A Review on Bioremediation Potential of Vetiver Grass

Tannery effluent treatments with mangrove fungi, grass root biomass, and biochar

Tannery effluents contain high amounts of polluting chemicals, such as salts and heavy metals released often to surface waters. New economic and eco-friendly purification methods are needed. Two adsorbing materials and five salt-tolerant fungal isolates from mangrove habitat were studied. Purification experiments were carried out using the pollutant adsorbents biochar and the biomass of vetiver grass (Chrysopogon zizanioides) roots and the fungi Cladosporium cladosporioides, Phomopsis glabrae, Aspergillus niger, Emericellopsis sp., and Scopulariopsis sp., which were isolated from mangrove sediment. They efficacy to reduce pollutants was studied in different combinations. Salinity, turbidity, total dissolved solids, total suspended solids, phenols, nitrogen, ammonia. Biological and chemical oxygen demand (BOD, COD) and several heavy metals were measured. The adsorbents were efficient reducing the pollutants to 15-50% of the original. The efficiency of the combination of biochar and roots was generally at the same level as the adsorbents alone. Some pollutants such as turbidity, COD and ammonium were reduced slightly more by the combination than the adsorbents alone. From all 14 treatments, Emericellopsis sp. with biochar and roots appeared to be the most efficient reducing pollutants to < 10-30%. BOD and COD were reduced to ca 5% of the original. The treatment was efficient in reducing also heavy metals (As, Cd, Cr, Mn Pb, Zn). The fungal species originating from the environment instead of the strains present in the tannery effluent reduced pollutants remarkably and the adsorbents improved the reduction efficiency. However, the method needs development for effluents with high pollutant concentrations to fulfil the environmental regulations.

Phytoremediation of electroplating wastewater by vetiver grass (Chrysopogon zizanoides L.)

The electroplating industry generates wastewater containing a variety of heavy metals which potentially contaminate water ecosystems. The available and well-known electroplating wastewater treatments are considered as an expensive and less effective method, therefore phytoremediation was used as an alternative friendly solution. This study aims to evaluate the uptake and elimination rate of heavy metals by vetiver (Chrysopogon zizanoides L.) on metal-polluted water. Vetiver was planted in artificial electroplating wastewater containing different levels (low, medium, high) of chromium (Cr) and nickel (Ni). Water, roots, and shoots were collected periodically to determine Cr and Ni contents using Atomic Absorption Spectrometry (AAS). Metal accumulation and elimination rate, Bioconcentration Factor (BCF), Biological Absorption Coefficient (BAC), and Translocation Factor (TF) were calculated to evaluate plant's effectiveness in metal remediation processes. The results showed that vetiver (C. zizanoides L.) was able to remove 61.10% Cr and 95.65% Ni on metal-contaminated water. The highest uptake rates for Cr and Ni are 127.21 mg/kg/day and 15.60 mg/kg/day respectively, while the elimination rates for Cr and Ni tend to slow 1.09 mg/kg/day and 12.24 mg/kg/day respectively. Vetiver BCF, BAC, and TF values on Cr and Ni contaminated water were greater than 1, which indicates that vetiver work through phytoextraction and phytostabilization to treat metals. The findings showed that vetiver has promise as a phytoremediation agent thus providing implication for electroplating wastewater treatment.

Removal of tetracycline and ciprofloxacin from wastewater by vetiver grass (Chrysopogon zizanioides (L.) Roberty) as a function of nutrient concentrations

Antibiotics have been widely used not only for the treatment and prevention of human infectious diseases but also to promote growth and prevent infections in farm animals. These antibiotics enter the environment via wastewater treatment plants, most of which cannot remove them. In addition to antibiotics, nutrients such as nitrogen (N) and phosphorus (P) also create major environmental pollution problems in surface water. Previously, we reported that vetiver grass [Chrysopogon zizanioides (L.) Roberty] successfully removed antibiotics from secondary wastewater effluent. In this study, our objective was to evaluate the potential of vetiver grass to remove two antibiotics, ciprofloxacin (CIP) and tetracycline (TTC), from wastewater in the presence of high N and P. Our results show that vetiver grass significantly (p < 0.05) removed antibiotics (60-94% CIP and 89-100% TTC) and nutrients (78-89% N and 71-97% P) from the secondary wastewater effluent. The removal of antibiotics dropped with increasing nutrient concentrations. The removal efficiency was mainly affected by the presence of N rather than P in the secondary wastewater effluent. The presence of CIP induced more stress on vetiver grass compared to TTC. Vetiver also removed total organic carbon (48-73%) and chemical oxygen demand (73-82%), but their removal was also affected by the nutrient content in the secondary wastewater effluent.

In Silico Identification of miRNA and Targets from Chrysopogon zizanioides (L.) Roberty with Functional Validation from Leaf and Root Tissues

microRNAs are small non-coding RNA molecule that plays an important role in metabolism. Chrysopogon zizanioides (L.) Roberty is an important aromatic plant used in perfumery industries, soil, water conservation, and agricultural practices. In this study, the transcriptomic sequence of vetiver leaf and root was subjected to miRNA identification by the computational methods. miRNA identification was carried out using a homology-based method by C-mii software with several other online tools. A total of 80 miRNA were identified from both leaf and root sequences. Target identification was done by identified miRNA sets. A total of 25 and 31 miRNA families were identified in both leaf and root, respectively, with ten common families involve in different ontological function. miR169 and miR5021 regulate most of the target in leaf and root. In vetiver, many primary and secondary metabolism elements are regulated by miRNA as photo-system, transcription factor, terpenoid metabolism, etc. Here is the first in silico study revealing the specific miRNAs and their target genes for corresponding root and leaf tissues respectively in C. zizanioides.