Chhabra, Meenu

2024, Meraj Ahmad, Chandra Prakash, Arti Sharma, Dixit, Ambesh, Chhabra, Meenu, Plappally, Anand K

The availability of safe drinking water in non-networked rural areas and disaster-affected zones is dependent on point-of-use water filters. This study describes the design and performance assessment of a personal portable ceramic water filter named “sip-up.” Four sample variants were made using clay, exfoliated graphite (EG), and sawdust as raw materials. Samples were made using a mold to ensure uniformity and sintered at 850 °C. The experimental results showed that the sample containing the maximum amount of sawdust had the highest porosity of 36.07 ± 1.8%, providing an average flow rate of 0.61 ml/min in passive mode. The average pore size radius of all variants varied in the range of 1–10 nm, classifying the material as having a mesoporous structure. Compressive test results indicate that the addition of an organic additive (sawdust) decreases the compressive strength of filters as compared to non-organic additives. It has been observed that the addition of EG to clay does not significantly improve water filtration parameters as compared to samples containing only sawdust and clay. However, due to the smaller pore size, samples containing EG performed better in E. coli removal as compared to sawdust-containing samples. The final prototype can act as a single-use personal water filtration device that can be inserted into any commercial water bottle, making it an affordable and effective solution for hikers, travelers, and natural disasters such as floods and cyclones.

2024, Arti Sharma, Chhabra, Meenu, Shashi Kumar

The photosynthetic microbial fuel cells (PMFCs) have showcased considerable potential for sustainable bioenergy and bioproduct generation while cultivating microalgae in the cathode chamber. Nevertheless, the exploration of genetically engineered microalgae as cathodic species in PMFCs is currently limited. This study systematically compares the performance of wild type (WT) and genetically modified (GM) Chlamydomonas reinhardtii in PMFCs, focusing on bioelectricity and bioproduct generation. The study showed that β-carotene productivity in MFCs with WT and GM strains has reached 1.55 ± 0.05 and 3.88 ± 0.14 mg/g DCW, respectively. Therefore, the MFC cathode environment significantly boosted the β-carotene production (2.49-fold) in microalgae compared to flask-grown cultures. Moreover, power generation in MFCs using GM strains (0.99 ± 0.15 W/m3) was not significantly different from that of WT species (1.26 ± 0.27 W/m3). The removal of anodic chemical oxygen demand (COD) reaches up to 79 % in MFCs with GM microalgae. Therefore, the current investigation presents a proof of concept for GM microalgae-based PMFCs, which may strengthen the existing bioproduct synthesis at a global scale by enhancing microalgae growth and carotenoid production.

2024, Arti Sharma, Akanksha Mishra, Chhabra, Meenu

The present study describes the development of a potentiometric sensor for microbial monitoring in water based on catalase activity. The sensor comprises a MnO2-modified electrode that responds linearly to hydrogen peroxide (H2O2) from 0.16 M to 3.26 M. The electrode potential drops when the H2O2 solution is spiked with catalase or catalase-producing microorganisms that decompose H2O2. The sensor is responsive to different bacteria and their catalase activities. The electrochemical sensor exhibits a lower limit of detection (LOD) for Escherichia coli at 11 CFU/ml, Citrobacter youngae at 12 CFU/ml, and Pseudomonas aeruginosa at 23 CFU/ml. The sensor shows high sensitivity at 3.49, 3.02, and 4.24 mV/cm2dec for E. coli, C. youngae, and P. aeruginosa, respectively. The abiotic sensing electrode can be used multiple times without changing the response potential (up to 100 readings) with a shelf-life of over six months. The response time is a few seconds, with a total test time of 5 min. Additionally, the sensor effectively tested actual samples (drinking and grey water), which makes it a quick and reliable sensing tool. Therefore, the study offers a promising water monitoring tool with high sensitivity, stability, good detection limit, and minimum interference from other water contaminants.

2024, Vandana Kumari Chalka, Khushi Maheshwari, Chhabra, Meenu, Rangra, Kamaljit, Dhanekar, Saakshi

A sensitive and rapid electrochemical sensor has been developed to detect Escherichia coli (E. coli) bacteria that is crucial for ensuring safe drinking water. E. coli significantly contributes to waterborne contamination, driven by overexploitation and insufficient cleanliness around water bodies. This work incorporates synthesis and characterization of graphene oxide (GO), sensor preparation, and sensor testing in the presence of varying E. coli dilutions via H2O2 decomposition. GO is used as a sensing layer and drop casted on the working electrode of screen printed electrode (SPE). The sensor is exposed to different bacterial solutions using varied bacterial concentrations and fixed percent solution of H2O2. The interface of GO and bacterial solution results in a change in potential. The cross-sensitivity tests have also been performed in the presence of chemical compounds found in wastewater samples, Pseudomonas aeruginosa and Citrobacter youngae. The sensor demonstrates a detection limit of 2.8 CFU/mL, with a sensitivity of 5.1 mV-mL/CFU, fast response time and excellent repeatability when tested with E. coli. Its performance has also been assessed by comparing the sensing results for regular tap water, reverse osmosis (RO) water, and deionized water samples. This work paves the way for developing a chip-based system to detect E. coli in water.

2024, Arti Sharma, Prachi Nawkarkar, Vikas U. Kapase, Chhabra, Meenu, Shashi Kumar

Microalgal biorefineries have emerged as significant reservoirs of therapeutic compounds, including pigments and proteins. Facilitating a robust circular bioeconomy necessitates the augmentation of pigment synthesis alongside algae biofuel production. Nevertheless, inherent constraints in ketocarotenoid synthesis exist in naturally fast-growing microalgae strains, such as Chlamydomonas reinhardtii. To address this limitation, we overexpressed two pivotal enzymes in the carotenoid biosynthetic pathway, namely β-carotene hydroxylase (crt) and β-carotene ketolase (bkt), in C. reinhardtii utilizing strong promoters to amplify carotenoid production. The genetically modified (GM) microalgae were validated through PCR, Southern hybridization, and Western blot assays, confirming the presence and expression of both genes in the C. reinhardtii strains. These GM lines exhibited a substantial enhancement over wild-type (WT) algae, showcasing a remarkable 5.39-fold increase in β-carotene concentration and twofold increase in total carotenoids compared to the WT microalgae. Notably, the GM microalgae achieved astaxanthin production up to 1.47 ± 0.063 mg/g DCW, a compound absent in WT C. reinhardtii. These findings indicate the successful functionalization of Hematococcus pluvialis genes through nuclear expression in C. reinhardtii, facilitating ketocarotenoid production. This study presents a valuable strategy to boost carotenoid production in microalgae by stable overexpression of two heterologous genes within the nuclear genome of C. reinhardtii. Graphical abstract: (Figure presented.) Graphical abstract for the study carried out which represents the in silico plasmid vector designing, algae transformation by electroporation, selection on antibiotic plates, PCR amplification for GM confirmation, Southern hybridization to confirm gene integration, Western blotting to check protein expression, pigment quantification, and algae growth determination.

2024, Arti Sharma, Chhabra, Meenu

2023, Akanksha Mishra, Chhabra, Meenu

This study investigated the effect of co-culturing the photobiont and mycobiont in the microbial fuel cell (MFC) cathode on biomass production, lipid generation, and power output. Chlorella vulgaris provides oxygen and nutrients for the yeast Cystobasidium oligophagum JRC1, while the latter offers CO2 and quench oxygen for higher algal growth. The MFC with co-culture enhanced the lipid output of biomass by 28.33%, and the total yield and productivity were 1.47 ± 0.18 g/l and 0.123 g/l/day, respectively. Moreover, with co-culture, the open circuit voltage of 685 ± 11 mV was two times higher than algae alone. The specific growth rate (day−1) at the cathode was 0.367 ± 0.04 in co-culture and 0.288 ± 0.05 with C. vulgaris only. The power density of the system was 5.37 ± 0.21 mW/m2 with 75.88 ± 1.89% of COD removal. The co-culture thus proved beneficial at the MFC cathode in terms of total energy output as 11.5 ± 0.035 kWh/m3, which was 1.4-fold higher than algae alone.

2024, Ritesh Mishra, Abhijit Mishra, Sushma Jangra, Shikha Pandey, Chhabra, Meenu, Prakash, Ram

In this work, a non-equilibrium cold plasma jet (NECPJ) operated by a bi-polar pulse power source was designed and developed, and its impact on red globe grapes (Vitis vinifera) was analyzed for shelf-life enhancement. A total of 17 separate experiments were conducted using a Box-Behnken design to identify the optimum plasma process parameters, i.e., applied voltage, gas flow rate, and treatment time. Food quality parameters such as pH, total suspended solids (TSS), weight loss, total phenol and flavonoid content, vitamin C, contact angle, and firmness were studied. Field emission scanning electron microscopy (FESEM) images were also taken to see the effect of NECPJ treatment on grape surfaces and E. coli bacteria. The results showed that the linear, quadratic, and interaction effects of all three process parameters were statistically significant (p < 0.001, p < 0.01). Accordingly, the optimized plasma process parameters were identified as applied voltage 3.36 kV, gas flow rate 2.87 SLPM, and treatment time 1 min. A shelf-life study of twenty-eight days was done with and without plasma treatment. It was found that NECPJ-treated grapes had a higher shelf-life. The treated grapes contained higher levels of vitamin C, firmness, red grape color index, and total soluble solids than controls. It is inferred that NECPJ can help reduce red globe grape deterioration and maintain quality during post-harvest storage.