MODULE 3 Flashcards
Virus
smallest/simplest bio entities
* depends on host cell for replication and metabolism
Bacteria
Unicellular
* free-living (own metabolism etc.)
* simple morphologies conceal complex biochem and interactions
Fungi
Eukaryotes
* uni or multicellular
* macro and micro
* fruiting body vs. spores of mushrooms.
Protists
Eukaryotes
* Protozoa: animal-like (predatory)
* diverse, hard to classify (polyphiletic)
Algae
Eukaryotes
* plant-like protists
* photosynthetic
Algae or Protozoa?
Euglena
* photosynthetic processes AND
* hunt down prey
Robert Hooke 1664
Describes microscopic structure of blue moulds, using a 30x magnification microscope
* drawings
Antonie van Leeuwenhoek 1684
develop powerful microscope (300x)
* first evidence of bacteria and protists
Louis Pasteur 1861
disproved the theory of spontaneous generation
Spontaneous Generation
the idea that non-living objects can give rise to living organisms
Robert Koch pioneered
- staining methods for microscopy
- use of solid growth media (agar)
- “Germ theory”
Koch 1876
Definitive proof that microbes cause disease (i.e. germ theory)
Koch’s postulates
An organism that causes a disease must :
* Be found in all cases of the disease
* Be isolated from the diseased host in pure culture
* Produce same disease in experimentally-infected host
* Be re-isolated from the experimentally-infected host
Alexander Fleming 1928
Found mould growing on a petri dish that killed the bacteria (Staphylococcus) around it
* bacteria causative agent for pneumonia etc.
Howard Florey and Ernst Chain 1935-45
Purified penicillin and developed mass production methods
* first effective antibiotic
* helped Allies win WWII
Normal Flora
- Found at specific sites
- Specialised
- Mostly bacteria
- Acquired at birth, diet, environment
Positive effects of Normal Flora
- ‘prime’ the immune system
- provide nutritional benefits
- compete with pathogens
Negative effects of Normal Flora
- Can cause disease if moved to wrong location
- Can cause disease even in normal location: if the habitat changes
obligate pathogens
are always harmful
opportunistic pathogens
cause disease in specific conditions
* Numbers – abnormally high cell density
* Location – wrong place
* Host health – immune system compromised
* Virulence factors – e.g. gain antibiotic resistance
One Health concept
consider animals, plants, and the environment when managing disease
MDR-TB
Multidrug resistant TB = bad
XDR-TB
Extensively drug-resistant TB = very bad
Microbes in food production
- Rumen microbes help cows digest grass
- Symbiotic fungi enhance plant growth
- Soil microbes recycle wastes into nutrients
- Decomposition
Microbes in food processing
Many foods require fermentation - flavour, preservative step etc.
Microbes in retail/restaurants
Some microbes are food sources
* (fungi, algae)
* Yeast
* Kelp, seaweed
microbes when eating
Gut microflora beneficial to health
* GI tract
Bad microbes in production
- Pathogens infect animals and plants
- Post-harvest contamination can ruin crops
- Irrigation water can be contaminated with pathogens
bad microbes in processing
Factories can be contaminated
bad microbes in distribution
Refrigeration needed to stop microbial growth
Bad microbes in restaurants
Poor hygiene > food poisoning
bad microbes while eating
Poor gut microbiome causes poor health
Microbes maintain soil health by
- Fixing nitrogen (N2 -> NH 4+)
- Breaking down organic wastes > inorganic nutrients
- Suppressing pathogens
- Breaking down toxins e.g. pesticides
Microbes enable animals to digest…
cellulose
Cellulose
a sugar polymer, abundant in plants, carbon-rich, but difficult to digest
Microbes promote plant growth via
mutualism
Mutualism
Ecological interaction where both partners benefit
Mycorrhizal fungi
enhance water + inorganic nutrient uptake > receive sugars from plant
Rhizobium bacteria
fix nitrogen > receive sugars in return
Tobacco mosaic virus
simple (3 genes)
* infect tobacco, tomato, cannabis
* cross-contamination
Animal and plant pathogens impact
- impact ~30% of total yield
- impact ~20% animal production
Foot-and-Mouth-Disease (FMD)
infect livestock
* UK outbreak: pigs fed waste products incl. meat illegally imported from infected animals
Zoonosis
Human infection arising from animals
how zoonosis cause disease
- Microbe may be pathogenic to both animal and human hosts
- Human pathogen may be normal flora for the animal
- Animal is a ‘vector’ for disease
Fermentation
- microbial transformation of foods by fungi or bacteria
- anaerobic metabolism of sugars alcohols, acids, CO2
Microbial food spoilage
the growth of fungi or bacteria, and/or due to enzymes that these microbes make and secrete
Food-borne infection
microbes grow in gut
Food-borne intoxication
microbes make toxins in food
Food ‘poisoning’ risk factors
- origins of food
- storage and prep
- human factors
Gut microbiome depends on diet
- High fibre diet: ↑ Bacteriodetes
- High protein & fat diet: ↑ Firmicutes
Healthy microbiome important for
- Proper food digestion
- Resistance to pathogens
- Immune functioning
- Mental health
The vast majority of all biodiversity is
microbes
The 4 laws of Ecology
- Everything is connected
- Everything must go somewhere
- Nature knows best
- There’s no such thing as a free lunch
Autotroph
“Self-feeder” – uses CO2 as carbon source
* algae
* sinks for CO2
photoautotrophs
use light as energy source
chemoautotrophs
use chemical energy sources
Methanogens
Consume CO2 and H2, produce methane (CH4)
* archaea
* anaerobic
* bad
Methanotrophs
Consume methane, produce CO2
* good
* heterotrophs
* bacteria
* degrade TCE
Heterotroph
“Other-feeder” – needs to eat other organisms, or other organic carbon sources; these also supply energy
* SOURCES of CO2
Decomposers
Recycle dead cells back to CO2
* heterotrophs
* fungi
Predators
Protozoa
* motility
* Amoebae engulfing bacteria
Pollutant degraders
Hydrocarbon-degrading bacteria (including methanotrophs) are very useful for “bioremediation”
Bioremediation
the cleanup of pollution by microbes
Coral symbiosis
- algae (photoautotrophs)
- coral (heterotrophs)
Lichen symbiosis
- Heterotrophic fungus: Helps feed algae with inorganic nutrients , anchor
- Autotrophic algae
Cellular biotechnology
- Need some biology skills (esp. microbiology)
- Don’t need understanding of DNA, RNA, proteins
Molecular biotechnology
- Need high-level biology skills (esp. microbiology)
- AND need understanding of DNA, RNA, proteins
Biotech processes - what do we need to provide?
The host cell factory needs instructions or a blueprint to tell it which products to make
* instructions = add DNA !
Plasmids
circular DNA elements found in microbes; replicate independently of the chromosome(s)
* Vectors
Key features of plasmids used for biotech
- ORI: Replication functions. Ensures persistence in host
- amp: Selectable marker. Enables us to force cells to take up plasmid
- lacZa: Cloning site. Add foreign genes here
Tools needed for DNA cloning
- Copying: Thermostable polymerase
- Cutting: Restriction enzyme
- Joining: T4 ligase
Vaccines may consist of…
- Live attenuated microbes - No longer causes serious disease - Risks
- Killed microbes - Not as pure
- Antigens (proteins) produced in a GMO host
- mRNA coding for antigens - Developed in the last two years