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#bioremediation

17 public questions tagged with this topic.

Bioremediation

White rot fungi degrade hydrocarbons using:

White rot fungi including Phanerochaete chrysosporium, Trametes versicolor and Pleurotus ostreatus possess unique extracellular oxidative lignin-degrading machinery evolved to depolymerize wood lignin polymer composed of phenylpropanoid units linked via ether and carbon-carbon bonds, which serendipitously attacks structurally similar persistent organic pollutants including benzo[a]pyrene, polychlorinated biphenyls, dioxins and pentachlorophenol. Key enzymes secreted under nutrient nitrogen limitation triggering secondary metabolism are lignin peroxidase LiP isoenzymes oxidizing veratryl alcoho

Ref: Pointing White rot fungi role in bioremediation Applied Microbiology Biotechnology 2001; Wesenberg et al. lignin peroxidase mechanism; PubMed PAH fungal.

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Bioremediation

Which microorganism is known to degrade aromatic hydrocarbons?

Pseudomonas putida strains such as KT2440 certified HV1 safety, mt-2 and F1 embody archetypal aerobic degraders of monoaromatic and polycyclic aromatic hydrocarbons due to extraordinary metabolic versatility conferred by large genome 6.2 megabases encoding more than 80 oxygenases and multiple catabolic plasmids including TOL plasmid pWW0 carrying upper pathway xylCMABN converting toluene and xylene to benzoate via xylene monooxygenase multicomponent system and meta-cleavage lower pathway xylXYZLTEGFJKIH, and NAH7 plasmid encoding naphthalene dioxygenase nahAc. Enzymatic repertoire includes tol

Ref: Timmis Pseudomonas putida review Nature Reviews Microbiology 2002; EPA aromatic degraders guide; PubMed KT2440 genome PMID 12055322.

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Bioremediation

Bioreactors used in bioremediation are:

Bioreactors in bioremediation function as engineered controlled systems where dissolved oxygen via sparging, agitation 100 to 500 rpm, pH 6 to 8 via dosing, temperature 20 to 35 Celsius via jackets, retention time 0.5 to 10 days, redox potential via ORP probes, and nutrient supply precisely manipulated via controllers maximizing degradation kinetics modeled by Monod equations. Configurations include stirred-tank slurry reactors 10 to 30 percent solids, packed-bed biofilters with immobilized biofilm for air and water, fluidized beds using sand carriers enhancing retention above 10 g per L, and

Ref: Chisti Bioreactors in Waste Management; EPA Bioreactor Design Manual 2002; Wang et al. Bioprocess Engineering principles.

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Bioremediation

Composting as a bioremediation method uses:

Composting as bioremediation modality exploits thermophilic and mesophilic microbial consortia developing during controlled decomposition of organic matter to co-metabolize and mineralize hazardous contaminants such as explosives trinitrotoluene, polycyclic aromatic hydrocarbons, chlorinated pesticides and petroleum hydrocarbons. System typically configured as aerated static windrows or mechanically turned piles where contaminated soil blended at 10 to 30 percent by volume with organic amendments including manure supplying nitrogen, straw providing carbon and structure, wood chips increasing p

Ref: Williams et al. Compost remediation of explosives 1992; EPA Composting Handbook; PubMed compost bioremediation mechanisms.

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Bioremediation

Land farming is characterized by:

Land farming represents oldest, simplest ex situ bioremediation for oily sludges from refineries and crude pits where biodegradable fraction high. Approach involves excavation, spreading soil in thin layer 30 to 50 cm over lined area with berms preventing runoff, periodic tilling every one to two weeks improving aeration 10-fold, breaking clods and mixing nutrients like urea, diammonium phosphate correcting deficiency. Indigenous degraders Pseudomonas aeruginosa, Arthrobacter, Rhodococcus and Aspergillus carrying alkane hydroxylases and catechol cleavage proliferate 10 to 100 fold oxidizing hy

Ref: EPA Landfarming Guidance 1994; Khan et al. Journal Environmental Management 2004 landfarm cost; PubMed low-cost remediation.

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Bioremediation

Biopile technique is an example of:

Biopile technique represents engineered ex situ bioremediation approach combining features of landfarming and composting but under more controlled conditions for petroleum-contaminated soils. Contaminated soil excavated from source zone, homogenized by screening to remove debris, mixed with amendments such as wood chips bulking agents enhancing permeability, fertilizers adjusting C:N:P ratio to 100:10:1, water to maintain 50 to 70 percent water holding capacity, sometimes microbial inocula, and heaped into above-ground mounds 2 to 3 meters high overlying impermeable high-density polyethylene l

Ref: EPA Biopile Design and Operation Manual 1995; Jorgensen et al. Biopile remediation Soil 2010; NCERT ex situ examples.

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Bioremediation

Surfactants enhance bioremediation by increasing:

Hydrophobic organic pollutants including crude oil aliphatic and polycyclic aromatic hydrocarbons, polychlorinated biphenyls and creosote components exhibit low aqueous solubility below 1 mg per L, strong sorption to soil organic matter estimated by high Koc, and presence as non-aqueous phase liquids limiting mass transfer to bacterial cells even when degradative enzymes encoded by alkB and nahAc are present. Addition of biosurfactants such as rhamnolipids composed of rhamnose glycosidically linked to beta-hydroxydecanoic acid from Pseudomonas aeruginosa, surfactin cyclic lipopeptide from Baci

Ref: Pacwa-Płociniczak et al. International Journal Molecular Sciences 2011 biosurfactants bioremediation; EPA surfactant enhanced recovery guide.

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Bioremediation

Which factor does NOT affect bioremediation?

Bioremediation success reflects interplay between microbial physiology and environmental physicochemistry governing enzymatic function, bioavailability and cell growth. Temperature directly influences membrane fluidity, protein folding and reaction rates according to Arrhenius relationship; mesophilic degraders exhibit optimum around 20 to 30 Celsius while psychrophiles slower and thermophiles require elevated energy for dioxygenase stability. pH around 6.5 to 8.0 maintains proton motive force across membrane, optimal ionization of catalytic residues histidine and aspartate in monooxygenase ac

Ref: EPA Factors affecting bioremediation 2000; Singh et al. Journal Environmental Biology 2008 environmental parameters; Campbell Ecology.

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Bioremediation

In situ bioremediation involves:

In situ bioremediation treats contamination directly within subsurface without excavation, preserving soil structure, minimizing disturbance to existing infrastructure and reducing expenses linked to transportation plus disposal. Treatment mobilizes indigenous microbes already adapted or introduced augmentative cultures capable of degrading target compounds within aquifer pores or vadose zone voids. Technologies include bioventing delivering low-flow air 1 to 3 cubic feet per minute per well to unsaturated zone to support aerobic oxidation of fuel hydrocarbons via alkane monooxygenase, biospar

Ref: EPA In Situ Bioremediation Technical Guide 2013; Bouwer & Zehnder Soil bioremediation; PubMed in situ review.

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Bioremediation

Bioremediation is defined as:

Bioremediation encompasses deliberate application of biological agents including bacteria, archaea, fungi and plants to neutralize, transform, degrade or immobilize environmental pollutants, ultimately converting hazardous organics into less harmful end products such as carbon dioxide, water, chloride and inorganic salts. Indigenous genera Pseudomonas, Sphingomonas, Rhodococcus harbor catabolic plasmids TOL encoding toluene degradation, OCT for octane, NAH for naphthalene, and chromosomal genes nahAc non-heme iron dioxygenase, alkB integral membrane alkane hydroxylase, xylE catechol 2,3-dioxyg

Ref: EPA Bioremediation overview https://www.epa.gov/remedy/bioremediation; Vidali I J Green Chem 2001; NCERT Environmental Biotechnology.

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