Dairy farming

Milk bacteria, such as Streptococcus thermophilus and Lactobacillus bulgaricus, are the micro-organisms most commonly used in dairy farming. These bacteria, which come in the form of bacilli or cocci, are anaerobic (they do not need oxygen to survive) and transform simple sugars (glucose and lactose) into lactic acid through a metabolic process which is known as fermentation. Lactic acid alters the chemical and physical features of milk, transforming it into something else: yoghurt. Butter-making also needs the aid of some micro-organisms: the typical taste of this product is due to the presence of diacetyl, a substance released by the milk bacteria that develop as the milk cream ages.
Some bacteria can produce substances, such as bacteriocins and nisins, that have an antibiotic effect, i.e. they fight the harmful bacteria that could contaminate cheese.
Special bacteria, known as “proponic”, develop in some types of cheese, such as Emmenthal and Gruyère, and produce large amounts of carbon dioxide. The gas forms gaps in the cheese paste which when aged exhibits the famous “holes”.

 
Download "Man and bacteria" pdf file
Download the junior version pdf file
 

Special reports

From the Multimedia section

  • life

    Streptococcus in the blood

    Look

    life

    Streptococci

    Look

    life

    Bacteria

    Look

  • life

    Bacterial colony

    Look

    life

    Cyanobacteria

    Look

    life

    Intestinal bacteria

    Look

  • life

    Microscopic structure of bacteria

    Look

    life

    Structure bacterium

    Look

    life

    The growth curve of a bacterial colony

    Look

Facts

  • Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

    Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...

    Bacteria as Sherlock Holmes

    A drop of blood, a fragment of skin or a hair found on the scene of a crime can supply…

  • Bacteria as detergents

    Enzymes are proteins produced by the cells of all living organisms...

    High-fashion bacteria

    Some bacteria, the Clostridia, were used to make textile fibres...

    Let’s eat!

    The economic importance of fungi is increased by the “edible” mushrooms...

  • Predator mushroom

    <em>Pleutrotus ostreatus</em> mushroom does not have teeth or claws but it is...

    Who lives well with low oxygen?

    <i><span style="font-style: normal; " class="Apple-style-span"><i><em>Aquandriella fermentas</em> </i>lives in stagnant waters and can stand complete anaerobiosis...</span></i>

    Decomposing organisms

    The ability to destroy organic matter has been used by man...

  • 13 May 2011

    Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

    Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...

  • Bacteria as Sherlock Holmes

    A drop of blood, a fragment of skin or a hair found on the scene of a crime can supply…

    Bacteria as detergents

    Enzymes are proteins produced by the cells of all living organisms...

  • High-fashion bacteria

    Some bacteria, the Clostridia, were used to make textile fibres...

    Let’s eat!

    The economic importance of fungi is increased by the “edible” mushrooms...

  • Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

  • Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...

  • Bacteria as Sherlock Holmes

    A drop of blood, a fragment of skin or a hair found on the scene of a crime can supply…