Siebel - Siebel Pure Yeast Library

By: Siebel Institute  09-12-2011
Keywords: Beer, breweries, Yeast

Since 1872, the Siebel Institute of Technology has been providing fresh liquid brewing yeast to professional brewers around the world, building a reputation for excellence in yeast quality and purity. What makes Siebel Institute yeast different from that of other manufacturers?

Assured performance.

We don’t carry hundreds of varieties of unproven yeast strains: We choose to offer a narrow range of strains with proven characteristics of reliable fermentation performance & accurate flavor production for your ales, lagers and specialty beers. Each of our Siebel Institute yeast strains is maintained using techniques that meet or exceed the standards used in the world’s biggest & best-known breweries. We don’t keep slurries on hand for shipment at the time of ordering. Instead, we begin production of your yeast order at the time the order is placed. During the production period of your culture slant or propagated slurry, our Microbiology Services team performs multiple tests using some of the most advanced techniques and equipment available to assure the purity & performance of your yeast. Your order is not shipped until we are 100% satisfied that it meets the highest possible standards of quality.

When the quality & consistency of your beer is dependent on the quality & consistency of your yeast, you can count on Siebel Institute, America’s oldest brewing industry laboratory & service provider.

Yeast Cultures

The Siebel Institute of Technology has selected our Siebel Institute BRY brewing yeast strains for their reliable performance in professional brewing applications.

Bry 96: This is a flocculent top fermenting ale yeast from a brewery formerly operating on the East Coast of the United States. It produces a very clean ale flavor which has been well accepted in a number of breweries.

Bry 118: A very flocculent lager yeast. It has been used by a number of breweries in the United States for many years. It shows good viability under a variety of brewing conditions and keeps its viability well during storage. This yeast produces a beer with a slightly fruity character, sometimes a little residual sugar is left because the yeast settles quickly. It tends to be a sulfur producer under some conditions.

Bry 144: This is a top fermenting Alt beer style yeast from Germany which produces a very full flavored but clean tasting beer, somewhat estery in flavor.

Bry 203: This yeast is a very popular and very flocculent lager strain from Northern Europe. It produces a beer with a good balance of flavors, particularly between the esters and higher alcohols, which makes a very drinkable beer. This yeast produces less sulfur compounds than most other flocculent strains.

Bry 204: This yeast originated from Northern Europe. It is a top fermenting Trappist type strain which ferments rapidly at relatively warm temperatures. It can be used to produce ales and wheat beers with a rather dry but estery flavor and a light clove-like spicy character.

Bry 235: A traditional Bavarian weizen yeast. Top fermenting and normally used at room temperatures to give a very vigorous fermentation. Produces a very estery beer with a mild clove-like spiciness.

Bry 264: A flocculent, bottom fermenting strain from England. Gives quick clarification of the beer after fermentation. Produces a clean ale type product, with an estery and slightly nutty character.

Bry 401: This is the most widely used yeast strain for brewing Kolsch beer in Germany. It is a non-flocculent yeast that ferments well and settles very slowly. It is an ale yeast that ferments well at lower temperatures (55 - 59 deg F or 13 – 15 deg C) and produces the mild flavors associated with Kolsch beer.

Our laboratory also provides services for isolation and evaluation of pure cultures from your own source. We will maintain such cultures for your exclusive use, and will propagate the strain as described above when needed.

We have many other yeast strains available besides the ones described here. Many of these alternate strains are described on a separate Yeast Culture Information sheet, which is available upon request. We will be pleased to assist in matching one of these strains with your specific requirements. For further assistance with our special yeast strains please contact the Siebel Institute Microbiological Services division.

Ordering Yeast

Any of the yeast strains described above can be provided as pure cultures. Allow at least 2 weeks for the culture to be grown and checked for purity in our laboratory. The following amounts are available:

YEAST CULTURE SLANTS - Two duplicate cultures growing on agar medium in screw cap test tubes. Suitable for storage in a refrigerator to be propagated when desired. Suggestions for propagation will be sent along with the culture if requested.

PROPAGATED LIQUID YEAST (1 liter) - Yeast which has been propagated in our laboratory under sterile and growth enhancing conditions to a final stage of 10 liters. Yeast is concentrated to 1 liter or less, refrigerated, and shipped overnight (U.S. and Canadian destinations only). This amount of yeast is sufficient for further propagation at the brewery starting with a volume of about 1 Hl (about 1 barrel).

Ordering products & services:

Yeast Maintenance & Evaluation Services

The Siebel Institute of Technology has been in the brewing yeast business since 1872, providing a full range of yeast banking & maintenance services to some of the greatest names in North American brewing. Now, with our expanded Microbiological Services division in Montreal, Canada, we are pleased to offer the industry’s most advanced yeast management & evaluation services.

Yeast Maintenance: We can maintain a slant of your own pure yeast culture. Cultures submitted are checked for purity, re-isolated if necessary, and stored in an ultra-low temperature freezer. This can provide a valuable insurance for your brewery's special yeast plus we will have your yeast in storage to more quickly propagate stocks for you upon request. Prices for our yeast banking & maintenance services can be found in our Yeast Services & Media catalog at


Siebel Institute Microbiological Services is pleased to offer testing using genetic methods for the differentiation of brewing yeast strains and for the detection of genomic mutations. For more information regarding these services (including pricing) see the contact information at the bottom of this page.


This method involves in vitro amplification of variable sized regions of DNA by PCR (Polymerase Chain Reaction). Specifically a Random Amplified Polymorphic DNA reaction (RAPD) is performed and the subsequent PCR products can be separated according to their size on an agarose gel. During the RAPD reaction, multiple regions of the genome are amplified, and as such, different strains of ale and lager yeast display different banding patterns or ‘fingerprints’. It should be noted that some strains which are particularly closely related may not be able to be differentiated using this method. In addition, although some genetic mutations may also be identified using this technique, smaller mutations to the genome may not be detected. However, this method is excellent for strain differentiation and has proven to be useful for detecting low levels of contamination in the instance that a yeast culture becomes contaminated with another strain.


The number and size of chromosomes is known to be variable amongst different strains of lager and ale yeast. Consequently analysis of chromosomes offers a means of differentiating brewing yeast. Standard electrophoresis cannot be used for this purpose due to the large size of the chromosomes. Consequently Pulsed Field Gel Electrophoresis (PFGE) is required to separate these large DNA molecules. The PFGE technique that we employ, known as contour-clamped homogenous electric field (CHEF), offers a means of differentiating strains by separating the chromosomes according to their size on an agarose gel. In this way, a chromosomal fingerprint or karyotype can be obtained.

This method has also been demonstrated to detect mutations and the genetic stability of yeast strains. However, the mutation needs to be large enough so that the chromosome size will significantly change.


This method is designed to target variable sequences within the Saccharomyces genome known as transposons. Yeast transposons are small pieces of DNA which display a tendency to move around the genome over the course of many generations. Therefore, the localization of these sequences generally differs from one strain to another. The RFLP (Restriction Fragment Length Polymorphism) technique that we employ utilizes a probe containing the transposon sequence, which is used to target digested pieces of DNA. Each time the complementary sequence of the transposon is found, the probe will stick to it. The precise location of probe binding is determined by an antibody reaction resulting in a band being produced for that particular DNA fragment. The resulting DNA fingerprint is particularly useful for detecting small mutations in yeast which may not be observed using other methods.

Mitochondrial DNA digest

There are more variable regions between the mitochondrial DNA in yeast than there are in the nuclear DNA. These variations can be exploited to differentiate strains. Cutting the cellular DNA using restriction enzymes with a low cutting frequency for mitochondrial allows a small number of large mtDNA molecules to be produced which can be separated using gel electrophoresis. Analysis of yeasts using this method has been demonstrated to be highly effective at differentiating strains and can be applied when RAPD-PCR, PFGE and RFLP are unable to differentiate a particular group of strains. mtDNA digests are also a relatively cheap means of analysis when compared to PFGE and RFLP.

Microsattelite PCR

This is a PCR based technique which employs primers aimed at microsatellite regions of genomic DNA. Microsatellites are short sequence repeats which have been shown to exhibit substantial levels of polymorphism in yeast. Analysis of yeasts using this method has been demonstrated to be highly effective at differentiating strains and can be applied when RAPD-PCR, PFGE and RFLP are unable to differentiate a particular group of strains. The use of microsattelite PCR is also a cheaper alternative to PFGE and RFLP.


ITS-PCR is a method which allows the identification of the genus and species of yeast. The amplification of a specific sequence of the ribosomal DNA will generate a fragment of variable size depending on the genus/species of yeast analyzed. If the size of a fragment is identical between two species, a digestion of the fragments is performed using restriction enzymes. The digestion will generate fragments cut at different places according to the species being analyzed. The size of the fragments (digested and non-digested) can be compared to a database comprising 200 species of yeast.

For information regarding pricing and suggested Yeast Maintenance & Evaluation Services and DNA fingerprinting services, contact:

Keywords: Beer, breweries, Brewing Industry, Professional Brewers, Yeast,

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