Download Biotechnology and the Environment: Microbial Ecology

Chapter 9
Bioremediation
Biotechnology and the
Environment
Environment – describes everything that
surrounds a particular organism
• Other organisms
• Soil, air, water
• Temperature, humidity, radiation
Biotechnology and the
Environment
Environmental Biotechnology the development, use and regulation of
biological systems for remediation of
contaminated environments (land, air,
water), and for environment-friendly
processes.
Bioremediation - the use of
microorganisms to remedy
environmental problems
Biotechnology and the
Environment
What
are the events that triggered the
interest in environmental biotechnology?
•Rachel Carlson’s Silent Spring (DDT)
•Love Canal
•Burning of a River
•Exxon Valdez in 1989
Biotechnology and the
Environment
What do they all have in common?
• The advent of the Industrial Revolution
• increase in products and waste
• people moved to the city
• increase in human population
Biotechnology and the
Environment
Regulations were passed:
• Resource Conservation and Recovery Act (1976)
• Must identify hazardous waste and establish standards for
managing it properly
• Requires companies that store, treat or dispose to have permits
stating how the wastes are to be managed
• Record of its travels: Chain of Custody
• EPA initiates the Superfund Program (1980)
• Counteract careless and negligent practices
• Environmental Genome Project
• Study and understand the impacts of environmental chemicals on
human diseases
Biotechnology and the
Environment
Waste
• Solid: landfills, combustion-including waste-to energy
plants, recovery
• slurries, composting
• Liquid: septic: sewage treatment, deep-well injection
• Gas: fossil fuels, chlorofluorocarbons
• Hazardous –anything that can explode, catch fire, release
toxic fumes, and particles or cause corrosion
Biotechnology and the
Environment
Garbage Test
Banana Peel
Wood Scrap/Sawdust
Wax Paper
Styrofoam Cup
Tin Can
Aluminum Soda Can
Plastic Carton
Glass Bottles
0.5 Years
4 Years
5 Years
20 Years
100 Years
500 Years
500 Years
>500 Years
There is no waste in Nature:
From rocks and soil to plants and animals
to air and water and back again:
Recycled largely by
Microbes
Biogeochemical Cycles are a major
part of the recycling process
 Carbon Cycle: The primary biogeochemical cycle
organic cmpds  CO2 and back
 Nitrogen Cycle: proteins amino acids
NH3NO2-NO3-NO2-N2ON2 NH3 etc_
 Sulfur Cycle: Just like the nitrogen cycle,
numerous oxidation states. Modeled in the
Winogradsky column
 Phosphorous Cycle: Doesn’t cycle between
numerous oxidation states only soluble and
insoluble form
Carbon Cycle
CO2
Organic compounds
Nitrogen Cycle
cyanobacteria
N2
leguminous
decomposition
Fixation
ammonification
NO2Pseudomonas
Bacillus Denitrification
Paracoccus
NO3-
NH3
Nitrification
nitrosomas
NO2nitrobacter
Sulfur Cycle
SO2
Atmosphere
H2SO4
Organic sulfur
S
SO4
H2S
Phosphorus Cycle
Sea simple
Phosphates
Phosphate
rocks
Phosphates too complex
for plants to absorb
from the soil
Microbes Breakdown
complex compounds
Biotechnology and the
Environment
Scientists learn from nature in the 1980’s
• The concept of Gaia –the total world is a living organism
and what nature makes nature can degrade
(bioinfalibility); only man makes xenobiotic compounds
• Clean up pollution-short and long term solutions (cost, toxicity,
time frame)
• Use compounds that are biodegradable
• Produce Energy and Materials in less destructive ways
• Monitor Environmental Health
• Increase Recovery of Minerals and Oil
Biotechnology and the
Environment
 Bioremediation finds its place
• Companies begin to specialize in cleaning up toxic waste spills by
using a mixture of bacteria and fungi because cleaning these spills
usually requires the combined efforts of several strains.
• Biotechnologists begin engineering “super bugs” to clean up
wastes.
• However, there are many microorganisms in nature that will
degrade waste products.
Bioremediation Basics
Naturally occurring marshes and wetlands have
been doing the job!
What Needs to be Cleaned UP?
• Everything!
• How do pollutants enter the environment?
• Runoff, leachates, air
• SO How bioremediation is used depends on
1) what is contaminated? (locations)
2) on the types of chemicals that need to be cleaned up
3) the concentration of the contaminants (amount and
duration)
Bioremediation Basics
Chemicals in the environment
• Sewage (by products of medicines and food we eat such
as estrogen (birth control pills) and caffeine (coffee)
• Products around the house (perfumes, fertilizers,
pesticides, medicines)
• Industrial
• Agricultural
Bioremediation Basics
Bioremediation Basics
Fundamentals of Cleanup Reactions
• Microbes can convert many chemicals into
harmless compounds HOW?
• Aerobic or anaerobically
• Both involve oxidation and reduction reactions
Bioremediation Basics
Fundamentals of Cleanup Reactions
• Oxidation and Reduction Reactions
• Oxidation involves the removal of one or more electrons
• Reduction involves the addition of one or more electrons
• Oxidizing agents gain electrons and reducing agents lose
electrons
• The rxns are usually coupled and the paired rxns are known
are redox reactions
Bioremediation Basics
Example:
reduced
0
0
+1 -1
Na + Cl2  NaCl
oxidized
Bioremediation Basics
 Aerobic and anaerobic
biodegradation
• Aerobic
• Oxygen is reduced to water and
the organic molecules (e.g.
petroleum, sugar) are oxidized
• Anaerobic
• An inorganic compound is
reduced and the organic
molecules are oxidized (e.g.
nitrate is reduced and sugar is
oxidized)
• NOTE: Many microbes can do both
aerobic and anaerobic respiration;
the process which produces the
most ATP is used first!
Bioremediation Basics

The Players: Metabolizing Microbes
•
•
•
•
•
Site usually contains a variety of microbes
Closest to the contaminant: anaerobes
Farthest away: aerobes
The most common and effective bacteria are the indigenous
microbes (e.g. Pseudomonas in soil)
Fungus and algae are also present in the environment and do a good
job of “cleaning up” chemicals (fungi do it better than bacteria)
Bioremediation Basics

Bioremediation Genomics Programs
•
Stimulating Bioremediation
• Add fertilizers (nutrient enrichment) to stimulate the
growth of indigenous microorganisms
• Adding bacteria or fungus to assist indigenous
microbes is known as bioaugumentation or seeding
Bioremediation Basics

Phytomediation
•
Utilizing plants to clean up chemicals
•
Ex: cottonwoods, poplar, juniper trees, grasses, alfalfa
•
Low cost, low maintenance and it adds beauty to the site
Cleanup Sites and Strategies
 Do the chemicals pose a fire or explosive hazard?
 Do the chemicals pose a threat to human health
including the health of clean-up workers? (what
happened at Chernobyl to the workers?)
 Was the chemical released into the environment through
a single incident or was there long-term leakage from a
storage container?
 Where did the contamination occur?
 Is the contaminated area at the surface of the soil?
Below ground? Does it affect water?
 How large is the contaminated area?
Cleanup Sites and Strategies
Soil Cleanup
• Either remove it (ex situ bioremediation) or in situ (in
place)
• In place:
• If aerobic may require bioventing
• Most effective in sandy soils
• Removed:
• Slurry-phase, solid phase, composting, landfarming, biopiles
Cleanup Sites and Strategies
Bioremediation of Water
• Wastewater treatment
Cleanup Sites and Strategies
Bioremediation of Water
• Groundwater Cleanup
Environmental Diagnostics
A promising new area of research
involves using living organisms to
detect and assess harmful levels of
toxic chemicals.
Environmental Diagnostics
Daphnia magna
Transparent
Thorax and
Abdomen
When healthy Daphnia are fed a sugar substrate (galactoside
attached to a fluorescent
marker), they
Environmental
Diagnostics
metabolize the sugar and fluoresce under UV light.
When Daphnia are stressed by toxins, they do not have the
enzymatic ability to digest the sugar and therefore do not
fluoresce under UV light.
Environmental Diagnostics
Toxicity reduction involves adding chemicals to
hazardous waste in order to diminish the toxicity.
• For example, if the toxicity results from heavy metals,
EDTA will be added to the waste and the effluent will
be tested again to determine if the toxicity has been
acceptably reduced.
• EDTA chelates (binds to) metals, thereby making them
unavailable to harm organisms in a particular body of water.
Applying Genetically Engineered Strains to
Clean Up the Enviroment
Petroleum eating bacteria
• Ananda Chakrabarty at General Electric
Heavy metals (bioaccumulation)
• Bacteria sequester heavy and radioactive
metals
Biosensors
• lux genes
Environmental Disasters: Case Studies
in Bioremediation
The Exxon Valdez Oil Spill
• In the end, the indigenous microbes did the best job
Oil Fields of Kuwait
• Poses a problem due to the environmental conditions
Future Strategies and Challenges
for Bioremediation
Microbial genetics
New types of microbes (from the ocean etc)
Radioactive materials
DO A BETTER JOB OF DETERMINING RISK and
ASSESSMENT OF EXISTING SITES
Careers in Environmental
Biotech
Biodegradation
• Wastewater treatment plants, organic farming
Bioremediation
• Environmental clean-up companies, labs developing
super bugs
Biocatalysis
• Plastics, degradable and recyclable products
Other
• Mining companies, oil companies