Biotechnology has played a significant role in enhancing crude oil recovery from the depleted oil reservoirs to solve stagnant petroleum production, after a three-stage recovery process employing ...mechanical, physical and chemical methods. Biotechnologically enhanced oil recovery processes, known as microbial enhanced oil recovery (MEOR), involve stimulating indigenous reservoir microbes or injecting specially selected consortia of natural bacteria into the reservoir to produce specific metabolic events that lead to improved oil recovery. This also involves flooding with oil recovery agents produced ex situ by industrial or pilot scale fermentation. This paper essentially reviews the operating mechanisms and the progress made in enhanced oil recovery through the use of microbes and their metabolic products. Improvement in oil recovery by injecting solvents and gases or by energizing the reservoir microflora to produce them in situ for carbonate rock dissolution and reservoir re-pressurization has been enunciated. The role of biosurfactants in oil mobilization through emulsification and that of biopolymers for selective plugging of oil-depleted zones and for biofilm formation have been delineated. The spoil sport played by sulfate-reducing bacteria (SRB) in MEOR has also been briefly reviewed. The importance of mathematical models used in predicting the applicability of an MEOR strategy and the microbial growth and transport has been qualitatively discussed. The results of some laboratory studies and worldwide field trials applying ex situ and in situ MEOR technologies were compiled and interpreted. However, the potential of the MEOR technologies has not been fully realized due to poor yield of the useful microbial metabolic products, growth inhibition by accumulated toxic metabolites and longer time of incubation. A complete evaluation and assessment of MEOR from an engineering standpoint based on economics, applicability and performance is required to further improve the process efficiency for writing more success stories. Thus, this review attempts to address almost all the issues concerning the MEOR, its past and recent trends and its future prospect and directions.
In spite of tremendous efforts and huge investments on resources, biodiesel from oleaginous microalgae has not yet become a commercially viable and sustainable alternative to petro-diesel. This is ...mainly because of the technological and economic challenges hovering around large scale cultivation and downstream processing of algae, water and land usage, stabilized production technology, market forces and government policies on alternative energy and carbon credits. This review attempts to capture and analyse the global trends and developments in the areas of biofuel and bio-product of microalgae and proposes possible strategies that can be adopted to produce biofuel, biochar and bio-products utilizing wastewater in a bio-refinery model. The strategies include “Zero waste discharge” concept with process integration, wherein microalgae is grown strategically using different wastewater combined with flue gas in cultivation system for simultaneous production of ‘high-value-low-volume’ product and ‘low-value-high-volume’ product with sharing of the remnant biomass to produce biochar. In addition, the CO2 present in the atmosphere is captured and sequestered long term in the form of biochar would help to attain carbon negativity, while remediating wastewater and balancing energy requirements. Therefore, “Zero waste discharge” concept holds the potential to make the process a sustainable one, while gaining on the carbon credits.
Display omitted
•Analysis of the trends and developments of biofuel and bio-product from microalgae•Microalgae provide an edge over lignocellulosic and solid waste based feedstock.•“Zero waste discharge” concept with process integration is presented.•Parallel synthesis of high value product and biochar as a co-product
Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biosurfactants have gained importance in the fields of enhanced oil recovery, ...environmental bioremediation, food processing and pharmaceuticals owing to their unique properties – higher biodegradability, lower toxicity, and effectiveness at extremes of temperature, pH and salinity. However, large-scale production of these molecules has not been realized because of low yields in production processes and high recovery and purification costs. This article describes some practical approaches that have been adopted to make the biosurfactant production process economically attractive: these include the use of cheaper raw materials, optimized and efficient bioprocesses and overproducing mutant and recombinant strains for obtaining maximum productivity. The application of these strategies in biosurfactant production processes, particularly those using hyper-producing recombinant strains in the optimally controlled environment of a bioreactor, might lead towards the successful commercial production of these valuable and versatile biomolecules in near future.
Display omitted
•Microbially derived surfactant and polymer were employed in enhanced oil recovery.•Biosurfactant exhibited a maximum emulsification activity of 81% against lube oil.•Biopolymer ...showed excellent viscosity, pore plugging and cementing ability.•Biosurfactant was conditioned using Ca2+ ions to improve its efficacy.•A maximum oil recovery of 45% was achieved by ANN-GA optimization.
A lipopeptide biosurfactant produced by marine Bacillus megaterium and a biopolymer produced by thermophilic Bacillus licheniformis were tested for their application potential in the enhanced oil recovery. The crude biosurfactant obtained after acid precipitation effectively reduced the surface tension of deionized water from 70.5 to 28.25mN/m and the interfacial tension between lube oil and water from 18.6 to 1.5mN/m at a concentration of 250mgL−1. The biosurfactant exhibited a maximum emulsification activity (E24) of 81.66% against lube oil. The lipopeptide micelles were stabilized by addition of Ca2+ ions to the biosurfactant solution. The oil recovery efficiency of Ca2+ conditioned lipopeptide solution from a sand-packed column was optimized by using artificial neural network (ANN) modelling coupled with genetic algorithm (GA) optimization. Three important parameters namely lipopeptide concentration, Ca2+ concentration and solution pH were considered for optimization studies. In order to further improve the recovery efficiency, a water soluble biopolymer produced by Bacillus licheniformis was used as a flooding agent after biosurfactant incubation. Upon ANN-GA optimization, 45% tertiary oil recovery was achieved, when biopolymer at a concentration of 3gL−1 was used as a flooding agent. Oil recovery was only 29% at optimal conditions predicted by ANN-GA, when only water was used as flooding solution. The important characteristics of biopolymers such as its viscosity, pore plugging capabilities and bio-cementing ability have also been tested. Thus, as a result of biosurfactant incubation and biopolymer flooding under the optimal process conditions, a maximum oil recovery of 45% was achieved. Therefore, this study is novel, timely and interesting for it showed the combined influence of biosurfactant and biopolymer on solubilisation and mobilization of oil from the soil.
Purpose
Curcumin (CUR), an antioxidant with p-glycoprotein inhibiting activity may be encapsulated with gemcitabine (GEM) as nanosuspension to enhance its anticancer potentiality synergistically.
...Methods
Folate conjugated single (CUR/GEM) and dual (CUR + GEM) drug-loaded nanoformulations were prepared and evaluated for P-glycoprotein-1 (pgy-1) gene resistance, followed by
in vitro
cellular uptake and cytotoxicity assay in cells. The
in vivo
biodistribution and scintigraphic imaging was done after radiolabeling the nanoparticles with
99m
Technetium (99
m
Tc). The tumor inhibition study was conducted in nude mice bearing MDA-MB-231 xenografts.
Results
The folate conjugated dual drug formulations (FCGNPs) gave better results in suppressing the pgy-1 gene and also showed higher cellular uptake, cytotoxicity, apoptosis, and cell cycle arrest. The radiolabeled nanoformulations were highly stable and FCGNPs showed higher accumulation in the MDA-MB-231 tumor region than folate unconjugated dual drug NPs (CGNPs) as evidenced by scintigraphic imaging and biodistribution studies. The
in vivo
therapeutic efficacy of FCGNPs was higher compared to unconjugated and respective single-drug formulations.
Conclusion
Two drugs in one platform lower breast adenocarcinoma by lowering drug resistance and improving cytotoxic effects.
Display omitted
•Apigenin-loaded galactosylated-PLGA nanoparticles ensure active liver targeting.•Galactosylation enhances liver cell internalization of apigenin.•Galactosylation improves ...pharmacokinetic attributes of Apigenin.•Galactosylation increases therapeutic efficacy against hepatocellular carcinoma.
Hepatocellular carcinoma (HCC) is the most common hepatic malignancy worldwide. Recent reports focusing on the efficacy of apigenin-loaded nanoparticles (NPs) in combating the progress of HCC encouraged us to develop galactose-tailored PLGA NPs loaded with apigenin (API-GAL-NPs) for active liver targeting to treat HCC. Two kinds of apigenin NPs, such as apigenin-PLGA NPs (API-NPs) and API-GAL-NPs were fabricated and characterized by size, surface morphology, encapsulation efficacy, and in vitro drug release kinetics. In vitro assays were performed on HepG2 cells to check the cellular internalization, cytotoxic potential, and apoptotic potential of free apigenin (API), API-NPs, and API-GAL-NPs. In this stdy, API-GAL-NPs exhibited improved cellular internalization of API resulting in significantly high cytotoxic and apoptotic potentials to HepG2 cells over API and API-NPs. In in vivo studies, API-GAL-NPs exhibited a better protective effect against DEN-induced HCC in rats evidenced by the significant reduction of nodule formation, downregulation of matrix metalloproteinases (MMP-2 and MMP-9), and induction of apoptosis in the liver than API and API-NPs. Histopathological studies and scintigraphic imaging also confirmed that API-GAL-NPs treatment achieved better therapeutic efficacy against DEN-induced HCC in rats over API-NPs. In conclusion, API-GAL-NPs may serve as a potential therapeutic agent against HCC in the future by achieving improved liver targeting.
Probiotic bacteria synthesize extracellular polysaccharides (EPSs) with commercially significant physiological and therapeutic activities. This important class of biomolecules is also characterized ...by their ability to remove reactive oxygen species (ROS) that are formed in the intestine by various metabolic reactions; hence, they exhibit antioxidant activities. Our probiotic bacterium, Bacillus coagulans RK‐02, produces an EPS during the exponential and stationary growth phases when grown in a glucose mineral salts medium. The time course of EPS synthesis was studied with respect to biomass growth. The antioxidant and free radical scavenging potential of isolated EPS were studied by various methods, including the β‐carotene‐linoleic acid model system, a superoxide radical scavenging assay using the PMS‐NADH‐nitroblue tetrazolium system, the 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity, a hydroxyl radical scavenging assay using the ascorbic acid‐Cu2+‐cytochrome c system and an in vitro microsome peroxidation inhibition study using a thiobarbituric acid assay. The antioxidant activities were compared to known antioxidants vitamin C and E, which were used as reference standards. The results showed that the EPS, which is a heteropolymer composed of four monosaccharides, produced by B. coagulans RK‐02 had significant antioxidant and free radical scavenging activities.
Ammonium and nitrate were compared as nitrogen sources for mixotrophic growth of
Microchloropsis salina
(formerly
Nannochloropsis salina
) on glycerol. The effects of nitrogen source and glycerol on ...the abundance, composition and profile of bacterial communities were examined by 16S rRNA sequencing. The effect of bacteria on culture performance was assessed by comparing ampicillin-containing and ampicillin-free cultures. The productivity of
M. salina
was higher with ammonium than with nitrate, and lower with bacteria present. Glycerol utilization by
M. salina
was minimal in the absence of a nitrogen source and the addition of glycerol increased the abundance of bacteria. Bacterial profiles were influenced by nitrogen source, with Pseudomonadaceae proliferating with ammonium, Alteromonadaceae with nitrate and Beijerinckiaceae prevalent with either. The presence of nitrate and glycerol led to aerobic-denitrifying bacteria capable of diverting both resources away from algal metabolism. These findings demonstrate significant advantages of providing ammonium during mixotrophic cultivation of
M. salina
on glycerol.
