The impact of cow dung augmentation on soil restoration and bio-accumulation of metals (Lead and Cadmium) in Pheretima posthuma (Annelida: Clitellata)

Bioremediation of heavy metals polluted environment and decolourization of black liquor using microbial biofilms

BACKGROUND

With increased urbanization and industrialization, modern life has led to an anthropogenic impact on the biosphere. Heavy metals pollution and pollutants from black liquor (BL) have caused severe effects on environment and living organisms. Bacterial biofilm has potential to remediate heavy metals and remove BL from the environment. Hence, this study was planned to investigate the potential of microbial biofilms for the bioremediation of heavy metals and BL polluted environments.

METHODS AND RESULTS

Eleven biofilm forming bacterial strains (SB1, SB2, SC1, AF1, 5A, BC-1, BC-2, BC-3, BC-4, BC-5 and BC-6) were isolated and identified upto species level via 16S rRNA gene sequencing. Biofilm strains belonging to Bacillus and Lysinibacillus sphaericus were used to remediate heavy metals (Pb, Ni, Mn, Zn, Cu, and Co). Atomic absorption spectroscopy showed significantly high (P ≤ 0.05) bioremediation potential by L. sphaericus biofilm (1462.0 ± 0.67 µgmL^-1) against zinc (Zn). Similarly, Pseudomonas putida biofilm significantly (P ≤ 0.05) decolourized (65.1%) BL. Fourier transform infrared (FTIR) analysis of treated heavy metals showed the shifting of major peaks (1637 & 1629-1647, 1633 & 1635-1643, and 1638-1633 cm^-1) corresponding to specific amide groups due to C = O stretching.

CONCLUSION

The study suggested that biofilm of the microbial flora from tanneries and pulp paper effluents possesses a strong potential for heavy metals bioremediation and BL decolourization. To our knowledge, this is the first report showing promising biofilm remediation potential of bacterial flora of tanneries and pulp-paper effluent from Kasur and Sheikhupura, Punjab, Pakistan, against heavy metals and BL.

Diversity and Abundance of Delineated Earthworm (Annelida: Clitellata) in Pakistan: A Review

Earthworm, a ubiquitous (but neglected) macro-invertebrate, is found in terrestrial vicinity of Pakistan. Moreover, the occurrence of earthworms is often diverse with fluctuating quantity depending upon abiotic factors and land usage patterns. The aim of this study was to summarize all the reported information related to earthworm diversity in different areas of Pakistan. Almost all the data published from year 2001 to 2021 were collected. Following data organization, total 42 earthworm's species including five families (Acanthodrilidae, Lumbricidae, Moniligastridae, Octochaetidae and Megascolecidae) were reported from various researchers. Among five families, family Acanthodrilidae was found to have only one specie (Ramiella bishambari), Lumbricidae consist of 10 species (Apporactodea rosea, Allolobophora trapezoids, Allolobophora chloroticaa, Aporrectodea longa, A. caliginosa, Bimastus parvus, Eisenia fetida, Helodrilus foetidus, Lumbricus terrestris and L. rubillus), Moniligastridae has two species (Drawida nepalensis and D. pellucida) while Octochaetidae possess only one specie (Eutyphoeus incommodus). The most abundant and diverse family Megascolecidae consist of 28 earthworm species in all habitats of different regions of Pakistan. Among geographical areas, Faisalabad was found as the richest territory with most reported earthworm species (i.e. 28). The current study suggests further in depth research to explore the unidentified and/ missing species of earthworms in Pakistan.

Effects of phosphorus-containing material application on soil cadmium bioavailability: a meta-analysis

Diverse phosphorus-containing materials (PCMs) were widely applied in remediation of cadmium-contaminated soils, and their effects on the change of soil cadmium availability (SCA) varied with their physicochemical characteristics and environmental conditions. Investigation on the effect of various PCMs on reducing SCA under different conditions favors the safe utilization of Cd-contaminated soil. Herein, a meta-analysis of literature published before August 2021 was carried out. A total of 342 independent observations were obtained from 42 published papers which included 9 factors that may affect the passivation effect of fertilizer content: phosphorus type, phosphorus application rate, soil pH, soil CEC, soil organic matter, experiment type, and time. Results of boosted regression tree analysis showed that the application rate is the most important factor contributing to the SCA, followed by soil pH and duration. Results of this meta-analysis showed that medium P input shows potential for reactivating the SCA. Under alkaline soil conditions and high soil CEC values, PCM input can better deactivate SCA. In addition, the difference from the previous understanding is that under the medium input of phosphorus-containing fertilizer (90-500 mg P∙kg^-1), it will significantly increase the content of available cadmium in soil. In addition, future recommendation for exploring novel PCMs and suitable strategies for controlling the SCA though PCM application were also proposed. Our works may promote the interpretation of the interference factors on the SCA changes and fill the research gaps on utilization of PCM in Cd-polluted soil remediation.

DNA Barcoding: Molecular Identification and Phylogenetic Analysis of Pheretimoid Earthworm (Metaphire sp. and Amynthas sp.) Based on Mitochondrial Partial COI Gene from Sialkot, Pakistan

The extremely difficult and challenging process is identifying pheretimoid species, genus Metaphire and Amynthas involving increased homoplasy in various morphological characteristics. The molecular identification, phylogenetic relationships, and evolutionary divergence time of earthworms belonging to the pheretimoid complex were investigated in this study using partial mitochondrial COI (cytochrome C oxidase subunit I) gene sequences ranging from 550-680 bp. Results revealed that 86 pheretimoid earthworms were morphologically different from a total of 342 mature worms. Moreover, 11 pheretimoid species were molecularly identified, including Metaphire posthuma (02), M. anomala (01), M. houlleti (02), M. californica (01), M. birmanica (02), Amynthas minimus (01), A. morrisi (01), and M. bununa (01). A phylogenetic tree was constructed with bootstrap values of 95%, which supported a monophyletic lineage of two well-supported clades formed by 12 partial COI sequences and 48 GenBank sequences using Hirudo medicinalis as an outgroup. The monophyly of these obtained genera indicated overall similarity at species level. Today, species like Amynthas, Metaphire and Pheretima have worm diversity in the form of pheretimoid earthworms, which dates to the Late Miocene (11.2-5.3 Mya) and the Pliocene (5.3-2.4 Mya). Compared to all relevant pheretimoid species, genetic p-distance values ranged from 0.0% to 0.57% (less than 1%). These low range values demonstrated that both genera Metaphire and Amynthas, supported the theory, which states that there are shared similarities among the species, despite different morphology. The current study is the first attempt in Pakistan to identify earthworms through DNA barcoding thus providing a genomic stamp. The work explored the significance of COI gene sequences to construct molecular tools that will be useful to overcome the different obstacles in morphologically similar earthworm identification and their phylogenetic study.