A field experiment was conducted in Delaware (USA) to evaluate three crude oil bioremediation techniques. Four treatments were studied: no oil control, oil alone, oil + nutrients, and oil + nutrients + an indigenous inoculum. The microbial populations were monitored by standard MPN techniques, PLFA profile analysis, and 16S rDNA DGGE analysis for species definition. Viable MPN estimates showed high but steadily declining microbial numbers and no significant differences among treatments during the 14-weeks. Regarding the PLFA results, the communities shifted over the 14-week period from being composed primarily of eukaryotes to Gram-negative bacteria. The Gram-negative communities shifted from the exponential to the stationary phase of growth after week 0. All Gram-negative communities showed evidence of environmental stress. The 16S rDNA DGGE profile of all plots revealed eight prominent bands at time zero. The untreated control plots revealed a simple, dynamic dominant population structure throughout the experiment. The original banding pattern disappeared rapidly in all oiled plots, indicating that the dominant species diversity changed and increased substantially over 14 weeks. The nature of this change was altered by nutrient-addition and the addition of the indigenous inoculum.

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Microbial Population Changes During Bioremediation of an Experimental Oil Spill

The global use of petroleum hydrocarbons for energy and raw materials in various applications has increased with extensive release of a wide variety of contaminants into the environment, affecting soil, surface water and groundwater. The effect results to numerous health, ecological and environmental issues. However, treatment of contamination and pollution caused by petroleum hydrocarbons is a huge and laborious work. It involves several in situ or ex situ treatments comprising containment, separation and destruction which include biological, chemical, physico-chemical, thermal and heat, electric and electromagnetic, acoustic and ultrasonic treatment methods. These treatment methods involve several other techniques and strategies as listed in this review. The health risks pose by petroleum hydrocarbon pollution have driven scientists to research, develop and implement risk-based remediation strategies for restoration and reclamation of affected environments. To select the best treatment option for remediation, it is important to comprehend the nature, composition, properties, sources of pollution, type of environment, fate, transport and distribution of the pollutants, mechanism of degradation, interaction and relationships with microorganisms, the intrinsic and extrinsic factors affecting remediation. It helps to evaluate and predict the chemical behaviour of the pollutants with the short and long-term effects and mitigate the effects of pollution and limit exposure to the pollutants. Despite the available remediation options for petroleum hydrocarbon management and removal, sufficient and complete remediation can be implemented by adoption of proper approach derived from risk-based management procedure that can be practical, scientifically defensible, widely adapted, sustainable, non-invasive, eco-friendly and cost-efficient. This paper provides an overview of the various remediation and treatment technologies derived from risk-based approaches that are used for isolation, containment, separation, restoration reclamation and remediation of soil, sediments, surface water and groundwater contaminated by petroleum hydrocarbons and organic compounds.

Remediation of soil and water contaminated with petroleum hydrocarbon: A review

Nowadays, pesticides are widely used in preventing and controlling the diseases and pests of crop, but at the same time pesticide residues have brought serious harm to human's health and the environment It is an important subject to study microbial degradation of pesticides in soil environment in the field of internationally environmental restoration science and technology This paper summarized the microbial species in the environment, the study of herbicide and pesticides degrading bacteria and the mechanism and application of pesticide microbial degrading bacteria Cypermethrin and other pyrethroid pesticides were used widely currently, while they were difficult to be degraded in the natural conditions, and an intermediate metabolite, 3-phenoxy benzoic acid would be produced in the degradation process, causing the secondary pollution of agricultural products and a series of problems Taking it above as an example, the paper paid attention to the degradation process of microorganism under natural conditions and factors affecting the microbial degradation of pesticide In addition, the developed trend of the research on microbial degradation of pesticide and some obvious problems that need further solution were put forward

https://www.mdpi.com/1420-3049/23/9/2313/pdf

Microbial Degradation of Pesticide Residues and an Emphasis on the Degradation of Cypermethrin and 3-phenoxy Benzoic Acid: A Review.

Today, environmental pollution is a serious problem, and bioremediation can play an important role in cleaning contaminated sites Remediation strategies, such as chemical and physical approaches, are not enough to mitigate pollution problems because of the continuous generation of novel recalcitrant pollutants due to anthropogenic activities Bioremediation using microbes is an eco-friendly and socially acceptable alternative to conventional remediation approaches Many microbes with a bioremediation potential have been isolated and characterized but, in many cases, cannot completely degrade the targeted pollutant or are ineffective in situations with mixed wastes This review envisages advances in systems biology (SB), which enables the analysis of microbial behavior at a community level under different environmental stresses By applying a SB approach, crucial preliminary information can be obtained for metabolic engineering (ME) of microbes for their enhanced bioremediation capabilities This review also highlights the integrated SB and ME tools and techniques for bioremediation purposes

Bioremediation through microbes: systems biology and metabolic engineering approach

There is a widespread repeated exposure of the population to the pesticides and heavy metals of occupational and environmental origin. Such population is forced to undergo continuous stress imposed by combined exposure of the heavy metals and different classes of the pesticides used in agricultural as well as health practices. The existing reports from several workers have indicated that heavy metals and pesticides in combination may lead more severe impact on the human health when compared to their individual effects. Such a combination of pesticides and heavy metals may also change or influence the detection of exposure. Several studies in past have shown the synergistic toxic effects of heavy metals and pesticides. Such evaluations have revealed the synergistic interactions of various heavy metals and pesticides in animals as well as humans. The aim of the present article is to provide a synthesis of existing knowledge on the synergistic effects of heavy metal and pesticides in living systems. The information included in this article may be useful for different environment protection agencies and policy makers to consider the combined effects of heavy metals and pesticides on humans while designing strategies towards environmental protection and safety regulations about human health.

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Synergistic Effects of Heavy Metals and Pesticides in Living Systems.

Synthetic chemicals foreign to a particular ecological system and has a biological activity can be called xenobiotic compounds. Xenobiotics include drugs, industrial chemicals, naturally occurring poisons and environmental pollutants. Some microorganisms have the ability of breaking down the xenobiotic compounds partially or entirely. But some xenobiotics are recalcitrant in nature because of various reasons. Some of them cannot be used as substrate by microbes, some cannot transport them due to absence of transporting enzymes and some are in accessible to microbes due to larger structure and insolubility. They can be divided into different groups depending on their chemical composition. Biological and non-biological remediation techniques are the most reliable techniques to degrade these compounds. Bacterial biodegradation used in land filling and composting are most economical methods which uses both the wild type and genetically modified bacterial strains. There are many non-biological techniques which have been grouped under thermal and non-thermal techniques which are suitable for xenobiotic degradation.

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Xenobiotic Compounds Present in Soil and Water: A Review on Remediation Strategies

Twenty hydrocarbon degrading microorganism were isolated from four hydrocarbon contaminated sites and were identified on the basis of morphological and biochemical characteristics as Bacillus cereus, Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The study revealed high density of bacteria acclimatized for biodegradation of hydrocarbon (Petrol) in soil. The isolates were examined for other hydrocarbon degradation in media supplemented with Benzene, Toluene, Xylene and Cyclohexane at three different concentrations viz 5%, 10% and 15% incubated for 3 different time intervals 5, 10 and 15 days. The results indicated that all the isolates possessed potential to degrade the wide variety of hydrocarbons. The most efficient among them was Pseudomonas aeruginosa which degraded all tested hydrocarbon showing maximum growth at 5% concentration and 10 days incubation. It could be concluded that native flora of hydrocarbon contaminated site adapt to the environmental condition and could be implicated to remove hydrocarbons.

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Hydrocarbon Bioremediation Efficiency by five Indigenous Bacterial Strains isolated from Contaminated Soils

Keratinolytic microorganisms have a great importance in feather waste degradation and its use for improvement oflivestock feed and production of protein hydrolysates. Annually several thousand tons of feather wastes are discharged into the surrounding environment as a by-product of commercial poultry processing. Microorganisms could minimize regulatory problems of uncontrolled accumulation of waste feathers. This residue is almost pure keratin, which is not easily degradable by common proteolytic enzymes.

Biodegradation of Keratin from Chicken Feathers by Fungal Species as a means of Sustainable Development

Keratinolytic microorganisms have a great importance in feather waste degradation and its use for improvement of livestock feed and production of protein hydrolysates. Annually several thousand tons of feather wastes are discharged into the surrounding environment as a by-product of commercial poultry processing. Microorganisms could minimize regulatory problems of uncontrolled accumulation of waste feathers. This residue is almost pure keratin, which is not easily degradable by common proteolytic enzymes.
The present study deals with identification of fungi that play a significant role in the degradation of chicken feather and keratin degradation ability of the isolated fungi. Feathers of broiler chicken were collected from Jaggi poultry farm, Mandir Hasaud, Raipur. Fungi were isolated by feather baiting technique. Feathers were inoculated in Sobouraud Dextrose Agar (SDA) medium and their pure culture was prepared. Fungus were identified by Lacto phenol cotton blue staining method as Trichoderma, Gliocladium, Fusarium, Syncephalastrum, Mucor, Aspergillus Flavus. The pure culture were grown in mineral media with 500 mg of feathers as a sole source of Nitrogen and Carbon and incubated for the period of 25 days. At 5 days intervals, the biochemical changes associated with biodegradation was evaluated by analyzing the culture filtrate. The release of Nitrate, Cystine, Cysteine and methionine components during the process of biodegradation was studied which proved the efficient degradation of keratin. There was also a change in pH of the medium towards alkalinity. Mucor and Aspergillus Flavus were the most powerful bio remedial fungus in the current study. With an increasing world-wide concern for the environment it is possible to use these six fungus for the degradation of enormous quantity of waste feathers. Biodegradation leads to recycle the wastes and thus maintaining the environmental quantity of the biosphere.

Biodegradation of Keratin from Chicken Feathers by Fungal Species as a Means of Sustainable Development

Among the various microbial biodegradation techniques, molecular microbiology methods have revolutionized microbial biotechnology, thus leading to rapid and high-throughput methods for culture-independent assessment and exploitation of microbes present in polluted environments. Whether organic or inorganic, pollutants present in contaminated sites can cause an imbalance in the ecosystem by affecting the flora and fauna. The efficiency of naturally occurring microorganisms for field bioremediation could be significantly improved by the microbial molecular biology approach for its comparatively high efficiency and safety. Many techniques, including polymerase chain reaction (PCR), fluorescent in situ hybridization (FISH), denaturing gradient gel electrophoresis (DGGE), ribosomal intergenic spacer analysis (RISA), amplified ribosomal DNA restriction analysis (ARDRA), terminal-restriction fragment length polymorphism (TRFLP), single-strand conformation polymorphism (SSCP), and ribosomal intergenic spacer analysis (RISA) can be selectively employed in microbial flora and ecology research. Recent methods such as genotypic profiling, metagenomics, ultrafast genome pyrosequencing, metatranscriptomics, metaproteomics, and metabolomics have provided exemplary knowledge about microbial communities and their role in the bioremediation of environmental pollutants.

Jai Godheja

Papers

Xenobiotic Compounds Present in Soil and Water: A Review on Remediation Strategies

Hydrocarbon Bioremediation Efficiency by five Indigenous Bacterial Strains isolated from Contaminated Soils

Biodegradation of Keratin from Chicken Feathers by Fungal Species as a means of Sustainable Development

Biodegradation of Keratin from Chicken Feathers by Fungal Species as a Means of Sustainable Development

Molecular Technologies for Assessment of Bioremediation and Characterization of Microbial Communities at Pollutant-Contaminated Sites