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•Petroleum hydrocarbon pollutants are classified as persistent organic pollutants.•These pollutants pose adverse effects on human and environmental health.•Combat environmental ...pollution due to hydrocarbon pollutants is big issue for scientists.•Biodegradation is an eco-friendly and economic method to control hydrocarbon pollution.•Oleophilic microorganisms can be used for oil spill bioremediation.
Petroleum hydrocarbon pollutants are recalcitrant compounds and are classified as priority pollutants. Cleaning up of these pollutants from environment is a real world problem. Bioremediation has become a major method employed in restoration of petroleum hydrocarbon polluted environments that makes use of natural microbial biodegradation activity. Petroleum hydrocarbons utilizing microorganisms are ubiquitously distributed in environment. They naturally biodegrade pollutants and thereby remove them from the environment. Removal of petroleum hydrocarbon pollutants from environment by applying oleophilic microorganisms (individual isolate/consortium of microorganisms) is ecofriendly and economic. Microbial biodegradation of petroleum hydrocarbon pollutants employs the enzyme catalytic activities of microorganisms to enhance the rate of pollutants degradation. This article provides an overview about bioremediation for petroleum hydrocarbon pollutants. It also includes explanation about hydrocarbon metabolism in microorganisms with a special focus on new insights obtained during past couple of years.
Control and prevention of environmental pollution has become a worldwide issue of concern. Aromatic hydrocarbons including benzene, toluene, ethyl benzene, xylene (BTEX) and polyaromatic hydrocarbons ...(PAHs) are persistent organic pollutants (POPs), released into the environment mainly by exploration activities of petroleum industry. These pollutants are mutagenic, carcinogenic, immunotoxic and teratogenic to lower and higher forms of life i.e. microorganisms to humans. According to the International Agency for Research on Cancer (IARC) and United States Environmental Protection Agency (U.S. EPA), Benzoapyrene (BaP) is carcinogenic in laboratory animals and humans. Aromatic hydrocarbons are highly lipid soluble and thus readily absorbed from environment in gastrointestinal tract of mammals. Treatment and remediation of petroleum refinery waste have been shown either to reduce or to eliminate genotoxicity of these pollutants. Bioremediation by using microorganisms to treat this waste is showing a promising technology as it is safe and cost-effective option among various technologies tested. The main aim of this review is to provide contemporary information on variety of aromatic hydrocarbons present in crude oil (with special focus to mono- and poly-aromatic hydrocarbons), exposure routes and their adverse effects on humans. This review also provides a synthesis of scientific literature on remediation technologies available for aromatic hydrocarbons, knowledge gaps and future research developments in this field.
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•Toxicity of persistent organic pollutants present in petroleum industry waste is summarized.•Physical-chemical and human health information for BTEX and PAHs are narrated.•Bioremediation of mono- and poly-aromatic hydrocarbon pollutants play vital role in sustainable development of environment.
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•Biosurfactants possess diversity in structural and functional properties.•Screening methodologies play important role to obtain desired biosurfactant producer.•Biosynthesis of ...rhamnolipid (RL) by Pseudomonas aeruginosa is discussed.•Rhamnolipids have potential application in microbial enhanced oil recovery.•Research should be focused on utilization of renewable substrates for RL production.
Surfactants are one of the most versatile group of chemicals used in various industrial processes. Their market is competitive, and manufacturers will have to expand surfactant production in ecofriendly and cost effective manner. Increasing interest in biosurfactants led to an intense research for environment friendly and cost-efficient production of biosurfactant. Structural diversity and functional properties of biosurfactants make them an attractive group of compounds for potential use in wide variety of industrial, environmental and biotechnological applications. Screening methods make task easier to obtain potential biosurfactant producing microorganisms. Variety of purification and analytical methods are available for biosurfactant structural characterization. This review aims to compile information on types and properties of biosurfactant, microbial screening methods as well as biosynthesis, extraction, purification and structural characterization of biosurfactant using rhamnolipid as a model biosurfactant. It also describes factors affecting rhamnolipid production. It gives an overview of oil recovery using biosurfactant from Pseudomonas aeruginosa.
In recent years, there has been increasing concern over public health threat presented by introduction of petroleum hydrocarbon pollutants in environment due to anthropogenic activities to a greater ...extent and natural processes to some extent. Many countries all over the world are currently facing severe problem due to these pollutants as they are one of the persistent organic pollutants (POPs). Remediation of polluted sites by biodegradation is a viable option as conventional physico-chemical methods for remediation seems technically as well as economically challenging. Biodegradation is non-invasive and could be cost-effective in removal of petroleum hydrocarbon pollutants. It is considered as ultimate mechanism for pollutants removal. Immobilized microbial cells give advantage over free microbial cells to improve the survival and retention of the bioremediation agents in polluted sites. However, current biodegradation approaches suffer from a number of limitations, which include pollutant characteristics, poor capabilities of microbial communities in the field, lesser bioavailability of pollutants, growth conditions, etc. Understanding the factors affecting microbial degradation is of great research interest in present scenario. This review selectively examines and provides a critical view on bioavailability of the substrates, microorganisms in petroleum hydrocarbon pollutants degradation and the molecular techniques for their characterization, degradation mechanisms under aerobic and anaerobic conditions, commercially available bioremediation agents and factors affecting biodegradation of these pollutants. Role of genetically modified organisms and biodegradation of petroleum hydrocarbon pollutants by immobilized will also be discussed.
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•Bioremediation is cost effective and eco-friendly method for cleanup of pollutants.•Electron acceptors play vital role in biodegradation of petroleum hydrocarbon pollutants.•Molecular techniques are effective tool to characterize microbial assemblages.•Commercial bioremediation agents are available to combat hydrocarbon pollutants.•Immobilization increases pollutant biodegradation rate with less environmental impact.
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•P. aeruginosa NCIM 5514 completely decolorized 2,6-dichlorophenol indophenol.•Oil droplets in the vicinity of the colonies showed oleophilic nature.•This isolate degraded C8–C36+ ...(60.63%) of crude oil based on GC analysis.•First report on the use of 3%v/v crude oil as sole carbon source by an individual strain.•Paraffin(s) degradation ability demonstrates its potential for removal of well clogging.
The aim of this work was to study the potential of an indigenous strain of Pseudomonas aeruginosa NCIM 5514, isolated from petroleum-polluted soil, for the biodegradation of crude petroleum oil. The isolate completely decolorized 2,6-dichlorophenol indophenol in 120h when grown at (37±1°C), indicating its hydrocarbon utilizing nature. Ex situ biodegradation study was performed to find out quantitative utilization and biodegradation of paraffin(s) present in crude oil. When the culture was grown in Bushnell-Hass medium containing crude oil (3%,v/v) at 37°C, 180rpm for 60days, the viscosity of the oil was reduced from 1883cp to 1002cp. Gravimetric and gas chromatographic analysis showed 61.03% and 60.63% of biodegradation of C8–C36+ hydrocarbons, respectively. These results indicated that the isolate has potential to be used for ex-situ and in-situ bioremediation of hydrocarbon pollutants and could have promising applications in petrochemical industry.
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•Petroleum oilfields are resource of reduced carbon for microbial growth.•Petroleum oil reservoirs are large geo-bioreactors, rich in wide range of anaerobic microbes.•Petroleum ...oilfields possess extreme environment in terms of temperature, pressure & salinity.•Petroleum reservoir characteristics are summarized.•Microbial dynamics of petroleum reservoirs including origin of microorganisms is explored.
Petroleum is produced by thermal decay of buried organic material over millions of years. Petroleum oilfield ecosystems represent resource of reduced carbon which favours microbial growth. Therefore, it is obvious that many microorganisms have adapted to harsh environmental conditions of these ecosystems specifically temperature, oxygen availability and pressure. Knowledge of microorganisms present in ecosystems of petroleum oil reservoirs; their physiological and biological properties help in successful exploration of petroleum. Understanding microbiology of petroleum oilfield(s) can be used to enhance oil recovery, as microorganisms in oil reservoirs produce various metabolites viz. gases, acids, solvents, biopolymers and biosurfactants. The aim of this review is to discuss characteristics of petroleum oil reservoirs. This review also provides an updated literature on microbial ecology of these extreme ecosystems including microbial origin as well as various types of microorganisms such as methanogens; iron, nitrate and sulphate reducing bacteria, and fermentative microbes present in petroleum oilfield ecosystems.
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•Production of biochar produced through pyrolysis of lignocellulosic biomass has been narrated.•The factors influencing pyrolytic conditions and pyrolytic conversion have been ...discussed.•Reviewed the modification of biochar and mechanism of pollutant adsorption using biochar.•Potential positive aspects of biochar applications towards pollutant removal are also discussed.
Thermochemical processing of biomass results in a producing char, a typical by-product. The char can be termed as biochar when specifically applied as a soil fertility enhancement. Biochar, when utilized efficiently, is basic for enhancing financial viability and also to maintain ecosystem. The properties of carbonized biomass rely upon raw materials (feedstock) and procedure conditions. Biochar shows an incredible potential to effectively handle water contaminants taking into consideration the wide accessibility of feedstock, suitable physical/chemical surface properties and low-cost. Pyrolysis technology for converting lignocellulosic biomass into biochar has emerged as a frontier research domain for the removal of pollutants. This review focused on production of biochar from various sources of lignocellulosic biomass (cellulose, hemicellulose and lignin) and its application in various fields such as agriculture, wastewater treatment process. Biochar is a significant resource however, its application require further examination of its properties and structure and techniques to alter those factors.
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•Provides information about green synthesis of industrial amphiphiles.•Enlists similarity in biosurfactant gene cassettes and biomolecules.•Biosurfactant roles and applications have ...been elucidated.
Microbial surfactants are a large number of amphipathic biomolecules with a myriad of biomolecule constituents from various microbial sources that have been studied for their surface tension reduction activities. With unique properties, their applications have been increased in different areas including environment, medicine, healthcare, agriculture and industries. The present review aims to study the biochemistry and biosynthesis of biosurfactants exhibiting varying biomolecular structures which are produced by different microbial sources. It also provides details on roles played by biosurfactants in nature as well as their potential applications in various sectors. Basic biomolecule content of all the biosurfactants studied showed presence of carbohydrates, aminoacids, lipids and fattyacids. The data presented here would help in designing, synthesis and application of tailor-made novel biosurfactants. This would pave a way for perspectives of research on biosurfactants to overcome the existing bottlenecks in this field.
•Nano zero valent iron stacked activated carbon has been synthesized and applied for dye wastewater.•New solid-liquid phase equilibrium model has been validated.•Langmuir biosorption capacity was ...measured as 187.3 mg/g.•Khan and pseudo-first order models satisfy the studied system.•Studied system was found to be feasible and exothermic nature.
The present work explains the biosorption of malachite green dye from aquatic systems by nano zero valent iron stacked activated carbon (NZVI-AC), which was prepared by dual surface modification strategy. NZVI-AC was characterized by using FTIR, SEM-EDX, XRD and TGA. NZVI-AC exhibited efficient performance in dye biosorption properties. Experimental variables such as time, pH, dye concentration, temperature and biosorbent dosage influenced Langmuir adsorption capacity of 187.3 mg/g. The present biosorption system was best described by pseudo-first order kinetics. The dye was completely knocked out of the solution within 60 min at equilibrium. The thermodynamic behaviour of NZVI-AC was exothermic, feasible and spontaneous. Experimental data was engaged to validate new solid-liquid phase equilibrium model, showing the average absolute relative deviation 7.72%. Hence the procedure was non-toxic, potential to retain biosorbent from the solution, applicable for multiple cycles. In context, NZVI-AC can be recommended for the treatment of dyes from industrial effluent.
Pesticides are the chemicals used to prevent plant diseases, weeds, pests and to enhance the quality of the food products. The uniqueness of their chemical structure, and/or their interactions with ...the environment characterize the nature of pesticides. In most scenarios, the end users such as farmers and consumers, who know the serious effects of pesticides cannot translate this awareness into their practice. The mobility, bioavailability of pesticides in soils (atmosphere, water bodies) is based upon their absorption and desorption mechanisms from soil particles. Pesticides have harmful effects in the soil ecosystem, and mankind (which affects biological molecules, tissues, and organs resulting in acute or chronic disorders). It affects humans of all ages including prenatal. These pollutants, when released into the water bodies affects the aquatic systems. The water molecules in the river are affected by the accumulation of these toxic contaminants with its alkaline pH and heavy metals which could adversely affect the health of flora and fauna. This article discusses the scientific literature on various remediation technologies available for the safer use of pesticides. The limitations and benefits of chemically polluted soil using microorganisms and other biological methods have been discussed. However, future development measures are still needed to ensure full implementation of these methods to save the environment.
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