Chhabra, Meenu

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.

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, Vandana Kumari Chalka, Akanksha Mishra, Chhabra, Meenu, Rangra, Kamaljit, Dhanekar, Saakshi

Recognizing the need for a hand-held device capable of quantitatively measuring the concentration of bacteria in water, this paper describes a label-free method for rapid detection of Escherichia coli (E. coli) in water via H2O2 decomposition using screen-printed electrodes (SPE) modified with nanostructured metal oxide layers. The study encompasses sensor preparation, bacteria culture, synthesis and characterization of nanostructures, and development of a readout circuitry for lab prototyping. During sensing measurements, the bacteria are first made to interact with H2O2 and subsequently, the H2O2 solution is exposed on the sensing surface. The electrochemical sensors are fabricated by modifying the working electrode of SPE with nanostructured metal oxide layers of MnO2 and TiO2 as these play a crucial role in the detection of E. coli in water. The sensing experiments of MnO2-modified SPE show a significant response to bacteria with a sensitivity of 0.82 mV.mL/log CFU and a limit of detection (LOD) of 1.8 CFU/mL, while the TiO2-modified SPE exhibits a linear response over a wide range of bacterial concentrations with a sensitivity of 1.12 mV·mL/log CFU and a limit of detection of 2.23 CFU/mL. Both sensors demonstrate a rapid response, stability, repeatability, and a recovery time of 70 ms. Additionally, selectivity with respect to other bacteria, wastewater components such as glucose, ammonium sulfate, and sodium carbonate, and testing with RO, DI, and tap water samples are conducted to evaluate the sensors’ performance. A detailed sensing mechanism has been developed to comprehend the results, including chemical and biological reactions, metal oxide interfaces, morphology, and other surface studies of the sensing surface. A prototype comprising a sensor chip, an Arduino board, and other necessary circuit components is tested with various bacterial solutions. This enables its use for on-field rapid detection of bacteria in water using smaller volumes and a portable system.

2024, Arti Sharma, Chhabra, Meenu

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

The effect of non-equilibrium cold plasma (NECP) treatment on functional and nutritional properties of finger millet flour was investigated. Finger millet flour was treated at two different exposure times for 5 min and 10 min, and functional and nutritional properties such as Water and oil holding capacity, water binding capacity, color, and dispersibility of the control and plasma treated flour were studied. There was no significant difference in the color intensity and the whitening index (WI) with the treatment. The functional properties such as water holding capacity (WHC), oil absorption capacity (OAC), foaming and emulsifying capacity have shown significant increment with treatment time. FTIR and DSC results depicted the depolymerization of starch in the treated flour. Plasma treatment was observed to enhance the functional properties of the finger millet flour, whilst the physical properties remained unchanged. Overall plasma treatment can be explored for development of a process to enhance functionality of finger millet flour for applications in food systems. There remains plenty of scope for commercial level expansion.

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.

2022-11-01, Tiwari, Chandni, Jha, Sagar Satish, Kumar, Rohitash, Chhabra, Meenu, Malhotra, B. D., Dixit, Ambesh

The continuous real-time monitoring of glucose is essential for patients suffering from diabetes. Therefore, the low-cost and flexible glucose sensor is necessary, showing enhanced sensitivity and limit of detection. We report results of studies resulting in developing a nanostructured exfoliated graphite carbon paper (ExGCP) based efficient electrode for application to a nonenzymatic glucose sensor. This glucose sensor showed ∼ sensitivity as 5.93 µA mM−1 cm−2 with a linear response in the 2–8 mM concentration range and ∼0.812 mM as the limit of detection. The diffusion-controlled sensing reaction on ExGCP reduces electron transfer resistance with increasing glucose concentration, revealing ExGCP as an efficient and flexible electrode material for glucose sensing applications.

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.

2025-03, Jyoti Gautam, Nupur Kanwar, Arti Sharma, Chetna Nagoda, Chhabra, Meenu, Mohit Mathuria, Ronit Kanojiya, Saahil Pritam Bhavsar

Ensuring safe drinking water is fundamental to public health, which necessitates effective detection of bacterial contamination in water. To ease the bacterial monitoring in low-resource settings, this study has developed a breakthrough colorimetric paper strip dip (PSD) test for the qualitative and quantitative monitoring of bacterial contamination. The test relies on Fenton chemistry where dye-coated paper strips are immersed in a solution of water sample and hydrogen peroxide (H2O2). The bacterial catalase in contaminated water competes with the Fenton catalyst for F, resulting in a visible color change in both the strip and the sample solution. The intensity of the decolorization on the strip/solution determines the bacterial contamination in the water sample. This test has reached detection limits of 20, 40, and 35 CFU/mL for Escherichia coli, Citrobacter youngae, and Pseudomonas aeruginosa, respectively, in spiked water samples within 5 min. The PSD test offers a high sensitivity of 0.477, 0.379, and 0.601 ΔE⁎/dec for E. coli, C. youngae, and P. aeruginosa, respectively. The reliability of the test is demonstrated by its low susceptibility to interference from potential contaminants present in natural drinking water sources during bacterial detection. Furthermore, the test is integrated with a mobile app that interrelates color on the strip with bacterial contamination in water samples and recommends the extent of disinfection required based on the result. Thus, the PSD test offers an ideal solution for on-site bacterial detection, characterized by its rapidity, precision, specificity, cost-effectiveness (∼0.060 USD per test), and ease of operation. © 2025 Elsevier Ltd

2024, Akanksha Mishra, Amitap Khandelwal, Chhabra, Meenu, Piet N.L. Lens

Due to population growth and rapid economic expansions, fossil fuels are depleting, while continued use contributes to climate change. Thus focus has been shifted to search for renewable energy sources. Among other biological methods, photosynthetic microbial fuel cells (PMFCs), or algae-based fuel cells have increased more attentions in the recent years. In PMFCs, algae produce oxygen at the cathode that helps to increase electron acceptor capacity while providing their biomass as a feed for electrogens. Additionally, photons are mainly used for biofuel production at the cathode. After rigorous research on the PMFCs, recently a new direction has been more focused, where PMFCs incorporated with macroalgae can yield benefits over microalgae, particularly in the realms of waste treatment and algal biomass extraction. Therefore this chapter describes main component used in PMFCs, types of PMFCs, and recent progresses in the domain.