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Cadmium binding and soil microbial diversity in Vetiveria zizanioides

crucial that we address the challenges in soil degradation by altering the physicochemical properties of the soil.
to safeguard food security and human health. It is Therefore, a comprehensive investigation of the structure
3,4
important to note that contamination of the lithosphere and function of rhizosphere microbial communities
has been aggravated in the past decade due to rapid is crucial for evaluating the quality of contaminated
industrialization, with petroleum and mining industries agricultural soils. Under HM stress, microbes either
being the primary contributors. 5 die due to the toxicity caused by the metals or survive
Among various contaminants, HMs such as zinc, and thrive by employing various resistance mechanisms
cadmium, arsenic (As), and lead are of particular against them. HM ions help protect the internal bacterial
concern due to their carcinogenic and mutagenic cells, and the formation of a biofilm on Pseudomonas
properties, and their removal from ecosystems aeruginosa increases its resistance to Cu, Pb, and Zn. 20,21
is imperative. Consequently, the urgency for While numerous studies have investigated the
6
environmental protection and the development of effectiveness of V. zizanioides in removing contaminants
effective remediation techniques has increased. from soils and groundwater, 22,23 there is a notable lack
7,8
In recent years, several remediation technologies— of research on the biological interactions between
including physical, 9,10 chemical, and biological 12,13 plants and microorganisms in the context of HM
11
approaches – have been considerably applied to treat phytoremediation. Recent studies have begun to explore
HM contamination. Traditional remediation methods, these interactions, demonstrating that combining plants
such as chemical techniques involving immobilization, with microorganisms can enhance phytoremediation
soil washing, and vitrification, are often expensive efficiency. Specifically, Serratia spp. has been shown
and not feasible for large-scale applications. As such, to significantly improve cadmium accumulation in
1
there is an urgent need for cost-effective, eco-friendly, V. zizanioides. Furthermore, research into microbial
24
and sustainable alternatives. Biological methods, diversity under HM stress has shown that microbes
14
particularly phytoremediation, offer a promising either survive through resistance mechanisms or
solution to this challenge. Phytoremediation involves perish due to metal toxicity. Ng et al. modified
25
26
15
the adsorption of contaminants, such as HMs, in plant the HM phytoremediation using V. zizanioides by
roots and leaves. This process can be further divided ethylenediaminetetraacetic acid addition into the soil
16
into various mechanisms such as phytostabilization, and ranked metal accumulation as follows: Zinc >>>
phytoextraction, phytovolatilization, rhizofiltration, Copper > Lead >> Cadmium. Since microorganisms
and others, which enable plants to remove, stabilize, or promote most biogeochemical cycles on the Earth, their
degrade pollutants. Among the various plant species role is not negligible to the ecosystems. 27
17
used in phytoremediation, vetiver stands out due to its In addition to plant leaves or roots, soil microorganisms
remarkable characteristics. Vetiver, previously identified are crucial in phytoremediation. The existing studies
25
as Vetiveria zizanioides Nash, has been reclassified as focus on investigating the phytoremediation process
Chrysopogon zizanioides (L.) Roberty, known for its rather than biological interactions. 28-30 By investigating
tall, fast-growing perennial nature and deep root system the impact of two grasses, V. zizanioides and Juncus
that can extend 3 – 4 m into the soil, which is particularly effusus L., on the wetland bacterial and archaeal
effective at remediating contaminated sites. This grass diversity, Long et al. revealed that archaea faced
31
can tolerate a wide range of harsh environmental decreasing abundance with increasing plant bacterial
conditions, including high concentrations of HMs, diversity. In another study, ecotoxicological impacts of
making it an ideal candidate for phytoremediation in Cd on the soil microorganisms were studied through
various contaminated environments. 18,19 polymerase chain reaction (PCR) denaturing gradient
In addition, microbes play a key role in most of gel technique, showing that bacteria, fungi, and
the Earth’s biogeochemical cycles and are crucial to actinomycete are sensitive to Cd. 32
the functioning of virtually all ecosystems. Certain The research to date has tended to focus on
microorganisms in the rhizosphere form symbiotic phytoremediation process rather than biological
relationships with plants, suggesting that phytoextraction, interactions. Overall, there is a lack of comprehensive
28
supported by plant growth-promoting bacteria, could be research thoroughly investigating soil biodiversity in
an effective approach to improve phytoremediation in the context of HM phytoremediation. To address this
heavily contaminated soil. For instance, Serratia spp., gap, this study primarily aims to examine the impact
isolated from cadmium-contaminated soils, has been of Cd phytoremediation on microbial variation in soils
shown to improve the efficiency of phytoremediation assessed using next-generation sequencing (NGS)

Volume 22 Issue 2 (2025) 33 doi: 10.36922/AJWEP025040021