Vetiver Root Research Articles

Transcriptome and metabolome analysis of sesquiterpene diversity in Indian vetiver (Chrysopogon zizanioides L. Roberty)

Vetiver is one of the valued plants in the aromatic world which has been extensively used in fragrances, aromatherapy, and medicines. The essential oils derived from vetiver root portions are mainly responsible for the organoleptic character of the plant. Vetiver essential oil is composed of diverse structural framework biosynthesized by using three isoprene units or sesquitepene leading to a number of bicyclic, tricyclic and tetracylic structures. Sequiterpenoids contribute major proportion to vetiver (Chrysopogon zizanioides) roots. However, the terpene synthases and their role in sesquiterpene biosynthesis in plant have not yet been studied. On the basis of volatile composition, two distinct stable vetiver genotypes viz., ‘CIM-Vridhi’ and ‘CIMAP-Khusinolika’ have been identified in ‘CSIR-CIMAP’ in recent years. Such a unique chemical difference is attributed to the array of structural diversity in sesquiterpenes and their derivatives. The root transcriptome of the two contrasting genotypes ‘CIM-Vridhi’ and ‘CIMAP-Khusinolika’ was carried out and three full length terpene synthase (TPS) genes were analyzed. These synthase genes, CZTPS1, CZTPS2, and CZTPS3 produce multiple sesquiterpenoids and were functionally characterized. In addition, the gene expression studies leading to metabolite biosynthesis in these genotypes were further confirmed by compound isolation and NMR based structural characterization of compounds from each genotypes. A bicyclic cadinane called khusinol identified as unique identifier in ‘CIMAP-Khusinolika’ while khusimol, a tricyclic zizaene dominates the ‘CIM-Vridhi’ oil composition. In conclusion, characterization of unique markers in each genotypes has been well supported by their transcriptomic data. Thus, present study can be utilized to investigate the vetiver terpenoid metabolism and its structure–odor correlations for the production of more potent odor threshold oriented chemicals from this plant.

Chemically Catalyzed Phytoextraction for Sustainable Cleanup of Soil Lead Contamination in a Community Garden in Jersey City, New Jersey

Soil lead (Pb) contamination in Pb paint-contaminated homes is a serious health risk in urban areas. Phytoextraction is a green and sustainable technology for soil Pb remediation, but its efficiency depends on the geochemical partitioning of Pb in soil. Following successful laboratory, greenhouse, and panel experiments, a field study was conducted to demonstrate the effectiveness of a chemically catalyzed phytoextraction model for Pb removal. A biodegradable chelating agent, ethylenediaminedisuccinic acid (EDDS) was applied during Pb phytoextraction by vetiver grass (Chrysopogon zizanioides) in a Pb-contaminated community garden in Jersey City, New Jersey. Results showed that soil Pb concentration was reduced from 1144 to 359 mg/kg in 3 years, despite ongoing Pb input to the field plots from a nearby construction site. EDDS was effective in converting non-plant-available forms of Pb (i.e., carbonate-bound, oxide-bound, and organic-bound forms) to plant-available forms (i.e., water-soluble and exchangeable forms). With EDDS application, vetiver roots accumulated 532, 231, and 401 mg/kg of Pb in Years 1, 2, and 3, respectively, which were higher than the values obtained without EDDS applications (228, 154, and 214 mg/kg). This field study demonstrated the effectiveness of a chemically catalyzed phytoextraction model for Pb removal from urban soils.

An enzyme-assisted method to extract vetiver (Vetiveria zizanioides L.) essential oil

Vetiver (Vetiveria zizanioides (L.) Nash) has various applications in many different fields, such as agriculture, medicine, etc. However, the traditional long vetiver essential oil (VEO) extraction process consumes a lot of energy. Therefore, this study is directed to the use of enzymes to support the VEO distillation. According to the results, the pretreated vetiver root with viscozyme was highly applicable as the extraction yield was enhanced by 23% and the extraction time was decreased by 10 h compared to the traditional method. The pretreatment conditions were surveyed to enhance the effectiveness of the viscozyme pretreatment. By using GC–MS, 63 active ingredients were identified and semi-quantified in hydrodistillation extracted VEO, accounting for about 84.72% of the total essential oil content obtained. The GC–MS results show that there was no significant difference between the non-enzyme-assisted and the viscozyme pretreatment samples.

Development of Creative Products for Strengthening the Community Economy through Products from Vetiver Grass Mixed Reed Fiber in Udon Thani Province

The purposes of this research were to 1) study the local wisdom of Khon Sai community in the production of reed products and exploring the capacity of production vetiver grass in Udon Thani province, 2) study for developing creative products made from vetiver grass leaves together with reeds, used of appropriate local natural dyes for manufacturing products in accordance with the market supply, and 3) assess the opinions on designed and developed products made of reed and vetiver grass leaves that can be used as a lesson learned for build a strong community in the future. The methodology of this study was a qualitative research method that consists of 4 steps: 1) collecting original local wisdom data by in-depth interviews and focus group discussions of 10 representatives from a community enterprise group, and by interviews of 30 consumers, 2) using the collected data to design and create a prototype, 3) evaluating products prototype by 2 experts and assessing the satisfaction on the prototype by 8 consumers 4) summarizing data analysis and synthesis. The results of this study found that there is the weaving of reed mats according to the local original wisdom in Khon Sai community. The most purchasing handicraft product by consumers was the mats (66.67 per cent) with the aim of utilizing in their families. The preferable product color of consumers was natural dyes. The researcher developed a handicraft products made from vetiver grass together with reeds, dyeing the natural color from vetiver roots and leaves. In this regard, it was used natural dyed reed and vetiver for weaving mats, and it was applied for designing and processing into 2 handbags prior to assessing such product by experts and consumers. According to evaluation, it was found that the product was beautiful, value-added, and applicable, resulting in a variety of products in the market and also reflects that reed and vetiver grass can be applied for maximum benefit and value addition creation in a concrete manner.

Production of vetiver root as a support for the cliffs of irrigation canals in the Bendung sub-district, Serang City

Irrigation canals in Bendung Village, Kasemen District, Serang, only partially have masonry installed, most of them are still open canals. As time went by, the condition became deplorable, due to rain which eroded the cliffs due to surface erosion. This program aims to provide education about the vetiver system as a method of controlling surface erosion in irrigation canals. The method used in this activity was socialization about prevention of surface erosion in irrigation canals with vetiver roots, training and mentoring in making a pilot arrangement of vetiver in irrigation canals. As a result of the community service activities that have been carried out, it can be concluded that the socialization activities and shallow landslide/erosion control training with the "vetiver system" have provided new knowledge and skills for the people of Bendung Village.

Roles of vetiver roots in desiccation cracking and tensile strengths of near-surface lateritic soil

Desiccation cracking is a major cause of shallow failure of lateritic soil slopes. Knowledge of soil tensile strength helps better understand the cracking behavior of vegetated lateritic soil. This study aims to examine the surficial cracking behavior and tensile strength of remolded lateritic soil containing horizontally arranged vetiver roots. Desiccation cracking tests, root pullout tests and direct tensile tests were performed on lateritic soil considering various porosities, degrees of saturation, and root contents. The mechanism underlying the root reinforcement was analyzed by scanning electron microscopy. The results demonstrate that adding 0.4% grass roots can reduce the crack width and crack intensity factor, and thus mitigate crack developments in lateritic soil. The interfacial shear strength exhibits a decreasing trend with increasing root diameter. As the root content increases from 0% to 1.0%, the tensile strength of lateritic soil increases to reach the peak at a root content of 0.4%-0.5% and then drops greatly. This is why the optimal root content in resisting crack development is about 0.4%. Microscopic tests show that the interfacial shear strength originates from the friction, interlocking force, cementation and capillary force between the rough root surface and surrounding soil particles. A power function-based empirical equation expressed by the root diameter and porosity is proposed to estimate the interfacial shear strength of rooted lateritic soil. Additionally, a semi-theoretical equation of the tensile strength of rooted lateritic soil is deduced based on the tensile strength of soil matrix and the interfacial shear strength between the roots and soil matrix. This equation considers the root content and root diameter distribution and is applicable to the soil of different state parameters (e.g., porosity, degree of saturation and water content). The results could provide insights into the mitigation of desiccation cracking in lateritic soil slopes with root-reinforcement technology.

Valorization of Vetiver Root Biochar in Eco-Friendly Reinforced Concrete: Mechanical, Economic, and Environmental Performance.

Biochar has shown great promise in producing low-cost low-carbon concrete for civil infrastructure applications. However, there is limited research comparing the use of pristine and contaminated biochar in concrete. This paper presents comprehensive laboratory experiments and three-dimensional nonlinear finite element analysis on the mechanical, economical, and environmental performance of reinforced concrete beams made using concrete blended with biochar generated from vetiver grass roots after the roots were used in an oil extraction process. Both pristine biochar and biochar that were used to treat wastewater through adsorbing heavy metals (100 mg/L of Pb, Cu, Cd, and Zn) were investigated. The biochar was used to replace up to 6% Portland cement in concrete. Laboratory experiments were conducted to characterize the workability, mechanical properties, shrinkage, and leaching potential of the concrete blended with biochar. The results showed that using biochar could increase the compressive strengths and reduce the shrinkage of concrete without causing a leaching problem. The results from finite element analysis of the reinforced concrete beams showed that the use of biochar was able to increase the flexural performance of the beams as well as their economic and environmental performance. This research will promote the development and structural applications of low-cost low-carbon concrete.

Enhanced phytoremediation of atrazine-contaminated soil by vetiver (Chrysopogon zizanioides L.) and associated bacteria.

The intensive and long-term use of atrazine (ATZ) has led to the contamination of agricultural soils and non-target organisms, posing a series of threats to human health through the transmission of the food chain. In this study, a 60-day greenhouse pot experiment was carried out to explore the phytoremediation by Chrysopogon zizanioides L. (vetiver). The uptake, accumulation, distribution, and removal of ATZ were investigated, and the degradation mechanisms were elucidated. The results showed that the growth of vetiver was inhibited in the first 10 days of the incubation; subsequently, the plant recovered rapidly with time going. Vetiver grass was capable of taking up ATZ from the soil, with root concentration factor ranging from 2.36 to 15.55, and translocating to the shoots, with shoot concentration factor ranging from 7.51 to 17.52. The dissipation of ATZ in the rhizosphere soil (97.51%) was significantly higher than that in the vetiver-unplanted soil (85.14%) at day 60. Metabolites were identified as hydroxyatrazine (HA), deethylatrazine (DEA), deisopropylatrazine (DIA), and didealkylatrazine (DDA) in the samples of the shoots and roots of vetiver as well as the soils treated with ATZ. HA, DEA, DIA, and DDA were reported first time as metabolites of ATZ in shoots and roots of vetiver grown in soil. The presence of vetiver changed the formation and distribution of the dealkylated products in the rhizosphere soil, which remarkably enhanced the occurrence of DEA, DIA, and DDA. Arthrobacter, Bradyrhizobium, Nocardioides, and Rhodococcus were the major atrazine-degrading bacterial genera, which might be responsible for ATZ degradation in the rhizosphere soil. Our findings suggested that vetiver grass can significantly promote ATZ degradation in the soil, and it could be a strategy for remediation of the atrazine-contaminated agricultural soil.

Influence of Vetiver Root Morphology on Soil–Water Characteristics of Plant-Covered Slope Soil in South Central China

The soil–water characteristic curve is an important tool to evaluate the water-holding capacity of unsaturated soil. Plant roots can affect the matric suction of soil and the water-holding capacity and permeability of the soil. Therefore, the morphological characteristics of plant roots will lead to the difference in soil–water characteristics between soil slope and plant-covered slope. This study aims to investigate the effect of Vetiver root morphology on soil–water characteristic curves of plant-covered slope soil. The hydrological effect of the root distribution on the root–soil system was also discussed. The results showed that: (1) The root surface area index (RAI) and root volume ratio (Rv) of each soil section of the vetiver root system varied with depth in accordance with the Gaussian function distribution; (2) In the process of natural drying, the matric suction generated within the root system is significantly higher than that generated by evaporation of bare soil in the same soil layer. The ability of vegetation soil to enhance soil matrix suction increases with the increase of soil root surface area index; and (3) The α and n values of the SWCC model decreased with the increase of Rv (root volume ratio of soil), while the air entry value increased. Under the same water content, the matric suction corresponding to vegetation soil is significantly greater than bare soil. In addition, the soil–water characteristic curve can be effectively predicted by combining the Rv of vegetated soils.

Thermochemical characterization of post-phytoremediated vetiver (Vetiveria zizanioides (L.) Nash) root and shoot for their prospective bioenergy potential

Critical information as regards the thermochemical characterization of biomass is imperative for the design of efficient biomass thermochemical systems. Present study deals with comprehensive characterization of vetiver root (VR) and vetiver shoot (VS) after being employed for phytoremediation of heavy metal-contaminated alluvial soil. Physico-chemical properties, thermal degradation behavior, functional groups, and surface morphology were determined and compared through proximate, ultimate, HHV, TGA, XRD, FTIR, and FESEM analyses. The cellulose and hemicellulose content put together was found to be significantly high in VR (87.73 wt%) and VS (87.65 wt%). VR was found to contain about twofold inorganic matter than VS. Amorphous nature of VS suggested its potential to produce more pyro-gas and biochar vis-a-vis VR. Volatile matter content of VR (80.25 wt%) and VS (79.42 wt%) was significantly higher as compared to other grass biomasses. Porous structures of VR and VS examined via FESEM micrographs, revealed a large surface area for the reactions to occur. The weight loss for VR and VS in the active zone was found to be 56.06% and 45.74%, respectively as per the thermogravimetric experiments. The average activation energy for pyrolysis of VS was found to be 129.76 and 131.93 kJ/mol and that for VR was found to be 162.15 and 162.19 kJ/mol from KAS and FWO methods, respectively. The thermal decomposition of VR and VS was found to follow reaction-order mechanism (specifically R1, R2, and R3 models) and diffusion mechanism (specifically D4 model proposed by Ginstling-Brounshtein) at lower and higher conversions, respectively. • Volatile matter content of VR (80.25%) and VS (79.42%) was significantly higher than some other biomasses. • TG curves revealed that VR released more volatiles (56.06%) vis-a-vis VS (45.74%) in stage-II. • E a for pyrolysis of VS was found to be lower than VR by both KAS and FWO methods. • Average pore size of VS and VR was found to be 51.53 µm and 19.97 µm, respectively. • Amorphous nature of VS suggested its potential to produce engineered biochar.

Influence of Waste Vetiver Root Fiber on Mechanical, Hydrophobicity, and Biodegradation of Soy-Based Biocomposites as Plastic Substitute

Influence of Waste Vetiver Root Fiber on Mechanical, Hydrophobicity, and Biodegradation of Soy-Based Biocomposites as Plastic Substitute

Enzyme-based green synthesis, characterisation, and toxicity studies of cellulose nanocrystals/fibres produced from the Vetiveria zizanioides roots agro-waste.

Vetiver zizanioides roots are considered the most useful part of the plant. It is widely used to extract oil. The aromatic oil is used in perfumery, food-flavouringand cosmetic industries. However, presently, there are no reports available for the usage of vetiver roots agro-waste after oil extraction in nano-based products. Considering the concept of value-added products and green-chemistry approaches, synthesising cellulose nanoparticles (CNPs) using enzymatic treatment from agro-waste has emerged as a viable option. CNP's non-toxicity, biodegradability, and biocompatibility have sparked the industry's interest in its production. Therefore, in the present study, 3 enzymes, cellulase, pectinase, and viscozymes, were used for the green synthesis of CNP. The characterisation of CNP was done using techniques like DLS, FTIR, TEM, SEM, AFM, and TG/DTG, and cytotoxicity of CNP was studied in human skin cell-line (HaCaT) using MTT assay. Results show that CNPs synthesised using viscozyme and pectinase were of crystalline nature (2.0-3.0nm) and cellulase were of fibres (40-60nm). The FTIR confirmed that CNPs were devoid of lignin/hemicellulose. The AFM pictures revealed thick and thin nanoparticles with a variety of morphologies. The thermal stability of cellulose was higher compared to CNP. All the synthesised CNPs were crystaline, with a 60-70% crystallinity index. Furthermore, CNP did not show cytotoxic effect on HaCaT cells upto 500µg/mL concentrations. In conclusion, pectinase and viscosyme may be used for synthesing cellulose-nanocrystals and cellulase enzyme for cellulose-nanofibers from the vetiver roots agro-waste. The findings revealed that Vetiveria zizanioides agro-waste-derived CNP is a sustainable material that can be used as a reinforcing agent/nanocarrier in textile and drug-delivery systems.

Stability Evaluation of Reinforced Slope Soil with Vetiver Grass against Erosion and Landslides Hazards by Using Finite Element Method

This work studied slopes with different geometric situations. The purpose is to select types of soil for embankment construction to stabilise the site by using nearby accessible filling materials. Then, PLAXIS-2D software was used including five (6) phases of sequential calculation such as soil, structure, mesh generation, conditions of flow and construction stage and the use of Vetiver grass for embakment stability reinforcement. Choices were made on soil properties, loading, water table effect, embankment geometry and reinforcement actions of vetiver grass. The method is based on using diverse filling materials and varied slope gradients with different heights. So, the slope analyse involves homogeneous soils, in addition to slope section by various soils strata. Results obtained showed that the increase in soil shear strength is related to the mechanical effects of vetiver roots and make the soil able to resist shear stress due to the presence of roots density within the soil mass and the root tensile strength. It is also noticed that the soil suction effects and roots reinforcement increased the apparent cohesion of the soil, showing an important role played by vetiver grass in stabilising shallow-seated slopes failure with significant effect on slopes stability.

Comparative study of vetiver root (Chrysopogon zizanioides) and other biochars for water purification

A lab experiment was conducted in Vanavarayar Institute of Agriculture (Affiliated to Tamil Nadu Agricultural University), Pollachi, Tamil Nadu, India during 2018-2019 in a completely randomized design to study the effect of vetiver root (Chrysopogon zizanioides) and other biochars on water quality and water nutrient status in Bore well water and Well water. The experiment consisted of five main factors and two sub-factors. The samples like vetiver root, vetiver root biochar, sugarcane bagasse, palmyrah fruit and banana peel were shade dried and dried in a hot air oven at different temperatures for uniform drying. The pyrolysis process i.e. dried samples into biochar with the recommended temperatures, was carried out in Dr. Mahalingam College of Engineering and Technology, Pollachi. Water from Bore well and well was filtered using vetiver root and different biochars. Water quality parameters such as pH, EC, TDS, potassium, alkalinity were analyzed. The analysis concludes that vetiver root biochar-treated water showed best results in pH, Electrical conductivity, TDS, Potassium and Sodium concentrations.

Antilithiac activity of Chrysopogon zizanioides Brushite crystallization in vitro

Urolithiasis or the formation of calculi at any level of urinary tract is a common disorder found throughout world. Brushite minerals, probably the initiator of stone formation under favorable physiological environment, are one of the most commonly occurring stones along with calcium oxalate mono and di-hydrates. An attempt was made to know the effectiveness of methanolic extract of Chrysopogon zizanioides L. (Vetiver) roots on the growth of brushite crystals. Brushite crystals grown by single gel diffusion technique were treated with different additives, and with increasing concentration of the herbal extract, the crystals showed reduced size, weight, transparency and complexity in morphology. Preliminary phytochemical analysis confirmed the presence of active components like flavonoids, saponins, phenols and anthocyanins. The Fourier Transform Infrared Spectroscopy (FTIR) spectrum of harvested brushite crystals from various treatments revealed band shifts, disappearance of existing and appearance of new peaks which indicated the action of extract. The work established the inhibitory activity of vetiver root extract on the formation of brushite and supports the conventional knowledge of using vetiver root for control and treatment of kidney stones.

VETIVER ROOT PLANTING FOR PREVENTION AND MITIGATION OF LANDSLIDES IN DISASTER-PRONE AREAS, NGANJUK, EAST JAVA

Landslide is the transfer of slope-forming material in the form of rocks, debris, soil moving down or out of the slope. Geolologically, landslides are a geological phenomenon with a movement of land such as falling rocks or large lumps of land (Nandi, 2007). The majority of Nganjuk Regency, East Java, is at high risk of landslides. Reporting from Tirto.id news on February 19, 2021, there was a landslide in Ngetos Subdistrict, Nganjuk which claimed many victims. Nineteen people died, 20 were injured and 10 houses were severely damaged. Ngetos village is the largest village with the most populous population in Nganjuk. Unit of Natural Disease Support from Faculty of Medicine, Community Service Team of the Department of Anesthesiology and Reanimation Faculty of Medicine Universitas Airlangga in collaboration with the Center of Environmental Health Engineering and Disease Control (BBTKLPP) Surabaya in efforts to overcome landslide disasters that occurred in Nganjuk. Assistance provided includes medical assistance and environmental development as one of the disaster mitigation efforts. One of the mitigation measures carried out through this activity is reforestation by planting vetiver roots. Vetiver Roots are known as landslide prevention plants because their roots can reach depths soil of down to 5 meters. One of the causes of landslides is the lack of vegetation on the ground so it is prone to movement, especially if it rains heavily because there is no anchoring. Therefore, this activity is considered important to prevent repeated landslides.

Functional Links between Biomass Production and Decomposition of Vetiver (Chrysopogon zizanioides) Grass in Three Australian Soils.

Plant roots are primary factors to contribute to surface and deep soil carbon sequestration (SCS). Perennial grasses like vetiver produce large and deep root system and are likely to contribute significantly to soil carbon. However, we have limited knowledge on how root and shoot decomposition differ and their contribution to SCS. This study examined biomass production and relative decomposition of vetiver which was grown under glasshouse conditions. Subsequently the biomass incubated for 206 days, and the gas analysed using ANCA-GSL. The results confirmed large shoot and root production potential of 161 and 107 Mg ha−1 (fresh) and 67.7 and 52.5 Mg ha−1 (dry) biomass, respectively with 1:1.43 (fresh) and 1:1.25 (dry) production ratio. Vetiver roots decomposed more rapidly in the clay soil (p < 0.001) compared with the shoots, which could be attributed to the lower C:N ratio of roots than the shoots. The large root biomass produced does indeed contribute more to the soil carbon accumulation and the faster root decomposition is crucial in releasing the carbon in the root exudates and would also speed up its contribution to stable SOM. Hence, planting vetiver and similar tropical perennial grasses on degraded and less fertile soils could be a good strategy to rehabilitate degraded soils and for SCS.

Vetiver root cohesion at different growth sites in Bogor, Indonesia

Abstract. Fata YA, Hendrayanto, Erizal, Tarigan SD, Wibowo C. 2022. Vetiver root cohesion at different growth sites in Bogor, Indonesia. Biodiversitas 23: 1683-1692.The plant root system, including the root system of vetiver grass, plays a critical role in enhancing soil cohesion, shear strength, and vegetated slope stability. Numerous studies on mechanical reinforcement of vetiver grass-roots have been conducted, with the majority of studies focusing on ground-planted vetiver with good maintainedor naturally grown vetiver, while mechanical reinforcement of vetiver grass roots planted in landslide areas at various growth sites with less maintenance is still uncommon.The purpose of this study was to examine the vetiver grass-roots cohesion that grew in the different growth sites that had been affected by landslides. Vetiver grass root samples were collected in January 2021, at the age of 8 months. Vetiver grass roots were collected from vetiver plants growing in the affected landslide areas of (a) bareland, (b) shrubland, and (c) bushland. The root tensile strength of root samples was determined using a Universal Testing Machine (UTM) with a capacity of 3 tons, and the measurement accuracy of the load cell was 1/10000. The test was conducted in accordance with ASTM D638-14 guidelines. Three repetitions were performed on roots representing the root length class of 10 cm. The results indicated that the growth sites influenced the morphological and architectural properties of the vetiver grass-roots. The vetiver grass that grew in bushland exhibited a higher root density than bareland or shrubland. The roots were denser and had a greater range of lengths. Short roots less than 10 cm in length were the most prevalent, and the majority of them were found near the soil surface. The greater the soil depth, the less the quantity of roots.The tensile strength (TR) tends to get smaller with longer roots, and vetiver grass rootsgrew in bareland have the highestTR(15-59 MPa) relative to their growth in bushland (9-37 MPa) and shrubland (16-29 MPa). The ratio of root fiber area to root growth area (RAR) also tends to get smaller with deeper roots. Likewise, is the tensile strength increasing caused by roots (tR) and root cohesion (CR) which are a function of RAR. The CR??of vetiver roots growing in bushland (0.015-0.275 kPa) were relatively higher than those growing in bareland (0.02-0.168 kPa) and shrubland (0.002-0.028 kPa) in the same root length class, at the same depth.

Screening of Antimicrobial Activities and Lipopeptide Production of Endophytic Bacteria Isolated from Vetiver Roots.

The exploration of certain microbial resources such as beneficial endophytic microorganisms is considered a promising strategy for the discovery of new antimicrobial compounds for the pharmaceutical industries and agriculture. Thirty-one endophytic bacterial strains affiliated with Bacillus, Janthinobacterium, Yokenella, Enterobacter, Pseudomonas, Serratia, and Microbacterium were previously isolated from vetiver (Chrysopogon zizanioides (L.) Roberty) roots. These endophytes showed antifungal activity against Fusarium graminearum and could be a source of antimicrobial metabolites. In this study, in particular, using high-throughput screening, we analyzed their antagonistic activities and those of their cell-free culture supernatants against three species of Fusarium plant pathogens, a bacterial strain of Escherichia coli, and a yeast strain of Saccharomyces cerevisiae, as well as their capacity to produce lipopeptides. The results showed that the culture supernatants of four strains close to B. subtilis species exhibited antimicrobial activities against Fusarium species and E. coli. Using mass spectrometry analyses, we identified two groups of lipopeptides (surfactins and plipastatins) in their culture supernatants. Whole-genome sequencing confirmed that these bacteria possess NRPS gene clusters for surfactin and plipastatin. In vitro tests confirmed the inhibitory effect of plipastatin alone or in combination with surfactin against the three Fusarium species.

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The present study aimed to visualize the chromium reduction in the rhizosphere of vetiver. Vetiver was grown in rhizoboxes supplemented with metal solutions such as Ni, Pb, Zn, and Cr(III) with sand as a medium for 30 days. At the end of the experiments, it was observed that Cr(III) (40.0 mg kg-1) was accumulated more in the roots than the shoots compared to Ni (14.5 mg kg-1), Pb (12.0 mg kg-1) and Zn (11.6 mg kg-1). But on the contrary, Zn is accumulated more (58.5 mg kg-1) in shoots than in the roots compared to Ni (23.1), Pb (19.3), and Cr(III) (21.9). In order to validate this, root exudate activity of Vetiver was observed visually as a change in pH using bromocresol purple as an indicator. More root acidification was triggered by Pb and Cr(III). The rhizofiltration of Cr(III) to roots can be attributed to the enhanced root acidification and hence more accumulation. The Cr(VI) reduction was also visualized around vetiver roots using DPC as an indicator. This method is test verified and can be used as a quick method to screen plants for their root exudation potential for metal mobilization or filtration onto roots.