Pediococcus

Introduction

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.

See Lactobacillus, Brettanomyces, Saccharomyces, and Mixed Cultures charts for other commercially available cultures.

Commercial Cultures

Name	Mfg#	Taxonomy	Note
White Labs	WLP661	damnosus	High diacetyl producer and slow growing. Fermentation temp: 70-85°F (21-29.4° C). Attenuation: 65%
Wyeast	5733	damnosus	May cause “ropiness” and produce low levels of diacetyl with extended storage time. Temp range: 60-95° F (15-35° C).
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.

Manufacturer Tips

Wyeast on 5733

"If using 1 pack of 5733 per 5 gallon batch; and either adding to secondary after alcoholic fermentation is complete, or co-inoculating with a Sacch' strain, then a starter would not be necessary. If you did want or need to propagate, I'd recommend 2 liters of 1.030-1.040 wort per pack, incubated at 80-90*F, without agitation." Michael Dawson, Wyeast.

White Labs on WLP661

"That one does well in 70-85 deg F. You can do a starter, but you shouldn't have to if you are doing a 5 gallon batch. It does take a while to sour, so just be patient and let it do it's thing." Sarah Neel, Sales and Customer Service, White Labs

Metabolism

Growth and Environment

One study showed that by starting growth in a medium (De Man Rogosa and Sharpe [MRS] broth [Oxoid]) that began with a pH of 6.7, and allowing the pH to drop to 4.14 naturally from fermentation, that better growth was observed. The addition of bacteriological peptone, MnSO4, and Tween 80 also increased activity .

P. damnosus is sensitive to environments that contain NaCl, and will not grow with concentrations of 4% NaCl. This species requires an anaerobic environment for growth .