Bacteria
   Very few bacteria are capable of growing in beer. These types are generally termed ‘beer spoilers’. They are not hazardous to human health, but are tremendously important because of their impact on the appearance, aroma and flavor of the beer.

   When a beer spoiler organism grows in beer it multiplies. This eventually causes beer turbidity or cloudiness. While the organism is alive, it metabolizes, producing chemical ‘by-products’ which can result in strong ‘off’ tastes and odors.

   These below are four of the most common types of bacteria found in beer.

Lactobacillus
   This type of bacteria is anaerobic (can grow with or without the presence of oxygen). When they grow in beer, they make the beer cloudy. Large amounts of lactic acid and acetic acids are produced. This causes the beer to become sour tasting.

Pediococcus
   This type of bacteria is anaerobic (can grow with or without the presence of oxygen). When they grow in beer, they produce diacetyl. This produces a compound that is desribed as having a popcorn, buttery aroma.

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