Download Experimental Ecology

Future developments
• Further refinement of methods - unlock more
information on how transformations that drive
life on earth work - vital in the context of
environmental degradation, growing human
population and climate change - huge field of
scientific endeavour
• Current research areas: What is the basis for
natural methane emissions? What are the
indicators of soil fertility and quality? What
effect does loss of macroorganism biodiversity
have? What are the specific effects of
pollution?
Biotechnological applications of
microbial ecology
• One of the largest areas of microbial
biotechnology is waste and wastewater
treatment
• Microbiological systems both aerobic and
anaerobic used to treat sewage and industrial
effluents to prevent environmental degradation
and ensure water quality
• Also used to clean up contaminated sites growing interest in using genetically engineered
bacteria for this purpose
Practical areas of application of
genetically engineered bacteria
• Pseudomonas fluorescens - genetically
altered to degrade polyaromatic
hydrocarbons, commonly found in
industrial wastes.
• Tracked by light emissions bioluminescence
Deinococcus radiodurans
• Bacterium 1000’s of time more resistant to radiation
than all other organisms
• Has unique and remarkable DNA repair - vitually
100% accurate and very rapid
• Genetically engineered to remove pollutants at
radioactive sites
Pesticides
Several bacteria engineered to enhance their
ability to kill or repel pests have been
approved for commercial use in US e.g Bacillus
thuringensis
Food Processing
E. coli has been genetically engineered to
produce rennet, an enzyme important in
making cheese. Approved for commercial use
and widely used by US cheese processors.
Animal Drugs
Bovine Growth Hormone (BGH) made
from engineered E. coli used
commercially to stimulate milk
production in cows. Used in about 10
percent of US dairy herds
Concerns…
• Not enough information available on the
natural environment - how can we predict
impacts - and once released into the
environment recovery is impossible
• Behaviour is essentially unpredictable
• Transfer of recombinant DNA to other,
undesirable organisms is likely
• Risk may be small but the consequences of
something going wrong could be catastrophic
• Advantages: represent an effective solution for
many difficulties such as soil contamination,
can be designed to die off quickly no residual
problem, rapid and cheap production of
important medicines.
• Disadvantages: Unknown impacts on the
natural populations and ecology leading to
undesirable and unpredictable outcomes.
Potential for gene transfer in the environment,
creation of new species (and pathogens) and
unwanted new characteristics. Loss of diversity
leading to increased sensitivity in habitats
Environmental Gene Transfer
• DNA can be tranferred between microbes
in a number of different ways: via DNA
uptake from dead cells (A), Plasmids (B)
and phage infection (C)
• Plasmids are circular, mobile genetic
elements capable of replication and
transfer from one bacterium to another
Plasmids - Summary
• Several different types of plasmid classed into
groups based on the genes they carry
• Plasmids have their own origin of replication
and also can genetically control transfer
• Many plasmids carry antibiotic resistance and
have been implicated in the spread of ab
resistance, particularly in hospitals
• Major risk in introduction of GM organisms
Recommended Reading
• In addition to Brock:
Microbial Ecology - Atlas and
Bartha (4th edition)
• Lecture Notes Available On:
www.nuigalway.ie/microbiology/mel/courses
Exam Information
• 1 Question: Overview rather than detail on a
single specific subject
• High marks for the ability to identify and
summarise the important points and to
cohesively illustrate your answer
• Information in notes will be the basis for
majority of marks - supplementary information
will be rewarded
GOOD LUCK!