Bacteria
Pectinatus
   This type of bacteria is an obligate anaerobe (cannot grow in the presence of oxygen). When they grow in beer, they produce acetic, lactic and propionic acids, methyl mercaptan, dimethyl sulfide and hydrogen sulfide. Beer which has been broken down by this organism is cloudy and smells like rotten eggs. Also has a foul taste.

Acetobacter
   This type of bacteria is an obligate anaerobe (can not grow in the presence of oxygen). When they grow in beer, they produce large quantities of acetic acid (vinegar), and can cause beer to become sour, ropy, turbid and visibly discolored.

Note : the information in this section was provided by and reproduced with the permission of Coors Brewing of Golden, Colorado.

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