Maldner

C, H, N, O, P, S build up carbohydrates, lipids, proteins, nucleic acids

Mg2+, Ca2+, Fe2+, K+: ions necessary for protein function

Trace elements necessary for enyme function

Co, Cu, Mn, Zn

Fix CO2 & assemble into organic molecules (mainly sugars)

Use preformed organic molecules

Obtain energy from physico-chemical reactions triggered by light

Obtain energy from oxidation - reduction reactions

Use inorganic molecules as electron donor

Use organic molecules as electron donor

H+ gradient & charge difference from an electrochmemical potential at the membrane

Possess nitrogenase which converts N2 to ammonium ions (NH4+)

Oxidize ammonia to nitrate (NO3-)

Convert nitrate (NO3-) to N2

• helps solutes to move across a membrane from high to low concentration

• Does not use energy

• E.g. aquaporine family

Two molecules travel in the same direction

Actively transported molecules move in the opposite direction to the driving ion

• ATP-binding cassette superfamily

• Largest family of energy driven transport

• Uptake and Efflux ABC

  1. solute binds to its cognate periplasmatic binding protein & the complex then binds to the membrane transporter

  2. The ATPase activity of one component poers the opening of the channel & movement of the solute into the cell

• uses energy to chemically alter the substrate during its transport

• E.g. phosphotransferasesystem present in all bacteria: uses energy from phosphoenolpyruvate (PEP) to attach phosphate to specific sugars

Useful for studying the growth characteristics of a pure culture & obtain a large amount of cell

Useful to seperate mixed cultures from clinical specimens or natural environments

Dragging a loop across the surface of an agar plate

Tenfold serial dilutions are performed on a liquid culture, small amutn of each dilution is then plated

Nutrient rich, poorly defined

Precisely defined

Complex media to which specific blood components are added (media for pahtogens)

Favor the growth of one organims over another (e.g. Gram- are more persistant against detergents then Gram+)

Exploit differences between two species that grow equally well (e.g. E. Coli ferments lactose, salmonella doesnt: media contains pH indicator)

Microorganisms can be counted directly by placing dilutions on a special microscope slide: Petroff-Hauser counting chamber

• “fluorescent” cells are passed through a small orifice & then pass a laser

• Detectors measure light scatter in the forward direction (measure of particle size, shape & granularity)

Growth rate is proportional to the population size at a given time

If a cell divides by binary fission the number of cells is propotional to 2^n

The time it takes for a population to double

For cell undergoing binary fission:

Nt=N0 x 2^n

Nt= final cell number

N0= original cell number

n= number of generations

• cells cells in a population achieve a steady state which allows detailed study of bacterial physiology

• Ensures logarithmic growth by constantly adding & removing equal amounts of culture media

• can be constructed by one or multiple species

• Can form on a range of organic or inorganic surfaces

• Form when nutrients are plentiful - once nutriens become low individuals can detach

• Can be clued by different environmental signals in different species

• clostridium und bacillus species can produce dormant spores, that are heat resistant

• Starvation initiates an elaborate 8-hour genetic program that involves an asymmetrical cell division process that produces a forespore & ultimately an endospore

Specialized cells the allow anaerobical nitrogen fixation maintining oxygenic photosynthesis in other cells (e.g. anabaena)

Myxococcus xanthus uses gliding motility -> Starvation triggers the aggergation of 100 000 cells which form a fruiting body

Streptomyces bacteria form mycelia & sporangia aanalogous to those of fungi, as nutrients decline, aerila hyphae divide into arthrospores that are resistant to drying

• sea level

• Temperature 20°C - 40°C

• Neutral pH

• 0,9% salt &sample nutrienst

Organisms inhabiting an ecological niche outside the normal growth conditions

• rapid temperature changes experienced during growth activates batches of stress response genes resulting in the heat-shock response

• The protein products include chaperones that maintain protein shape & enzymes that change membrane lipid composition

Measure of the number of solute molecules in a solution & is inversely related to aw (Wasserkapazität)

1. In hypertonic media (higher osmolarity) bacteria protect their internal water by synthesizing or importing compatible solutes (e.g. proline or K+)

2. In hypotonic media (lower osmolarity) pressure sensitive or mechano sensitive channels can be used to leak solutes out of the cell

• halophiles (archaea) require high salt concentrations (from 2 - 4 M NaCl ~ 10-20% NaCl)

• To achieve a low internal concentraion of Na+, halophilic microbes use special ion pumps to excrete sodium & replace it with other cations such as K+

• Microbes can prevent the influx of protons by exchanging extracellular K+ for intracellular H+ when the internal pH becomes too low

• Under extremely alkaline conditions the cell can use the Na+/H+ antiporter to brin protons into the cell in exchange for expelling Na+

• oxygen is a benefit to aerobes: oxygen as electron acceptor to extract energy from nutrienst

• Oxygen is toxic to all cells that do not has enzymes to destroy reactive oxygen species (ROS)

1. special reducig agents (e.g. thioglycolate) or enzyme systems (oxyrase) can be added to ordinary liquid media

2. Anaerobic jar

3. Anaerobic chamber with glove ports - O2 is removed by vacuum & replaced with N2 and CO2

Sudden infusion of large quantities of a formerly limiting nutrient. -> can cause “bloom” of microbes

Killing of all living organisms (+ spores & viruses)

Killing or removal of pathogens from inanimate objects

Killing or removal of pathogens from the surface of living tissue

Reducing microbial populations to safe levels (purification & disinfection)

= decimal reduction time

The time it takes an agent to kill 90% of the population

121°C at 2 bar for 20 minutes

Kills spores and thermophiles

Low temperature long time: 63°C for 30 minutes

High temperature short time: 72°C for 15 seconds

• micropore filters with pore sizes of 0,2µm can remove microbial cells but not viruses from solutions - samples from 1 ml to several liters can be drawn through a membrane filter by vacuum or forced through it wit a syringe

• Air can be also sterilized by filtration: laminar flow biological safety cabinetsforce air through HEPA filters which remove 99,9% airborne materila 0,3µm in size or larger

Contain certain microbes that when ingested aim to restore balance to intestinal flora (Lactobacillus & Bifidobacterium)

Aims to treat infectious diseases with a virus targeted to the pathogen: A possible alternative to antibiotics in the face of rising antibiotic resistances