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STAMFORD UNIVERSITY BANGLADESH

Assignment OnMicrobial Bioremediation of Polluted

Environments

Submitted To

Dr. Md. Anisur Rahman Khan

Lecturer

Dept. of Microbiology

Stamford University Bangladesh

Submitted By

RIPAN CHANDRA DAS

ID : MBO 03605183

Batch : 36th

STAMFORD UNIVERSITY BANGLADESH

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Submission Date: 21/08/2011

Bioremediation

Remediate" means to solve a problem, and "bio-remediate" means to use

biological organisms to solve an environmental problem such as contaminated soil or

groundwater.

Bioremediation is the use of living microorganisms to degrade environmental

pollutants or to prevent pollution. In other words it is a technology for removing

pollutants from the environment thus restoring the original natural surroundings and

preventing further pollution.

The rapid expansion and increasing sophistication of the chemical industries in

the last century has meant that there has been increasing levels of complex toxic effluents

being released into the environment. Many major incidents have occurred in the past

which reveal the necessity to prevent the escape of effluents into the environment, such

as the Exxon Valdez oil spill, the Union-Carbide (Dow) Bhopal disaster, large -scale

contamination of the Rhine River, the progressive deterioration of the aquatic habitats

and conife r forests in the Northeastern US, Canada, and parts of Europe, or the release of

radioactive material in the Chernobyl accident, etc.

Principles of Bioremediation

Recent studies in molecular biology and ecology offers numerous opportunities for more

efficient biological processes. Notable accomplishments of these studies include the

cleanup of polluted water and land areas. Bioremediation is defined as the process

whereby organic wastes are biologically degraded under controlled conditions to an

innocuous state, or to levels below concentration limits established by regulatory

authorities (Mueller 1996). By definition, bioremediation is the use of living organisms,

primarily microorganisms, to degrade the environmental contaminants into less toxic

forms. It uses naturally occurring bacteria and fungi or plants to degrade or detoxify

substances hazardous to human health and/or the environment. The microorganisms may

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be indigenous to a contaminated area or they may be isolated from elsewhere and brought

to the contaminated site. Contaminant compounds are transformed by living organisms

through reactions that take place as a part of their metabolic processes. Biodegradation of

a compound is often a result of the actions of multiple organisms. When microorganisms

are imported to a contaminated site to enhance degradation we have a process known as

bioaugmentation. For bioremediation to be effective, microorganisms must enzymatically

attack the pollutants and convert them to harmless products (Vidali 2001). As

bioremediation can be effective only where environmental conditions permit microbial

growth and activity, its application often involves the manipulation of environmental

parameters to allow microbial growth and degradation to proceed at a faster rate. Like

other technologies, bioremediation has its limitations. Some contaminants, such as

chlorinated organic or high aromatic hydrocarbons, are resistant to microbial attack. They

are degraded either slowly or not at all, hence it is not easy to predict the rates of cleanup

for a bioremediation exercise there are no rules to predict if a contaminant can be

degraded. Bioremediation techniques are typically more economical than traditional

methods such as incineration, and some pollutants can be treated on site, thus reducing

exposure risks for cleanup personnel, or potentially wider exposure as a result of

transportation accidents.

Since bioremediation is based on natural attenuation the public considers it more

acceptable than other technologies. Most bioremediation systems are run under aerobic

conditions, but running a system under anaerobic conditions (Colberg and Young 1995)

may permit microbial organisms to degrade otherwise recalcitrant molecules.

Essential factors for microbial bioremediation

FACTOR DESIRED CONDITIONS

01. Microbial population 01. Suitable kinds of organisms that can

biodegrade all of the contaminants.

02. Oxygen 02. Enough to support aerobic

biodegradation.

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03. Water 03. Soil moisture should be from 50-70%

of the water holding capacity of the

soil.

04. Nutrients 04. Nitrogen, phosphorous, sulfur, and

other nutrients to support good

microbial growth.

05. Temperature 05. Appropriate temperature for

microbial growth ( 0-40 degree

Celsius )

06. Ph 06. Best range is from 6.5 to 7.5

Example of microorganisms involved in bioremediation process

Many different types of organisms such as plants can be used for bioremediation

but microorganisms show the greatest potential.

Microorganis ms (primarily bacteria and fungi) are nature's original recyclers.

Their capability to transform natural and synthetic chemicals into sources of energy and

raw materials for their own growth suggests that expensive chemical or physical

remediation processes might be replaced with biological processes that are lower in cost

and more environmentally friendly.

Microorganisms therefore represent a promising, largely untapped resource for

new environmental biotechnologies. Research continues to verify the bioremediation

potential of microorganisms. For example, a recent addition to the growing list of

bacteria that can reduce metals is Geobacter metallireducens, which removes uranium, a

radioactive waste, from drainage waters in mining operations and from contaminated

groundwaters. Even dead microbial cells can be useful in bioremediation technologies.

These discoveries suggest that further exploration of microbial diversity is likely to lead

to the discovery of many more organisms with unique properties useful in

bioremediation.

The use of microorganisms is not limited to one field of study of bioremediation,

it has an extensive use Petroleum, its products and oils constitute hydrocarbons and if

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present in the environment causes pollution. Oil slicks caused by oil tankers and petrol

leakage into the marine environment is now a constantly occurring phenomenon. A

number of microorganisms can utilize oil as a source of food, and many of them produce

potent surface-active compounds that can emulsify oil in water and facilitate its removal.

Unlike chemical surfactants, the microbial emulsifier is non-toxic and biodegradable.

The microorganisms capable of degrading petroleum include pseudomonads, various

corynebacteria, mycobacteria and some yeasts.

Apart from degrading hydrocarbons, microbes also have the ability to remove

industrial wastes, reduce the toxic cations of heavy metals (such as Selenium) to a much

less toxic soluble form. For example, plants like locoweed remove large amounts of the

toxic element selenium. The selenium is stored in plant tissues where it poses no harm

until and unless the plant is eaten. Many algae and bacteria produce secretions that attract

metals that are toxic in high levels. The metals are in effect removed from the food chain

by being bound to the secretions. Degradation of dyes are also brought about by some

anaerobic bacteria and fungi.

To boost the worlds food production rate to compensate for the increasing

population, pesticides are being used. The extensive use of these artificial boosters have

lead to the accumulation of artifical complex compounds called xenobiotics. By

introducing genetically altered microbes, it is possible to degrade these compounds. Once

again thanks to the bioremediation technology.

1. Pseudomonas putida

2. Dechloromonas aromatica

3. Nitrosomonas europaea

4. Nitrobacter hamburgensis

5. Paracoccus denitrificans

6. Deinococcus radiodurans

7. Methylibium petroleiphilum

Types of bioremediation

There are three main types of bioremediation, such as

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1. Biostimulation

2. Bioaugmentation

3. Intrinsic bioremediation

Describe the given below above the following point :

01. Biostimulation

Nutrient and oxygen in a liquid or gas form are added to contaminated water or soil to

encourage the activity of bacteria already existing in the soil or water. The disappearance

of contaminants is monitored to ensure that remediation occurs.

02. Bioaugmentation

Microorganisms that can clean up a particular contaminant are added to the contaminated

soil or water. Bioaugmentation is more commonly and successfully used on contaminants

removed from the original site, such as in municipal wastewater treatment facilities.

4. Intrinsic bioremediation

Also known as natural attenuation, this type of bioremediation occurs naturally in

contaminated soil or water.

Bioremediation strategies

Different techniques are employed depending on the degree if saturation and aeration of

an area. In situ techniques are defined as those that are applied to soil and ground water at

the site with minimal disturbance. Ex situ techniques are those that are applied to soil and

ground water at the site which has been removed from the site via excavation or

pumping. Bioaugmentation techniques involve the addition of microorganisms with the

ability to degrade pollutants.

In situ bioremediation

These techniques are generally the most desirable options due to lower cost and less

disturbance since they provide the treatment in place avoiding excavation and transport of

contaminants. The most important land treatments are :

** Bioventing : Bioventing is the most common in situ treatment and involves supplying

air and nutrients through wells to contaminated soil to stimulate the indigenous bacteria.

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** In situ biodegradation : In situ biodegradation involves supplying oxygen and

nutrients by circulating aqueous solution through contaminated soil to stimulate naturally

occurring bacteria to degrade organic contaminants.

**Biosparging : Biosparginginvolves the injection of air under pressure below the water

table to increase groundwater oxygen concentration and enhance the rate of biological

degradation of contaminants by naturally occurring bacteria.

** Bioaugmentation : Bioaugmentation frequently involves the addition of

microorganisms indigenous or exogenous to the contaminated sites.

Advantages of in situ bioremediation

1. The method ensures minimal exposure to public or site personnel.

2. There is limited or minimal disruption to the site of bioremediation.

3. Due to these factors it is cost effective.

4. The simultaneous treatment of contaminated soil or water is possible.

Disadvantages of in situ bioremediation

1. The sites are directly exposed to environmental factors like temperature, oxygen

etc.

2. The seasonal variation of microbial activity exists.

3. Problematic application of treatment additives like nutrients, surfactants, oxygen

etc.

4. It is a very tedious and time consuming process.

Ex situ bioremediation

These techniques involve the excavation or removal of contaminated soil from ground.

** Landfarming is a simple technique in which contaminated soil is excavated and

spread over a prepared bed and periodically tilled until pollutants are degraded.** Composting is a technique that involves combining contaminated soil with non

hazardous organic amendants such as manure or agricultural waste.

** Biopiles are a hybride of landfarming and composting.

** Bioreactors slurry reactors or aqueous reactors are used for ex situ treatment of

contaminated soil and water pumped up from a contaminated plume.

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Advantages of ex-situ bioremediation

1. As the time required is short, it is a more efficient process.

2. It can be controlled in a much better way.

3. The process can be improved by enrichment with desired and more efficient

microorganisms.

Disadvantages of ex-situ bioremediation

1. The sites of pollution remain highly disturbed.

2. Once the process is complete, the degrade waste disposal becomes a major

problem.

3. It is a costly process.

Uses of bioremediation

1. On site treatment of the chemical substances to reduce risk to acceptable level.

2. Off site treatment of excavated soil to reduce risk to acceptable level, after which

the treated soil is returned to the site.

3. Containment of soil on site with a properly designed barrier.

4. Disposal of affected soil to an approved landfill.

Biotechnology in Pollution Management

Biotechnology can be applied to assess the well being of ecosystems, transform

pollutants into benign substances, generate biodegradable materials from renewable

sources and develop environmentally safe manufacturing and disposal processes.

Biotechnology utilizes the application of genetic engineering to improve the efficiency

and cost, which are key factors in the future widespread exploitation of microorganisms

to reduce the environmental burden of toxic substances. Keeping in view of the urgent

need of a most efficient environmental biotechnological process, researchers have

devised a technique called bioremediation, which is an emerging approach to

rehabilitating areas contaminated by pollutants or otherwise damaged through

ecosystem mismanagement. Bioremediation applies living microorganisms to degrade

environmental pollutants or to prevent pollution or it is a technology for removing

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pollutants from the environment thus restoring the original natural surroundings and

preventing further pollution. The rapid expansion and increasing sophistication of the

chemical industries in the last century has meant that there has been increasing levels of

complex toxic effluents being released into the environment (Vidali 2001). Many

major incidents have occurred in the past which reveal the necessity to prevent the

escape of effluents into the environment, such as the Exxon Valdez oil spill, the

UnionCarbide

(Dow) Bhopal disaster, largescale

contamination of the Rhine River,

the progressive deterioration of the aquatic habitats and conifer forests in the

Northeastern US, Canada and parts of Europe, or the release of radioactive material in

the Chernobyl accident, etc. The conventional techniques used for remediation have been

to dig up contaminated site and remove it to a landfill, or to cap and contain the

contaminated areas of a site. The methods have some drawbacks. The first method simply

moves the contamination elsewhere and may create significant risks in the excavation,

handling, and transport of hazardous material. Additionally, it is very difficult and

increasingly expensive to find new landfill sites for the final disposal of the material. The

cap and contain method is only an interim solution since the contamination remains on

site,requiring monitoring and maintenance of the isolation barriers long into the future,

with all the associated costs and potential liability. A better approach than these

traditional methodsis to completely destroy the pollutants if possible, or at least to

transform them to innocuous substances. Some technologies that have been used are

hightemperature incineration and various types of chemical decomposition.

Bioremediation is an option that offers the possibility to destroy or render harmless

various contaminants using natural biological activity (Gupta 2003). As such, it uses

relatively lowcost, lowtechnology techniques, which generally have a high public

acceptance and can often be carried out on site. It will not always be suitable, however, as

the range of contaminants on which it is effective is limited, the time scales involved are

relatively long and the residual contaminant levels achievable may not always be

appropriate. Although the methodologies employed are not technically complex,

considerable experience and expertise may be required to design and implement a

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successful bioremediation program, due to the need to thoroughly assess a site for

suitability and to optimize conditions to achieve a satisfactory result. Because

bioremediation give the impression a good alternative to conventional cleanup

technologies.

Some groups of microbes

1.Aerobic: Examples of aerobic bacteria recognized for their degradative abilities are

Pseudomonas, Alcaligenes, Sphingomonas, Rhodococcus, and Mycobacterium. These

microbes have often been reported to degrade pesticides and hydrocarbons, both

alkanes and polyaromatic compounds. Many of these bacteria use the contaminant as

the sole source of carbon and energy.

2. Anaerobic. Anaerobic bacteria are not as frequently used as aerobic bacteria. There is

an increasing interest in anaerobic bacteria used for bioremediation of polychlorinated

biphenyls (PCBs) in river sediments, dechlorination of the solvent trichloroethylene

(TCE) and chloroform.

3. Ligninolytic fungi. Fungi such as the white rot fungusPhanaerochaete chrysosporium

have the ability to degrade an extremely diverse range of persistent or toxic

environmental pollutants. Common substrates used include straw, saw dust, or corn

cobs.

4. Methylotrophs. Aerobic bacteria that grow utilizing methane for carbon and energy.

The initial enzyme in the pathway for aerobic degradation, methane monooxygenase,

has a broad substrate range and is active against a wide range of compounds,

including the chlorinated aliphatic trichloroethylene and 1, 2dichloroethane.

For degradation it is necessary that bacteria and the contaminants must be in contact. This

is not easily achieved, as neither the microbes nor contaminants are uniformly spread in

the soil. Some bacteria are mobile and exhibit a chemotactic response, sensing the

contaminant and moving toward it. Other microbes such as fungi grow in a filamentous

form toward the contaminant. Many different types of organisms such as plants can be

used for bioremediation but microorganisms show the greatest potential. Microorganisms

primarily bacteria and fungi are nature's original recyclers. Their capability to transform

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natural and synthetic chemicals into sources of energy and raw materials for their own

growth suggests that expensive chemical or physical remediation processes might be

replaced with biological processes that are lower in cost and more environmentally

friendly. Therefore, microorganisms represent a promising, largely untapped resource for

new environmental biotechnologies. Research continues to verify the bioremediation

potential of microorganisms. For instance, a recent addition to the growing list of bacteria

that can reduce metals is Geobacter metallireducens, which removes uranium, a

radioactive waste from drainage waters in mining operations and from contaminated

groundwater. Even dead microbial cells can be useful in bioremediation technologies.

These discoveries suggest that further exploration of microbial diversity is likely to lead

to the discovery of many more organisms with unique properties useful in bioremediation

(U.S. EPA Seminars 1996). Application of microorganisms is not limited to one field of

study of bioremediation, it has an extensive use Petroleum, its products and oils

constitute hydrocarbons and if present in the environment causes pollution. Oil slicks

caused by oil tankers and petrol leakage into the marine environment are now a

constantly occurring phenomenon. Several microorganisms can utilize oil as a source of

food, and many of them produce potent surfaceactive

compounds that can emulsify oil in water and facilitate its removal. Unlike chemical

surfactants, the microbial emulsifier is nontoxic and biodegradable. The microorganisms

capable of degrading petroleum include pseudomonads, various corynebacteria,

mycobacteria and some yeast (Mueller 1996). Apart from degrading hydrocarbons,

microbes also have the ability to remove industrial wastes, reduce the toxic cations of

heavy metals to a much less toxic soluble form. For instance, plants like locoweed

remove large amounts of the toxic element selenium. The selenium is stored in plant

tissues where it poses no harm until and unless the plant is eaten. Many algae and

bacteria produce secretions that attract metals that are toxic in high levels. The metals are

in effect removed from the food chain by being bound to the secretions. Degradation of

dyes is also brought about by some anaerobic bacteria and fungi (Colberg 1995). To

boost the worlds food production rate to compensate for the increasing population,

pesticides are being used. The extensive use of these artificial boosters has lead to the

accumulation of artificial complex compounds called xenobiotics. By introducing

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genetically altered microbes, it is possible to degrade these compounds. Effect of crude

oil pollution on the environment and on microbial populations The toxicity of crude oil

or petroleum products varies widely, depending on their composition and concentration,

on environmental factors and on the biological state of the organisms at the time of the

contamination. Petroleum distillates up to and including gas oils are more severely toxic

on a short time scale than the other components of crude oil. In heavily polluted areas,

there are immediate detrimental effects on plant and animal life, including agriculture

(Baker, 1970 Steinhart and Steinhart, 1972 Rowell, 1977 Fagbami et al., 1988

NDWC., 1995). Nevertheless, different species and different life stages of organisms

have different susceptibilities to pollution (Nelson-Smith, 1973).

In addition to its effects on visible plants and animals, petroleum contamination impacts

microbial populations (Ahearn and Meyers, 1976). The effect of oil on microbial

populations depends upon the chemical composition of the oil and on the species of

microorganisms present.

Populations of some microbes increase typically, such microbes use the petroleum

hydrocarbons as nutrients. The same crude oil can favor different genera at different

temperatures (Westlake et al., 1974). However, some crude oils contain volatile

bacteriostatic compounds that must degrade before microbial populations can grow (Atlas

and Bartha, 1972 Atlas, 1975).

On the other hand, some microbial populations decrease or show a neutral response to

petroleum hydrocarbons. The overall effects of petroleum hydrocarbons on total

microbial diversity remain unclear.

Remediation of crude oil-polluted sites

Methods for restoring oil-polluted sites vary from complete removal of the affected soil

to doing nothing at all and letting nature take its course (McGill and Nyborg, 1975).

Natural revegetation of an area affected by light crude oil spillage has occurred without

any special treatment (Baker, 1970 Stebbings, 1970 Odu, 1978). At low levels of

contamination of crude oil, cultivation of soil without nutrient amendment is possible

(Toogood, 1974).

Physical methods such as incineration may destroy indigenous organisms, including oil-

degrading microbes, and increase the toxicity of the petroleum residue. Sinking the oil

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with heavy hydrophobic agents such as ground chalk merely removes the oil to anaerobic

sediments or deep ocean floor, where long persistence of the oil pollutant is bound to

occur. Large quantities of oil accumulating on the bottom foul the ocean floor and also

tend to coalesce and rise again as large droplets. Mechanical removal of stranded oil from

sand dunes or salt marshes is far more damaging than leaving it alone: Not only is the

ecological balance disturbed, but the aesthetic effect may also be irreparable (Nwangwu

and Okoye, 1981).

Chemical methods for removing or dispersing spilled oil from the environment were

condemned by Nelson-Smith (1973) because of their side-effects on the ecosystem and

their toxicity, which is sometimes more pronounced than that of the oil itself. Chemical

dispersants may inhibit microbial activity by damaging cell membranes or essential

enzymes, or by altering the surface tension of the water in which microbes live.

Furthermore, dispersed oil is never recovered from the environment, and its ultimate fate

remains unknown. The parameters of bioremediation processes The factors that must be

optimized for successful bioremediation are: oxygen and inorganic nutrients, pH,

temperature, water availability, and adsorption effects.

Adequate supply of oxygen and inorganic nutrients

Most fungi and bacteria that degrade petroleum hydrocarbons require free or dissolved

oxygen (Odu, 1981). In the presence of adequate oxygen, oil degradation also requires

mineral elements such as C, Ca, Mg, K, S, Fe, N, P and various trace elements (Odu,

1978).

pH

The optimum pH for biodegradation of hydrocarbons is around pH 6 8 (Mentzer and

Ebere, 1996). Biodegradation of crude petroleum in an acid soil (pH 4.5) could be

doubled by liming to pH 7.4.

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Temperature

Temperature as a limiting factor does not seem to be a problem in tropical and temperate

zones. Disappearance of hydrocarbon contaminant from agricultural land can be

correlated with monthly temperature averages (Dibble and Bartha, 1979) generally,

hydrocarbon biodegradation increases with temperature and peaks around 30 40oC

(Mentzer and Ebere, 1996).

Water availability

Soil that is hydrated with 50% to 80% of the maximum water-holding capacity has the

greatest microbial activity (Mentzer and Ebere, 1996). Below that level, osmotic and

Adsorption Effects

Hydrocarbons that are adsorbed onto organic matter are less susceptible to microbial

attack. Indeed, the rate-limiting process in biodegradation may be the desorption of

contaminants (Mentzer and Ebere, 1996).

Alternative Bioremediation Technologies

The bioremediation technologies for responding to oil spills may be divided into three

categories:

Seeding with Naturally-Occurring Microorganisms

Microbial seeding of petroleum-polluted sites has been proposed by a number of

investigators as an alternative to mechanical removal (Obire, 1988, 1990). An active

remediation programme using adapted microbes will yield significantly greater,

commercially viable rates of oil removal than the experimental rates already reported

(Obire, 1988).

Seeding with Genetically-Engineered Microorganisms

Fungi and bacteria can be genetically engineered to detoxify man-made pollutants

(Ogden and Adams, 1989). The oil service industry already utilizes genetically

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manipulated microbes as producers of surfactants and polysaccharide polymers

(Chakrabarty,1985 1986).

The use of mutant organisms to get rid of spilled oil has merits and demerits. The

induction of a wild type strain by a mutagen such as acridine orange may lead to

enhanced ability to degrade oil but it may be difficult to get rid of the mutant population

after the desired effect (Obire, 1990). However, disinfectants that selectively kill mutant

strains, rather than wild-types, could be used. The disadvantage is that irrelevant genes

can also be affected by direct mutation processes. The actual genetic engineering of the

relevant genes is what is necessary.

Nutriation (Nutrient Enrichment)

Nutrient imbalance can hinder biodegradation. Inadequate provision of nitrogen,

phosphorus, potassium and sulphur (which is probably the most important and the most

easily modified of all the factors) could limit the rate of hydrocarbon degradation in the

terrestrial environment (McGill and Nyborg, 1975).

According to the United States Office of Technology Assessment (1990), the addition of

limiting nutrients to the spill site is necessary.

There are enough hydrocarbon-utilizing organisms in the soil environment to perform

biodegradation once nutrient limitation is alleviated (Stone et al., 1942). Soybean lecithin

and ethyl allophanate, which are natural phospholipids, are the best available phosphorus

and nitrogen sources, respectively, for microorganisms that degrade oil (Olivieri et al.,

1978).

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Interaction between Microorganisms and Hydrocarbons Petroleum contains a wide range

of organic compounds that are nutrients for microorganisms. Petroleum degradation is

primarily an oxidation process, although there is some evidence for anaerobic

hydrocarbon degradation (Gutnick and Rosenberg, 1977). Microbes capable of degrading

petroleum hydrocarbons share the following characteristics:

Efficient hydrocarbon uptake via special receptor sites for binding hydrocarbons

and/or unique compounds that assist in the emulsification and transport of

hydrocarbons into the cell.

Enzymes that introduce molecular oxygen into the hydrocarbon and generate

intermediates that subsequently enter common energy-yielding catabolic

pathways.

Inducer specificity: Exposure to petroleum and its constituents activate the two

systems above.

Fungi as agents of bioremediation

Fungi can possess all three traits, are found in oil-contaminated environments, and are

known to degrade hydrocarbons (Llanos and Kjoller, 1976). Further, the ease of

transportation, genetic engineering, and scaling-up makes fungi the organisms of choice

in bioremediation. In a taxonomic study of fungi, Nyns et al. (1969) found that

hydrocarbon assimilation is most common in the orders Mucorales and Monilales, as well

as in the genera Aspergillus and Penicillium (order Eurotiales). Furthermore, in

comparison with eight other genera, Aspergillus and Penicillium species were the most

efficient metabolizers of hydrocarbons (Obire et al., 2008). Hydrocarbon assimilation

was, however, relatively rare, and was a property of individual strains, not of species or

higher taxa (Nyns et al. 1968). Nevertheless, diverse fungi have been isolated from oil-

contaminated environments, and/or shown to degrade hydrocarbons in the lab. As one

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striking example, yeast populations in a fresh water stream increased by several orders of

magnitude in the five days after an oil spill (Turner and Ahearn, 1970, cited by Jones,

1976).

In addition to degrading hydrocarbons directly, fungal mycelia can penetrate oil, thereby

increasing the surface area available for biodegradation and bacterial attack. Fungi can

also grow under environmentally stressed conditions such as low pH and poor nutrient

status, where bacteria growth might be limited (Davis and Westlake, 1979). It was also

reported that although bacteria initiated the degradation of a synthetic petroleum mixture,

twice as much was degraded when both bacteria and fungi were present.

Species in many fungal genera are known to metabolize hydrocarbons/ and or thrive in

oil-contaminated sites. They include: Acremonium (Llanos and Kjoller, 1976)

Aspergillus (Bartha and Atlas, 1977 Obire et al., 2008).

Fungi for bioremediation in the Niger Delta

Although there have been reports of commercial production of fungal and bacteria

inocula for treatment of oil spills in developed countries (Bartha and Atlas, 1977), species

of microorganisms are habitat specific (Obire, 1988). One region that might benefit from

fungal bioremediation is the Niger Delta. Nigeria is one of the worlds largest producers

of crude oil. In recent times, the Niger Delta region has become a hotbed of violent

conflicts that portend several dangerous outcomes for national political and socio-

economic stability. These conflicts, exacerbated by environmental factors, have also

affected the oil industry, as well as international economies and security. Table 1 shows

the oil spillage data in the Eastern Operations in Nigeria.

In petroleum-producing regions of Nigeria, Obire (1988) found several species oil-

degrading aquatic fungi in the genera Candida, Rhodotorula, Saccharomyces and

Sporobolomyces (yeasts) and, among filamentous fungi, Aspergillus niger, Aspergillus

terreus, Blastomyces sp., Botryodiplodia theobromae, Fusarium sp., Nigrospora sp.,

Penicillium chrysogenum, Penicillium glabrum, Pleurofragmium sp., and Trichoderma

harzianum.

In Nigeria, no information is yet available regarding the commercial production of fungi

or microbial inocula for use in bioremediation of oil polluted environments.

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References

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2009-08-31. Retrieved 2011-03-22.

02.Meagher, RB (2000). "Phytoremediation of toxic elemental and organic pollutants".

Current Opinion in Plant Biology 3 (2): 153162. doi:10.1016/S1369-5266(99)00054-0.

PMID 10712958.

03.Diaz E (editor). (2008). Microbial Biodegradation: Genomics and Molecular Biology

(1st ed.). Caister Academic Press. ISBN 1904455174. ISBN 978-1-904455-17-2.

04.Agarwal SK, 1998, Environmental Biotechnology, (1 st ed), APH Publishing

Corporation, New Delhi, India, pp 267289.

05.Anon. (1990). Bioremediation of Alaskan sites on the way. Oil and Gas Journal

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