Earthworm Species Research Articles

Ovary organization and ultrastructure in six species of Amynthas and Metaphire earthworms (Annelida, Crassiclitellata, Megascolecidae)

Ovaries in earthworms belonging to the family Megascolecidae are paired structures attached to the septum in the anterior part of the XIII segment. They are fan to rosette shaped with numerous rows of growing oocytes, known as egg strings, radiating from the ovary center towards the segmental cavity. The histological and ultrastructural ovary organization in megascolecids and the course of oogenesis remain unknown. The paper presents the results of light and electron microscopy analyses of ovaries in six megascolecid species, three from the genus Amynthas and three from Metaphire. Both parthenogenetic and sexually reproducing species were included in the study. The organization and ultrastructure of ovaries in all studied species are broadly similar. Considering the histological organization of ovaries, they could be divided into two zones. Zone I (proximal, close to the connection with the septum) is tightly packed with germline and somatic cells. Germ cells are interconnected via intercellular bridges and thin strands of the central cytoplasm (known as cytophore) and form syncytial cysts. Cysts unite oogonia, early meiotic cells (till diplotene), and clustering cells develop synchronously. During diplotene, interconnected cells lose developmental synchrony; most probably, one cell per cyst grows faster than others, detaches from the cysts, and becomes an oocyte. The remaining cells grow slightly and are still interconnected via the thin and reticular cytophore; these cells are considered nurse cells. Zone II has a form of egg strings where growing oocytes are isolated one from another by thin somatic cells and form short cords. We present the ultrastructural details of germline and somatic cells. We propose the term "Amynthas" type of ovaries for this ovary organization. We suppose that such ovaries are characteristic of other megascolecids and related families.

Bioaccumulation of pesticide residue in earthworms collected from the agricultural soils of Kuttanad-a unique agroecosystem in India.

Earthworms encompass significant soil faunal biomass and have tremendous potential to provide vital ecosystem services. Earthworms are considered bioindicators of chemical contaminants and can provide early warnings of ecosystem deterioration. Studies pertaining to the accumulation of pesticide residues in earthworm in biomass in agrarian ecosystems are scarce. The Kuttanad agroecosystem (KAE), situated on the southwest coast of India, is one of the few regions globally supporting farming on land below the mean sea level. This investigation was conducted to assess the bioaccumulation of pesticide residues in earthworms from the KAE. The earthworms species Glyphidrilus annandalei collected from agricultural soils of the study area were analyzed for the presence of pesticides residues such as α-BHC, γ-BHC, atrazine, heptachlor, α-chlordane, γ-chlordane, 4,4-DDE, 4,4-DDD, 4,4-DDT, β-endosulfan, and endrin ketone in their biomass. Analysis of the earthworm samples using a gas chromatograph revealed the presence of ten pesticide residues with notable concentrations (α-BHC, 0.36ng/g; γ-BHC, 0.41ng/g; heptachlor, 0.10ng/g; atrazine, 0.89ng/g; α-chlordane, 0.07ng/g; γ-chlordane, 0.10ng/g; 4,4-DDE, 0.05ng/g; 4,4-DDD, 0.11ng/g; 4,4-DDT, 0.31ng/g; β-endosulfan, 0.19ng/g; and endrin ketone, 0.13ng/g). Six groups of pesticide residues are ΣBHC, ΣDDT, atrazine, Σchlordane, endrin ketone, and β-endosulfan were observed during bioaccumulation factor analysis, and the results show the following trend: atrazine > ΣBHC > ΣDDT > Σchlordane > Σendosulfan > Σendrin. As earthworms are a crucial component of this region's food chains, bioaccumulation of pesticide residues in earthworms can pause adverse consequences. Increasing trends in pesticide application in the KAE and bioaccumulation of pesticide residues in earthworm biomass can affect the entire food web.

Earthworms neutralize the influence of components of particulate pollutants on soil extracellular enzymatic functions in subtropical forests.

Human activities are increasing the input of atmospheric particulate pollutants to forests. The components of particulate pollutants include inorganic anions, base cations and hydrocarbons. Continuous input of particulate pollutants may affect soil functioning in forests, but their effects may be modified by soil fauna. However, studies investigating how soil fauna affects the effects of particulate pollutants on soil functioning are lacking. Here, we investigated how earthworms and the particulate components interact in affecting soil enzymatic functions in a deciduous (Quercus variabilis) and a coniferous (Pinus massoniana) forest in southeast China. We manipulated the addition of nitrogen (N, ammonium nitrate), sodium (Na, sodium chloride) and polycyclic aromatic hydrocarbons (PAHs, five mixed PAHs) in field mesocosms with and without Eisenia fetida, an earthworm species colonizing forests in eastern China. After one year, N and Na addition increased, whereas PAHs decreased soil enzymatic functions, based on average Z scores of extracellular enzyme activities. Earthworms generally stabilized soil enzymatic functions via neutralizing the effects of N, Na and PAHs addition in the deciduous but not in the coniferous forest. Specifically, earthworms neutralized the effects of N and Na addition on soil pH and the effects of the addition of PAHs on soil microbial biomass. Further, both particulate components and earthworms changed the correlations among soil enzymatic and other ecosystem functions in the deciduous forest, but the effects depended on the type of particulate components. Generally, the effects of particulate components and earthworms on soil enzymatic functions were weaker in the coniferous than the deciduous forest. Overall, the results indicate that earthworms stabilize soil enzymatic functions in the deciduous but not the coniferous forest irrespective of the type of particulate components. This suggests that earthworms may neutralize the influence of atmospheric particulate pollutants on ecosystem functions, but the neutralization may be restricted to deciduous forests.

Vermitechnology: A Sustainable Approach to Manage Organic Waste in Urban Areas

Vermicomposting is the natural process of compost formation by converting organic wastes into organic fertiliser utilising earth worms and cow dung. It is being widely used for solid waste management. Many species of earthworms are utilised in this process such as Eisenia fetida, Eudrilus eugeniae, Eisenia andrei, Lampito rubellus and Drawida willis. They feed on the organic waste to produce vermicompost, vermiwash and more earthworms as resultant products. Composting process with this technique takes around 28-120 days and it depends upon the type of worms and organic waste used. Kirori Mal College of the University of Delhi is pioneer in adopting the vermicomposting on a large scale. It has put 15 beds in place in its nursery. This set of fifteen composting beds is able to utilise about 1.7 tons of dry leaves in a single cycle and converts them into very nutritious fertilizer. As we could run four such cycles in a year, the Kirori Mal College has the potential of consuming about seven tons of dry leaves annually and put it to a better use, which otherwise, would have been a responsibility of the Municipal Corporation of Delhi. Along with the vermicompost, the process also produces vermiwash, a concentrated liquid fertilizer, which is stored and is being utilized after dilution. The vermicomposting also leads to rapid multiplication of earthworms, which can be sold in the market and the spare ones can be utilised for the next cycle. Vermicomposting for the disposal of the dry organic waste is very cost effective and energy efficient.

Endogeic Earthworms Avoid Soil Mimicking Metal Pollution Levels in Urban Parks

In response to long-lasting high levels of metallic trace elements (MTEs) in urban soils, we expect soil invertebrates inhabiting urban environments to have evolved detection and avoidance and/or tolerance mechanisms to MTE pollution. In this study, I used artificial soils with concentrations of lead, zinc, copper, chromium and nickel that reflect pollution levels in the soils of Parisian parks. Using choice experiments, I compared habitat preference (i.e., the occurrence of individuals in the polluted vs. unpolluted soil) and health status (i.e., body mass maintenance, mobility, mortality) between three species of endogeic earthworms—Aporrectodea caliginosa, Aporrectodea icterica and Allolobophora chlorotica—originating either from urban or rural grasslands. This study highlights a clear avoidance of MTE-polluted soils in all three species, as well as MTE-induced health impairments, especially in A. chlorotica. Interestingly, earthworm response to MTE exposure only slightly differed between earthworms of urban and rural origin, suggesting the absence of widespread acclimatization or adaptation mechanisms to MTE pollution in cities. As a consequence, MTE pollution is expected to significantly shape earthworm spatial distribution in both urban and rural environments and, as a consequence, affect ecosystem functioning.

Environmental distances are more important than geographic distances for predicting earthworm gut bacterial community composition

Distance-decay of similarity is one of the most widely studied patterns in biogeography. Both geographic distance and environmental distance can cause distance-decay of similarity in ecological communities. Here, we studied distance-decay relationships of bacteria in the gut of an earthworm species, Eisenia nordenskioldi, which is widely distributed in Eurasian boreal region. Using high-throughput sequencing, we investigated bacterial community composition in different gut sections, together with the surrounding soil. We specifically quantified the effects of geographic distance and environmental distance on distance-decay pattern of both soil and earthworm gut bacteria. Environmental distance significantly affected soil bacteria, and bacteria in the foregut and midgut of earthworms, with those in the foregut changing most, whereas geographic distance only significantly affected bacteria in the foregut of earthworms. Both, environmental and geographic distance explained bacterial community composition in the gut of earthworms and in surrounding soil, with environmental distance being more important than geographic distance. The results indicate that bacteria in the foregut of earthworms are most sensitive to environmental changes than those in the other sections. Overall, the results suggest that homogenization processes during gut passage of earthworms contribute to similarity of soil microbial communities in space due to the production of casts of similar bacterial community composition.

Optimizing Household Waste and Cow Dung Proportions for Quality Vermicompost Production

Aim: To standardize the ratio of household waste and cow dung for quality vermicompost based on physical properties.
 Study Design: Completely Randomized Design (Factorial).
 Place and Duration of Study: Vermicompost Production Unit, RPCAU, Pusa during April 2018 to June 2018.
 Methodology: Household waste was combined with cow dung in three different proportions (35:65, 50:50 and 65:35 ratio of household waste and cow dung, respectively) along with rock phosphate and suitable species of earthworms @ 2 kg per ton of material at suitable temperature and moisture (370C and 65% w/w respectively) under shade. Various physical parameters were analyzed at 30, 60 and 90 days after setting the windrows.
 Results: Vermicompost prepared from household waste and cow dung in (50:50) ratio recorded lowest moisture content 16.0% and highest water holding capacity (20.7%) at the end of vermicomposting process (90 days) and 94% of material passed through 4.0 mm IS sieve.
 Conclusion: Vermicompost prepared from household waste and cow dung in equal proportion (50:50) emerged out as better quality vermicompost based on the observed physical characteristics.

Arsenic toxicity to earthworms in soils of historical As mining sites: an assessment based on various endpoints and chemical extractions

Eisenia fetida is an earthworm species often used to assess the toxicity of contaminants in soils. Several studies indicated that its response can be unpredictable because it depends both on total concentrations of contaminants and also on their forms that differ in susceptibility to be released from soil solid phase. The issue is complex because two various uptake routes are concurrently involved, dermal and ingestion in guts, where the bioavailability of contaminants can considerably change. The aim of this study was to analyze the toxicity of arsenic (As) in various strongly contaminated meadow and forest soils, representative for former As mining and processing area, to earthworms E. fetida and its accumulation in their bodies. An attempt was made to find relationships between the response of earthworms and chemical extractability of As. In the bioassay, carried out according to the standard ISO protocol, different endpoints were applied: earthworm survival, fecundity measured by the numbers of juveniles and cocoons, earthworm weight and As accumulation in the bodies. The results proved that E. fetida can tolerate extremely high total As concentrations in soils, such as 8000 mg/kg, however, the individual endpoints were not correlated and showed different patterns. The most sensitive one was the number of juveniles. No particular soil factor was identified that would indicate an exceptionally high As susceptibility to the release from one of soils, however, we have demonstrated that the sum of non-specifically and specifically bound As (i.e. fractions F1 + F2 in sequential extraction according to Wenzel) could be a good chemical indicator of arsenic toxicity to soil invertebrates.

Earthworms Species Diversity and Populations in Initao-Libertad Protected Landscape and Seascape, Misamis Oriental, Philippines

Earthworm diversity and populations in the seaward and landward portions of Initao-Libertad Protected Landscape and Seascape (ILPLS) were assessed. Soil physico-chemical properties in the area were also assessed to explain such oc- currence. Pheretima cf. lantapanensis, Amynthas sp. and Polypheretima sp., all belonging to family Megascolecidae, were detected in the area. ILPLS has a very low diversity of earthworms and the soil physico-chemical properties had no significant relationship with earthworm species diversity. The soil physico-chemical properties between the seaward and landward portions of the protected area were not significantly different. This study was undertaken to provide baseline in- formation on earthworm species diversity in ILPLS, which will serve to help strengthen the policy on the conservation and protection of biodiversity in the protected area.

Role of bulking agents, process optimization, and different earthworm species in the vermiremediation process of industrial wastes: A review

Rapid industrialization and consumerism have aggravated the generation of industrial waste globally, consequently posing a serious problem related to their treatment, disposal, and management. Industrial wastes or sludges are mainly characterised by undesirable levels of heavy metals, toxic chemicals, and other toxic organic compounds. Deposition of such wastes in the environmental matrices for prolonged periods may result in serious contamination, and the consequent accumulation of these harmful constituents in the ecological food chain. Unavailability of appropriate disposal mechanisms for these sludges is a matter of serious concern that could severely pollute the environment and risk human health. Vermicomposting has emerged as a feasible and environmentally friendly bioremediation technology that could provide a solution to this problem. However, the vermicomposting of industrial sludges requires a better understanding of its inextricable factors to make it a viable process. Thus, the present study was undertaken to provide insights on the influence of different bulking agents and abiotic factors on the vermicomposting process, as well as, the role of different earthworm species in the successful implementation of this process in the bioremediation of industrial waste.

Spatial patterns and species associations of earthworms in relation to micro-topography and insolation

Despite significant advancements in our understanding of the relationship between soil animal life and environmental gradients, as well as their impact on ecosystem functioning, there is a growing need for quantitative research that considers the spatial and temporal heterogeneity of soil biodiversity. Such research can help to address current knowledge gaps and support the development of legislation and conservation measures aimed at preserving soil biodiversity in the future. Earthworms, one of the most important group of soil animals, show patchy horizontal distribution in response to spatial heterogeneity in soil physico-chemical parameters, food availability and biological interactions at various scales.The aim of this study was to explore whether the spatial and temporal variability and co-occurrence probability of earthworm species and ecological categories (epigeic, endogeic and anecic) can be characterized by exploiting habitat micro-topography and insolation.Field research was carried out in spring and summer at seven locations using a regular grid of 49 sampling points with 5 m inter-sample distance over an altitudinal gradient. The results of Geary's C and Moran's I indices, as well as the semivariograms calculated for each species, season and location confirmed a patchy spatial distribution. The range of semivariograms varied from 3.2 m to 32.8 m in spring, and from 0.3 m to 32.8 m in summer. Overall (all locations and both seasons), the mean range was similar for adult (8.4 m) and juvenile (9.2 m) earthworms. In spring, epigeic species had a larger range than endogeic species. Abundances of juvenile earthworms were negatively correlated with microtopographic elevation in spring (at most locations) and in summer (at all locations). The relationship between adult earthworms and microtopographic elevation could not be interpreted generally within season. Additionally, correlations between earthworm abundance and average monthly insolation were weak. Pairwise analysis of species co-occurrence revealed a random pattern for most species. In the analysis of co-occurrence of ecological categories, endogeics and epigeics had more positive probabilities than other pairs. The obtained results could be useable in soil biodiversity assessments, or creation of monitoring protocols.

Biochemical response of two earthworm taxa exposed to freezing.

Several earthworm species are known to be able to withstand freezing. At the biochemical level, this ability is based on cryoprotectant accumulation as well as several other mechanisms. In this study, we used 1H NMR to investigate metabolomic changes in two freeze-tolerant earthworm taxa, Dendrobaena octaedra and one of the genetic lineages of Eisenia sp. aff. nordenskioldi f. pallida. A total of 45 metabolites were quantified. High concentrations of glucose were present in frozen tissues of both taxa. No other putative cryoprotectants were found. We detected high levels of glycolysis end products and succinate in frozen animals, indicating the activation of glycolysis. Concentrations of many other substances also significantly increased. On the whole, metabolic change in response to freezing was much more pronounced in the specimens of Eisenia sp. aff. nordenskioldi f. pallida, including signs of nucleotide degradation.

Agricultural farming intensification significantly reduced earthworm abundance and diversity in Usangu agro-ecosystems, Tanzania

Earthworms an ecologically important group of invertebrates that are crucial to delivery of many ecosystem services, but also considered ecosystem engineers playing an important role in soil fertility and land productivity. Earthworms facilitate breakdown and decomposition of plant and animal materials releasing plant nutrients. Earthworm burrows allow air and water movement in the soil but also improve soil fertility and drainages. Earthworm population in agricultural soils is influenced by different factors i.e., tillage, farming activities, soil chemistry as well as chemical contaminants. Agricultural (paddy farming) intensification with increased and excessive use of agrochemicals (fertilizers, pesticides, and herbicides) may affect earthworm population in agricultural soils. Recently, there scant studies conducted to characterize earthworm abundance and diversity in Tanzania's agro-ecosystem. Therefore, the present study characterized earthworm population in agricultural soils of contrasting intensification in Usangu agro-ecosystem (UA) to understand influence of current land use on earthworm abundance and their diversity as they have a vital role in agro-ecosystem productivity and sustainability. This study found that current paddy farming and associated activities in UA negatively affect earthworm occurrence, distribution, and diversity. Where only four dominant earthworm species were determined (Apporectodea caliginosa (endogeic), Lumbricus terrestris (Anecic), Pontoscolex corentrurus (endogeic), Fimoscolex sporadochactus (Anecic)) compared to other tropical areas. But also, highly intensified paddy farming areas (i.e., Chimala, Igalako, Ihahi, Kapunga, Mahongole, and Uturo) were observed to have earthworm abundance <25 individuals/m2 an FAO recommended earthworm count/m2 in healthy soils compared to less intensified schemes (25-40 earthworm/m2). The earthworm abundance and biomass determined in UA was below global average of 78 individuals per m2 and 150 g/m2, indicating that UA is in deteriorating quality. Thus, current farming practices creates unfavourable environmental conditions which likely leads to migration of earthworm to other land use or death due to harsh environment created. High earthworm abundance and biomass improve land productivity via nutrient recycling, thus low earthworm counts and diversity in UA likely to threaten agro-ecosystem sustainability. The present study provides baseline information on earthworm abundance and their diversity in UA and Tanzania.

IMPACT OF TRIAZOPHOS, CHEMICAL USED IN SOYBEAN CROP, ON THE GROWTH AND REPRODUCTION OF EISENIA FETIDA

Earthworms are crucial for maintaining soil quality and supporting agricultural practices. Soil conditions, such as nutrients, toxicants, moisture, fertilizers, and pesticides, can impact earthworm populations, growth, and reproduction. Of particular concern is the potential negative effects of pesticides on higher ecological levels. This study aims to evaluate the toxicity of Triazophos, a commonly used insecticide during Soybean cultivation, on the earthworm species Eisenia fetida in Kota, Rajasthan, India. In this experiment, five sets of 10 earthworms were exposed to concentrations of Triazophos ranging from 0.158 to 15.8 mg/kg dry weight, while one set served as the control. The growth of earthworms was monitored after four weeks, and the number of juveniles was counted after eight weeks. The results showed that the growth rate and reproduction of Eisenia fetida were significantly reduced by exposure to Triazophos. These findings highlight the potential ecological risks associated with the use of Triazophos in agricultural settings.

Responses of earthworms exposed to low-density polyethylene microplastic fragments

The interest in the effect of microplastics (MPs) on the terrestrial environment has been increasing recently. Different species of earthworms have been used to study the effects of MPs on different aspects of earthworm health. However, there is still a need for more studies because different studies report different effects on earthworms depending on the properties (e.g., types, shapes, sizes) of MPs in the environment and exposure conditions (e.g., exposure period). This study used Eisenia fetida as a test earthworm species to investigate the effect of different concentrations of low-density polyethylene (LDPE) MPs (≤125 μm) in soil on the growth and reproduction of earthworms. The exposure of the earthworms to the different concentrations of LDPE MPs (0–3% w/w) for 14 d and 28 d neither caused death of the earthworms nor showed significant effects on the earthworm weights in this study. The number of cocoons produced by the exposed earthworms were also similar to that of the controls (i.e., no exposure to MPs). Some previous studies reported similar results to what have been observed in this study, while some studies reported different results. On the other hand, the number of ingested MPs by the earthworms increased with increasing MPs concentrations in soil, suggesting a potential for damage to digestive tract. Also, the earthworm skin surface was damaged after exposure to MPs. The ingested MPs and the skin surface damage suggest that there is a potential for adverse effects on the earthworm growth after a longer-term exposure. Overall, the results of this study show that the effects of MPs on earthworms need to be studied using various endpoints including growth, reproduction, ingestion, and skin damage and such effects can be different depending on the exposure conditions such as MPs concentration and exposure period.

Polyethylene mulch film-derived microplastics enhance the bioaccumulation of atrazine in two earthworm species (Eisenia fetida and Metaphire guillelmi) via carrier effects

Microplastics (MPs) may significantly affect the bioavailability of coexisting pollutants in soil by adsorption-desorption behavior. However, the mechanisms underlying these interaction remain unclear. Herein, the influence of unused polythylene mulch film-derived MPs (MFMPs) and farmland residual polyethylene mulch film-derived MPs (MFMPs-aged) on the adsorption-desorption behavior and bioavailability of atrazine (ATZ) in soil were investigated. The adsorption kinetics and the adsorption isotherms of ATZ on soil, MFMPs, and MFMPs-aged fitted well by the pseudo-second-order model and the Langmuir model, respectively. ATZ were easier to desorb from soil, MFMPs, and MFMPs-aged in the simulated earthworm digestive fluid than that in the CaCl2 solution. The adsorption and desorption capacities of MFMPs and MFMPs-aged for ATZ were higher than those of soil, especially for MFMPs-aged. The existence of MPs in soil strengthened the adsorption and desorption capacities of ATZ, and the strengthened effects were promoted by the addition amount and aging process of MPs. Moreover, the occurrence of MPs significantly increased the bioaccumulation of ATZ in earthworms, especially for MFMPs-aged. This study deepens the knowledge of the interaction mechanisms of mulch film-derived MPs and pesticide pollution.

Evaluation of Physico-chemical Parameters of Soil in Different Cropping Systems and their Co-relation with Earthworm Diversity

Aim: The present study is an attempt to evaluate the impact of earthworm diversity on physico-chemical parameters of soil in different cropping systems (i.e. basmati-wheat, basmati-chickpea, soybean-wheat, moong-wheat) under organic and conventional farming systems.&#x0D; Place and Duration of Study: The study was conducted at the School of Organic Farming, Punjab Agricultural University, Ludhiana, Punjab, India from June, 2020 to March 2021.&#x0D; Methodology: The four earthworm species found during the study period are Metaphire posthuma, Lampito mauritti, Amynthas morissia and Travoscolides chengannure, which belong to two families i.e. Megascolicidae and Octochateidae. Out of these Travoscolides chengannure was reported for the first time in Punjab.&#x0D; Results: The results indicate that richer earthworm diversity was found in the organic farming systems as compared to the conventional farming systems. The correlation analysis of earthworm abundance with the physicochemical parameters of soil in different farming systems revealed that the abundance of earthworms in organic farming system shows positive but non-significant correlation with pH, nitrogen and potassium levels. In conventional farming system, significant positive correlation (p=0.01) was found for organic carbon, electric conductivity and nitrogen.&#x0D; Conclusion: The findings of this encourage switching from conventional to organic farming practices. These practices not only increase earthworm diversity, but enrich the soil with many major and micro-nutrients. The agriculture practices which are earthworm-friendly should be adopted for long-term soil productivity.

Optimization and scale up of the enzymatic hydrolysis of Californian red worm protein (Eiseniafoetida)

Although the best-known use of the different species of earthworm is the production of organic fertilizer, they can also be considered a rich source of biologically and pharmacologically-active compounds, for use in the treatment of various diseases. In recent decades, with the development of biochemical technologies, research on the pharmaceutical effects of compounds extracted from different species of earthworms has begun. Enzymatic hydrolysis is the most common and widely used technique for producing bioactive hydrolysates, because it uses moderate operating conditions, with a certain specificity for the substrate. In the present study, the objective was to optimize and scale up the enzymatic hydrolysis of Eisenia foetida protein to obtain peptides with biological activity. The substrate characterization was carried out according to AOAC, a response surface design was performed for the optimization of the enzymatic hydrolysis and then the scaling was performed by means of dimensional analysis. The results show that the major component of the paste is protein, 65% of which is albumin, and the absence of pathogenic microorganisms was also found. Regarding optimization, it was found that the optimal hydrolysis conditions are achieved with pH = 8.5; temperature = 45 °C; amount of substrate = 125 g and volume of enzyme = 1245μL. For the scaling, 4 dimensionless pi-numbers were calculated which describe the process with no statistically significant differences between the model and the prototype; it can be concluded that the enzymatic hydrolysate of Eisenia foetida presents high values of antioxidant activity evaluated by different methodologies.

Earthworm granules: A model of non-classical biogenic calcium carbonate phase transformations.

Different non-classical crystallization mechanisms have been invoked to explain structural and compositional properties of biocrystals. The identification of precursor amorphous nanoparticle aggregation as an onset process in the formation of numerous biominerals (crystallization via particle attachment) constituted a most important breakthrough for understanding biologically mediated mineralization. A comprehensive understanding about how the attached amorphous particles transform into more stable, crystalline grains has yet to be elucidated. Here, we document structural, biogeochemical, and crystallographic aspects of the formation as well as the further phase transformations of the amorphous calcium carbonate particles formed by cultured specimens of earthworm Lumbricus terrestris. In-situ observations evidence the formation of proto-vaterite after dehydration of earthworm-produced ACC, which is subsequently followed by proto-vaterite transformation into calcite through nanoparticle attachment within the organic framework. In culture medium spiked with trace amounts of Mn2+, the cauliflower-like proto-vaterite structures become longer-lived than in the absence of Mn2+. We propose that the formation of calcite crystals takes place through a non-classical recrystallization path that involves migration of proto-vaterite nanoparticles to the crystallization site, and then, their transformation into calcite via a dissolution-recrystallization reaction. The latter is complemented by ion-by-ion crystal growth and associated with impurity release. These observations are integrated into a new model of the biocrystallization of earthworm-produced carbonate granules which highlights the sensibility of this process to environmental chemical changes, its potential impact on the bioavailability of contaminants as well as the threat that chemical pollution poses to the normal development of its early stages. STATEMENT OF SIGNIFICANCE: Understanding the mechanisms of nucleation, stabilization and aggregation of amorphous calcium carbonate (ACC) and factors controlling its further transformation into crystalline phases is fundamental for elucidation of biogenic mineralization. Some species of earthworms are natural workbench to understand the biogenic ACC, stabilization and the transformation mechanisms, because they create millimeter-sized calcareous granules from amorphous calcium carbonate, which crystallize to a more stable mineral phase (mostly calcite). This study undergoes into the mechanisms of ACC stabilization by the incorporation of trace elements, as manganese, and the ulterior precipitation of calcareous granules by a coupled process of amorphous particle attachment and ion-by-ion growth. The study points to sensibility of this process to environmental chemical changes.

Vermicompost Application in Crop Production and Urban Waste Management: A Review Article

The marvelous increase in population, industrialization, urbanization, and agricultural output results in buildup amounts of solid wastes which lead to serious problematic in the environment. The waste management and crop residues are serious problems in the world. The burning of crop residues causes environmental pollution like smog. Disposal of these wastes safely can be achieved by bio-composting and vermicomposting of farm, agro-industrial waste and urban wastes. To manage all kind of waste vermicomposting is the best technique that is economically viable, environment friendly and socially acceptable approach which converts garbage in to black gold; called vermicomposts. Vermicomposts enhances soil biodiversity by promoting the beneficial microbes which in turn enhances plant growth directly by production of plant growth-regulating enzymes and hormones and indirectly by controlling plant diseases, nematodes and other pests, thereby enhancing plant health and minimizing the yield loss. Vermicompost may be used to promote sustainable agriculture due to its distinctive biochemical, biological and physiochemical properties and also used for the safe management of agricultural, domestic, industrial and hospital wastes which may otherwise pose serious threat to life and environment. In preparation of vermicompost, organic waste products are being oxidized via the mutual activity of useful microbes and earthworm. Vermicompost is rich source of all macro and micro nutrients, i.e., Nitrogen (N), Phosphorous (P), Potassium (K), Iron (Fe), Zinc (Zn), Copper (Cu), manganese (Mg), growth promoters and regulators hormones like Auxin, gibberellin, enzymes i.e., protease, lipase, chitinase, beneficial bacteria and fungi. Almost 3,000 species of earthworms are identified for vermicomposting, in which Eisenia fetida, Eisenia Andrei, Eudrilus eugeniae and Perionyn excavates are most suitable for vermicompost preparation. This review focuses on relevant research performed and success in using vermicomposts during the last decade that can help us improve sustainable crop production and municipals and household waste disposal.