Constructed wetlands for the removal of organic micropollutants from wastewater: Current status, progress, and challenges.

In this work, the practical utility of constructed wetlands (CWs) is described as a promising treatment option for micropollutants (MPs) in wastewater with the aid of their eco-friendly, low-energy, economically feasible, and ecologically sustainable nature. This paper offers a comprehensive review on CW technology with respect to the key strategies for MP removal such as phytoremediation, substrate adsorption, and microbial degradation. It explores the important factors controlling the performance of CWs (e.g., in terms of configurations, substrates, plant-microbe interactions, temperature, pH, oxygen levels, hydraulic loading rate, and retention time) along with the discussions on the pivotal role of microbial populations in CWs and plant-microbe cooperative remediation dynamics, particularly in relation to diverse organic MP patterns in CWs. As such, this review aims to provide valuable insights into the key strategies for optimizing MP treatment and for enhancing the efficacy of CW systems. In addition, the process-based models of constructed wetlands along with the numerical simulations based on the artificial neural network (ANN) method are also described in association with the data exploratory techniques. This work is thus expected to help open up new possibilities for the application of plant-microbe cooperative remediation approaches against diverse patterns of organic MPs present in CWs.

A holistic approach for process intensification of nicotinamide mononucleotide production via high cell density cultivation under exponential feeding strategy.

Nicotinamide mononucleotide (NMN) subsists in all living organisms and has drawn tremendous attention as a nutraceutical and pharmaceutical product for several diseases such as Alzheimer's, cancer, aging, and vascular dysfunction. Here, NMN was produced intracellularly in a high cell density bioreactor using an engineered Escherichiacoli strain via exponential feeding of co-substrates. Fed-batch culture via exponential feeding of co-substrate (glucose) and continuous feeding of substrate (nicotinamide) were performed using different cumulative nicotinamide concentrations. The highest concentration of 19.3 g/L NMN with a dry cell weight of 117 g/L was acquired from a cumulative nicotinamide concentration of 7.2 g/L with a conversion of 98 % from nicotinamide in 28 h. Further, liquid chromatography-mass spectrometry analysis validated the NMN production. This approach will be beneficial in achieving simultaneously low cost and ensuring high quality and quantity of NMN production.

Valorization of organic wastes using bioreactors for polyhydroxyalkanoate production: Recent advancement, sustainable approaches, challenges, and future perspectives.

Microbial polyhydroxyalkanoates (PHA) are encouraging biodegradable polymers, which may ease the environmental problems caused by petroleum-derived plastics. However, there is a growing waste removal problem and the high price of pure feedstocks for PHA biosynthesis. This has directed to the forthcoming requirement to upgrade waste streams from various industries as feedstocks for PHA production. This review covers the state-of-the-art progress in utilizing low-cost carbon substrates, effective upstream and downstream processes, and waste stream recycling to sustain entire process circularity. This review also enlightens the use of various batch, fed-batch, continuous, and semi-continuous bioreactor systems with flexible results to enhance the productivity and simultaneously cost reduction. The life-cycle and techno-economic analyses, advanced tools and strategies for microbial PHA biosynthesis, and numerous factors affecting PHA commercialization were also covered. The review includes the ongoing and upcoming strategies viz. metabolic engineering, synthetic biology, morphology engineering, and automation to expand PHA diversity, diminish production costs, and improve PHA production with an objective of "zero-waste" and "circular bioeconomy" for a sustainable future.

Green Production of Functionalized Few-Layer Graphene-Silver Nanocomposites Using Gallnut Extract for Antibacterial Application.

Recently, there has been much attention paid to functionalized few-layer graphene (FFG) owing to its many biomedical applications, such as in bioimaging, biosensors, drug delivery, tissue scaffolds, nanocarriers, etc. Hence, the preparation of FFG has now become of great interest to researchers. The present study systematically investigates the utilization of gallnut extract (GNE) during the process of high-shear exfoliation for the efficient conversion of expanded graphite to FFG. Various parameters, such as GNE concentration, graphite concentration, exfoliation time, and the rotation speed of the high-shear mixer, were initially optimized for FFG production. The prepared FFG was characterized in terms of surface functionality and morphology using Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, and scanning electron microscopy analyses. Further, the conjugation of FFG with Ag was confirmed by XRD, XPS, and energy-dispersive X-ray spectra. The Ag-FFG composite exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria through the agar well diffusion method. This study provides an efficient, economical, and eco-friendly FFG and Ag-FFG production method for biomedical applications.

Internal limiting membrane peeling in macular hole surgery.

Since the era when macular hole was considered untreatable, macular hole surgery has come a long way to being one of the most successful surgeries. Internal limiting membrane (ILM) peeling has been an essential step of macular hole surgery since the establishment of the role of ILM in the aetiopathogenesis and progression of macular hole. However, the novel technique was not all virtuous. It had some vices which were not evident immediately. With the advent of spectral domain optical coherence tomography, short- and long-term effects of ILM peeling on macular structures were known; and with microperimetry, its effect on the function of macula could be evaluated. The technique has evolved with time from total peeling to inverted flap to just temporal peeling and temporal flap in an attempt to mitigate its adverse effects and to improve its surgical outcome. ILM abrasion technique and Ocriplasmin may eliminate the need of ILM peeling in selected cases, but they have their own limitations. We here discuss the role of ILM in the pathogenesis of macular hole, the benefits and adverse effects of ILM peeling, and the various modifications of the procedure, to then explore the alternatives.

Nanomaterial-Based Therapy for Wound Healing.

Poor wound healing affects millions of people globally, resulting in increased mortality rates and associated expenses. The three major complications associated with wounds are: (i) the lack of an appropriate environment to enable the cell migration, proliferation, and angiogenesis; (ii) the microbial infection; (iii) unstable and protracted inflammation. Unfortunately, existing therapeutic methods have not solved these primary problems completely, and, thus, they have an inadequate medical accomplishment. Over the years, the integration of the remarkable properties of nanomaterials into wound healing has produced significant results. Nanomaterials can stimulate numerous cellular and molecular processes that aid in the wound microenvironment via antimicrobial, anti-inflammatory, and angiogenic effects, possibly changing the milieu from nonhealing to healing. The present article highlights the mechanism and pathophysiology of wound healing. Further, it discusses the current findings concerning the prospects and challenges of nanomaterial usage in the management of chronic wounds.

Uncovering the phytochemicals of root exudates and extracts of lead (Pb) tolerant Chrysopogon zizanioides (L.) Roberty in response to lead contamination and their effect on the chemotactic behavior of rhizospheric bacteria.

The chemical composition of root exudates and root extracts from Chrysopogon zizanioides (L.) Roberty cv KS-1 was determined in the presence of lead [Pb(II)]. Hitherto, no information is available in the literature concerning the phytochemical components of root exudates of C. zizanioides. Significantly higher concentrations of total carbohydrates (26.75 and 42.62% in root exudates and root extract, respectively), reducing sugars (21.46 and 56.11% in root exudates and root extract, respectively), total proteins (9.22 and 23.70% in root exudates and root extract, respectively), total phenolic acids (14.69 and 8.33% in root exudates and root extract, respectively), total flavonoids (14.30 and 12.28% in root exudates and root extract, respectively), and total alkaloids (12.48 and 7.96% in root exudates and root extract, respectively) were observed in samples from plants growing under Pb(II) stress in comparison to the respective controls. GC-MS profiling showed the presence of a diverse group of compounds in root exudates and extracts, including terpenes, alkaloids, flavonoids, carotenoids, plant hormones, carboxylic/organic acids, and fatty acids. Among the detected compounds, many have an important role in plant development, regulating rhizosphere microbiota and allelopathy. Furthermore, the results indicated that C. zizanioides exudates possess a chemotactic response for rhizospheric bacterial strains Bacillus licheniformis, Bacillus subtilis, and Acinetobacter junii Pb1.

Reduction of Hexavalent Chromium [Cr(VI)] by Heavy Metal Tolerant Bacterium Alkalihalobacillus clausii CRA1 and Its Toxicity Assessment Through Flow Cytometry.

A chromate-resistant bacterial strain was isolated from tannery effluent; based on morphological, biochemical, and 16S rRNA gene sequencing, it was identified as Alkalihalobacillus clausii and designated A. clausii CRA1. It was found to be halophilic, alkaliphilic, and resistant to multiple heavy metals like Cr(VI), Cd(II), As(II), Pb(II), Ni(II), Hg(II), Cu(II), Zn(II), and Fe(II). The strain was found to reduce 72% of chromate in 6 days in Cr(VI) spiked Luria Bertani medium with unaffected bacterial growth at an initial C(VI) concentration of 50 mg L-1. Chromate reductase activity of culture supernatant (cultivated in LB broth) and cell lysate of the bacterium was found to be 23 and 43U, where 1U is µmol of Cr(VI) reduced/min/mg protein. Flow cytometry studies revealed that no significant effect of Cr(VI) on cell viability was observed till 12 h of exposure at 100, 200, 400 mg L-1 concentrations, indicated by non-significant cell death (propidium iodide positive cells). However, at 800 and 1000 mg L-1 Cr(VI) concentration, toxicity (cell death) was observed after 12 h of exposure. FACs studies also indicated that exposure to Cr(VI) increases cell size and cell granularity, which was also confirmed in SEM and TEM images of Cr(VI) treated cells. The presence of Cr(III) species in EDX spectra of Cr(VI) treated cells confirms that reduction of Cr(VI) to Cr(III) is the primary mechanism of Cr(VI) removal by the bacterium. Therefore, the bacterium A. clausii has potential for application in chromate removal from industrial waste effluents.

Evaluation of the cytotoxicity and interaction of lead with lead resistant bacterium Acinetobacter junii Pb1.

This study explores the potential of lead resistant bacterium Acinetobacter junii Pb1 for adsorption/accumulation of lead using various techniques. In the present work, growth of A. junii Pb1 was investigated in the presence of a range of Pb(II) concentrations (0, 100, 250, 500, and 1000 mg l-1). Lead was found to have no toxic effect on the growth of A. junii Pb1 at 100 and 250 mg l-1 concentrations. However, further increase in Pb(II) concentration (500 mg l-1) showed increase in lag phase, though growth remained unaffected and significant growth inhibition was observed when concentration was increased to 1000 mg l-1. Same was confirmed by the observations of flow cytometry. Further, the effect of Pb(II) on A. junii Pb1 was evaluated by using fluorescence microscopy, spectrofluorimetry, and flow cytometry. The spectrofluorimetry and fluorescence microscopy results revealed the accumulation of Pb(II) inside the bacterial cells as evident by green fluorescence due to lead binding fluorescent probe, Leadmium Green AM dye. Flow cytometry observations indicate an increase in cell size and granularity of exposure to lead. Thus, present work provides a new understanding of Pb(II) tolerance in A. junii Pb1 and its potential use in remediation of lead from contaminated soil.

Intraoperative Ocular Decompression Retinopathy During 23 Gauge Transconjunctival Vitrectomy: A Case Report.

PURPOSE: To report an uncommon case of intraoperative ocular decompression retinopathy (ODR). CASE REPORT: A 48-year-old man presented with decreased vision and pain in the left eye (LE) for 10 days following trauma with a bamboo stick. He had visual acuity of counting finger close to face in the same eye, along with corneal edema, dilated pupil and posteriorly dislocated lens. Intraocular pressure (IOP) was 42 mm of mercury (Hg). He underwent 23-gauge pars plana vitrectomy with removal of the dislocated lens. Towards the end of otherwise uneventful surgery, blot hemorrhages appeared over the posterior pole and equator. The following day, his vision was counting finger close to face and IOP was 16 mm of Hg. Fundus examination revealed large blotches of hemorrhages at different levels of the retina, later confirmed by optical coherence tomography. Disc hyperfluorescence and blocked fluorescence corresponding to blot hemorrhages were seen on fundus fluorescein angiography. Blood investigations to rule out blood dyscrasias were within normal limits. CONCLUSION: Ocular decompression retinopathy, though not common, has been reported to occur following various types of surgeries, especially if associated with preoperatively raised IOP. The event can also occur intraoperatively and the preoperative control of IOP is of paramount importance in the prevention of ODR.

A critical review on speciation, mobilization and toxicity of lead in soil-microbe-plant system and bioremediation strategies.

Lead accumulation in soils is of serious concern in agricultural production due to the harmful effects on soil microflora, crop growth and food safety. In soil, speciation of lead greatly affects its bioavailability and thus its toxicity on plants and microbes. Many plants and bacteria have evolved to develop detoxification mechanisms to counter the toxic effect of lead. Factors influencing the lead speciation include soil pH, organic matter, presence of various amendments, clay minerals and presence of organic colloids and iron oxides. Unlike, other metals little is known about the speciation and mobility of lead in soil. This review focuses on the speciation of lead in soil, its mobility, toxicity, uptake and detoxification mechanisms in plants and bacteria and bioremediation strategies for remediation of lead contaminated repositories.

A new insight to adsorption and accumulation of high lead concentration by exopolymer and whole cells of lead-resistant bacterium Acinetobacter junii L. Pb1 isolated from coal mine dump.

A lead-resistant bacterial strain was isolated from coal mine dump and identified as Acinetobacter junii Pb1 on basis of 16S rRNA (ribosomal ribonucleic acid) gene sequencing. The minimum inhibitory concentration of lead for the strain was 16,000 mg l-1 and it showed antibiotic and multi metal resistance. In aqueous culture, at an initial lead (Pb(II)) concentration of 100 and 500 mg l-1, lead adsorption and accumulation by the isolate was 100 and 60%, at pH 7 at 30 °C after 48 and 120 h, respectively. The two fractions of exopolysaccharide (EPS), loosely associated EPS (laEPS) and bound EPS (bEPS), and whole cells (devoid of EPS) showed high binding affinity towards Pb(II). The binding affinity of laEPS towards Pb(II) (1071 mg Pb g-1) was three times higher than that of bEPS (321.5 mg Pb g-1) and 6.5 times higher than that of whole cells (165 mg Pb g-1). The binding affinity of EPS and whole cells with Pb(II), reported in the current study, is considerably higher as compared to that reported in the literature, till date. SEM analysis, showed an increase in thickness of cells on exposure to Pb(II) and TEM analysis, revealed its accumulation (interior of cell) and its adsorption (with the external cell surface). The isolate was also found to be positive for indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production which helps in promoting plant growth. Thus, this study provides a new understanding towards Pb(II) uptake by A. junii Pb1, highlighting its potential on the restoration of Pb(II) contaminated repositories.