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Soil Microorganisms and Nematodes for Bioremediation and Amelioration

significant role in organic matter decomposition, nutrient cycling, enhance soil

microbial activity and modify the composition of the microbial community

structure (Ferris, Venette, & Scow, 2004; Xiao et al., 2010; Landesman, Treonis,

& Dighton, 2011). They are ubiquitous and have successfully adapted to

nearly every ecosystem of any climatic extreme. They are prevalent in a varied

range of soils and aquatic systems, in heavily polluted soil, in deep-sea sedi­

ments and in decomposing plant and animal products. Conventional physical

assessment of environment pollution provides an absolute value of pollutant

concentration instead of its pathway and bioavailability. Therefore, biomonitor

species could be employed as a feasible means to assess the bioavailability

of pollutants and for risk assessment. Nematodes are quite sensitive to envi­

ronmental factors and xenobiotic substances (organic and/or heavy metals)

in soil and aquatic environment. Nematodes have several unique features

viz. relatively short generation time, easy identification without employing

biochemical procedures, resistant stages allowing them to survive inactively

during stress condition and have heat shock proteins (HSPs) which express

themselves during heat stress (Bongers & Ferris, 1999) (Figure 1.3). Thus, the

use of nematodes as indicators of environmental stress caused by xenobiotic

substance has caught the interest of researchers worldwide. However, there are

several problems that could narrow the scope of use of nematode for environ­

mental biomonitoring, the most important being the masking effect of other

environmental factors on the actual effect of contaminants on nematode (Devi

et al., 2021; Lal et al., 2020; Altaf et al., 2021).

FIGURE 1.3 Pros and cons of use of nematode as a suitable environmental indicator.

This could be avoided by minimizing the effect of external environ­

mental factors other than the pollutants which could be facilitated by taking

reference sites in a study which should be similar to contaminated locali­

ties (Sochová, Hofman, & Holoubek, 2006). Several studies have found

that nematode community structure and diversity, not overall nematode