Development of a biofilm-forming bacterial consortium and quorum sensing molecules for the degradation of lignin-containing organic pollutants.

The presence of lignin along with other pollutants makes effluent more complex when it is discharged from Pulp and paper mills. The present study investigates the use of biofilm-forming bacteria isolated from pulp paper mill effluent contaminated sites (PPMECSs) for lignin degradation. Isolated biofilm-forming and lignin-degrading bacteria were identified as Bacillus subtilis, Enterobacter cancerogenus, and Bacillus licheniformis by 16S rRNA gene sequencing. Thin liquid chromatography (TLC) analysis showed that the consortium of bacteria produced acyl-homoserine lactone (AHL) as quorum sensing molecules and extracellular polymeric substances (EPS) that protect the bacterial consortium under unfavorable conditions. The potential consortium was able to reduce lignin (900 ppm) by 73% after 8 days of incubation in a minimal salt medium containing kraft lignin and glucose at pH 7.0 and 37 °C as compared to individual strains. The degradation by-products were identified as amides, alcohols, and acids. The major organic pollutants in the effluent were reduced after treatment of the constructed consortium, thus confirming active biotransformation and biodegradation of the lignin. Microscopic examination also indicated the presence of lignin induced biofilm formation. Hence, the constructed biofilm-forming bacterial consortia based on quorum sensing offered a sustainable and effective solution to treat lignin-containing complex pollutants.

A novel technology of solarization and phytoremediation enhanced with biosurfactant for the sustainable treatment of PAH-contaminated soil.

Hydrocarbon-contaminated land has been a significant issue throughout Nigeria's Niger Delta since the discovery of crude oil in 1956. This paper proposes a novel and sustainable technique involving soil solarization, phytoremediation and biosurfactant to treat polycyclic aromatic hydrocarbon (PAH) contamination. The treatment effect on PAH reduction, plant growth, rhizosphere microorganisms and their enzymatic activities was evaluated. Twenty-eight days of solarization was carried out before the introduction of Chromolaena odorata seedlings for an 84-day phytoremediation period using a 4 × 4 (vegetated) and 2 × 4 (non-vegetated) cell microcosms to simulate the Niger Delta's subtropical conditions. Soil solarization resulted in significant PAH reduction (p ≤ 0.01) of phenanthrene, fluoranthene and benzo(a)pyrene with means reduction of 60.0%, 38.7% and 36.1% compared to their non-solarized counterparts with 18.0%, 18.0% and 18.8% at 95% CI (32.7, 51.3), (15.4, 26.1) and (8.0, 26.6), respectively. In post-solarization, all solarized and vegetated treatment groups significantly reduced (p ≤ 0.01) PAHs compared to their respective counterparts, while biosurfactant contribution in this combination was negligible (p ≥ 0.05). The growth parameters of C. odorata, total soil/rhizosphere heterotrophic microorganisms and their enzymatic activities of dehydrogenase and urease increased in all solarized treatments indicating essential biochemical processes. The novel and successful integration of soil solarization and phytoremediation using indigenous C. odorata as a combined technique to treat even the most recalcitrant form of hydrocarbons (PAHs) brings up new opportunities for a sustainable method of cleaning up contaminated land in Nigeria's oil-rich Niger Delta.

Plant growth promoting strain Bacillus cereus (RCS-4 MZ520573.1) enhances phytoremediation potential of Cynodon dactylon L. in distillery sludge.

Elevated levels of physico-chemical pollution including organic pollutants, metals and metalloids were detected in distillery sludges despite of the anaerobic digestion treatment prior to disposal. The concentrations of the metals were (in mg kg-1): Fe (400.98 ± 3.11), Zn (17.21 ± 0.54), Mn (8.32 ± 0.42), Ni (8.00 ± 0.98), Pb (5.09 ± 0.43), Cr (4.00 ± 0.98), and Cu (3.00 ± 0.10). An invasive grass species, Cynodon dactylon L., demonstrated its ability to remediate the distillery waste sludge (DWS) in the field study. All the physico-chemical parameters of the sludge significantly improved (up to 70-75%) in the presence of Cynodon dactylon L. (p < 0.001) than the control with no plant growth. The highest phytoremediation capacity was associated with the uptake of Fe in the root and shoot. Sludge samples collected near the rhizosphere also showed lower amount of organic compounds compared to control sludge samples. Metal resistant Bacillus cereus (RCS-4 MZ520573.1) was isolated from the rhizosphere of Cynodon dactylon L. and showed potential to enhance the process of phytoremediation via plant growth promoting activities such as production of high level of ligninolytic enzymes: manganese peroxidase (35.98 U), lignin peroxidase (23.98 U) and laccase (12.78 U), indole acetic acid (45.87(mgL-1), phosphatase activity (25.76 mg L-1) and siderophore production (23.09 mg L-1). This study presents information on the performance of Cynodon dactylon L., an abundant invasive perennial grass species and its associated plant growth promoting rhizobacteria demonstrated good capacity to remediate and restore contaminated soil contained complex organic and inorganic pollutants, they could be integrated into the disposal system of distillery sludge to improve the treatment efficiency.

Regulatory and innovative mechanisms of bacterial quorum sensing-mediated pathogenicity: a review.

Quorum sensing (QS) is a system of bacteria in which cells communicate with each other; it is linked to cell density in the microbiome. The high-density colony population can provide enough small molecular signals to enable a range of cellular activities, gene expression, pathogenicity, and antibiotic resistance that cause damage to the hosts. QS is the basis of chronic illnesses in human due to microbial sporulation, expression of virulence factors, biofilm formation, secretion of enzymes, or production of membrane vesicles. The transfer of antimicrobial resistance gene (ARG) among antibiotic resistance bacteria is a major public health concern. QS-mediated biofilm is a hub for ARG horizontal gene transfer. To develop innovative approach to prevent microbial pathogenesis, it is essential to understand the role of QS especially in response to environmental stressors such as exposure to antibiotics. This review provides the latest knowledge on the relationship of QS and pathogenicity and explore the novel approach to control QS via quorum quenching (QQ) using QS inhibitors (QSIs) and QQ enzymes. The state-of-the art knowledge on the role of QS and the potential of using QQ will help to overcome the threats of rapidly emerging bacterial pathogenesis.

A critical review of household recycling barriers in the United Kingdom.

The UK recycling rate fluctuates between 45% and 47% and has consistently failed to meet the 65% target set by the post-Brexit Resource and Waste Strategy. Understanding the issues surrounding the low recycling rate in metropolitan cities in the United Kingdom will help to overcome these recycling challenges. The review examines the current situation with regard to the recycling rate and tonnage of waste produced in the United Kingdom based on available secondary waste flow data and explores different barriers related to household recycling. Many areas giving rise to the recycling challenges have been identified, including waste policy constraints, lack of effective communication, public engagement, physical barriers, service constraints, human factors and socio-economic barriers. The literature review reveals that factors such as waste policy, communication and physical factors were the most important aspects in influencing recycling rate or output. It is concluded that a multi-dimension intervention is required, which includes a thorough review of waste policy, a more stringent enforcement, an improved communication strategy and a more integrated planning development policy to mitigate issues affecting the United Kingdom's low recycling rate or output. This approach will propel the local authorities to launch or initiate effective recycling management and to put in place the required infrastructure to facilitate effective recycling activities.

Residual pollutants in treated pulp paper mill wastewater and their phytotoxicity and cytotoxicity in Allium cepa.

Discharged pulp and paper mill wastewater (PPMW) were collected near M/s K. R. pulp and papers Limited, Shahjahanpur, India. Chemical analysis of the wastewater showed high BOD (3653-4180 mg L-1) and COD (17,890-19100 mg L-1) values from two different sampling sites. The levels of total phenol were in the range of 389-432 mg L-1; nitrogen (125-234 mg L-1), sulfate (1926-2098 mg L-1), chloride (3.12-5.43 mg L-1) and lignin (38,950-39,000 mg L-1) along with various heavy metals (Fe, 87-79; Zn, 34-22; Cu, 3.28-2.57; Cd, 1.90-0.36; Ni, 6-5, and Pb, 41.23-36.54 mg L-1) were above the permissible limits recommended by the CPCB and the USEPA. The BOD/COD ratio was < 0.2 which indicated very low biodegradability of the organic matters present in the effluent. The organometallic complex generated from the pulp and paper industry persists in the environment and might be toxic to aquatic organisms. The organic polymers, lignin, metals and ions present in the PPMW were characterized using SEM, EDAX, FTIR, and UV-VIS spectroscopy. The major pollutants detected in the discharged PPMW included nonacosane, heptacosane, octadecanoic acid, hexadecane, and 6-benzamide- 3- [2- [1-(phenylmethyl)-4-piperidinyl] ethyl]-1, 2-benzisoxazole, as well as a group of plant fatty acids classified as EDCs, and mutagenic pollutants. The cytotoxic and androgenic properties of these complex organics were examined. The seed germination test with Phaseolus mungo and cytotoxicity test with Allium cepa showed that at > 20% concentration of PPMW, α-amylase production was inhibited and chromosomal segregation at metaphase and anaphase during cell division was disturbed, which resulted in c-mitosis, sticky chromosomes, and laggard chromosomes. In addition, SEM of the root of A. cepa showed fissures and fractured tissues of the root cap, probably due to the inhibition of auxins that were responsible for root cap formation. The findings indicated A. cepa as a good test model for examining the DNA damage and cytotoxicity by PPMW, and the discharged effluent should be treated at a tertiary stage for environmental protection.

Phytoremediation of Heavy Metal-Contaminated Sites: Eco-environmental Concerns, Field Studies, Sustainability Issues, and Future Prospects.

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders, and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physicochemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metal-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches; evaluates their efficacy to remove toxic metals from our natural environment; explores current scientific progresses, field experiences, and sustainability issues; and revises world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in the twenty-first century.

Exploitation of nitric oxide donors to control bacterial adhesion on ready-to-eat vegetables and dispersal of pathogenic biofilm from polypropylene.

BACKGROUND: Nitric oxide (NO) donors have been used to control biofilm formation. Nitric oxide can be delivered in situ using organic carriers and acts as a signaling molecule. Cells exposed to NO shift from biofilm to the planktonic state and are better exposed to the action of disinfectants. In this study, we investigate the capability of the NO donors molsidomine, MAHAMA NONOate, NO-aspirin and diethylamine NONOate to act as anti-adhesion agents on ready-to-eat vegetables, as well as dispersants for a number of pathogenic biofilms on plastic. RESULTS: Our results showed that 10 pM molsidomine reduced the attachment of Salmonella enterica sv Typhimurium 14 028 to pea shoots and coriander leaves of about 0.5 Log(CFU/leaf) when compared with untreated control. The association of 10 pmol L-1 molsidomine with 0.006% H2 O2 showed a synergistic effect, leading to a significant reduction in cell collection on the surface of the vegetable of about 1 Log(CFU/leaf). Similar results were obtained for MAHMA NONOate. We also showed that the association of diethylamine NONOate at 10 mmol L-1 and 10 pmol L-1 with the quaternary ammonium compound diquat bromide improved the effectiveness of biofilm dispersal by 50% when compared with the donor alone. CONCLUSIONS: Our findings reveal a dual role of NO compounds in biofilm control. Molsidomine, MAHMA NONOate, and diethylamine NONOate are good candidates for either preventing biofilm formation or dispersing biofilm, especially when used in conjunction with disinfectants. Nitric oxide compounds have the potential to be developed into a toolkit for pro-active practices for good agricultural practices (GAPs), hazard analysis and critical control points (HACCP), and cleaning-in-place (CIP) protocols in industrial settings where washing is routinely applied. © 2020 Society of Chemical Industry.

Competition of As and other Group 15 elements for surface binding sites of an extremophilic Acidomyces acidophilus isolated from a historical tin mining site.

An arsenic-resistant fungal strain, designated WKC-1, was isolated from a waste roaster pile in a historical tin mine in Cornwall, UK and successfully identified to be Acidomyces acidophilus using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS) proteomic-based biotyping approach. WKC-1 showed considerable resistance to As5+ and Sb5+ where the minimal inhibitory concentration (MIC) were 22500 and 100 mg L-1, respectively, on Czapex-Dox Agar (CDA) medium; it was substantially more resistant to As5+ than the reference strains CBS 335.97 and CCF 4251. In a modified CDA medium containing 0.02 mg L-1 phosphate, WKC-1 was able to remove 70.30% of As5+ (100 mg L-1). Sorption experiment showed that the maximum capacity of As5+ uptake was 170.82 mg g-1 dry biomass as predicted by the Langmuir model. The presence of Sb5+ reduced the As5+ uptake by nearly 40%. Based on the Fourier-transform infrared spectroscopy (FT-IR) analysis, we propose that Sb is competing with As for these sorption sites: OH, NH, CH, SO3 and PO4 on the fungal cell surface. To our knowledge, this is the first report on the impact of other Group 15 elements on the biosorption of As5+ in Acidomyces acidophilus.

The Tomato Variety Affects the Survival of Shigella flexneri 2a in Fruit Pericarp.

The presence of enteric pathogens in produce can serve as a significant means of transmitting infections to consumers. Notably, tomatoes, as a type of produce, have been implicated in outbreaks caused by various human pathogens, such as Salmonella enterica and pathogenic Escherichia coli. However, the survival characteristics of Shigella spp. in tomatoes have not been thoroughly investigated. In this study, we assess the survival of S. flexneri 2a in two distinct varieties of post-harvested tomatoes. S. flexneri 2a was used to inoculate both regular-sized Vine tomatoes and cherry-type Mini Plum tomatoes. Our findings reveal no significant difference in Shigella survival in the pericarp of both varieties on day 2 post-inoculation. However, a significant disparity emerges on day 6, where all recovered Shigella colonies exclusively belong to the Mini Plum variety, with none associated with the Vine type. When Shigella was inoculated into the locular cavity (deep inoculation), no significant difference between varieties was observed. Additionally, we investigate the potential role of the SRL pathogenicity island (SRL PAI) in the survival and fitness of S. flexneri 2a in post-harvested tomatoes. Our results indicate that while the SRL PAI is not linked to the survival of the strains in tomato, it does impact their fitness. These findings underscore the variability in Shigella strains' survival capabilities depending on the tomato variety, highlighting the importance of understanding Shigella ecology beyond the human host and identifying molecular determinants influencing bacterial survival to mitigate the risk of future outbreaks. The significance of this data on Shigella persistence in fresh vegetables should not be underestimated, as even a small number of Shigella cells can pose a threat to the health of individuals.

Molding the future: Optimization of bioleaching of rare earth elements from electronic waste by Penicillium expansum and insights into its mechanism.

The recovery of rare earth elements (REE) from electronic waste is crucial for ensuring future demand security, as there is a high supply risk for this group of elements, and mitigating the environmental impacts of conventional mining. This research focuses on extracting REE from waste printed circuit boards through bioleaching, addressing the limited attention given to this source. A strain of Penicillium expansum demonstrated efficient bioleaching under optimal conditions of 7.5 initial pH, 0.1 mM phosphate concentration, and excluding a buffering agent. The study achieved significant improvements in La and Tb extraction and enhancements in Pr, Nd, and Gd recovery, approaching 70 % within 24 h. Fungal mechanisms involved in REE extraction included fungal pH control, organic acid biosynthesis, phosphate bioavailability, and potential fungal proton pump involvement. This approach offers a promising solution for sustainable REE recovery from e-waste, contributing to resource security and circular economy.

Combining phytoremediation with bioenergy production: developing a multi-criteria decision matrix for plant species selection.

The use of plants to extract metal contaminants from soils has been proposed as a cost-effective means of remediation, and utilizing energy crops for this phytoextraction process is a useful way of attaining added value from the process. To simultaneously attain both these objectives successfully, selection of an appropriate plant species is crucial to satisfy a number of imporTant criteria including translocation index, metal and drought tolerance, fast growth rate, high lignocellulosic content, good biomass production, adequate calorific value, second generation attribute, and a good rooting system. In this study, we proposed a multi-criteria decision analysis (MCDA) to aid decision-making on plant species based on information generated from a systematic review survey. Eight species Helianthus annuus (sunflower), Brassica juncea (Indian mustard), Glycine max (soybean), Salix spp. (willow), Populus spp. (poplar), Panicum virgatum (switchgrass), Typha latifolia (cattails), and Miscanthus sinensis (silvergrass) were examined based on the amount of hits on a number of scientific search databases. The data was normalized by estimating their min-max values and their suitability. These criteria/indicators were weighted based on stipulated research objectives/priorities to form the basis of a final overall utility scoring. Using the MCDA, sunflower and silvergrass emerged as the top two candidates for both phytoremediation and bioenergy production. The multi-criteria matrix scores assist the process of making decisions because they compile plant species options quantitatively for all relevant criteria and key performance indicators (KPIs) and its weighing process helps incorporate stakeholder priorities to the selection process.

Emerging pollutants characterization, mitigation and toxicity assessment of sewage wastewater treatment plant- India: A case study.

India faces major challenges related to fresh water supply and the reuse of treated wastewater is an important strategy to combat water scarcity. Wastewater in Gorakhpur, India, is treated by a decentralised wastewater treatment system (DEWATS) and the treated wastewater is reused in the rural area. This research provides important scientific data that ascertain the safety of wastewater reuse in this region. The physicochemical characteristics, including pigment, ionic strength, BOD, COD, TDS, TSS, salinity, total N, ammonium N, phenolics, heavy metals, and sulphate, of the inlet and outlet sewage water samples (SWWs) from a wastewater treatment facility was conducted. These parameters were found to be significantly over the national limit. The inlet and outlet samples were further characterised by using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS). SEM showed microstructure and the presence of various metals, polymers, and other co-pollutants in the samples and FT-IR confirmed the presence of aldehyde, hard liquor, and nitrogen molecules in the SWW's discharge. Many endocrine disruptors and potentially mutagenic chemical substances (e.g., Dodecane, Hexadecane, Octadecane etc.) were identified in the outlet SWW by the GC-MS analysis. Toxicity of the SWW was assessed via phytotoxicity assessment using Phaseolus mungo L. and histological and biochemical analyses of Heteropneustes fossilis in a 24-h exposure study. Results confirmed the wastewater was harmful and inhibited germination of P. mungo L. by >80% compared to the control, destroyed gill laminae and significantly increased oxidative stress (above 5% increase in catalase production) in H. fossilis. This work clearly demonstrated that the quality of the treated wastewater in Gorakhpur was poor and immediate action is needed before it can be discharged or reused.

Environmental impact of e-waste management in Indian microscale informal sectors.

Inappropriate e-waste processing in the informal sector is a serious issue in developing countries. Field investigations in microscale informal recycling sites have been performed to study the impact of hazardous metal(loid)s (released from e-waste dismantling) on the environment (water and soil). Eight hazardous metal(loid)s (Pb, Cd, Cu, Zn, As, Hg, Ni, and Cr) were primarily found in the monitored water and soil samples (Sangrampur, West Bengal) because of widespread informal e-waste handling and primitive processing. Elevated concentrations of Cd, Pb, As, Cu, and Cr were observed in pond water samples (0.04, 1.62, 0.03, 1.40, 1.74 mg/L respectively). These ponds, which are regularly used for e-waste handling/dismantling, are usually flooded during the monsoon season mixing with further larger water resources - posing a serious threat to public health. Enriched levels of Pb, Cd, Cu, and Zn were detected in collected soil samples, both top surface soil (Pb up to 2042.27 ± 206.80, Cd up to 25.90 ± 9.53, Cu up to 6967.30 ± 711.70, and Zn up to 657.10 ± 67.05 mg/Kg) and deeper subsurface soil (Pb, 419.70 ± 44.70; Cd, 18.34 ± 3.81; Cu, 3928.60 ± 356.40; and Zn, 134.40 ± 33.40 mg/Kg), compared to the levels of As, Hg, Ni, and Cr. Seasonal variation of soil metal(loid) content indicated that higher levels of most of the metal(loids) were detected in the pre-monsoon (Nov-May) season, possibly due to the monsoonal dilution effect, except for Pb and Cd. The results highlighted that the composition and the handling of e-waste were important factors affecting the metal(loid) concentrations. E-waste policy and legislation have great influence on the handling and disposal procedures. An improved e-waste management practice has been proposed to encourage eco-friendly and safe e-waste disposal. It is recommended that regulatory agencies and manufacturers should create a road map to convince the informal sector to develop a systematic approach towards a more standardized formal e-waste management practices at the microscale field level.

An electrokinetic-biocementation study for clay stabilisation using carbonic anhydrase-producing bacteria.

This study investigates the feasibility of biocementing clay soil underneath a railway embankment of the UK rail network via carbonic anhydrase (CA) biocementation, implementing the treatments electrokinetically. Compared to previous biocementation studies using the ureolytic route, the CA pathway is attractive as CA-producing bacteria can sequester CO2 to produce biocement. Clay soil samples were treated electrokinetically using biostimulation and bioaugmentation conditions to induce biocementation. The effects of the treatment were assessed in terms of undrained shear strength using the cone penetration test, moisture content, and calcium carbonate content measurements. Scanning electron microscopy (SEM) analyses were also conducted on soil samples before and after treatment to evaluate the reaction products. The results showed that upon biostimulation, the undrained shear strength of the soil increased uniformly throughout the soil, from 17.6 kPa (in the natural untreated state) to 106.6 kPa. SEM micrographs also showed a clear change in the soil structure upon biostimulation. Unlike biostimulation, bioaugmentation did not have the same performance, although a high amount of CaCO3 precipitates was detected, and bacteria were observed to have entered the soil. The prospects are exciting, as it was shown that it is possible to achieve a considerable strength increase by the biostimulation of native bacteria capturing CO2 while improving the soil strength, thus having the potential to contribute both to the resilience of existing railway infrastructure and to climate change mitigation.

The association of food ingredients in breakfast cereal products and fumonisins production: risks identification and predictions.

Breakfast processed products are remarkably at risk of fungal contamination. This research surveyed the fumonisins concentration in different breakfast products and carried out in vitro experiments measuring fumonisins content in different substrates inoculated with Fusarium verticillioides. The pipeline started with the identification of combinations of ingredients for 58 breakfast products. Twenty-three core ingredients, seven nutritional components and production types were analyzed using a Pearson correlation, k-means clustering, and principal component analysis to show that no single factor is responsible for high fumonisins detection in processed cereals products. Consequently, decision tree regression was used as a means of determining and visualizing complex logical interactions between the same factors. We clustered the association of ingredients in low, medium, and high risk of fumonisin detection. The analysis showed that high fumonisins concentration is associated with those products that have high maize concentrations coupled especially with high sodium or rice. In an in vitro experiment, different media were prepared by mixing the ingredients in the proportion found in the first survey and by measuring fumonisins production by Fusarium verticillioides. Results showed that (1) fumonisins production by F. verticillioides is boosted by the synergistic effect of maize and highly ready carbohydrate content such as white flour; (2) a combination of maize > 26% (w/w), rice > 2.5% (w/w), and NaCl > 2.2% (w/w) led to high fumonisins production, while mono-ingredient products were more protective against fumonisins production. The observations in the in vitro experiments appeared to align with the decision tree model that an increase in ingredient complexity can lead to fumonisins production by Fusarium. However, more research is urgently needed to develop the area of predictive mycology based on the association of processing, ingredients, fungal development, and mycotoxins production.

Microbial fuel cell: A green eco-friendly agent for tannery wastewater treatment and simultaneous bioelectricity/power generation.

This review paper emphasised on the origin of hexavalent chromium toxicity in tannery wastewater and its remediation using novel Microbial Fuel Cell (MFC) technology, including electroactive bacteria, which are known as exoelectrogens, to simultaneously treat wastewater and its action in the production of bioenergy and the mechanism of Cr6+ reduction. Also, there are various parameters like electrode, pH, mode of operation, time of operation, and type of exchange membrane used for promising results shown in enhancing MFC production and remediation of Cr6+. Destructive anthropological activities, such as leather making and electroplating industries are key sources of hexavalent chromium contamination in aquatic repositories. When Cr6+ enters the food chain and enters the human body, it has the potential to cause cancer. MFC is a green innovation that generates energy economically through the reduction of toxic Cr6+ to less toxic Cr3+. The organic substrates utilized at the anode of MFC act as electrons (e-) donors. This review also highlighted the utilization of cheap substrates to make MFCs more economically suitable and the energy production at minimum cost.

The Bacterial Urban Resistome: Recent Advances.

Cities that are densely populated are reservoirs of antibiotic resistant genes (ARGs). The overall presence of all resistance genes in a specific environment is defined as a resistome. Spatial proximity of surfaces and different hygienic conditions leads to the transfer of antibiotic resistant bacteria (ARB) within urban environments. Built environments, public transportation, green spaces, and citizens' behaviors all support persistence and transfer of antimicrobial resistances (AMR). Various unique aspects of urban settings that promote spread and resilience of ARGs/ARB are discussed: (i) the role of hospitals and recreational parks as reservoirs; (ii) private and public transportation as carriers of ARGs/ARB; (iii) the role of built environments as a hub for horizontal gene transfer even though they support lower microbial biodiversity than outdoor environments; (iv) the need to employ ecological and evolutionary concepts, such as modeling the fate of a specific ARG/ARB, to gain enhanced health risk assessments. Our understanding and our ability to control the rise of AMR in an urban setting is linked to our knowledge of the network connecting urban reservoirs and the environment.

Microbial community dynamics and their relationships with organic and metal pollutants of sugarcane molasses-based distillery wastewater sludge.

Distillery sludge is a major source of aquatic pollution, but little is known about their microbial community and their association with the organic and metal pollutants. Sugarcane molasses-based distillery is an important industry in India, although the waste is usually treated prior to disposal, the treatment is often inadequate. The adverse effects of the organic and metal pollutants in sugarcane molasses-based distillery sludge on the microbial biodiversity and abundance in the disposal site have not been elucidated. This study aims to address this gap of knowledge. Samples were collected from the discharge point, 1 and 2 km downstream (D1, D2, and D3, respectively) of a sugarcane distillery in Uttar Pradesh, India, and their physico-chemical properties characterised. Using QIIME, taxonomic assignment for the V3 and V4 hypervariable regions of 16 S rRNA was performed. The phyla Proteobacteria (28-39%), Firmicutes (20-28%), Bacteriodetes (9-10%), Actinobacteria (5-10%), Tenericutes (1-9%) and Patescibacteria (2%) were the predominant bacteria in all three sites. Euryechaeota, were detected in sites D1 and D2 (1-2%) but absent in D3. Spirochaetes (5%), Sinergistetes (2%) and Cloacimonetes (1%) were only detected in samples from site D1. Shannon, Simpson, Chao1, and Observed-species indices indicated that site D1 (10.18, 0.0013, 36706.55 and 45653.84, respectively) has higher bacterial diversity and richness than D2 (6.66, 0.0001, 25987.71 and 49655.89, respectively) and D3 (8.31, 0.002, 30345.53 and 30654.88, respectively), suggesting the organic and metal pollutants provided the stressors to favour the survival of microbial community that can biodegrade and detoxify them in the distillery sludge. This study confirmed that the treatment of the distillery waste was not sufficiently effective and provided new metagenomic information on its impact on the surrounding microbial community. It also offered new insights into potential bioremediation candidates.

Characterization of persistent organic pollutants and culturable and non-culturable bacterial communities in pulp and paper sludge after secondary treatment.

Due to the presence of various organic contaminants, improper disposal of pulp-paper wastewater poses harm to the environment and human health. In this work, pulp-paper sludge (PPS) after secondary treatment were collected from M/s Century Pulp-paper Mills in India, the chemical nature of the organic pollutants was determined after solvent extraction. All the isolates were able to produce lipase (6.34-3.93 U ml-1) which could account for the different fatty acids detected in the PPS. The dominant strains were in the classes of α and γ Proteobacteria followed by Firmicutes. The Shannon-Weiner diversity indexes for phylotype richness for the culturable and non-culturable bacterial community were 2.01 and 3.01, respectively, indicating the non-culturable bacterial strains has higher species richness and diversity compared to the culturable bacterial strains. However, the culturable strains had higher species evenness (0.94 vs 0.90). Results suggested only a few isolated strains were resistant to the POPs in the PPS, where as non-cultural bacteria survived by entering viable but non-cultural state. The isolated strains (Brevundimonas diminuta, Aeromonas punctata, Enterobacter hormaechei, Citrobacter braakii, Bacillus pumilus and Brevundimonas terrae) are known for their multidrug resistance but their tolerance to POPs have not previously been reported and deserved further investigation. The findings of this research established the presence of POPs which influence the microbial population. Tertiary treatment is recommended prior to the safe disposal of pulp paper mill waste into the environment.