About Inland Island Yeast Laboratories

Our Story


Inland Island Yeast Laboratories was founded in 2014 by two friends, homebrewers and colleagues. At the time, John Giarratano and Matthew Peetz were growing yeast on an industrial scale for the biofuel industry. Taking the skills and knowledge they gained during their education and professional experiences, John and Matthew decided to take what they learned and apply it to something they were passionate about….BEER. Inland Island initially produced yeast pitches for home brewing and established a following with the local Denver home brewing community. Realizing that this could be a viable business in the growing Colorado craft brewing industry, John and Matthew decided to quit their stable day jobs and pursue the dream of owning a laboratory and yeast production facility. Over the last year, Inland Island Yeast Laboratories has grown to produce yeast for dozens of breweries, including multiple 2015 GABF medal winners! In September 2015, Inland Island launched new home brew vials which are intended for national distribution. Whatever the future holds, we at Inland Island sincerely appreciate the Colorado craft brewing community’s willingness to embrace all things local. Thank you for giving us the opportunity to share our products with beer enthusiasts everywhere!

Our Experience


John Giarratano received his Bachelor’s degree in Molecular, Cellular and Developmental Biology from the University of Colorado and a Master’s of Science in Bioengineering from Denver University. John spent five years working in Clinical Cell Culture Operations for a pharmaceutical giant in California. During this time he became an expert in technology transfer, sterile technique and Good Manufacturing Practice (GMP). Next, John worked for a biofuel company focusing on scale up from 20L to 1.0E6L production fermentations. During this time he helped design and build several pieces of novel and proprietary equipment for use in yeast propagation and fermentation. Since August of 2014, John has been working full time to develop Inland Island’s propagation techniques and facility as well as sales and customer service.

Matthew Peetz received his Bachelor’s and Master’s degrees in Cellular Biology from the University of Colorado. While in college, he collected yeast from around the world including strains never before brewed within the United States. After earning his degrees, Matthew spent time as a professional research assistant at Anschutz Medical Campus working in a yeast laboratory. During this time he honed his skills in yeast isolation, culture maintenance and sterile technique. He then took his skills from academia to the biofuel industry where he specialized in yeast propagation, media optimization and contamination mitigation at the 2L and 1.0E6L scale. Since February of 2015, Matthew has been at Inland Island full time, developing our unique media formula, strain bank and culture maintenance.

See what our customers are saying about us

"Hands down the best customer service and quality. We have always been very satisfied with every pitch they delivered. Clean and reliable."- Zach, Mockery Brewing
"Thanks Inland Island, we could not have won a Gold Medal without your yeast! Great yeast with proper cell counts and fantastic customer service."- Brad, Prost Brewing
"Their service and quality control provides a competitive advantage for highly efficient breweries like ourselves."- Grant, Joyride Brewing