randhir bharti - Academia.edu (original) (raw)

Papers by randhir bharti

Science of the total environment, Mar 1, 2024

Clean Energy Production Technologies, 2022

A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole... more A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was identified as Serratia sp. ISTD04 by 16S rRNA sequencing. The bacterium was tested for product formation in form of calcite crystals in presence of 5% CO 2 . Carbon dioxide sequestering capacity of bacterium was detected by 14 C labeling and purification of carbonic anhydrase enzyme and RuBisCO. 14 C labeling analysis revealed that the rate of assimilation of CO 2 by the strain is 0.756 x 10 -9 μmol CO 2 fixed cell -1 h -1 . Whole cell soluble proteins of Serratia sp. grown under autotrophic and heterotrophic conditions were resolved by two-dimensional gel electrophoresis and MALDI-TOF/MS for differential expression of proteins. In proteomic analysis of 63 protein spots, 48 spots were significantly up-regulated in the autotrophically grown cells; seven enzymes showed its utilization in autotrophic carbon fixation pathways and other metabolic activities of bacterium including lipid metabolisms indicated sequestration potency of carbon dioxide and production of biomaterials. The bacterium produced 0.647 mg mg -1 per unit cell dry weight of lipids. After transesterification of lipids, the total saturated and unsaturated FAME was found to be 51% and 49% respectively. The major FAME contained in the biodiesel was C16:0, C18:1 and C19:1.

International Journal of Green Energy, Dec 20, 2017

Generation of biodiesel from microalgae has been extensively investigated; however, its quality i... more Generation of biodiesel from microalgae has been extensively investigated; however, its quality is often not suitable for use as fuel. Our investigation involved the evaluation of biodiesel quality using a native isolate Chlorella sorokiniana MIC-G5, as specified by American Society for Testing and Materials (ASTM), after transesterification of lipids with methanol, in the presence of sodium methoxide. Total lipids extracted from dry biomass, of approximately 410 to 450 mg g-1 , was characterized using FTIR and 1 H NMR. After transesterification, the total saturated and unsaturated FAMEs were 43% and 57% respectively. The major FAMEs present in the biodiesel were methyl palmitate (C16:0), methyl oleate (C18:1) and methyl linoleate (C18:2), and the 1 H NMR spectra matched with criteria prescribed for high quality biodiesel. The biodiesel exhibited a density of 0.873 g/cc, viscosity of 3.418 mm 2 /s, CN of 57.85, HHV of 40.25, iodine value of 71.823 g I 2 100 g −1 , DU of 58% and a CFPP of-5.22 • C. Critical fuel parameters, including oxidation stability, cetane number, high heating value, iodine value, flash point, cloud point, pour point, density and viscosity were in accordance with the methyl ester composition and A c c e p t e d M a n u s c r i p t 2 structural configuration. Hence, Chlorella sorokiniana can be a promising feedstock for biodiesel generation.

Biomass, Biofuels, Biochemicals, 2022

Bioresource Technology, Feb 1, 2014

A chemolithotrophic bacterium, Serratia sp. ISTD04, enriched in the chemostat in presence of sodi... more A chemolithotrophic bacterium, Serratia sp. ISTD04, enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was evaluated for potential of carbon dioxide (CO2) sequestration and biofuel production. CO2 sequestration efficiency of the bacterium was determined by enzymatic activity of carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Further, Western blot analysis confirmed presence of RuBisCO. The bacterium produced 0.487 and 0.647mgmg(-1) per unit cell dry weight of hydrocarbons and lipids respectively. The hydrocarbons were within the range of C13-C24 making it equivalent to light oil. GC-MS analysis of lipids produced by the bacterium indicated presence of C15-C20 organic compounds that made it potential source of biodiesel after transesterification. GC-MS, FTIR and NMR spectroscopic characterization of the fatty acid methyl esters revealed the presence of 55% and 45% of unsaturated and saturated organic compounds respectively, thus making it a balanced biodiesel composition.

Colloids and Surfaces B: Biointerfaces, 2011

Bio-directed synthesis of metal nanoparticles is gaining importance due to their biocompatibility... more Bio-directed synthesis of metal nanoparticles is gaining importance due to their biocompatibility, low toxicity and eco-friendly nature. We used culture supernatant of Pseudomonas aeruginosa strain BS-161R for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Pseudomonas aeruginosa culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, EDAX, FT-IR and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 430 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were mono-dispersed and spherical in shape with an average particle size of 13 nm. The EDAX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FT-IR analysis revealed that the protein component in the form of enzyme nitrate reductase and the rhamnolipids produced by the isolate in the culture supernatant may be responsible for reduction and as a capping material. The XRD spectrum showed the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against gram-positive, gram-negative and different Candida species at concentrations ranging between 4 and 32 μg ml(-1).

Clean Energy Production Technologies, 2022

An Innovative Role of Biofiltration in Wastewater Treatment Plants (WWTPs), 2022

New Trends in Removal of Heavy Metals from Industrial Wastewater, 2021

Abstract Increased industrial activities have contributed majorly toward the generation of wastew... more Abstract Increased industrial activities have contributed majorly toward the generation of wastewater comprising hazardous heavy metals. These are invariably released into the water bodies like rivers and streams. Microorganisms such as bacteria and algae play pivotal role in remediating these heavy metals through their inherent mechanisms of bioaccumulation and biosorption. Although laboratory studies have described the remediation of heavy metals via bacteria and algae in small setups. But remediation of heavy metals in actual wastewater is difficult because of its complex nature (multiple organic and inorganic contaminants are present simultaneously) and hence the heavy metal removal efficiency of bacteria and algae decreases drastically. This chapter mainly focused on the studies describing metal removal efficacies of bacteria and algae in synthetic and actual wastewaters. In addition to this, studies highlighting various bioreactor systems, their configuration, and their optimization for improved remediation have also been included. Moreover, it was also realized that further research is important to understand the insights of process mechanisms, selection of best microbial strains, and development of suitable bioreactors for efficient removal of heavy metals.

Effluents from different industries are rampantly being discharged into the natural water bodies.... more Effluents from different industries are rampantly being discharged into the natural water bodies. Thus it is pertinent to treat this wastewater pollution from different sources before discharging it to the environment. The most extensively used biological process for the treatment of wastewater plant is the activated sludge process. The activated sludge process has shown high nutrient removal, biomass retention capacities, and removal of toxins, due to which activated sludge processes are a lucrative option for treating the wastewater. The diverse microbial communities comprising bacteria, fungi, protozoa, viruses, algae, and metazoa account for 95% of the microbes and play a chief role in the wastewater treatment. Many high-throughput techniques, such as metagenomics, metatranscriptomics, and metaproteomics, are utilized to decipher the functional aspects of these microbial communities.

Fungus is a lucrative option and has received much attention in biofuel production of bioethanol,... more Fungus is a lucrative option and has received much attention in biofuel production of bioethanol, biodiesel and biogas. Bioethanol is obtained when lignocellulosic biomass (agriculture waste) is saccharified into a mixture of sugars by fungal assisted enzymatic pretreatment. Further, several oleaginous fungi such as Zygomycetes species are valuable feedstock for biodiesel production, as they are rich in oleic and palmitic acid. Apart from this, anaerobic fungus possesses an arsenal of extracellular multienzyme complexes that improve the digestion of various biomass for biogas production. One of the latest developments in the biofuel sector has been the fungal based microbial fuel cell technology that has the combined advantage of wastewater treatment and electricity generation. Thus, this review is a compilation of all the biofuels that can be obtained from fungus from waste materials and wastewater.

In the last few decades, there has been a surge in the hazardous chemicals contamination in the w... more In the last few decades, there has been a surge in the hazardous chemicals contamination in the water bodies in various parts of India. Consequently, bioremediation of these hazardous chemicals by microorganisms has emerged as a lucrative option. Furthermore, advancement in the various physicochemical and robust molecular techniques such as 1D-SDS-PAGE followed by LC-MS/ MS analysis as well as metabolite identification by 1 H-NMR has shed light on the various cellular strategies adopted by a microorganism for remediation of a cocktail of metals and pesticide that were either poorly highlighted or unexplained. With this background the present chapter aims to understand the complete process of a metal or cocktail of multimetal and pesticide mixture remediation by

A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole... more A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was identified as Serratia sp. ISTD04 by 16S rRNA sequencing. The bacterium was tested for product formation in form of calcite crystals in presence of 5% CO 2 . Carbon dioxide sequestering capacity of bacterium was detected by 14 C labeling and purification of carbonic anhydrase enzyme and RuBisCO. 14 C labeling analysis revealed that the rate of assimilation of CO 2 by the strain is 0.756 x 10 -9 μmol CO 2 fixed cell -1 h -1 . Whole cell soluble proteins of Serratia sp. grown under autotrophic and heterotrophic conditions were resolved by two-dimensional gel electrophoresis and MALDI-TOF/MS for differential expression of proteins. In proteomic analysis of 63 protein spots, 48 spots were significantly up-regulated in the autotrophically grown cells; seven enzymes showed its utilization in autotrophic carbon fixation pathways and other metabolic activities of bacterium inc...

Chemistry in the Environment, 2021

Journal of Water Process Engineering, 2021

Abstract The explosion in urban population are increasing burdens on water and energy systems, wh... more Abstract The explosion in urban population are increasing burdens on water and energy systems, which ultimately release harmful pollutants such as wastewater and toxic gases into the natural ecosystems. In order to eliminate these pollutants, the production of vehicular quality biodiesel along with the phycoremediation of wastewater using two different Chlorella species (Chlorella minutissima and Chlorella sorokiniana) was investigated. Both the Chlorella sp., due to their stress tolerance behavior showed higher growth rate, lipid content and biomass productivity, when cultivated in wastewater than in control. Chlorella sorokiniana exhibited 19.14% higher lipids than Chlorella minutissima, when cultivated in wastewater. The fatty acid methyl esters (FAMEs)/biodiesel profiling has shown the decrease in poly unsaturated fatty acids (PUFAs) with enhancement in saturated fatty acids (SFAs) and oleic acid content. The physical properties of biodiesel derived from Chlorella sorokiniana, exceeded the existing biodiesel standards for USA and Europe e.g. the biodiesel (89.23 ± 0.21%; w/w of lipids) obtained from Chlorella sorokiniana, grown in wastewater was having lower cold filter plugging point (−6.22 °C), higher cetane number (47) and average oxidative stability (3.43 h). During the process, these Chlorella species have also removed total phosphate (TP), total nitrogen (TN), chemical oxygen demand (COD) and total organic carbon (TOC) from wastewater. The removal efficiency of TOC was found to be 95% and 98% by Chlorella minutissima and Chlorella sorokiniana respectively. Overall, Chlorella sorokiniana grown in wastewater was found to be a better candidate for the biodiesel production together with phycoremediation of wastewater.

Development in Wastewater Treatment Research and Processes, 2022

Progress in Biomaterials, 2020

The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has alr... more The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has already been applied in various fields i.e., electronics, optics, catalysis, food, health and environment. With advancement in research, it is possible to develop nanoparticles of various size, shape, morphology, and surface to volume ratio utilizing biological systems. A number of different agents and methods can be employed to develop choice based AgNPs using algae, plants, fungi and bacteria. The use of plant extracts to produce AgNPs appears to be more convenient, as the method is simple, environmental friendly and inexpensive, also requiring a single-step. The microbial synthesis of AgNps showed intracellular and extracellular mechanisms to reduce metal ions into nanoparticles. Studies have shown that different size (1-100 nm) and shapes (spherical, triangular and hexagonal etc.) of nanoparticles can be produced from various biological routes and these diverse nanoparticles have various functions and usability i.e., agriculture, medical-science, textile, cosmetics and environment protection. The present review provides an overview of various biological systems used for AgNP synthesis, its underlying mechanisms, further highlighting the current research and applications of variable shape and sized AgNPs.

Biofuels, 2019

Microalgae are considered potential feedstocks to generate biodiesel; however, the area requires ... more Microalgae are considered potential feedstocks to generate biodiesel; however, the area requires further refinement and metabolic engineering to enhance productivity along with cost reduction. Our study involved the production and quality evaluation of biodiesel from the lipids of Botryococcus sp. MCC31, after conventional and in situ transesterification. Lipids extracted fell within the range of 330 to 410 mg g À1 Dry Weight (DW) (33-41% w/w) and these were identified by 1 H Nuclear Magnetic Resonance (NMR) and 13 C NMR spectrum. After identification, the reaction conditions for indirect transesterification, in terms of catalyst type, were optimized for maximizing Fatty Acid Methyl Ester (FAME) yield. The total unsaturated and saturated fatty acids were 54% and 46%, respectively, and the results indicated higher amounts of methyl palmitate and methyl oleate, which comprised almost 65% of the total FAMEs. The biodiesel exhibited a density of 0.853 g/cc, viscosity of 3.512 mm 2 /s, Cetane Number (CN) of 57.57, Higher Heating Value (HHV) of 38.88, iodine value of 75.56 g I 2 /100 g, Degree of Unsaturation (DU) of 58% and a Cold Filter Plugging Point (CFPP) of 4.8 C. The results were in accordance with the details as specified by American Society for Testing and Materials (ASTM) and European Norms (EN) standards. The study illustrates that Botryococcus sp. MCC31 can be a valuable feedstock for generation of high-quality biodiesel.

Environmental Science and Pollution Research, 2019

The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mi... more The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mixotrophically to augment production of biodiesel. The cultivation of Chlorella sp. using CL as media was carried out by employing a fed-batch technique in open tray (open tray+CL) and in software (BioXpert V2)-attached automated photobioreactor (PBR+CL) systems. Data showed the limit of nitrogen substituent and satisfactory organic source of carbon (OSC) in CL, causing > 2-fold higher lipid content in cells, cultivated in both the systems than in control. For the cells grown in both the systems, ≥ 3-fold enhancement in lipid productivity was observed than in control. The total fatty acid methyl ester (FAME) concentrations from lipids extracted from cells grew in PBR+CL and in open tray+CL techniques were calculated as 50.59% and 38.31%, respectively. The PBR+CL system showed improved outcomes for lipid content, lipid and biomass productivity, FAME characteristics and physical property parameters of biodiesel than those obtained from the open tray+CL system. The physical property parameters of biodiesel produced from algal cells grown in PBR+CL were comparable to existing fuel standards. The results have shown lower cold filter plugging point (− 6.57°C), higher cetane number (58.04) and average oxidative stability (3.60 h). Collectively, this investigation unveils the novel deployment of CL as a cost-effective feedstock for commercialisation of biodiesel production.

Science of the total environment, Mar 1, 2024

Clean Energy Production Technologies, 2022

A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole... more A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was identified as Serratia sp. ISTD04 by 16S rRNA sequencing. The bacterium was tested for product formation in form of calcite crystals in presence of 5% CO 2 . Carbon dioxide sequestering capacity of bacterium was detected by 14 C labeling and purification of carbonic anhydrase enzyme and RuBisCO. 14 C labeling analysis revealed that the rate of assimilation of CO 2 by the strain is 0.756 x 10 -9 μmol CO 2 fixed cell -1 h -1 . Whole cell soluble proteins of Serratia sp. grown under autotrophic and heterotrophic conditions were resolved by two-dimensional gel electrophoresis and MALDI-TOF/MS for differential expression of proteins. In proteomic analysis of 63 protein spots, 48 spots were significantly up-regulated in the autotrophically grown cells; seven enzymes showed its utilization in autotrophic carbon fixation pathways and other metabolic activities of bacterium including lipid metabolisms indicated sequestration potency of carbon dioxide and production of biomaterials. The bacterium produced 0.647 mg mg -1 per unit cell dry weight of lipids. After transesterification of lipids, the total saturated and unsaturated FAME was found to be 51% and 49% respectively. The major FAME contained in the biodiesel was C16:0, C18:1 and C19:1.

International Journal of Green Energy, Dec 20, 2017

Generation of biodiesel from microalgae has been extensively investigated; however, its quality i... more Generation of biodiesel from microalgae has been extensively investigated; however, its quality is often not suitable for use as fuel. Our investigation involved the evaluation of biodiesel quality using a native isolate Chlorella sorokiniana MIC-G5, as specified by American Society for Testing and Materials (ASTM), after transesterification of lipids with methanol, in the presence of sodium methoxide. Total lipids extracted from dry biomass, of approximately 410 to 450 mg g-1 , was characterized using FTIR and 1 H NMR. After transesterification, the total saturated and unsaturated FAMEs were 43% and 57% respectively. The major FAMEs present in the biodiesel were methyl palmitate (C16:0), methyl oleate (C18:1) and methyl linoleate (C18:2), and the 1 H NMR spectra matched with criteria prescribed for high quality biodiesel. The biodiesel exhibited a density of 0.873 g/cc, viscosity of 3.418 mm 2 /s, CN of 57.85, HHV of 40.25, iodine value of 71.823 g I 2 100 g −1 , DU of 58% and a CFPP of-5.22 • C. Critical fuel parameters, including oxidation stability, cetane number, high heating value, iodine value, flash point, cloud point, pour point, density and viscosity were in accordance with the methyl ester composition and A c c e p t e d M a n u s c r i p t 2 structural configuration. Hence, Chlorella sorokiniana can be a promising feedstock for biodiesel generation.

Biomass, Biofuels, Biochemicals, 2022

Bioresource Technology, Feb 1, 2014

A chemolithotrophic bacterium, Serratia sp. ISTD04, enriched in the chemostat in presence of sodi... more A chemolithotrophic bacterium, Serratia sp. ISTD04, enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was evaluated for potential of carbon dioxide (CO2) sequestration and biofuel production. CO2 sequestration efficiency of the bacterium was determined by enzymatic activity of carbonic anhydrase and ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). Further, Western blot analysis confirmed presence of RuBisCO. The bacterium produced 0.487 and 0.647mgmg(-1) per unit cell dry weight of hydrocarbons and lipids respectively. The hydrocarbons were within the range of C13-C24 making it equivalent to light oil. GC-MS analysis of lipids produced by the bacterium indicated presence of C15-C20 organic compounds that made it potential source of biodiesel after transesterification. GC-MS, FTIR and NMR spectroscopic characterization of the fatty acid methyl esters revealed the presence of 55% and 45% of unsaturated and saturated organic compounds respectively, thus making it a balanced biodiesel composition.

Colloids and Surfaces B: Biointerfaces, 2011

Bio-directed synthesis of metal nanoparticles is gaining importance due to their biocompatibility... more Bio-directed synthesis of metal nanoparticles is gaining importance due to their biocompatibility, low toxicity and eco-friendly nature. We used culture supernatant of Pseudomonas aeruginosa strain BS-161R for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Pseudomonas aeruginosa culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, EDAX, FT-IR and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 430 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were mono-dispersed and spherical in shape with an average particle size of 13 nm. The EDAX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FT-IR analysis revealed that the protein component in the form of enzyme nitrate reductase and the rhamnolipids produced by the isolate in the culture supernatant may be responsible for reduction and as a capping material. The XRD spectrum showed the characteristic Bragg peaks of 111, 200, 220 and 311 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against gram-positive, gram-negative and different Candida species at concentrations ranging between 4 and 32 μg ml(-1).

Clean Energy Production Technologies, 2022

An Innovative Role of Biofiltration in Wastewater Treatment Plants (WWTPs), 2022

New Trends in Removal of Heavy Metals from Industrial Wastewater, 2021

Abstract Increased industrial activities have contributed majorly toward the generation of wastew... more Abstract Increased industrial activities have contributed majorly toward the generation of wastewater comprising hazardous heavy metals. These are invariably released into the water bodies like rivers and streams. Microorganisms such as bacteria and algae play pivotal role in remediating these heavy metals through their inherent mechanisms of bioaccumulation and biosorption. Although laboratory studies have described the remediation of heavy metals via bacteria and algae in small setups. But remediation of heavy metals in actual wastewater is difficult because of its complex nature (multiple organic and inorganic contaminants are present simultaneously) and hence the heavy metal removal efficiency of bacteria and algae decreases drastically. This chapter mainly focused on the studies describing metal removal efficacies of bacteria and algae in synthetic and actual wastewaters. In addition to this, studies highlighting various bioreactor systems, their configuration, and their optimization for improved remediation have also been included. Moreover, it was also realized that further research is important to understand the insights of process mechanisms, selection of best microbial strains, and development of suitable bioreactors for efficient removal of heavy metals.

Effluents from different industries are rampantly being discharged into the natural water bodies.... more Effluents from different industries are rampantly being discharged into the natural water bodies. Thus it is pertinent to treat this wastewater pollution from different sources before discharging it to the environment. The most extensively used biological process for the treatment of wastewater plant is the activated sludge process. The activated sludge process has shown high nutrient removal, biomass retention capacities, and removal of toxins, due to which activated sludge processes are a lucrative option for treating the wastewater. The diverse microbial communities comprising bacteria, fungi, protozoa, viruses, algae, and metazoa account for 95% of the microbes and play a chief role in the wastewater treatment. Many high-throughput techniques, such as metagenomics, metatranscriptomics, and metaproteomics, are utilized to decipher the functional aspects of these microbial communities.

Fungus is a lucrative option and has received much attention in biofuel production of bioethanol,... more Fungus is a lucrative option and has received much attention in biofuel production of bioethanol, biodiesel and biogas. Bioethanol is obtained when lignocellulosic biomass (agriculture waste) is saccharified into a mixture of sugars by fungal assisted enzymatic pretreatment. Further, several oleaginous fungi such as Zygomycetes species are valuable feedstock for biodiesel production, as they are rich in oleic and palmitic acid. Apart from this, anaerobic fungus possesses an arsenal of extracellular multienzyme complexes that improve the digestion of various biomass for biogas production. One of the latest developments in the biofuel sector has been the fungal based microbial fuel cell technology that has the combined advantage of wastewater treatment and electricity generation. Thus, this review is a compilation of all the biofuels that can be obtained from fungus from waste materials and wastewater.

In the last few decades, there has been a surge in the hazardous chemicals contamination in the w... more In the last few decades, there has been a surge in the hazardous chemicals contamination in the water bodies in various parts of India. Consequently, bioremediation of these hazardous chemicals by microorganisms has emerged as a lucrative option. Furthermore, advancement in the various physicochemical and robust molecular techniques such as 1D-SDS-PAGE followed by LC-MS/ MS analysis as well as metabolite identification by 1 H-NMR has shed light on the various cellular strategies adopted by a microorganism for remediation of a cocktail of metals and pesticide that were either poorly highlighted or unexplained. With this background the present chapter aims to understand the complete process of a metal or cocktail of multimetal and pesticide mixture remediation by

A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole... more A chemolithotrophic bacterium enriched in the chemostat in presence of sodium bicarbonate as sole carbon source was identified as Serratia sp. ISTD04 by 16S rRNA sequencing. The bacterium was tested for product formation in form of calcite crystals in presence of 5% CO 2 . Carbon dioxide sequestering capacity of bacterium was detected by 14 C labeling and purification of carbonic anhydrase enzyme and RuBisCO. 14 C labeling analysis revealed that the rate of assimilation of CO 2 by the strain is 0.756 x 10 -9 μmol CO 2 fixed cell -1 h -1 . Whole cell soluble proteins of Serratia sp. grown under autotrophic and heterotrophic conditions were resolved by two-dimensional gel electrophoresis and MALDI-TOF/MS for differential expression of proteins. In proteomic analysis of 63 protein spots, 48 spots were significantly up-regulated in the autotrophically grown cells; seven enzymes showed its utilization in autotrophic carbon fixation pathways and other metabolic activities of bacterium inc...

Chemistry in the Environment, 2021

Journal of Water Process Engineering, 2021

Abstract The explosion in urban population are increasing burdens on water and energy systems, wh... more Abstract The explosion in urban population are increasing burdens on water and energy systems, which ultimately release harmful pollutants such as wastewater and toxic gases into the natural ecosystems. In order to eliminate these pollutants, the production of vehicular quality biodiesel along with the phycoremediation of wastewater using two different Chlorella species (Chlorella minutissima and Chlorella sorokiniana) was investigated. Both the Chlorella sp., due to their stress tolerance behavior showed higher growth rate, lipid content and biomass productivity, when cultivated in wastewater than in control. Chlorella sorokiniana exhibited 19.14% higher lipids than Chlorella minutissima, when cultivated in wastewater. The fatty acid methyl esters (FAMEs)/biodiesel profiling has shown the decrease in poly unsaturated fatty acids (PUFAs) with enhancement in saturated fatty acids (SFAs) and oleic acid content. The physical properties of biodiesel derived from Chlorella sorokiniana, exceeded the existing biodiesel standards for USA and Europe e.g. the biodiesel (89.23 ± 0.21%; w/w of lipids) obtained from Chlorella sorokiniana, grown in wastewater was having lower cold filter plugging point (−6.22 °C), higher cetane number (47) and average oxidative stability (3.43 h). During the process, these Chlorella species have also removed total phosphate (TP), total nitrogen (TN), chemical oxygen demand (COD) and total organic carbon (TOC) from wastewater. The removal efficiency of TOC was found to be 95% and 98% by Chlorella minutissima and Chlorella sorokiniana respectively. Overall, Chlorella sorokiniana grown in wastewater was found to be a better candidate for the biodiesel production together with phycoremediation of wastewater.

Development in Wastewater Treatment Research and Processes, 2022

Progress in Biomaterials, 2020

The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has alr... more The evolving technology of nanoparticle synthesis, especially silver nanoparticle (AgNPs) has already been applied in various fields i.e., electronics, optics, catalysis, food, health and environment. With advancement in research, it is possible to develop nanoparticles of various size, shape, morphology, and surface to volume ratio utilizing biological systems. A number of different agents and methods can be employed to develop choice based AgNPs using algae, plants, fungi and bacteria. The use of plant extracts to produce AgNPs appears to be more convenient, as the method is simple, environmental friendly and inexpensive, also requiring a single-step. The microbial synthesis of AgNps showed intracellular and extracellular mechanisms to reduce metal ions into nanoparticles. Studies have shown that different size (1-100 nm) and shapes (spherical, triangular and hexagonal etc.) of nanoparticles can be produced from various biological routes and these diverse nanoparticles have various functions and usability i.e., agriculture, medical-science, textile, cosmetics and environment protection. The present review provides an overview of various biological systems used for AgNP synthesis, its underlying mechanisms, further highlighting the current research and applications of variable shape and sized AgNPs.

Biofuels, 2019

Microalgae are considered potential feedstocks to generate biodiesel; however, the area requires ... more Microalgae are considered potential feedstocks to generate biodiesel; however, the area requires further refinement and metabolic engineering to enhance productivity along with cost reduction. Our study involved the production and quality evaluation of biodiesel from the lipids of Botryococcus sp. MCC31, after conventional and in situ transesterification. Lipids extracted fell within the range of 330 to 410 mg g À1 Dry Weight (DW) (33-41% w/w) and these were identified by 1 H Nuclear Magnetic Resonance (NMR) and 13 C NMR spectrum. After identification, the reaction conditions for indirect transesterification, in terms of catalyst type, were optimized for maximizing Fatty Acid Methyl Ester (FAME) yield. The total unsaturated and saturated fatty acids were 54% and 46%, respectively, and the results indicated higher amounts of methyl palmitate and methyl oleate, which comprised almost 65% of the total FAMEs. The biodiesel exhibited a density of 0.853 g/cc, viscosity of 3.512 mm 2 /s, Cetane Number (CN) of 57.57, Higher Heating Value (HHV) of 38.88, iodine value of 75.56 g I 2 /100 g, Degree of Unsaturation (DU) of 58% and a Cold Filter Plugging Point (CFPP) of 4.8 C. The results were in accordance with the details as specified by American Society for Testing and Materials (ASTM) and European Norms (EN) standards. The study illustrates that Botryococcus sp. MCC31 can be a valuable feedstock for generation of high-quality biodiesel.

Environmental Science and Pollution Research, 2019

The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mi... more The present study reports the use of Citrus limetta (CL) residue for cultivating Chlorella sp. mixotrophically to augment production of biodiesel. The cultivation of Chlorella sp. using CL as media was carried out by employing a fed-batch technique in open tray (open tray+CL) and in software (BioXpert V2)-attached automated photobioreactor (PBR+CL) systems. Data showed the limit of nitrogen substituent and satisfactory organic source of carbon (OSC) in CL, causing > 2-fold higher lipid content in cells, cultivated in both the systems than in control. For the cells grown in both the systems, ≥ 3-fold enhancement in lipid productivity was observed than in control. The total fatty acid methyl ester (FAME) concentrations from lipids extracted from cells grew in PBR+CL and in open tray+CL techniques were calculated as 50.59% and 38.31%, respectively. The PBR+CL system showed improved outcomes for lipid content, lipid and biomass productivity, FAME characteristics and physical property parameters of biodiesel than those obtained from the open tray+CL system. The physical property parameters of biodiesel produced from algal cells grown in PBR+CL were comparable to existing fuel standards. The results have shown lower cold filter plugging point (− 6.57°C), higher cetane number (58.04) and average oxidative stability (3.60 h). Collectively, this investigation unveils the novel deployment of CL as a cost-effective feedstock for commercialisation of biodiesel production.