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'''Lactobacillus''' (often referred to as ''LactoLactobacillus'') is a genus of Gram-positive, rod-shaped lactic acid bacteria (LAB) which produces acidity and sour flavors in the form of lactic acid (and sometimes acetic acid) found in lambics, Berliner Weiss, sour brown ales, and gueuze. All ''Lactobacillus'' species are aerotolerant anaerobes, which means they grow anaerobically but can also grow in the presence of oxygen <ref>[http://textbookofbacteriology.net/lactics.html Lactic Acid Bacteria. Todar's Online Texbook of Bacteriology. Kenneth Todar, PhD. Pg 1. Retrieved 08/09/2015.]</ref>. There are more than 100 species, many of which are found in the human gastrointestinal track <ref>[http://textbookofbacteriology.net/lactics_4.html ''Lactic Acid Bacteria''. Todar's Online Texbook of Bacteriology. Kenneth Todar, PhD. Pg. 4. Retrieved 07/28/2015.]</ref><ref>[http://textbookofbacteriology.net/nutgro_4.html ''Nutrition and Growth of Bacteria''. Todar's Online Texbook of Bacteriology. Kenneth Todar, PhD. Retrieved 07/28/2015.]</ref>. In addition to beer, some species of ''LactoLactobacillus'' are also used to ferment yogurt, cheese, sauerkraut, pickles, wine, cider, kimchi, cocoa, and kefir <ref>[https://en.wikipedia.org/wiki/Lactobacillus ''Lactobacillus''. Wikipedia. Retrieved 07/28/2015.]</ref>. ''LactoLactobacillus'' can form a [[pellicle]] (need reference). See [[Pediococcus]], [[Brettanomyces]], [[Saccharomyces]], and [[Mixed Cultures]] charts for other commercially available cultures. See the [[Sour Worting]] and [[Mixed Fermentation]] pages for brewing techniques with ''Lactobacillus''. See the [[Alternative Bacteria Sources]] section for culturing ''Lactobacillus'' from grains, yogurt, probiotics, and other sources.

This blend is very susceptible to hops. It is recommended to not use any hops when souring with this ''LactoLactobacillus''. If hops must be used (some commercial breweries have to use hops for legal reasons), a maximum of 2 IBU is recommended.

In addition to the starter information given in the [[Lactobacillus#Manufacturer_Tips|Manufacturer Tips]] above, this section includes general advice for ''Lactobacillus'' starters for homebrewers and brewers. For growing ''Lactobacillus'' in a lab environment, or from an initial grouping of cells from a plate/slant or smaller cell count, MRS media is the most efficient growth media. However, for full pitches of ''Lactobacillus'' in beer/wort, brewers probably don't want to add that much MRS media to their beer since MRS media has a distinct odor and smell that would not be desirable in beer <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1152135114814701/?comment_id=1152674674760745&offset=0&total_comments=9&comment_tracking=%7B%22tn%22%3A%22R0%22%7DConversation with Lance Shaner and Nick Impellitteri on Lacto starters on MTF. 09/22/2015.]</ref>. Therefore, growing ''LactoLactobacillus'' in a wort-based starter media is recommended for building full pitches of ''LactoLactobacillus''. See [[Lactobacillus#External_Resources|External Resources]] for additional starter guides.

Pitching ~0.5-1 liter per ~20 liters of wort (~0.75-1 gallon per barrel) of ''Lactobacillus'' starter is the general guideline. The exact advisable pitching rates of commercial cultures may differ from manufacture to manufacturer. <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1077639885597558/ MTF thread started by Brad Primozic. 5/29/2015.]</ref>. Counting cells and pitching an exact cell count is the best approach. However, counting cells of ''LactoLactobacillus'' under a microscope can be difficult to achieve due to the small size of bacteria cells, so starter volumes are generally used instead when talking about pitching rates for ''Lactobacillus'' <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1068323126529234/?comment_id=1068337639861116&offset=0&total_comments=47&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation on MTF with Bryan Heit. 5/6/2015.]</ref>. Matt Miller of Sour Beer Blog and Richard Preiss of Escarpment Yeast Labs advise that if ideal growth (1-2 billion cells/mL) can be achieved (for example by using [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's starter procedure]]), then pitching as little as 100-125 mL of fresh ''LactoLactobacillus'' starter for 5 gallons of beer can achieve desirable acidity within 24 hours <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1180630378631841/?comment_id=1180733761954836&reply_comment_id=1180740128620866&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Richard Preiss on MTF regarding Lacto starters. 11/19/2015.]</ref><ref name="sbb2.0"></ref>. Moderately ideal growth in a starter results in around 500 million cells/mL, resulting in a 400 mL starter for 5 gallons, and low growth results in around 100 million cells/mL, resulting in a 2 liter starter for 5 gallons, according to Matt Miller (see [http://sourbeerblog.com/lactobacillus-2-0-advanced-techniques-for-fast-souring-beer/ Matt Miller's article] for more details) <ref name="sbb2.0"></ref>. However, it is difficult to verify how much growth has occurred with cheaper microscopes, so these rates may or may not be helpful to the brewer.

Another thing to consider is that achieving a pH of 4 as fast as possible is advisable for preventing off-flavors from other microbes <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1180630378631841/?comment_id=1181674265194119&reply_comment_id=1181715048523374&comment_tracking=%7B%22tn%22%3A%22R7%22%7D Conversation with Bryan Heit on MTF regarding speed of acid production with Lacto. 11/20/2015.]</ref>. Larger pitch rates tend to achieve a lower pH faster <ref name="heit_lacto_starters"></ref>. Therefore, unless using [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's starter procedure]], pitching 0.5-1 liters of starter for 5 gallons of wort is advisable in general. Even when using [[Lactobacillus#Samuel_Aeschlimann.27s_Starter_Procedures|Samuel Aeschlimann's starter procedure]], over-pitching ''Lactobacillus'' is not a concern (pitching an overly massive starter wort could produce undesirable flavors), so the same pitch rate should still be considered unless the brewer is confident that high growth rate has been achieved in the starter. Other factors that might affect the effectiveness of a volume based starter is the species/strain of the ''LactoLactobacillus'' being used, how much yeast contamination has occurred, and how old the ''LactoLactobacillus'' starter is. Some species/strains may require a larger volume of starter, as well as if yeast has contaminated the starter or wort (see [[Lactobacillus#100.25_Lactobacillus_Fermentation|100% Lactobacillus Fermentation]]). If a ''LactoLactobacillus'' culture is older than 1 month, a fresh starter should be made. Keeping a separate Erlenmeyer flask for ''LactoLactobacillus'' starters can help to prevent yeast contamination <ref>Private correspondence with Richard Preiss to Dan Pixley. 11/20/2015.]</ref>.

Although 100% apple juice or 100% DME starters will "work" for ''LactoLactobacillus'' starters, they do not provide optimal growth conditions. [https://eurekabrewing.wordpress.com/2015/05/18/evaluate-starter-media-to-propagate-lactobacillus-sp/ Samuel Aeschlimann from Eureka Brewing Blog] ran a set of experiments that found a DME based recipe for starter wort that produces a very high cell density similar to that of MRS media (MRS media provides optimal growth rates for ''LactoLactobacillus''). The recipe for this starter wort is: '''1.040 SG (10°P) Dried Malt Extract wort with 10% apple juice + 20 grams of chalk (CaCO3) per liter + yeast nutrients'''. Regarding the use of chalk, it is the preferred buffer because it does not react with CO2 (unlike baking soda), so it won't be consumed by exposure to air due to CO2 production by the Lacto. It also has a pKa (maximum buffering capacity) of around 4.6, which is ideal for ''LactoLactobacillus'' growth. The fact that it easily precipitates out also makes it ideal to use as a buffer <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1180630378631841/?comment_id=1181674265194119&reply_comment_id=1181743348520544&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Bryan Heit regarding the use of chalk as a buffer in Lacto starters. 11/20/2015.]</ref>. To create a 1 liter starter for 20 liters of wort, follow these directions:

# The chalk is not desirable to pitch into the beer because of its buffering effect. The chalk will sediment within hours of being added to the starter, or if a stir plate is used, a couple of hours after the stir plate is turned off <ref>[https://en.wikipedia.org/wiki/Stokes%27_law Stokes' law. Wikipedia. retrieved 09/24/2015.]</ref><ref name="Sam_starter2"></ref>. The ''LactoLactobacillus'' should stay in suspension for at least a day or two after the starter is done, so swirling the starter isn't necessary, although it is certainly an option. If the starter is swirled, allow a couple of hours for the chalk to sediment out again. After the chalk sediments to the bottom of the flask, pour all of the liquid from the top of the starter into the wort/beer, and leave the chalk sediment behind. Avoid cold crashing the starter because it can have an adverse effect on the bacteria's health <ref name="heit_lacto_starters">[http://suigenerisbrewing.blogspot.ca/2015/05/lacto-starters.html Heit, Bryan. Lacto Starters. Sui Generis Blog. Retrieved 6/15/2015.]</ref><ref name="sam_starter"></ref>.

Maximum cell densities of ''Pedio'' and ''LactoLactobacillus'' are around 50-80 million cells/mL. Since they tend to have high nutrient demands, this number varies based on the conditions of the propogation <ref>[https://www.reddit.com/r/Homebrewing/comments/3qp7b7/advanced_brewers_round_table_neva_parker_white/cwh7iqq Neva Parker, Reddit thread. 10/29/2015.]</ref>.

There is a fair bit of research into hop tolerance out there; its not a simple topic as a number of factors come into play to produce hop tolerance. To make things even more complicated, hop tolerance is an inducable trait in many ''LactoLactobacillus'' species - meaning that a seemingly susceptible strain can become resistant by culturing in ever-increasing doses, and a seemingly resistant strain can become susceptible after a generation or four in a hop-free media.

* [https://www.youtube.com/watch?v=J2g5P7ZlGn4 Per Buer's Video Demonstration of how Dry Hopping Affects multiple ''LactoLactobacillus'' species.]

For dried ''Lactobacillus'', such as probiotics or [[Dry Yeast for Sour Ales BlackManYeast]] products, [http://suigenerisbrewing.blogspot.com/ Bryan Heit's] lab studies have shown that they can lose viability ~80 times faster at room temperature than when stored at refrigeration temperatures. Therefore, it is recommended to store dried ''LactoLactobacillus'' at refrigeration temperatures.

Liquid cultures become stressed by two factors: storage in an acidic environment, and storage without sugar <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1154970097864536/?comment_id=1156656834362529&offset=0&total_comments=12&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Bryan Heit on stress factors in storing Lacto. 09/28/2015.]</ref>. Sugar storage creates more acid as the ''LactoLactobacillus'' ferments it, so it may not be ideal unless the ''LactoLactobacillus'' is continually fed. Ideally, liquid cultures of ''LactoLactobacillus'' should be stored frozen with 20% glycerol, or refrigerated as slants with water or mineral oil. Also, there is anecdotal evidence that certain species may survive better at room temperature. Bryan hypothesizes that stable temperatures may be more important than storing at an "ideal" temperature <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1067614393266774/ Conversation with Bryan Heit on Milk The Funk. 05/04/2015.]</ref>.

Lance Shaner's experiment on testing [[100% Lactobacillus Fermentation]] showed that '''pure cultures''' of WLP677, WLP672, Wyeast 5335, Wyeast 5223-PC, and the ''L. plantarum'' from Omega Yeast OYL-605, could not fully attenuate a 1.037 SG wort. The most attenuative ''LactoLactobacillus'' culture, WLP677, was only able to attenuate down to 1.03255 SG. It is likely that all species and strains of ''Lactobacillus'' available to brewers cannot fully attenuate wort. In addition, this study showed at most a 0.29% ABV in 100% ''LactoLactobacillus'' fermentations (attributed to WLP677). See [[100% Lactobacillus Fermentation]] for more information. If a higher attenuation is achieved, cross contamination of yeast is most likely the cause.

Elde Arendt, a brewing scientist that specializes in ''Lactobacillus'' presented her work at the Belgian Brewing Conference 2015. In it she explained that LAB will only ferment 0.5°P of wort regardless of the gravity of that wort. When asked at the end of the presentation why ''LactoLactobacillus'' only ferments ~0.5°P (note that Shaner's experiment shows ''LactoLactobacillus'' fermenting ~1°P, although this may be due to a margin of error since Shaner only performed this experiment once), considering that ''LactoLactobacillus'' ferments maltose and there is plenty of maltose in wort, Arendt responded that she believes that the bacteria reaches max cell density in the wort with relatively little sugar requirements (~16 mins in and ~25 mins in):

Some species/strains of ''Lactobacillus'' can create their own amino acids (this is to say they are '''prototrophic'''), whereas other species/strains cannot (this is to say they are '''autotrophic'''). Autotrophic ''LactoLactobacillus'' can break down proteins, including foam forming proteins in beer, through a process called '''proteolysis''' <ref name="Todar"></ref>, the breakdown of various proteins into smaller polypeptides or amino acids through the use of various enzymes <ref>[https://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/26351/ShellhammerThomasH.FoodScience.TextureProteolysisViable.pdf?sequence=1 Texture, proteolysis and viable lactic acid bacteria in commercial Cheddar cheeses treated with high pressure. Cheryl Wick, Uwe Nienaber, Olga Anggraeni, Thomas H Shellhammer and Polly D Courtney. 2002. Retrieved 7/7/2015.]</ref><ref name="Haq_Mukhtar">[http://www.researchgate.net/profile/Hamid_Mukhtar4/publication/230245468_PROTEASE_BIOSYNTHESIS_FROM_LACTOBACILLUS_SPECIES_FERMENTATION_PARAMETERS_AND_KINETICS/links/00b7d52c403b158288000000.pdf Protease Biosynthesis from Lactobacillus Species: Fermentation Parameters and Kinetics. Ikram-Ul_Haq and Hamid Mukhtar. Jan 2007. Retrieved 7/7/2015.] </ref><ref>[https://en.wikipedia.org/wiki/Proteolysis Proteolysis. Wikipedia. Retrieved 7/7/2015.]</ref>. Both homofermentative and heterofermentative species have been observed to have proteolytic activity <ref>[https://books.google.com/books?id=qMreBwAAQBAJ&pg=PA133&lpg=PA133&dq=lactobacillus+homofermentative+proteolytic&source=bl&ots=bjxq9rGdha&sig=pCz4WeKek3zTv5oL6Rui1dUuEqw&hl=en&sa=X&ei=AJqcVeT0O8XkoAS0-oC4CQ&ved=0CF0Q6AEwBw#v=onepage&q=lactobacillus%20homofermentative%20proteolytic&f=false Brewing Microbiology. Fergus Priest. Springer Science & Business Media, Jun 29, 2013. Pg 133.]</ref>. This process is a large part of cheese and yogurt fermentation. ''Lactobacillus'' species that have been identified as breaking down proteins (mostly in cheese or yogurt) include ''Lactobacillus bulgaricus'', ''Lactobacillus rhamnosus'', ''Lactobacillus casei'', ''Lactobacillus paracasei'', ''Lactobacillus helveticus'', ''Lactobacillus delbrueckii'', ''Lactobacillus brevis'', ''Lactobacillus cellobiosus'', ''Lactobacillus fermentum'', and ''Lactobacillus plantarum'' <ref name="Haq_Mukhtar"></ref>. Results of using various species/strains appears to demonstrate that different species/strains are worse for degrading head retention proteins than others. For example, it's been reported that B.H. Meyer says that souring with ''L. delbruekii'' creates better head retention than souring with other species such as ''L. brevis''. <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1105663546128525/?comment_id=1105772812784265&offset=0&total_comments=107&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Kristen England on MTF. 7/7/2015.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1096427697052110/?comment_id=1096496983711848&offset=0&total_comments=45&comment_tracking=%7B%22tn%22%3A%22R9%22%7D Conversation with Jace Marti on MTF about L. delbruekii head retention problems. 6/21/2015.]</ref>. Different strains of the same species may also have different levels of ''proteolytic activity'' <ref>[http://www.ncbi.nlm.nih.gov/pubmed/8568030 Comparison of proteolytic activities in various lactobacilli. Sasaki M, Bosman BW, Tan PS. 1995.]</ref>.

Proteolytic activity has been shown to decrease as pH falls below 5.0 for some species of ''Lactobacillus'' <ref name="Haq_Mukhtar"></ref>. In order to combat poor head retention in beers that are soured with ''LactoLactobacillus'', it has been suggested by German brewing scientist, Burghard Hagen Meyer, to [[Sour_Worting#How_to_Pre-Acidify|lower the pH of the wort to 4.5-4.8]] with food grade lactic acid or phosphoric acid before pitching ''Lactobacillus'' <ref name="Gail">[https://sourbrewster.wordpress.com/2012/09/18/berliner-weisse-the-old-time-kettle-souring-technique/ ''Berliner Weisse – the old-time kettle-souring technique.'' Brewing Sour blog, by Gail Ann Williams.September 18, 2012. Retrieved 7/7/2015.]</ref><ref>[http://ingenuitybrew.blogspot.com/2013/06/berliner-weisse-test.html ''Berliner Weisse Test''. Ingenuity Brew Blog. June 4, 2013. Retrieved 7/7/2015.]</ref><ref>[http://www.themadfermentationist.com/2012/06/100-lactobacillus-berliner-weisse.html ''100% Lactobacillus Berliner Weisse.'' The Mad Fermentationist Blog, by Michael Tonsmeire. June 25, 2012. Retrieved 7/7/2015.]</ref>. Although the lowering of the wort's pH inhibits the proteolytic activity of ''LactoLactobacillus'', it does not stop it completely, so continued exposure to ''Lactobacillus'' over time may still degrade the available head formation proteins. Additionally, ingredients that increase head retention such as unmalted chit, malted wheat, and carafoam have been used to help combat poor head retention in beers soured by ''Lactobacillus'' <ref name="Gail"></ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1105839682777578/?comment_id=1105942362767310&offset=0&total_comments=27&comment_tracking=%7B%22tn%22%3A%22R8%22%7D Conversation with Richard Preiss on MTF. 7/7/2015.]</ref>. Professional brewer [https://www.facebook.com/groups/MilkTheFunk/permalink/1105839682777578/ Kristen England of Bent Brewstillery] tested [http://www.mbaa.com/districts/MidSouth/mash/Documents/2014%20PDF%20Hop%20Product%20Applications%20Presentation.pdf?Mobile=1&Source=%2Fdistricts%2FMidSouth%2Fmash%2F_layouts%2Fmobile%2Fview.aspx%3FList%3D85ff6384-aa05-491f-8ef3-d2e9eea713f2%26View%3Da234a10f-469b-4edd-a8a9-9a96b00750ee%26CurrentPage%3D1 Hexa Iso Hop Extract] by dosing at 4 times the recommended dosage and found that it greatly increased head retention in a Berliner Weisse (3.5% abv, pH 3.1, TA ~1, BU 5), with a minor taste difference. Kristen recommends experimenting with lower dosages to avoid too much flavor impact.

Another method that has been reported to help with head retention when [[Sour Worting]] (kettle souring) is to add a pound of DME per 5 gallons of wort during the heat pasteurization process (after the wort has been soured with ''Lactobacillus''). One could also steep specialty grains such as wheat malt, chit malt, carafoam, or carapils, and add the extract into the kettle during the heat pasteurization or boiling process. This will add back head formation proteins that were lost during the ''LactoLactobacillus'' fermentation <ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1069228273105386/?comment_id=1069266549768225&offset=0&total_comments=24&comment_tracking=%7B%22tn%22%3A%22R8%22%7D Conversation with Gareth Young on MTF. 05/08/2015.]</ref><ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/1137179879643558/?comment_id=1137362989625247&offset=0&total_comments=8&comment_tracking=%7B%22tn%22%3A%22R%22%7D Conversation with Paul Finney on MTF in regards to head retention of Berliner Weisse. 08/29/2015.]</ref>.

* [http://phdinbeer.com/2015/08/05/beer-microbiology-lactobacillus-ph-expeirment/ Beer Microbiology – Lactobacillus pH experiment] - Matt Humbard's experiment to determine final pH of individual ''LactoLactobacillus'' strains used in the graphs on this page.