| or different microbial species into the environment to







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 Consider a
scenario in which an Oil carrying ship, XYZ has grounded at seaport and its oil spill contaminated the
seashore and the surrounding area badly. The sea water as well as the marine
life has been affected severely. Analyze the techniques that can be applied to
rehabilitate and restore the sea water and the marine life; by keeping in view
the knowledge of bioremediation.

Answer: Here is detailed answer of this question


Bioremediation is the application of biological process principles to
the treatment of groundwater, soil and sludge contaminated with spilled oil and
hazardous chemicals. Chemical substances are
degraded by bacteria and other microorganisms.

Oil spill

An oil spill is the release of a liquid petroleum hydrocarbon into the
environment, especially the marine ecosystem, due to human activity, and is a
form of pollution.

Environmental Impact
of oil spill

Oil spill have negative environmental impact both short
term and long term. Chemical toxicity on environment means chemicals within the
oil spill area are absorbed into tissues of plants and animals and could create
both non-lethal and non-lethal effects depending on the chemical. Crude oil can
contain nickel, benzene, toluene and many more toxic substances. Other problem
that can occur of physical smothering of organisms, ecological change and also
other indirect changes oil.



Oil spill from this ship can be remediated by
bioremediation and bioremediation communities can be enhanced by
bioaugmentation, biostimulation or a combination of both technologies.

To use these technologies firstly we will must consider

Type of spill or contamination

Location where oil spilled

Proximity to sensitive environment


Having knowledge about these
factor will help us in selection of type of bacteria that we can use for
remediation because many times specific type of bacteria can degrade specific
matter in contamination.


Single strain mix cultures with or without genetic
engineered organisms are added to the site of interest. Its purpose is to
introduce more or different microbial species into the environment to better
reduce the oil in the natural flora can achieve.

Bioaugmentation with additional bacteria may become necessary when
bacteria capable of remediating an effective site or present. In fact
insufficient population of microbes may be present and can break down the whole
amount of oil because of this oil may persist for decades especially on the shoreline.
Even if there is a sufficient population, component of oil still may persist
because the species present are not capable of breaking down all of the
chemical components of the oil. in other instances the site may be entirely
lacking in bacteria capable of degrading oil.

Factors to consider

Before beginning the process of bioremediation for degradation of oil
spill on seashore and in the ocean, we must consider the following factors:

The chemical composition of the oil as some species break down only some
chemical components of the oil such as alkanes, aromatics etc.

The concentration and physical state of the oil is also important even
oil degrading bacteria can’t break down a toxic level of oil.

How successfully inoculate the site with bacteria if using a culture and
the ramification might be if the culture becomes the dominant species.

Strain selection

Either we use single strain or microbial consortium it must be highly
adapted to the affected environment a single strain

One option for bioaugmentation is using a single strain of microbes.
Culturing it and introducing it to the affected site so that it can degrade the
oil at an enhanced rate. Studies shows that this is often more effective in the
beginning of a remediation treatment but rate of oil decomposition soon become
what they may have been naturally without the addition of larger populations of
bacteria .even when the strain being used as one taken directly from the
effective site and cultured with the same the same pattern continues to emerge.
This early high efficacy is probably due to large population and introduction
which then rapidly declines in number before setting. a microbial consortium

More than one species may also be used. Using multiple species allows for
metabolic diversity and enhance the degradation rate. These cultures may
struggle in the natural environment they are needed to function in pH,
temperature change, water availability and toxic pollutant levels. Techniques

Use of genetically engineered strains and plasmid genes have been
isolated and cloned for the ability to degrade oil and have been engineered
into streams used in remediation.Foregin DNA being inserted into the culture.
Genes could be introduced to native species using other genetic vectors such as

Improvement for success

Some steps can be taken to increase treatment success when using
cultures and even a successful lab test environmental seeding may still fail.
Sometimes added food source such as through the process of nutrient
augmentation can help to increase tlhe chances of culture surviving.

Select native to the site that has been selected for augmentation. This
strain can be cultured and then reintroduced and studies show that they often
survive more successfully then they are introduced non-native counterparts.
Moreover few more factors taken into account that can lead to failure in
process that are:

Loss of microbial viability during inoculation

Eventual cell death after inoculation

Competition for nutrients by microbes





Biostimulation refer
to addition of nutrients, an electron acceptor is such as nitrogen, oxygen or
phosphorus that may otherwise be acting as a limited nutrients and the
biological degradation of the contaminant.


Nutrients added for this purpose are divided into two

Micronutrients-required in small amount for enzyme function
and protein structure. Mostly inorganic compound such as zinc, cobalt,
manganese etc.

Macronutrients-required in large quantities and includes
nitrogen, phosphorus, and sulphur. Oxygen is also required in large quantity because
most of the oil degrading bacteria area aerobic in nature. Carbon is also
considered a macronutrient for cellular growth in oil spill remediation that
will pour hydrocarbons act as a carbon source while hydrogen atom in
hydrocarbons maintains the pH.

Limiting nutrients and nutrients that are not in high
enough quantity within the site for the microbes to fully or quickly enough
degrade the oil. Whenk oil spilled microbial communities that can consume that
will begin to degrade but may not be able to fully reduce the hydrocarbons to
CO2  because microbial
population is lacking vital nutrients such as nitrogen and phosphorus for
continued growth. The most common limiting nutrient added for biostimulation in
oil spill are the macronutrients and more specifically oxygen, nitrogen and

Addition of nutrient
in effected environment

Biostimulation can be performed either in situ or ex
situ.insitu being injecting the nutrients into the environment and exsitu being
the process of removing the contaminated solar water treating

it outside of the contaminated environment that are placing the
solar water back into its original location.gases, nutrients injunction is an
application need where oxygen is a limiting nutrient.Bioventing is the most
common method for all spill degradation soil and water.bioventing provides a
very low airflow to not disrupt the environment.the goal is to reach a desired
oxygen content within a contaminated set that is necessary for microbes to
fully reduce the hydrocarbons to carbon dioxide hydrocarbons to carbon dioxide oxygen.
enhancement can also be achieved by injecting liquid hydrogen peroxide.
hydrogen peroxide is readily converted into oxygen and water and the
environment thus yielding higher oxygen content within the areas of injection.
however hydrogen peroxide can have negative effects on the microbes.required
for the old reduction so Apollo study prior to injection would be the best way to determine how much hydrogen peroxide should be added nutrients Fleury injection
is the most common biostimulation practice and refers to the addition of nitrogen phosphorus or any nutrient that may be limiting microbial kinetics. common nutrient products include mineral
salts ,salts such as potassium nitrate,
sodium nitrate ammonium nitrate, potassium phosphate or any commercial garden
fertilizers such as a 23 2 – nitrogen
phosphorus fertilizer .for the marine
environment the typical application of
nutrients is with a spreading of
soluble granules or a slurry spray.

Site specifics

 each remediation site-specific in the mountain nature is needed and the particular ratios and nutrients
required but laboratory results have
shown that the optimum ratio and
microbial degradation of oil is with a 100 to
10 of one carbon to nitrogen to
phosphorus ratio. also the compound in which
the nutrient is found depends on the
environment for example the addition of
nitrogen could be through potassium
nitrate or ammonium nitrate.there are
also options on the top of nutrient
that is water soluble slow release or  hydrophilic water soluble compounds are typically granules and are readily available. For microbial uptake and the ratio of nutrients is easily achieved
and but these water soluble compounds have a high potential for washout slow release nutrients could be a better choice depending on the environment
particularly in high washout areas in a lot
with a lot of tidal movement these
nutrients consists of a hydrophobic outer
layer which is usually vegetable oil.

 slow-release nutrients provide a continuous source of nutrient but the rate at which the nutrient is released is difficult to control olioPHILIC nutrients are nutrients dissolve in oil. these
nutrients adhere to oil so they are at the
old water interface making them
readily available to microbes however this nutrient method is expensive and
contains hydrocarbons in itself that could
compete with the oil as a carbon source
for the microbes. some bio stimulation
is important to know as much about the
environment as possible so if they by
stimulation efforts do not describe the
current ecosystem with eutrophication of
waterways or air of control microbial growth populations and areas that may be sensitive to microbial community changes
BIOstimulation has been proven to be
a successful about remediation
enhancement. effort and with new tackled
technologies such as olioPHILIC  nutrients they can become an even better by remediation technique for old degradation.

oil has been treated in bio
remediation trials by either bio
stimulation by augmentation or both processes


Biostimulation had little effect of oil degradation efficacy but interestingly
showed no change in dominance of
species but then later post trial showed
greater biodiversity this was very
different from the bioaugmentation trial which changed the  community
composition over time this exemplified a
previously mentioned concern of that
possibility the  scientists from
the mesocosm trial and from other
research we read came to the same conclusion
that a combination of bioremediation
strategies would be most effective


we came to the following conclusions after
reading varying research the characteristics of the target site will greatly influence
the techniques used for bioremediation this is mainly due to varying
environmental factors such as pH and temperature as well as other species in the environment. bioaugmentation seems to lead to more efficient oil degradation
but only if indigenous microbes are cultured and  used as opposed
to non-native microbial species both
techniques have their issues when used
individually but a combination of
strategies may be the answer using a combination of bio augmentation and bio stimulation may allow for more
oil to be broken down as  it will be easier to break down difficult to degrade chemical components  of oil.