25, 30 and 40 wt%, followed by compression molding to form thin sheet. The experimental investigation was carried out to study the weight loss of the PLA/DSF subjected to soil burial for 80 days and hygrothermal test for 14 days. Results showed that the incorporation of DSF can accelerate the weight loss of PLA, higher weight loss was observed at higher fiber content in both soil burial and hygrothermal test. Scanning electron microscope (SEM) micrographs showed the presence of crack line and voids, signs of degradation for soil buried sample.

[ FULL TEXT PDF 21-25 ] DOI: 10.22587/aeb.2019.13.3.3


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