Pediococcus

Pediococcus are gram positive lactic acid bacteria used in the production of Belgian style beers where additional acidity is desirable. They are often found in gueuze and other Belgian styles of sour beer. Due to their continued metabolism of longer chain polysaccharides, acid production will increase with storage time. Pediococcus species are generally more tolerant of antimicrobial hop acids and higher levels of acidity than Lactobacillus.

Pediococcus may also cause “ropiness” (also called a "sick beer") due to the production of exopolysaccharides. "Ropy" or "sick" beer is more viscous and, in extreme circumstances, can form strands. Sickness effects mostly the mouthfeel and appearance of beer, and may have no influence on the flavor. Pediococcus species can also produce diacetyl with extended storage time. Brettanomyces can break down exopolysaccharides and diacetyl produced by Pediococcus and the two are often used together.

Name	Mfg#	Taxonomy	Note
White Labs	WLP661	damnosus	High diacetyl producer and slow growing.
Wyeast	5733	damnosus	May cause “ropiness” and produce low levels of diacetyl with extended storage time.
RVA Yeast Labs	RVA 601	damnosus	Lactic acid bacteria used in souring Belgian-style beers such as gueze and Lambic. Acid production increases with storage. Temperature range is 60-95º F.