Reasons to choose List Labs as your Microbiome CDMO:

  • We support a very diverse offering in Bacterial Manufacturing.
  • We are a passionate and transparent CDMO.
  • We are flexible and cohesive enough to be an extension of our customer’s team.
  • We offer end-to-end solutions for our customers.

Learn more about List Labs’ 45 years of experience with Bacterial Manufacturing by watching our video below:

This interview between Jessica Thompson from Kisaco Research and Stacy Burns-Guydish, PhD, President of List Labs, talks about the growth of the Microbiome field for Microbiome CDMOs and digs deep into the Live Biotherapeutics side of this burgeoning industry.

To get further insight into the future of the Microbiome field, check out the video below:


Jessica Thompson (Kisaco Research)

Hi, and welcome to the latest of our interview spotlights in the run-up to Microbiome Connect USA. My name is Jessica Thompson. I’m the Portfolio Director of the Life Sciences and Microbiome Portfolio for Kisaco Research. And it’s a pleasure to be joined by Stacy Burns- Guydish, who is the president at List Labs. Stacy, thank you so much for joining.

Stacy Burns-Guydish, PhD, President (List Labs)

Well, thanks for having me.

Jessica Thompson (Kisaco Research)

So to start off Perhaps, it would be great if you could give a little bit of an introduction about yourself and your background in the space.

Stacy Burns-Guydish, PhD, President (List Labs)

Yeah, so I’m the president of List Labs and my background is in microbiology. I got my PhD at Baylor College of Medicine and then did my postdoc at Stanford. A lot of my early microbiome career was focused on more on infectious disease of bacteria and that host-pathogen interaction. Before I joined List Labs, I joined a startup company that was using a strict anaerobic clostridium organism to make a biofuel or a biochemical. So, we improved this organism for making that biochemical, and we scaled the fermentation process up to 100,000 liters. So, this was a really good experience that I brought to List labs and working with strict anaerobes and that scale-up of that fermentation and immediately applied it to Live Biotherapeutic Products (LBPs) and that process development. So, since I’ve been at List Labs now for over six years, I’ve been involved with many of the LBP companies and moving their products to clinical trials.

Jessica Thompson (Kisaco Research)

Great. and what excites you about working in microbiome research

Stacy Burns-Guydish, PhD, President (List Labs)

So, I’m going back a little bit in my history. When I was in high school, in my first biology class the first time, I looked under a microscope, and I was hooked. I knew that I wanted to be a microbiologist, and I knew that I wanted to do something that would benefit society. But I think what I didn’t realize then is how beneficial those organisms in the microbiome could be to our health. You know, bacteria tended to get a bad rap. They’ve always been thought of as ones that cause infection, but they are important to our health. The research in the Microbiome field is revealing all these important synergies that these bacteria serve in our bodies. So, they helped develop our immune and endocrine systems. They help us digest our food, they provide vitamins and nutrients, and they also prevent and protect us from infection. So, it’s exciting to watch the growth in this field from more uncharacterized donor derived products. And now we’re seeing more characterized single organisms or a consortium of bacteria that are being used as a therapeutic to improve patient lives. The field is also evolving from there. So, we’re seeing engineered organisms that can deliver a therapeutic to a specific site. Also, we’re seeing you know a kill switch inserted into the organism, so they provide their function and then they’re eliminated. Then we’re also seeing companies go on to identify the metabolites and the proteins that are also derived from this microbiome associated bacteria.

Jessica Thompson (Kisaco Research)

Yeah, I think it’s an exciting field so far. There’s been so many developments in the field over the past few years for this. Given all the excitement, there’s still obviously a lot of challenges to overcome within the space. What do you think are some of the major challenges that are facing the LBP industry or the microbiome industry more broadly?

Stacy Burns-Guydish, PhD, President (List Labs)

I think there’s two major challenges for me, one is that you know this is a unique product, this LBP Live bacterial organism. So that organism’s viability needs to be maintained through the whole entire manufacturing process. So, this can be a hurdle for some organisms that are difficult to grow. You know these strict anaerobes that oxygen is toxic to them, right? It impacts their viability, and this becomes even more of an issue as you scale up these organisms. It’s one of the reasons why you know people want to probably partner with a Contract Development Manufacturing Organization (CDMO). CDMOs understand what those hurdles are, they know about what you’re going to encounter as you scale up these organisms. So, they can help you optimize that process and knows how to overcome those hurdles as part of the scale up.

I think the second the biggest challenge in the industry is the investment arena. They’re being cautious. There’s no commercial product approved yet, so everyone’s waiting for that BLA approval from you know either fairing or series. And then once that happens, I think that’s really going to drive the field forward.

Jessica Thompson (Kisaco Research)

Yeah, I would agree for sure. And turn into List Labs a little bit more. So, if you’re going to hear a bit about what your company sort of focus in the space your expertise is and how you’re hoping to help overcome those challenges really.

Stacy Burns-Guydish, PhD, President (List Labs)

List Labs was started in 1978. So, we have over 40 years of experience with bacteria. We started with bacterial-derived products. And we have over 100 products in our catalog of high-quality reagent-grade products used in medical research and vaccine development. We also have the experience that we designed and built our facility specifically for containment and segregation to be able to do GMP manufacturing. Also, it was designed for the use of spore formers. So, we have a long history of working with all different kinds of organisms. Strict anaerobes, aerobic organisms, and spore formers. We also have the experience performing GMP manufacturing for many different companies that have gone on to late-stage clinical phase and who now have commercial products.

So, you know, we have quite a bit of history of moving companies through their clinical phase to success to commercial. So, with all this experience that we have, it fits well with the microbiome space. Because we have experience with all those different organisms, we are one of the first companies to produce and manufacture a live biotherapeutic that went into clinical trials. Since then, we’ve manufactured dozens of LBPs that have gone into clinical trials. We’ve also just recently installed a 500-liter fermenter here at our facility. So, we can continue to support companies through their phase 2 manufacturing when they need larger capacity.

Jessica Thompson (Kisaco Research)

And, of course, you partnered with genome and company last year to further your capabilities even further than that. Can you speak to what motivated this partnership and how you’re hoping it will be beneficial over the coming years?

Stacy Burns-Guydish, PhD, President (List Labs)

Yeah. So, List Labs here at the California facility has served customers for Phase 1 and Phase 2 manufacturing, but we aspired to provide our customers with an end-to-end solution. We also saw that there was an opportunity that there wasn’t a lot of capacity in the market for commercial LBP Manufacturing. Genome And Company also had a large pipeline of LBPs that they also wanted to secure their early and late phase manufacturing for. So, this was really a very synergistic relationship with List Labs and Genome And Company. List Labs had the expertise we’d manufactured LBPs and have GMP experience. We have experience designing our own facility, while Genome And Company have very interested investors that are ready to build a new facility for commercial manufacturing.

Jessica Thompson (Kisaco Research)

It sounds like it will be a really exciting development to watch. And with that. And just for this lab, I suppose as well, what are your ambitions then for the next 5, 10 years? What are you hoping for in terms of your next steps?

Stacy Burns-Guydish, PhD, President (List Labs)

You know, so it’s all about supporting our customers that ended in a solution. So, we’re planning to build a new facility in fishers, Indiana, for Phase 3 and commercial manufacturing. That facility is going to be 130,000 square feet specifically for LBPs. It will have four manufacturing lines, and it will be able to accommodate all different types of organisms, from aerobes to strict anaerobes and spore formers.

The production lines will include a 2000-liter fermenter and it will either be stainless steel or single use type fermenter to provide flexibility for our customers. We’re also going to have the ability to formulate and fill in a strict anaerobic environment which we really believe is a differentiator for us. In this facility, we also have QC laboratories, office space, and GMP warehouse space as well. And our ambitions are to expand from there. You know, we want to have sites around the world and we see ourselves as a global Microbiome CDMO company.

Jessica Thompson (Kisaco Research)

I’ll be watching this space then to see where you’re emerging over the next few years. So, we’re really excited to be welcoming you as a platinum sponsor at Microbiome Connect next month in Boston. What are you looking forward to about attending the conference?

Stacy Burns-Guydish, PhD, President (List Labs)

List Labs is super excited about being a part of this conference and to support and advance the microbiome field. I’m really looking forward to the amazing agenda that Kisaco Research has put together. I’m looking forward to hearing updates regarding emerging therapeutics and specifically about Microbiome derived metabolites that might be used in autism as a therapy.

We’re also excited to hear about gut microbiome candidates that improve the efficacy of checkpoint inhibitors for cancer. Also, how companies are advancing their process strategies, such as co-culturing for consortium organisms and single-use alternatives as well. We’re going to hear about engineered organisms for specific delivery of a therapeutic to a site and also great talks from regulatory and quality representatives as well.

So, I think this conference is going to be excellent, not just for a seasoned microbiome veteran but also for those new scientists and innovators that are coming into the field.

Jessica Thompson (Kisaco Research)

Yeah, it was a real pleasure putting together the program this year. There’s so much exciting work that’s being done in the space. It’s almost too much to choose from in terms of when it comes to putting together the talks, and obviously, you’re going to be presenting as part of our bio-processing strategies track as well as chairing that track of the conference in terms of your presentation. Can you give us a quick snippet for the audience in terms of the key takeaways you’re hoping they’ll get from your presentation?

Stacy Burns-Guydish, PhD, President (List Labs)

So, I think we’re going to do something a little bit different than what other CDMOs have previously done. You know, you’re going to get to hear a success story from one of our actual clients, Sciota Biosciences. They have a groundbreaking phase one clinical trial that they’ve just completed using a unique activated bacterial therapeutic for autism. We worked alongside Sciota to develop their process and specifically to develop and manufacture a unique vehicle that’s a part of their drug product. This project was truly a partnership, and I think it’s a great example of List Lab’s ability to be a partner. We’re transparent, and we want to drive to innovate, solve problems and provide solutions.

Stacy Burns-Guydish, PhD, President (List Labs)

Sciota’s story is inspirational, and it’s really going to tug on your heartstrings a little bit. But, I think it enforces, at least, what motivates me, and I think others and their passion for advancing LBP therapies for a healthier world.

Jessica Thompson (Kisaco Research)

Great, well, I definitely look forward to listening, and I think it’s going to be a great addition to the program. So, thanks so much for taking the time to talk to me. It’s great to hear a little bit more about List Labs, and I look forward to seeing what you guys all do in the future. Thanks so much.

Stacy Burns-Guydish, PhD, President (List Labs)

Thank you so much for your time

I’d like to tell you about some of the obstacles you may encounter as you develop your live biotherapeutic product (LBP) and how List Labs can help you navigate through them.

Harnessing bacteria’s potential for a healthier world is our company mission.  Our history and experience have been devoted to bacteria – what bacteria can produce – cultivating bacteria, purifying proteins, and polysaccharides.  List Lab’s passion is to support innovators with quality bacterial products for research and development of vaccines and medical products and to perform contract development and manufacturing service for transformative therapies such as LBPs.

I am very excited to share that List Labs has partnered with BetterLife Pharma to develop and manufacture Altum Pharmaceutical’s novel and transformative therapeutic for the treatment of COVID-19.  It is an honor to join in the fight against one of the greatest challenges of this decade.

Who is List Labs?

List is a privately held, woman-owned, and operated company in California, and about a quarter of our staff has advanced degrees.  Initially, the core part of our business was manufacturing bacterial products.  Beginning with selling one bacterial product in 1978, we now have over 100 stock products, including a GMP product.  List Labs is a GMP-compliant facility, but we’re more than a collection of state-of-the-art equipment, List is much greater than the sum of its parts. Live biotherapeutic projects are not a cookie-cutter process and we are uniquely qualified to provide insight and flexibility to match the needs and requirements of each individual project.  We typically take on 2 to 3 microbiome projects at a time, providing your project with individual attention and the critical advantage necessary to achieve a successful outcome.

Our cGMP compliant facility has 7 expertly designed manufacturing suites allowing segregation of product campaigns and spore containment if needed. The suites undergo treatment with vaporous hydrogen peroxide prior to GMP manufacturing to ensure the quality of your product.  Due to the design of the facility and equipment options, we have the ability to manufacture several products in parallel.

Leveraging decades of experience cultivating a variety of microorganisms and GMP manufacturing experience for our products and partners, the transition to the microbiome space was a natural extension of our capabilities and expertise. We began a project about 7 years ago with a partner to develop and manufacture a live bacteria product.  One of the first in the burgeoning microbiome field.

We have now worked on dozens of projects for indications in the gut, skin, women’s vaginal and urinary tract health, and CNS.  We manufacture products for Phase I and II clinical trials. And we have produced over 20 different LBP products.   These projects not only include manufacturing but also typically require a lot of development, many of which come straight from the academic bench with very little development past a shake flask or bottle cultivation.  We are a partner who is invested in the success of your project and work as an extension of your team.

Let’s use climbing Mt Everest as an analogy. We are climbing the mountain with you, right alongside you.  It’s a great analogy because it gets harder and harder the higher you get, and what you do at the bottom, your preparation will make or break you at the top.  Aggressive timelines, budget constraints, these are the shear cliffs we can see but so many of the obstacles that await are unseen black ice, or bottomless crevasse’s…  I know it’s a bit dramatic but getting a LBP to market is much the same, full of potential pitfalls.

So, today I want to share with you what some of these pitfalls look like and give you a glimpse of how List Labs can help you avoid becoming one of the many, that never realize the ultimate goal.

Source of Strain

If there is anything you take home from this talk, it should be this. “Choose Wisely!” Your choice of strain is made early in the project and changing mid-ascent even to “quote” the same species has a compounding impact. If you need to change strains, all of your in vivo and in vitro assay will need to be repeated along with all your development.  The result can be very costly and cause a substantial delay to your timeline.  A strain identified as a particular species is not equal to another strain identified as the same species.  Each is unique and the characteristics or phenotypes that are important for your strain and indication may not be representative of another strain although identified as the same species.

But whatever your strain of choice is, it is highly likely that we have worked with it or a similar strain before. This is a sample list, although not exhaustive, of the strains we have worked with and of course not giving away any confidentiality of our clients.

Animal-Free Media Replacement

Another potential obstacle is replacing the media with animal-free alternatives.  Since you need to establish a product that is BSE/TSE-free, many clients choose to switch to animal-free media. This is not trivial as there are many animal-derived components that are difficult to replace and are necessary for the robust growth of the organism.  Shown in the graph below, is an animal-based media compared to an animal-free base media missing a critical animal-derived component which when the client came to us they had been unsuccessful in replacing.  Growth in an animal-free media may impact growth rate, final cell density, phenotype (which may be an important characteristic for your indication), potency, and viability.  All of which has implications to the scale of the process in order to have enough viable cells for your dose requirements.  This directly impacts your Return on investment.

Live Biotherapeutic Products

But we know how to tackle the problem. This is an example using the graph I showed you before where growth rate and final cell density were impacted without a very critical animal-derived component.  Once we identified a suitable replacement, we demonstrated similar or better growth than with the animal-derived media.  Then we realized further improvements in cell density with process improvements resulting in a 5-10X improvement in cell density.

Preserving Viability

Another pitfall is loss in viability of your organism through the process. This is a typical manufacturing process flow for a live biotherapeutic product.  Initially, the strain is cultivated in a seed culture either anaerobically or aerobically and inoculated into the large vessel (such as a stainless steel bioreactor or single-use bioreactor), then harvested by tangential flow filtration, formulated, lyophilized, sieved, and then filled into vials, applicators, or formulated to fill capsules.

Different organisms will have different sensitivities to the process that may impact its viability including the growth phase at which the strain was harvested, the harvest process, and the environment during the harvest, or during the lyophilization, sieving, and encapsulation process. Understanding the viability of the organism throughout the process is important to know where to focus your development efforts.

We understand these risks and what tools we can use to improve the yield of the live organism at the end of your process. We have demonstrated substantial improvements in viability by 2 to 100 fold by optimizing these variables.

Scale Up

Another hurdle to overcome is the scale-up of the process. We often start with a process that is at the tube, bottle, or shake flask scale which requires a substantial amount of scale-up development.  The process development of the cultivation and harvest should be performed in a scaled-down version of the process such that performance will be predictable at scale with the necessary process controls to demonstrate similar performance.  List has 1L bioreactors and scaled-down versions of the harvest process so we can isolate specific variables and understand the impact on the process.  We typically perform 10X scale up from 1L to 10L to the 100L process to minimize the surprises at scale and provide a robust process.  Your timeline and costs for development should include these activities.

QC Analytical Development

An obstacle of the QC Analytical Development of your LBP is the development of the bioburden assays, USP<61>/<62> which is not straightforward with a live organism.  For LBPs these assays need to be tailored and developed for each organism and we have experience working on these assays. We are also able to harness a lot of efficiencies for the customer by not only working on the manufacturing but also working on the analytical development in-house. Analytical assays are necessary for both in-process testing and final QC testing for release.

Is List Labs the right CDMO for your project?

As a novice climber, would you attempt to scale Mt. Everest with anything less than the most experienced Sherpa? We are a passionate and dedicated team with the expertise and experience that is critical to reach the summit. We have been there many times.  We recognize the obstacles and while no two ascents are exactly the same, we have the flexibility to guide you to the top and deliver a quality product for the success of your project.  We look forward to working with you!

If you have any questions, please contact us at or through our contact page.

By: Stacy Burns-Guydish, Ph.D., President

Stacy Burns-Guydish, PhD

Check out the Overcoming Obstacles in the development of Live Biotherapeutic Products video!

On May 14, 2020, a team spanning the University of California San Diego, San Francisco General Hospital, Cook County Health and Hospitals System in Chicago, and Washington University in St. Louis published a milestone study in the New England Journal of Medicine. Cohen et al demonstrated the effectiveness of LACTIN-V, a new Live Biotherapeutic Product (LBP) created by Osel, Inc. for the treatment of bacterial vaginosis (BV).

LACTIN-V is a single-strain, topically-administered LBP containing Lactobacillus crispatus CTV-05, a protective human vaginal bacterium that helps to combat the pathogenic bacteria and dysbiosis observed in recurrent BV and urinary tract infections. Its success marks the first single-strain LBP to show clinically significant efficacy in a randomized, double-blind, placebo-controlled Phase 2b trial in the US.

The study was supported by grants from the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH). List Labs is excited by this landmark discovery, by the prospects of this discovery for women’s health around the world, and for further supporting the use of LBPs as a viable therapeutic.  We had a chat with Osel’s Director of Product Development, Tom Parks, to find out more about the project, it’s challenges, and why the product is successful:

What are dysbiosis and BV?

Dysbiosis is a disruption of the human microbiome: the collection of microorganisms, including bacteria, that naturally live on and in our bodies. The full function of the microbiome isn’t fully understood, but dysbiosis is known to be involved in a wide range of skin disorders, intestinal problems and gum diseases, among many others.

Bacterial vaginosis is an ecological disorder of the vaginal microbiota in which hydrogen peroxide-producing lactobacilli are displaced by predominantly anaerobic bacteria (e.g. Prevotella and  Mobiluncus species), Gardnerella vaginalis, and Atopium vaginae. It is the most common vaginal infection worldwide among women of reproductive age, and affects about 30% of women in the US. Treatment usually consists of a course of an antibiotic such as metronidazole lasting about five days. The treatment itself is usually effective, but in about 75% of cases BV returns within a year, often within just a few weeks.

Why is treating BV so challenging?

The tendency of BV to recur is due to failure to re-establish a Lactobacillus-dominated vaginal microbiome. Since the only treatment is another course of metronidazole or a similar antibiotic, this can lead to a cycle of re-infection. In addition to the discomfort and negative impact on the quality of life, BV is a risk factor for a wide range of sexually transmitted infections, including HIV/AIDS. It is also a risk factor for premature birth and other reproductive health complications.

Currently there is no approved treatment to prevent the recurrence of BV. Women have tried a range of home remedies, from yogurt to tea tree oil. As might be expected, these are often ineffective, and may have side effects of their own.

Osel has developed a treatment for BV that breaks the cycle of dysbiosis. LACTIN-V is a live biotherapeutic product (LBP) containing the hydrogen peroxide-producing strain Lactobacillus crispatus CTV-05, which is a protective member of the native microbiome. Administered after the normal course of antibiotics (once a day for five days, and then twice a week for 10 weeks), LACTIN-V helps to restore the normal vaginal environment and prevent re-emergence of the organisms that cause BV. In the study reported in NEJM, BV recurrence was significantly less in women treated with Lactin-V (30%) compared to the placebo group (45%) (P=0.01).

What goes into manufacturing an LBP?

An LBP is a therapeutic agent based around a live microorganism, intended to restore a balance in the microbiome disrupted by a disease condition. A contract development and manufacturing organization (CDMO) can provide essential expertise for developing an LBP, but finding the right CDMO is tricky since many contract manufacturing organizations do not have experience with maintaining viability of the microorganism through the entire manufacturing process or are flexible for the process nuances of an LBP product. In addition, many organisms of interest as LBPs are anaerobic to some extent (for example, Lactobacillus are facultative anaerobes), and/or spore-forming. Working with such organisms takes special expertise and facilities to provide necessary containment and segregation, maintain viability, maximize yield, and avoid pitfalls.

Osel’s Tom Parks explains, “Relevant live biologic product experience and GMP manufacturing capabilities are obviously important. Flexibility to handle a number of product formats is also helpful. Since the field is relatively new, companies that manufacture LBPs are few and far between.”

Are you looking for a CDMO for your LBP project?  List Labs has 40 years of experience manufacturing bacterial products and many different LBP products for Phase 1 and 2 clinical trials for indications in the gut, skin, vaginal mucosa, and CNS. List Labs has the expertise for handling and cultivating anaerobic bacteria and spore formers.  We are uniquely qualified to provide insight and the flexibility to match the needs and requirements of each individual project, such as filling different product formats.  We are a passionate and dedicated partner who works as an extension of your team to ensure the success of your project.  If you are interested in an LBP project, contact us at

By: Stacy Burns-Guydish, Ph.D., Senior Director, Microbiology

The human body is home to a vast ecosystem of microbes, called the microbiome.  Research is shedding light on the importance of the microbiome as a benefactor to our health and development.  Perturbation of the microbiome has been associated with a growing number of diseases including inflammatory bowel disease, allergies, asthma, autism, and cancer.

Microbiome Bacteria as Potential Therapy

Commensal bacteria of the microbiome are thought to be potential therapies for prevention or treatment of infections such as Clostridium difficile, acne, and bacterial vaginosis. Live biotherapeutic products (LBP) manufactured from commensal bacteria are being investigated by many companies and several clinical trials are underway.

Anaerobic Cultivation & Containment Required for Microbiome Research

Many of these commensal microorganisms for the manufacture of LBP are obligate or strict anaerobes and spore forming organisms,  presenting unique challenges to the emerging microbiome therapeutic space.  Expertise and proper equipment for anaerobic cultivation and proper containment of spore forming organisms is lacking in the industry and only a handful of contract manufacturing companies have the capabilities to perform GMP manufacturing anaerobic organisms, creating a bottleneck.

An alternative for companies is to build their own GMP facility, as Seres Therapeutics has done.  But start-ups typically do not have the funds to build their own facilities thus the CMO backlog impacts timelines.  Most CMO’s quote a wait of 9-12 months for projects to begin.  So how will these burgeoning companies meet their aggressive timelines to produce their LBP for clinical trials?

Questions to Ask Partner GMP Labs

If you are a startup, sound advice is to start conversations now with potential CMOs and find out if their capabilities align with your organism cultivation requirements and specifications.

List Labs Is well suited to Partner in GMP Microbiome Research

List Biological Laboratories, a boutique contract manufacturing company, has the expertise and infrastructure for manufacturing both obligate and strict anaerobes and spore forming organisms.  List has over 30 years’ experience cultivating anaerobic organisms.  We have produced master and working cell banks and LBP for several customers currently in Phase 1 and 2 clinical trials.  In addition, we have expertise in the development of the non-trivial required purity/bioburden assays, including USP61 and UPS62, for testing and release of these unique live microorganism products.

Contact List Labs to get your microbiome research project off the ground today.