Environmental Biotech

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Oct 22, 2013 (3 years and 9 months ago)

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Environmental biotechnology

Environmental biotechnology includes the application of biotechnology
processes or products to any aspects of the environment.

biotechnology is being utilised to tackle :


pollution and contamination which has already affected land, water and
air, this includes a range of techniques to reduce or remove xenobiotics
from contaminated environments.



Processing of current waste streams from industry, agricultural and
domestic homes. Wastewater treatment exploits the natural capabilities
of living organisms to reduce the polluting potential of effluents.


Devising new reduced
-
waste, renewable, environmentally friendly
technologies to replace current industrial processes. The development of
“clean industries” is a potentially huge growth area for environmental
biotechnology.


The improvement of crops or livestock through genetic manipulation.

How useful is biotechnology within the environmental sector?


Since all commercial industries produce some form of waste there are
almost no limits to the types of business (chemical, pharmaceutical, leisure,
manufacturing, energy generation, agriculture
etc
.)to which environmental
biotechnology can be applied .


The increasing costs of waste disposal have resulted in a greater emphasis
on identifying less expensive mechanisms of dealing with waste.


the key drivers for this increase are likely to be:


an increased acceptance of biotechnology for clean manufacturing
processes and the production of energy.


The production of bioethanol from sugar cane has been use to provide an
energy source in developing countries.


increased landfill charges and waste management legislation changes


Biotechnology makes significant
contributions to Environmental
technology

1.
Molecular ecology

2.

Bioremediation

3.
Biosensors

4.
Various
Environmental
applications of genetically
modified organisms

5.

Biofuels

6.
Process improvement



1.

Molecular Ecology

Understanding nature by molecular techniques
of:


DNA fingerprinting

for population genetic
studies; become more important for
biodiversity research to study kinship
relationship


Authentication
; inspect endangered
species with minimal samples using non
-
invasive technique


Forensic

analysis, to properly identify the
“evidence” for species identification

WHAT FOR?


Phylogenetic study
: e.g. horse family; compare
between species or strains.


Population study
: compare within species
collected from different locations, e,g, compare
between Asian and African populations.
Molecular Ecology.


Authentication study
: external morphology
cannot give positive identification of a species,
e.g. specimen of meat samples or dried plants
ground in powder form.



2.
Bioremediation (site restoration) and
Biotechnology for Waste Treatments


Ocean ranching

for stock restoration (e.g. cultured
salmon, grouper and abalone released to the sea or
artificial reef).


Recovering

of damaged sites to a “clean” or less
harmful site after dredging.


Remove chemicals

using biological treatments on
site (in situ) or ex situ.


Chemicals:

heavy metals, trace organics or mixtures.


Bacterial or fungal degradation of chemicals


Engineered microbes for better and more efficient
removal of chemicals on
-
site


Problems with bioremediation


Work
in vitro
, may not work in large scale.
Work well in the laboratory with simulation,
may not work in the field. Engineering
approach is needed.


Alternatively, select adapted species on site
(indigenous species) to remediate similar
damage.


Most sites are historically contaminated, as a
results of the production, transport, storage or
dumping of waste. They have different
characteristics and requirements.


Those chemicals are persistent or recalcitrant
to microbial breakdown.


Use of bacteria in bioremediation


Greatly affected by unstable climatic and
environmental factors from moisture to
temperature.


For examples, pH in soil is slightly acidic;
petroleum hydrocarbon degrading bacteria do
not work well < 10 C.


These microbes are usually
thermophilic
anaerobic
.


Fertilizers are needed. Seeding or
bioaugmentation could be useful too.


They contain monooxygenases and
dehydrogenases to break down organic
matters including most toxic substances.


Soil and land treatment:



Both in situ (in its original place) and ex situ (somewhere else)methods
are commercially exploited for the cleanup of soil and the associated
groundwater.



In situ treatments may include the introduction of micro
-
organisms
(bioaugmentation), ventilation and/or adding nutrient solutions
(biostimulation).


Ex situ treatment involves removing the soil and groundwater and
treating it above ground in fermenters or barns at higher temperatures



Biorestoration using plants is often cheaper than physical methods and
its products are harmless if complete mineralisation takes place.


Bioremediation using plants is called phytoremediation.


already used to remove metals from contaminated soils and
groundwater and is being further explored for the remediation of other
pollutants. The combined use of plants and bacteria is also possible.

Solid wastes


Anaerobic digestion of solid wastes in high
-
rate
anaerobic digesters has gained increasing
public acceptance because it permits the
recovery of substantial amounts of high
-
value
biogas together with a high quality stable
organic residue and without giving rise to
environmental nuisance.


Anaerobic digestion of mixed solid wastes is
under intensive development because in the
near future it may be an important step in
recycling of solid wastes and constitute an
alternative to incineration

Composting solid wastes

End product

Pseudomonas


Genetically engineered bacteria
(
Pseudomonas
) with plasmid producing
enzymes to degrade octane and many
different organic compounds from crude
oil.


However, crude oil contains thousands
of chemicals which could not have one
microbe to degrade them all.


Controversial as GE materials involved.

Use of fungi in bioremediation


Lipomyces

can degrade paraquat (a
herbicide).


Rhodotorula

can convert benzaldehyde to
benzyl alcohol.


Candida
can degrade formaldehyde.


Gibeberella

can degrade cyanide.


Slurry
-
phase bioremediation is useful too but
only for small amounts of contaminated soil.


Composting can be used to degrade
household wastes

White rot fungi


White rot fungi can degrade organic
pollutants in soil and effluent and
decolorize kraft black liquor, e.g.
Phanerochaete chrysosporium

can
produce aromatic mixtures with its
lignolytic system.


Pentachlorophenol,
dichlorodiphenyltrichloroethane (e.g.
DDT), even TNT (trinitrotoluene) can be
degraded by white rot fungi.


Phyto
-
remediation


Effective and low cost


Soil clean up of heavy metals and organic
compounds.


Pollutants are absorbed in roots, thus plants
removed could be disposed or burned.


Sunflower plants were used to remove
cesium and strontium from ponds at the
Chernobyl nuclear power plant.


Transgenic plants with exogenous
metallothionein (a metal binding protein) used
to remove metals .


Waste water and industrial effluents:


Micro
-
organisms in sewage treatment plants remove
the more common pollutants from waste water before it
is discharged into rivers or the sea.


Increasing industrial and agricultural pollution has led to
a greater need for processes that remove specific
pollutants such as nitrogen and phosphorus
compounds, heavy metals and chlorinated compounds.


New methods include aerobic, anaerobic and physico
-
chemical processes in fixed
-
bed filters and in
bioreactors in which the materials and microbes are
held in suspension. The costs of waste water treatment
can be reduced by the conversion of wastes into useful
products.

e.g. 1. heavy metals and sulphur compounds can be
removed from waste streams of the galvanisation
industry by the aid of sulphur metabolising bacteria and

reused.

2. the production of animal feed from the fungal biomass
which remains after the production of penicillin.

3. Most anaerobic waste water treatment systems produce
useful biogas.

4. Marmite

Waste water treatments


Bioremediation of water or groundwater or
materials recovered from polluted sites.


Ex situ
: As many bacteria work better in
controlled conditions, e.g. anaerobic, higher
temperature, effluent (sewage treatment) or
solid materials (composting) can be treated with
bacteria to decompose organic matters.


Primary treatment: screening and emulsification.


Secondary treatments: Nutrient removal and
chemical removal.

Nutrient removal


Phosphate removal by polyphosphate
accumulating organisms and glycogen
accumulating organisms.


Nitrogen removal by
Nitrosomonas

which denitrify nitrite to nitrogen gas.
Anaerobic ammonium oxidation is also
important.


Algae could absorb many nutrients and
pollutants.
Dunaliella. Chlorella

and
Spirulina
are valuable species.

3.

Biosensor

(monitor pollution)


Measurement of mutagenic activity
(microtox and mutatox tests with lux gene
from Vibrio)


Biomarkers of exposures to pollutants
(stress proteins)


Detection of pathogens by multiplex
-
PCR


Detection of toxins (Ciguatoxin)

DETECTION AND MONITORING AND ANALYSIS


wide range of biological methods are already in use to detect
pollution incidents and for the continuous monitoring of pollutants


.e.g counting the number of plant, animal and microbial species,
counting the numbers of individuals in those species or analysing
the levels of oxygen, methane or other compounds in water.



More recently, biological detection methods using biosensors and
immunoassays and molecular biology have been developed and are
now being commercialised.

Biosensors are a combination of biological and electronic devices
-

often built onto a microchip.


The biological component might be simply an enzyme or antibody,
or even a colony of bacteria, a membrane, neural receptor, or an
entire organism.


Immobilised on a substrate, their properties change in response to
some environmental effect in a way that is electronically or optically
detectable.


It is then possible to make quantitative measurements of pollutants
with extreme precision or to very high sensitivity

Adapted from Lowy, D.R. 1996 The Causes of
Cancer. In: American Scientific Molecular
Oncology. Sci. Amer., Inc., New York, pp41
-
59.

Ames 1973 developed a
rapid screening method
based on mutation of
Salmonella typhimurium. The
mutant strains used in the
Ames Tests are histidine
defective (unable to
synthesize histidine). Back
mutation make them able to
survive on plates without
histidine.

4.

Environmental applications of
genetically modified organisms


Insect Bt resistance,
producing a
bacterial toxin called
bacillus toxin (Bt) so
that insects
(dipterans) die when
eating the plants


Extensively used in
the past 20 years


Green groups
complained that this
is “gene pollution”

New Traits


74% Herbicide resistant


19% Insect resistant


7% Both

Major GM crops


58% Soybean


23% corn


12% cotton


6% Canola

Ref: Brown, K. 2001. Genetically
Modified Foods: Are they safe?

Scientific American 284(4):39
-
45.


Genetic Exchange in the
Environment



Risk Assessments and Biotechnology
Regulations (e.g. environmental use
permits).


Check for foreign DNA sequence by
Quantitative PCR for GMO detection.


GMOs: Bacteria is associated with disease
and hence is always held up by fears. E.g.
antibiotic

resistance.


GEM: The concern is antibiotic resistant
plasmid horizontally transferred to other
microorganisms.

5.

Bio
-
fuels


Plant
-
derived fuels
: plant species
for hydrocarbon (oil) production, e.g.
rape
-
seed, sunflower, olive, peanut
oils. Or ethanol production of sugars
(or cellulose) derived from plants.


Conversion of used cooking oil to
bio
-
fuel (called
bio
-
diesel
)


Biogas
: gases from composts or
landfill, but methane is a green
house gas

Bioethanol and biofuel cell:


Sugar cane
, sugar beet wastes, high starch material
(cassava, potatoes, millet) to be hydrolyzed by
starch
hydrolyzing enzyme

to
convert sucrose or glucose to
ethanol
. Mainly used in Brazil.


Corn ethanol:
22% less carbon emission, used in the US.


Bio
-
diesel
: 68% less carbon emission; oils from soybean
(US) or canola oil (Germany)


Cellulosic ethanol
: 91% less carbon emission, but difficult
to change cellulose to ethanol


Hydrogen energy however is the trend of future renewable
energy without carbon emission: a journey to forever…….


Problem is how to generate the hydrogen; too costly with
conventional chemical methods or reverse osmosis.

Process improvement:


Many industrial processes have been made more environmentally
friendly by the use of enzymes.



Enzymes are biological catalysts that are highly efficient and have
numerous advantages over non
-
biological catalysts.


They are non
-
toxic and biodegradable, work best at moderate
temperatures and in mild conditions, and have fewer side reactions
than traditional methods because they are highly specific.


The leather processing industry has introduced enzymes to replace
harsh chemicals traditionally used for cleaning the hide


enzymes have superseded chemicals for bleaching, including the
“stone washing” of jeans


The grease and protein digesting enzymes in washing powders
significantly reduce the quantity of detergents needed for a given
washing effect.


They also mean that the washing temperature can be reduced.
Lowering the temperature 20
°
C saves more than a third of the
energy used by the machine.

Biotechnological solutions for pollution

Pigs and chickens cannot utilize phosphate from phytate in their feed,
which therefore ends up in their manure.



By adding the enzyme phytase to their feed the amount of
phosphate which is excreted by these animals can be reduced by
more than 30 %.

In South Africa bacteria are used for the isolation of gold from gold
-
ore.


This so
-
called biomining saves an enormous amount of smelting
energy and generates much less waste.

The chemical production of indigo, the dye which is used for blue jeans,
takes eight steps, the use of very toxic chemicals and special
protection measures for the process operators and the environment.


The biotechnological production of indigo, which uses a genetically
modified bacterium containing the right enzymes, takes only three
steps, proceeds in water, uses simple raw materials like sugar and
salts and generates only indigo, carbon dioxide and biomass which
is biodegradable.

Product innovation:


Biotechnology also can help to produce new products which have
less impact on the environment than their predecessors.


The production of new biomaterials like bioplastics avoids the use of
non
-
renewable resources like fossil fuels. E.g bottle from corn


Potatoes normally contain 80% amylopectin but also 20% amylose
which is unwanted in many applications. For the isolation of pure
amylopectin large amounts of water and energy are consumed.


A Dutch company has developed a genetically modified potato
variety which no longer contains amylose and hence can be
processed with less impact on the environment.



The use of genetically modified plant varieties that are resistant
against insects and/or diseases may considerably diminish the use
of pesticides which not only prevents the use of the nasty chemicals
but also allows reduction in energy and labor necessary for their
application