Bacteria Energy & Respiration

How Bacteria Obtain Energy  Some bacteria can make their own food These are called AUTOTROPHS  Some bacteria require that food be made for them These are called HETEROTROPHS

AUTOTROPHS  There are two types of AUTOTROPHS 1. Phototrophic 2. Chemotrophic

Phototrophic Autotrophs  They use the sun’s energy to make their own food (sugar)  Eg’s : Cyanobacteria and photsynthetic Eubacteria

Chemotrophic Autotrophs  They are able to use inorganic molecules (ie: hydrogen sulfides, nitrides, sulphur & iron) as food  They tend to live in harsh environments  Eg: Nitrosomonas uses ammonia as a food source

HETEROTROPHS  There are three types of heterotrophs 1. Phototrophic 2. Chemotrophic 3. Saprotrophic

Phototrophic Heterotrophs  These bacteria are able to use sunlight to produce food molecules but ALSO require organic compounds for nutrition  Very rare

Chemotrophic Heterotrophs  These bacteria take in organic food molecules from their environment to use for energy  Humans are chemotrophic heterotrophs and therefore we often compete with bacteria for the same food source  Eg: Salmonella gets food from raw meat, poultry and eggs. When it grows where food is available it releases poisons which, if the food is not cooked properly, cause food poisoning

Saprotrophic Heterotrophs  These bacteria digest organic matter (food) externally and absorb the resulting nutrients across their cell membranes  Some are involved in recycling matter in ecosystems, these are saprophytic decomposers and are necessary for the functioning of all ecosystems

How bacteria use food energy  There are two processes by which bacteria convert “food” energy into energy that they can use 1. Respiration 2. Fermentation

Respiration  This process requires oxygen to break down food molecules  Therefore it is an AEROBIC process oxygen + sugar  carbon dioxide + water 38 ATP produced (ATP = energy molecule)

Fermentation  This process does NOT require oxygen to break down food molecules to produce energy  Therefore this is an ANAEROBIC process 2 ATP produced

Classification based on respiration  There are three classifications of bacteria based on their mode of respiration 1. Obligate aerobes 2. Obligate anaerobes 3. Facultative anaerobes

Obligate Aerobes  These bacteria carry out aerobic respiration  They MUST live in oxygen rich environments to survive

Obligate Anaerobes  These bacteria carry out fermentation to produce energy from food  They must live in environments where there is NO oxygen  If oxygen is present they will die

Facultative Anaerobes  These bacteria usually carry out aerobic respiration  If deprived of oxygen they can switch to anaerobic fermentation for a short time

Summary-Complete the tables Energy Source AutotrophsHeterotrophs Phototrophic Chemotrophic Saprotrophic Respiration AerobesAnaerobes Obligate Falcultative