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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5714_Библиотеки_им_академика_М_И_Перельмана.pdf
INTRODUCTION
Environmental biotechnology refers to the development, use and regulation of biological systems
for remediation of contaminated environments (land, air, water) and for environment-friendly
processes (green manufacturing technologies and sustainable development). Environmental
biotechnology employs a diverse set of methodology approaches to explore and exploit the natural
biodiversity of microorganisms and their enormous metabolic capacities.
It is a rapidly expanding area of biotechnology that involves introduction of selected
microorganisms into the environment for a diversity of purposes, such as rhizobium and mycorrhizal
inoculants, enhanced silage production, pollutant dispersal, mineral leaching, degradation of
crop residue in situ, improved nitrogen status of soil, etc. The environmental biotechnology, as
compared to other areas of biotechnology, is focused on achieving microbial function in complex
environment that is not subject to the precise experimental control as visible in bioreactors. The scope
of environmental biotechnology is enlarged to address issues such as environmental monitoring,
restoration of environmental quality, waste management, substitution of the nonrenewable resource
base with renewable resources, etc. Environmental biotechnology has been successfully applied
to major oil spills and numerous contaminated sites, thereby reducing the environmental damage
caused by pollutants and decreasing the risk they pose to human health. Different methods of
aerobic and anaerobic biological treatments are being successfully employed in the treatment of
domestic and industrial waste. It has played significant role in improving human environment by
converting complex organic matter from the waste into simpler one that can be recycled (e.g.
single-dwelling septic tanks, municipal trickling filters, activated sludge system, lagoons, etc.).
Environmental Biotechnology
3
CHAPTER
Introduction
Bioremediation
Management of Environmental Pollution
Management of Air, Waste Gases and
Water Pollution
Questions
Textbook of Pharmaceutical Biotechnology
36
Recombinant DNA methodology can also be effectively used to genetically engineer
microorganisms with the capacity to degrade many of these compounds.
BIOREMEDIATION
Bioremediation refers to the use of biological systems to reduce pollution from air, aquatic or
terrestrial systems. Plants and microorganisms are the biological systems generally used for
bioremediation. It is an emerging technology that offers significant potential for cost-effective
and eco-friendly treatments of contaminated water and soils. Bioremediation is one of the few
processes that actually destroys pollutants, converting organic matter into CO
2
, water, chloride and
other materials.
The techniques employed for bioremediation can be broadly classified as discussed below.
Ex-Situ Bioremediation
It involves design, construction and operation of an engineered reactor above the ground. It involves
the removal of waste materials and their collection at a place to facilitate microbial degradation.
The process has many limitations and disadvantages.
In-Situ Bioremediation
Natural Bioremediation
This action is initiated other than monitoring the sites for the degradation by microorganisms.
Engineered In-Situ Bioremediation
The materials are added to stimulate growth of organisms. The compounds used successfully for
bioremediation are petroleum hydrocarbons, benzene, toluene, ethyl benzene, xylene, alcohols,
kerosene, esters, polynuclear aromatic hydrocarbons, creosote, chlorinated aromatic hydrocarbons,
chlorofluorocarbons, chlorinated benzene, polychlorinated benzene, polychlorinated biphenyls,
phenols, chlorinated phenols, nitroaromatics, pesticides, alachlor, atrazine, etc.
MANAGEMENT OF ENVIRONMENTAL POLLUTION
The strategic approaches for management of environmental pollution are based on following five
considerations:
1. CO
2
Reduction of atmospheric
2. Sewage treatment by bacteria and algae
3. Eutrophication and phosphorous pollution
4. Management of metal pollution
5. Immobilized cells in the management of pollution
Environmental Biotechnology
37
Reduction of Atmospheric CO
2
There are mainly two types of approaches adopted for reduction of carbon dioxide in the
atmosphere:
1. Photosynthesis
2. Biological classification
Photosynthesis
The utilization of CO
2
for photosynthesis by plants is the most significant process to reduce CO
2
content in the atmosphere.
Sunlight
6CO
2
+ 6H
2
O C
6
H
12
O
6
+ 6O
2
B
Chlorophyll
Biological Classification
Certain organisms present in the deep sea such as corals, green and red algae, etc., are capable of
storing CO
2
through a process of biological classification.
The overall bioprocess may be represented as follows:
H
2
O + CO
2
H
2
CO
3
Ca
2+
+ 2HCO
–
3
+ OH
–1
CaCO
3
+ CO
3
2–
+ H
+
+ H
2
O
(insoluble) (soluble)
Sewage Treatment by Bacteria and Algae
Most algae are quite flattened, which maximize the surface area for absorbing water, minerals
and sunlight. The vegetative form of algae is represented by thallus. For single-celled algae, the
thallus is just the single cell. In multicelled algae, the thallus represents the entire continuous
organism. In most of the wastewater treatment plants of recent times, degradation of organic
matter is effected through bacterial activity. When bacterial activity is promoted by aerobic
bacteria ( bacteria that survive in oxygenated environment)—involving arrangements supplying
oxygen to water—the process is known as aerobic treatment. The process of supplying air may
be different, such as through fixed or floating aerators or through diffused aeration. The purpose
is simply to aerate water so that bacteria survive and eat away the organic matter and clean up
water (Fig. 3.1).
Anaerobic wastewater treatment is the biological treatment of wastewater without the use of
air or elemental oxygen. Many applications are directed towards the removal of organic pollution
in wastewater, slurries and sludges. The anaerobic microorganisms convert organic pollutants into
a gas containing methane and carbon dioxide, i.e. biogas.
Textbook of Pharmaceutical Biotechnology
38
Eutrophication and Phosphorus Pollution
Eutrophication is a scientific term that describes the overfertilization of lakes with nutrients and the
changes associated therewith. In other terms, it is the ‘bloom’ or great increase of phytoplankton
in a water body. Negative environmental effects include anoxia or loss of oxygen in water with
severe reduction in fish and other animal populations. The plants have high nitrogen requirement, so
addition of nitrogen compounds stimulates plant growth. Ecosystems having more nitrogen than the
plants would require are known as nitrogen-saturated ecosystems. Such kind of saturated terrestrial
ecosystems contribute both inorganic and organic nitrogen to freshwater and marine eutrophication,
where nitrogen is also a limiting nutrient. Phosphorus is much more important as a limiting nutrient
in aquatic systems. When present in very high levels, phosphates are toxic to people or animals. In
freshwater lakes and rivers, phosphorus is often found to be the growth-limiting nutrient, as it is
present in low concentration as compared to the needs of plants. If excessive amounts of phosphorus
and nitrogen are added to the water, they facilitate algae and aquatic plants to grow in large quantities.
When these algae die, bacteria decompose them and use up the oxygen liberated. This process is
referred to as eutrophication. The loss of oxygen in the bottom waters can free phosphorus previously
trapped in the sediments, further increasing the available phosphorus (Fig. 3.2).
Management of Metal Pollution
Environment pollution with heavy metals, such as lead, cadmium, mercury, etc., causes several
toxic manifestations, including cancer, in living organisms. Some characteristic features of metal
pollution are disussed ahead.
Algae
Bacteria
Reclaimed
water
Wastewater
Organics
CO
2
N
P
Sun
CO
2
CO
2
N
P
B
i
o
m
a
s
s
O
2
Figure 3.1 Sewage treatment by bacteria and algae.
Environmental Biotechnology
39
1. Bioaccumulation
2. Biomagnifications
3. Biomethylation
Plants and microorganisms are also used for control of metal pollution. As small but significant
amounts of mercury still remain in water, existing techniques of mercury removal by precipitation
or ion exchange are expensive and not sufficiently efficient. Researchers discovered that many
bacteria develop high tolerance to heavy metals, which relate to the binding of these metals to
proteins, e.g. metallothionein that binds mercury. As naturally thriving mercury-tolerant bacteria
are rare and cannot be grown easily in culture, researchers at Cornell University, New York, inserted
the metallothionein gene into E. coli. A sufficiently large number of genetically engineered bacteria
can thus treat mercury-polluted water inside a bioreactor. By using this process, mercury can be
removed from polluted water down to a few nanograms per litre. Once the bacteria die, they are
incinerated to recuperate the accumulated pure mercury.
Immobilized Cells in Management of Pollution
The technique that uses immobilized cells—particularly microbial whole cells, for the control of
environment pollution—is of recent origin. The immobilized cell lines can be effectively used for
the treatment of wastewater and for recovery of metal (Table 3.1).
Nutrients, primarily from
agricultural and urban
sources, are delivered by
stormwater runoff and
atmospheric decomposition
Plants
Wind and waves oxygenate surface layer
Lighter, fresher, warmer surface layer
Pycnocline layer blocks oxygen flow to bottom water
Organic material from sources
such as dead or decaying algae
and plankton falls to the
seafloor and decomposes
Heavier,
saltier and
cooler lower
layer
Sediment
O
2
O
2
O
2
Sun
Fig 3.1
Figure 3.2 Eutrophication process.
Textbook of Pharmaceutical Biotechnology
40
MANAGEMENT OF AIR, WASTE GASES AND WATER POLLUTION
Industrial waste gas treatment systems were originally based on cheap compost-filled filters that
removed odours. Despite their short life and slow processing rates, such filters are still in use. The
development of biorubbers, wherein the pollutants are washed out using a cell suspension was
a welcome feature. Biotrickling fi lters—in which the pollutant is degraded by microorganisms
immobilized on an inert matrix and provided with an aqueous nutrient film trickling through
the device—was another important development of commercial success. The selection of
microorganisms that are more efficient against metabolizing pollutants has also led to better air-
and gas-purifying biofilters.
Removal of Formaldehyde, Methanol, Dimethylether and Carbon Monoxide from
Waste Gases
Bioreactors
A series of biofilters and biotrickling filters are commonly used in bioreactors. The conventional
biofilters have a packing volume between 1.0 and 3.4 L, whereas the biotrickling filters contain
packing material between 1.0 and 2.0 L. Lava rock is commonly employed as filter bed. The
bioreactor systems are operated with a downward flow at room temperature, and fed with a nutrient
solution.
Biocatalysts
Two different types of inocula are used for the batch studies. The sludge from the wastewater treatment
plant of a formaldehyde resin-producing facility is usually employed. The sludge is also employed as
inoculum in almost all bioreactor studies. Additionally, a pure Oligotropha carboxidovorans OM5
culture is employed for a series of batch studies. O. carboxidovorans OM5 is a carboxidotrophic
Gram-negative bacillus able to catalyse the biodegradation of carbon monoxide.
Batch Experiments
The batch assays are carried out in 635 mL glass vials, containing 100 mL inoculum and the nutrient
solution used for the bioreactor studies. The pH is adjusted to 7.5, and distilled water is added to
Table 3.1 Immobilized cells for wastewater treatment
Immobilized cells Pollutants
Arthrobacter sp.
Triethyl lead
Thiosphaera sp.
Ammonia
Escherichia coli
Chlorophenol
Rhizopus arrhizus
Copper
Environmental Biotechnology
41
icroorganism Sludge Heavy metals Hydroponic water
Process design
Biotreatment, e.g. living organism Physical treatment, e.g. filter
Wastewater treatment rinking water purification
Figure 3.3 Management of water pollution.
make up to 150 mL. After adding the substrate ( formaldehyde, methanol, dimethylether or carbon
monoxide), the vials are sealed and maintained at 30°C with constant shaking at 200 rpm. The gas
samples of the headspace are periodically taken in order to measure the substrate concentration.
Pollutant concentrations in the liquid could be calculated by means of Henry’s law. All the vials
are prepared in duplicate, including for ‘blank’ and ‘control’ assays. Blank vials are identical to the
experimental vials with the highest pollutant concentration but have been previously submitted to
sterilization at 120°C for 30 min. Control vials also have the same composition but contain distilled
water instead of sludge.
Management of Water Pollution
The conventional wastewater treatment methods are being re-examined in view of major changes
that have taken over the past few years. Among these are growing problems of worldwide energy
and food shortages and nutrients not being removed by conventional secondary processes causing
algal blooms and other problems in the receiving waters. Biotreatment systems utilizing living
organisms are being preferred since they are ecologically sound, cheap and applicable in areas
without land constraints. Filter feeders are promising in this area since they can remove suspended
organic matter and bacteria, even in the size range of microns (Fig. 3.3).
Aerobic Biotreatment of Wastewater Pollution
Aerobic bioprocesses have been viewed as effective methods for wastewater treatment to remove
biodegradable organics and, to a lesser extent, nutrients and phosphorus. On the basis of microbial
development, these processes can be broadly classified into the following two categories:
1. Suspended growth processes
2. Attached growth processes
The fixed film processes offer good protection against toxic substances and provide higher
treatment efficiencies. They also cause long retention of biomass solids.
Textbook of Pharmaceutical Biotechnology
42
QUESTIONS
1. What is bioremediation?
2. Discuss in brief the techniques employed for bioremediation.
3. Discuss the biotechnological methods used for management of pollution.
4. Write a short note on sewage treatment by bacteria and algae.
5. Write a short note on immobilized cells in management of pollution.
6. Write a short note on management of air, waste gases and water pollution.
INTRODUCTION
Proteomics refers to the identification and quantification of all proteins present in cells and
organisms. It is the study of the proteome, the protein complement of the genome. The terms
proteomics and proteome were first coined by Marc Wilkins and colleagues in the early 1990s.
Genomics and genome describe the entire collection of genes in an organism.
After genomics, proteomics is considered to be important in the study of biological systems. It
is much more complicated than genomics. While genome of an organism is more or less constant,
the proteome differs from cell to cell and varies from time to time. This is because of the fact that
distinct genes are expressed in distinct cell types. It means that even the basic set of proteins that are
produced in a cell needs to be determined. In the past, this was done by mRNA analysis. It is now
established that mRNA is not always translated into protein, and the amount of protein produced for
a given amount of mRNA depends on the gene it is transcribed from and on the current physiological
state of the cell (Fig. 4.1).
Proteomics includes the characterization and functional analysis of all proteins that are
expressed by the genome at a certain moment, under certain conditions. Since expression levels of
many proteins strongly depend on complex but well-balanced regulatory systems, the proteome,
unlike the genome, is highly dynamic. This variation depends not only on the biological function
of a cell, but also on signals from its environment.
Protein chemistry involves the study of structure and functions of proteins and most
commonly manifests in the field of physical biochemistry. Proteomics is the study of multiprotein
systems, in which the focus is on the interplay of multiple, distinct proteins and their roles
as part of longer systems. The difference between protein biochemistry and proteomics is
reflected in Table 4.1.
Proteins and Proteomics
4
CHAPTER
Introduction
Proteins
Proteomics
Questions
Textbook of Pharmaceutical Biotechnology
44
PROTEINS
Proteins are organic compounds made up of amino acids arranged in a linear chain and folded into a
globular form. The amino acids are joined together by the peptide bonds between the carboxyl and
amino groups of adjacent amino acid residues. The sequence of amino acids in a protein is defined
by the sequence of a gene, which is encoded in the genetic code. Proteins were first described by
the Dutch chemist Gerardus Johannes Mulder and were named by the Swedish chemist Jons Jakob
Berzelius in 1838.
Proteins are involved in almost all cellular processes and fulfil many functions. They are
involved in enzyme catalysis, transport, mechanical support, organelle constituents, storage
reserves, metabolic control, protection mechanisms and osmotic pressure.
Structure of Proteins
Proteins are macromolecules consisting of one or more polypeptides, each polypeptide consisting
of a chain of amino acids linked together by peptide bonds. A polypeptide chain folds up, assuming
Table 4.1 Differences between protein biochemistry and proteomics
Protein biochemistry Proteomics
Individual chemistry in biological context Complex mixture of genome. Study of protein compliment.
Complete sequence analysis Partial sequence analysis
Emphasis on structure and function Emphasis on identification by database matching
Structural biology Systems biology
Figure 4.1 Biochemical context of genomics and proteomics.
DNA
Genome
mRNA
Proteins
Proteome
Cell function
Genomics
Proteomics