Future developments

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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?

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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

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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

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Deinococcus radiodurans

• Bacterium 1000s 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

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• 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.

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• 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

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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

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• 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

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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

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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

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Recommended Reading

• In addition to Brock
• Microbial Ecology - Atlas and Bartha (4th
  edition)
• Lecture Notes Available On
• www.nuigalway.ie/microbiology/mel/courses

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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!