Biodegradation of endosulfan in broth medium and in soil microcosm by Klebsiella sp. M3

An inclusive outlook on the fate and persistence of pesticides in the environment and integrated eco-technologies for their degradation

Intensive and inefficient exploitation of pesticides through modernized agricultural practices has caused severe pesticide contamination problems to the environment and become a crucial problem over a few decades. Due to their highly toxic and persistent properties, they affect and get accumulated in non-target organisms, including microbes, algae, invertebrates, plants as well as humans, and cause severe issues. Considering pesticide problems as a significant issue, researchers have investigated several approaches to rectify the pesticide contamination problems. Several analyses have provided an extensive discussion on pesticide degradation but using specific technology for specific pesticides. However, in the middle of this time, cleaner techniques are essential for reducing pesticide contamination problems safely and environmentally friendly. As per the research findings, no single research finding provides concrete discussion on cleaner tactics for the remediation of contaminated sites. Therefore, in this review paper, we have critically discussed cleaner options for dealing with pesticide contamination problems as well as their advantages and disadvantages have also been reviewed. As evident from the literature, microbial remediation, phytoremediation, composting, and photocatalytic degradation methods are efficient and sustainable and can be used for treatment at a large scale in engineered systems and in situ. However, more study on the bio-integrated system is required which may be more effective than existing technologies.

Impact of textile dyes on health and ecosystem: a review of structure, causes, and potential solutions

The rapid growth of population and industrialization have intensified the problem of water pollution globally. To meet the challenge of industrialization, the use of synthetic dyes in the textile industry, dyeing and printing industry, tannery and paint industry, paper and pulp industry, cosmetic and food industry, dye manufacturing industry, and pharmaceutical industry has increased exponentially. Among these industries, the textile industry is prominent for the water pollution due to the hefty consumption of water and discharge of coloring materials in the effluent. The discharge of this effluent into the aquatic reservoir affects its biochemical oxygen demand (BOD), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and pH. The release of the effluents without any remedial treatment will generate a gigantic peril to the aquatic ecosystem and human health. The ecological-friendly treatment of the dye-containing wastewater to minimize the detrimental effect on human health and the environment is the need of the hour. The purpose of this review is to evaluate the catastrophic effects of textile dyes on human health and the environment. This review provides a comprehensive insight into the dyes and chemicals used in the textile industry, focusing on the typical treatment processes for their removal from industrial wastewaters, including chemical, biological, physical, and hybrid techniques.

Bioremediation of greywater using a novel bacterial-fungal consortium: optimization and validation of the operating parameters in vitro

In the present study, removal of pollutants in greywater was investigated using a novel bacterial-fungal consortium. Response surface methodology was used for the optimization of process variables like pH, temperature, inoculum size, and Carbon/Nitrogen (C/N ratio) for degradation of pollutants. Experiments were based on Box Behnken statistical design and the results show a good fit with the quadratic model, coefficient of determination (R²) value of 0.9499. The reliability of the model was established by various statistical parameters like lack of fit, pure error, and residual sum of squares. The optimized conditions for maximum reduction in chemical oxygen demand, oil & grease and sulphate were found to be 78.7%, 82.6% and 89.7%, respectively after 96 h of incubation of the reaction mixture at pH 7; temperature 35°C; inoculum size 150 µl and C/N ratio of 1:2. Our results clearly demonstrate that the developed novel bacterial-fungal consortium can be a cost-effective, safe, and environment-friendly alternative for remediation of greywater.

Bioremediation of lindane contaminated soil: Exploring the potential of actinobacterial strains

Lindane, an organochlorine pesticide, causes detrimental impacts on the environment and human health owing to its high toxicity, low degradation, and bioaccumulation. Its toxic nature can be overcome by biological and eco-friendly approaches involving its degradation and detoxification. The biodegradation of lindane was assessed using actinobacterial species Thermobifida cellulosilytica TB100 (T. cellulosilytica), Thermobifida halotolerans DSM 44931 (T. halotolerans) and Streptomyces coelicolor A3 (S. coelicolor). The degradation conditions of Lindane such as pH, temperature, inoculum volume, glucose concentration and number of days were optimized under broth conditions. Lindane degradation at different concentrations was studied in soil using reverse phase-high performance liquid chromatography over a 30 day period. A bioassay test was performed on seeds of Lactuca sativa (Lettuce) to assess the success of bioremediated soil. Maximum lindane degradation in soil was observed using T. cellulosilytica sp. The degradation trend for different concentrations of lindane using T. halotolerans in sterilized soil was 55 mg kg^-1 (82%) ˃ 155 mg kg^-1 (75%) ˃ 255 mg kg^-1 (70%) after an incubation period of 30 days. Lindane degradation in soil followed the first order reaction kinetics. Phytotoxicity test on seeds of Lactuca sativa showed considerably good vigor index values for the bioremediated sterilized and non-sterilized soil by T. cellulosilytica, T. halotolerans and S. coelicolor in comparison to the contaminated soil without bacteria. This confirms that these actinobacterial species can be implemented in bioaugmentation of contaminated sites to efficiently remediate high lindane concentrations.

Individual and cellular responses of earthworms (Eisenia fetida) to endosulfan at environmentally related concentrations

The presence of endosulfan at high levels in soils poses a potential risk for terrestrial ecosystems and human health via the food chain. Therefore, the effects of endosulfan at environmentally related doses on the terrestrial biota are of great concern. The present study measured the mortality, growth inhibition and ultrastructure of the stomach and skin of earthworms exposed to endosulfan at environmentally related concentrations to identify the individual and cellular effects of endosulfan on terrestrial biota. The results demonstrated that the growth inhibition of earthworms was significantly and positively correlated with the endosulfan dose and little mortality was found. The nuclei, microvilli and cuticles in the stomachs and skin cells of earthworms exhibited marked abnormalities. Endosulfan injured the ultrastructure of the nucleus even at low doses (0.5 mg·kg^-1). Endosulfan seriously affected stomach microvilli and the cuticle structure of the skin, and this damage increased with increased exposure time and dose. Notably, cuticle damage was worse than the microvilli damage. These experiments demonstrated that the morphological changes in the tissue ultrastructure of the earthworm were more sensitive than growth inhibition, and these changes may be used as an early warning indicator of endosulfan pollution. The degree of damage to microvilli and cuticle is a promising bio-indicator to evaluate pesticide risk. The results of this study provide evidence of endosulfan toxicity and the importance of risk assessment on the terrestrial ecosystem.

Influence of plant growth promoting rhizobacterial strains Paenibacillus sp. IITISM08, Bacillus sp. PRB77 and Bacillus sp. PRB101 using Helianthus annuus on degradation of endosulfan from contaminated soil

Endosulfan is a broad spectrum insecticide used in agriculture for protection of various food and non-food crops. It is persistent in nature and hence found in soil, air and water. The potential use of plants and microorganisms for the removal of endosulfan from soil was studied. Helianthus annuus plant was grown in soil spiked with 5, 10, 25 and 50 mg kg^-1 concentrations of endosulfan and inoculated with plant growth promoting rhizobacterial strains Paenibacillus sp. IITISM08, Bacillus sp. PRB77 and Bacillus sp. PRB101 for 40, 80 and 120 days. Potential of plant for endosulfan uptake was evaluated by investigating the endosulfan levels in plant tissues (root and shoot). The results indicated that endosulfan accumulation followed the pattern of root > shoot as well as decrease in uptake of endosulfan in root and shoot of a plant grown in bacterial inoculated soil as compared to un-inoculated soil. Bacterial inoculation had a positive effect on endosulfan degradation. Maximum degradation of 92% at 5 mg kg^-1 of endosulfan in soil was observed on inoculation with PRB101 after 120 days of inoculation. The results showed that plant growth promoting bacteria enhances plant biomass production. Lipid peroxidation was also estimated by determining the malondialdehyde (MDA) production, which is a biomarker of oxidative damage. Decrease in MDA formation by root and leaves of plants grown in the bacteria inoculated plant was also observed. The results suggested the effectiveness of plant growth promoting rhizobacteria to boost accumulation potential, biomass production and enhance remediation of endosulfan contaminated soil.

Effect of endosulfan tolerant bacterial isolates (Delftia lacustris IITISM30 and Klebsiella aerogenes IITISM42) with Helianthus annuus on remediation of endosulfan from contaminated soil

Endosulfan contaminated soil has become an important risk to the environment and human health worldwide. In the present study, endosulfan tolerant bacterial strain Delftia lacustris IITISM30 and Klebsiella aerogenes IITISM42 were isolated from pesticide stressed agricultural soil and tested for plant growth promoting activities. A pot experiment was performed using Helianthus annuus, grown in soil supplemented with endosulfan and inoculated with pure and consortium of bacterial strain IITISM30 and IITISM42. Inoculation increased plant biomass production and endosulfan degradation, maximum degradation (90% at 5 mg kg^-1 of soil) was observed by inoculation with a consortium of bacterial strain IITISM30 and IITISM42. Moreover, there was significantly less endosulfan accumulation was observed in roots and shoots of bacterial inoculated plants as compared to uninoculated plants. Decrease in production of malonialdehyde (MDA) was noticed on inoculation of a bacterial strain. The study demonstrated that inoculation of a consortium of endosulfan tolerant plant growth promoting bacterial isolates could more effectively remediate endosulfan contaminated soils and decrease endosulfan residues in plants, than individual strains. Moreover, it revealed that combined use of H. annuus and endosulfan tolerant bacterial isolates IITISM30 and IITISM42 has great potential for remediating endosulfan contaminated soil.

Endosulfan Degradation by Selected Strains of Plant Growth Promoting Rhizobacteria

Sixty endosulfan tolerant bacterial strains were isolated from pesticide stressed agricultural soils. Five most tolerant strains were tested for plant growth promoting (PGP) activities and endosulfan degradation under different optimizing conditions in broth and soil. The strains PRB101 and PRB77 were the most efficient in terms of endosulfan degradation and PGP activities and showed solubilization indexes of 3.3 and 3.1 mm, indole acetic acid production of 71 and 68 μg mL^-1, siderophore zones of 13 mm each at the recommended dosage, respectively. Hydrogen cyanide and ammonia production remained unaffected in the presence of endosulfan. PRB101 and PRB77 strains were able to degrade 74% and 70% of endosulfan in broth and 67% and 63% in soil, respectively. Based on 16S rDNA analysis, the strains PRB101 and PRB77 exhibited 99% homology with Bacillus sp. KF984414 and Bacillus sp. LN849696, respectively.

Microbial degradation of endosulfan in contaminated soil with the elution of surfactants

In this work, an endosulfan-degrading strain was isolated from the aged soil contaminated by endosulfan, and identified as Ochrobactrum sp. EB-4 by 16S rDNA sequence analysis. The microbial degradation characteristics of endosulfan in three eluents (Tween 80 + SDS, Tween 80 + Na2SiO3, Tween 80 + SDS + Na2SiO3) were investigated. The results showed that the degradation percents of α-, β-endosulfan in the three eluents were 86.83 %∼92.91 % and 88.90 %∼93.94 % in 15 days, respectively. The degradation process can be well described by the first-order kinetic model, and the half-times of α-endosulfan in eluent 1∼eluent 3 were 3.83, 5.29, and 4.53 days, while those of β-endosulfan were 3.35, 4.50 and 3.79 days, respectively. The endosulfan diol and endosulfan sulfate as main metabolites were detected, and the former can be further degraded by this strain, which revealed that the simultaneously happened hydrolysis and oxidation reactions were the main degradation processes, and dominated by hydrolysis reaction. After 5 days of washing with the eluents, 56.00∼84.33 % of α-endosulfan, and 46.49∼68.56 % of β-endosulfan in soil were eluted, respectively, and can be entirely biodegraded in 12 days, which indicated that the microbial degradation was the rate-determining step.

Residues of endosulfan in surface and subsurface agricultural soil and its bioremediation

The persistence of many hydrophobic pesticides has been reported by various workers in various soil environments and its bioremediation is a major concern due to less bioavailability. In the present study, the pesticide residues in the surface and subsurface soil in an area of intense agricultural activity in Pakkam Village of Thiruvallur District, Tamilnadu, India, and its bioremediation using a novel bacterial consortium was investigated. Surface (0-15 cm) and subsurface soils (15-30 cm and 30-40 cm) were sampled, and pesticides in different layers of the soil were analyzed. Alpha endosulfan and beta endosulfan concentrations ranged from 1.42 to 3.4 mg/g and 1.28-3.1 mg/g in the surface soil, 0.6-1.4 mg/g and 0.3-0.6 mg/g in the subsurface soil (15-30 cm), and 0.9-1.5 mg/g and 0.34-1.3 mg/g in the subsurface soil (30-40 cm) respectively. Residues of other persistent pesticides were also detected in minor concentrations. These soil layers were subjected to bioremediation using a novel bacterial consortium under a simulated soil profile condition in a soil reactor. The complete removal of alpha and beta endosulfan was observed over 25 days. Residues of endosulfate were also detected during bioremediation, which was subsequently degraded on the 30th day. This study revealed the existence of endosulfan in the surface and subsurface soils and also proved that the removal of such a ubiquitous pesticide in the surface and subsurface environment can be achieved in the field by bioaugumenting a biosurfactant-producing bacterial consortium that degrades pesticides.

Novel fungal consortium for bioremediation of metals and dyes from mixed waste stream

The present study is targeted towards development of a three member fungal consortium for effective removal of metals [Cr(6+) and Cu(2+)] and dyes [AB and PO] from mixed waste streams. Initial studies using individual fungal strain showed that Aspergillus lentulus was best for Cu(2+) and AB removal, Aspergillus terreus for Cr(6+) removal whereas, Rhizopus oryzae was best for PO removal. Based on the complementary pollutant affinities and positive interactions, a consortium comprising all three strains was developed. Consortium removed 100% Cr(6+) and 81.60% Cu(2+) from metal mixture which was significantly higher than that achieved individually by A. lentulus (Cr(6+): 83.11%; Cu(2+): 67.32%), A. terreus (Cr(6+): 95.57%; Cu(2+): 65.77%) or R. oryzae (Cr(6+): 25.34%; Cu(2+): 30.20%). Further, 98.0% AB and 100.0% PO was removed after 48 h by the consortia. Unlike individual strains, consortium's performance was unaltered irrespective of the complexity of metal-dye mixtures, thereby establishing its superiority.