Lecture 31-33 Flashcards
What is biocontrol?
Definition:
-A method of introducing an agent organism into a new ecosystem to naturally prey on a suppress target pest organism
Agent:
-The newly introduced species-Predator
Target:
-The defined pest, whose population is suppressed by the agent-Prey
What is the purpose of biocontrol?
- Biocontrol decreases but does not eradicate target species
- Biocontrol effective for farming to reduce invasive pests without using pesticides, GMO’s
What are the three case study examples?
- Viral
- Bacteria
- Fungal
- Myxomatosis to suppress explosive European rabbit population in Australia
- Myxoma virus
- Enveloped virions
- Brick shaped with a bio concave core
- Non-segmented linear ds DNA genome
- During lifecycle produces proteins that interfere with host immune systems (capsases)
What is myxamotosis?
- Lumps (myxomata) and puffiness appear around the head and genital area
- Progresses to acute conjunctivitis
- Loss of appetite, fever, listlessness
- Death within 14 days, usually less than 48h
What was the plan and were they successful?
Problem: too many rabbits, too few predators
Initiative: Introduce virus to suppress rabbits
Desired Result: Reduce rabbit population
-Many rabbits grew resistant to the virus
Case study 2: Bacteria drastically reduce crop lost to insects
- Bacillus thuringiensis
- Toxin produced by bacteria is protective to the plant
- Delta endotoxins are proteins produced during Bacillus thuringiensis SPORE formation
Bacillus thuringiensis
- Common soil bacteria
- Produces crystalline toxin during sporulation
- As proteinaceous inclusion crystals, Cry
- Cry genes located on a plasmid
- Makes insects cry
What is the mechanism of actions of cry toxin?
- It causes sepsis and death of the insect
- Happens in the gut
- ALP, APN and CAD.
- Cry toxin binds to CAD and it is activated and then it oligomerizes with the help of ALP and APN
- Then the toxin complex forms pores in cell membrane
- The membrane is disrupted, the ion channel is disrupted.
What are the other strains of BT that protect against different insects?
- Kurstaki Strain-targets leaf and needle feeding caterpillars
- Israelensis-targets mosquitoes and black flies
- San Diego Strain-targets beetles
- The more specific the agent the more controlled the intervention and fewer unintended consequences arise
- Narrow host range is the key
What is the BT GM CROP
- Bt crops were among the first GM croops
- Cry genes inserted into plant genomes
- Expressed by plant to confer resistance to insect plants
- Controversal for use in food crops
- Have been in textile crops for many years
- Bt cotton
- Pest resistance to Cry is a problem
- Secondary pest infestations can emergy
Case study 3: Research discovers new uses of fungus to protect food
- Tricoderma harzianum
- Plasmopara viticola
- Downy mildew infection
Trichoderma harzianum
- Fungus of Ascomycota divison
- Most prevalent culturable fungus in soil
- Mycoparasites
- Attack and kill a wide range of fungi
- Some of which are problematic pathogens of plants
- T. harzianum is problematic itself in the mushroom growing industry
Plasmopara viticola
- Cause of downy milder of grapevines
- Devastating crop disease
- 50-100% crop loss can occur
P. viticola oocytes germinate in the spring
-Cold T and wet soil
- Released zoospores require surgace wetness to infect the host
- Infection takes place only through the stomata
- Hyphae grow intercellularly, damaging plant tissue
- The pathogen sporulates through stomata during warm, humid nights completing the lifecycle
Benefits of T. harzianum
- Easy to apply
- Often dried and powedered for use as a root dip
- Associates with roots and helps to solubilize phosphates and micronutrients for plant uptake
- Product lytic enzymes with activity against other fungi, including P. viticola
- Induces deferense responses in many crop plants
- Providing natural resistance against pathogens
What are the risks of biocontrol?
-It is important to RESEARCH
- Unintentional targeting of non pest species
- Provides competition with existing predators
- Unintentional transport, introduction and evolution of parasites
- New species can have unintended effect on large ecosystem
Define: Classical biological control 1.
- Learning how to manage biocontrol
- Control of pests introduced from another region through importing specialized enemies of the pest from their native range,
- Aim: to establish a sustained population of the new enemies
Define: Conservation biological control
-Manipulation of the environment to favor natural enemies of the pest
Define: Augmentation biological control
- Number of biological control agents is supplemented
- Commonly used when biocontrol agent cannot adapt and survive long term in the new environment
Inoculation:
-Introduction of a small number of individulas of the biological control agent
Inundation:
-Introduction of vast number of individuals
Microbial Bioremediation
- Microroganism mediated transformation or degradation of contaminants into non hazardous or less hazardous substances
- Most pollutants can be broken down or detoxified by microbes under ideal conditions
- Plastics
- Radioactive compounds and heavy metals
- Halogenated products
Could microbes help in plastic recycling?
-On land optimal conditions can be managed
- In the ocean, no
1. Cold T
2. Salinity
3. Dilution
4. Depth (P)
-Microbes found to be part of the biofilms that form on plastics in the Arctic and Antarctic regions may be useful for biodegradation,
Many are novel species
What is mutagenomics?
-Taking a sample, fragemnt DNA and the computers puts it together and tell us which species it is.
Has microbe diversity been eroded?
Missing microbe hypothesis
-loss of microbiota generally compounds over generations and recent changes in lifestyle have greatly affects
Missing microbiota hypothesis
- Prevotella strains, fiber degrading enzymes
2. Bacteroides strains
What is gut dysbiosis?
A black box=Reduced microbiota diversity+poor lifestyle choices+poor diet
-We don’t have a definition of what is normal
What are probiotics?
-They are alive organisms that when administred in adequate amounts confer a health benefit to the host
- Fermented foods are NOT probiotics
- Fecal transplants are NOT probiotics
When choosing a probiotic look for
a strain and clinically approved
What are prebiotics?
- Food for your gut microbes
- Typically non digestible fibre compunds
- Not a one size fits all approach
Fermented foods
- Naturally transformed by microbes to create novel textures and flavours
- Benefits of fermented food may not be the microbes but their chemical products of fermnetation
- Small organic molecules (short a.a, alcohols, esters, amides) diffuse through the membrane
How do microbes talk?T
Through small organic molecules
Fecal transplants
-C. diff infections in cure of 90%
Her lab solutions
Met-1= 33 bacterial strains
-Old women
-Really sick
Instead of poop use a complex, defined ecosystem of pure microbes
-Bc it is defined we can monitor long term effects
Microbes as food: FUNGI
-edible fungi includes compost grown AGARICUS BISPORUS
- Button and Portobello mushrooms
- Grown in the dark on manure
-Some fungi are grown by inoculating spawn into logs of wood
Edible algae
- Red algae Porphyra can be toasted in sheets and used to wrap sushi
- Carbohydrate active enzymes made by the gut microbiota helpt to process carbohydrates to provide calories for the host
-Transfer of Porphyranases genes to the gut microbiota of people who traditionally eat a lot of nori
Spriulina
- Most single celled microbes cannot be eater
- Contain a large amount of nucleic acids
- Purinesp-uric acid which is degraded to and it is causes diseases
-Spirulina has a low purine contenT
Rich in B12, protein and minerals
Fermentation of Food (3 reasons why it is conducted)
- Perservation
- Fermentation products limit growth of microbes and preserve food - Improvment of digestibility
- Fibrous macromolecules in meat and vegetables can be broken down by microbial action - Addition of nutrients and flavours
- Fermenting foods makes vitamine, B12, as well as compounds that generate flavour
Acidic fermentation for cheese
- Used for cheeses and sausages
- Primarily made by Lactobacillus
Carbohydrates-glucose-pyruvic acid-lactic acid-propion acid, acetic acid, water, co2
Heterolactic fermentation
- Used for fermentation of some vegetables
- Sauerkraut
- Acidic fermentation
- Carried out by LECUONOSTOC
Ethanolic fermentation
-No lactic acid is used in the leavening of bread and the production of alcoholic beverages
- Alcholic fermnetation
- Carried out by yeast
Alkaline fermentation
- Generates ammonia which results in a ph rise
- Beans and vegetables can be fermenteted in this way
- Bacillus is the bacteria
-Pidan and Natto
- Bacillus breaks down the bad components of soy bean and makes it more difestible
- 100 year old egg
Soy beans fermentation
- Source of protein but contain a lot of phytates, protesease
- To reduce the levels of these, but maintain the protein levels of the bean, ACIDIC fermentation is used
- Ofteen bacterial and mold fermentation is carried out together in succession
- Acidic fermentation of soy (with rice or wheat) by Aspergillus oryzae generates glutamic acid
- Soy sauce and miso
Brine fermentation
- Kimchi
- Salt limits the number of microbial species, offers some control of the process
-Kimichi is an examples of complex fermentation with at least 3 microbial species
Chocolate
- Complex food fermentation
- No started culture has yet been commercialized
- Must be close to the harvesting on the forest floor
Baker’s yeast
-The champion fermenter
-Brewers yeast
S. cerevisiae
-The CO2 is useful in bread and beer
