Environmental biotechnologyEnvironmental 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

technology1. Molecular ecology2. Bioremediation3. Biosensors4. Various Environmental

applications of genetically modified organisms

5. Biofuels6. Process improvement

1. Molecular EcologyUnderstanding 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 wastesEnd 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% BothMajor 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 pollutionPigs 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