100 for 100: Tiny Organisms, Big Impact

Item 60/100: Fly Parasites make for Life-Changing Diagnostic Tools
Ana Eckert, BS, Lead Innovation Specialist
ATCC® 30258™ – Crithidia luciliae (Strickland) Wallace and Clark

If a fly speeds in through your open window, you may have another surprisingly influential house guest: Crithidia luciliae, a parasitic protozoan that uses the common housefly as a host. This organism has a giant mitochondrion with a kinetoplast, a large network of concentrated mitochondrial DNA.¹ This kinetoplast is used as a substrate in the C. luciliae immunofluorescence test (CLIFT), which is a diagnostic test used to detect double-stranded DNA antibodies in patients suspected of having systemic lupus erythematosus, commonly known as lupus.² Lupus is a chronic autoimmune disease that affects many parts of the body such as the heart, skin, lungs, kidneys, and more. The broad spectrum of symptom manifestations makes this disease particularly complex to diagnose and treat. Antinuclear antibodies (ANAs), found in more than 95% of lupus patients, can be detected through CLIFT.³ Using CLIFT in combination with other tests can help improve diagnostic accuracy, which can make a big difference in the treatment of lupus.

Item 61/100: From Spoilage to Synthetic Biology: The Legacy of Lore A. Rogers and the Rise of Yarrowia lipolytica
Jonathan Jacobs, PhD, Senior Director, Bioinformatics
ATCC® 20460™ – Yarrowia lipolytica (Wickerham et al.) van der Walt et von Arx

In the early 20^th century, ATCC’s founder, Dr. Lore A. Rogers, was on a mission to improve the quality and shelf life of dairy products.⁴ This interest also contributed to identifying one of the most important platform-organisms for modern biotechnology and industrial microbiology: Yarrowia lipolytica. In 1904, Rogers was a microbiologist at the USDA’s Bureau of Dairy Industry that was actively trying to understand the causative agents of butter spoilage—a major problem for the dairy industry at the time. Rogers’ work revealed that a group of “fat-splitting Torula yeasts” were the primary agents responsible for rancidity and were capable of growing on pasteurized butter. One of these organisms was later renamed Yarrowia lipolytica, a yeast with extraordinary metabolic capabilities that has since had a tremendous impact on industrial microbiology and modern biotechnology. Rogers went on to become the President of the Society of American Bacteriologists, and in 1925 he and seven other microbiologists co-founded the American Type Culture Collection (ATCC).⁵

In the decades that followed Rogers’ early work on Y. lipolytica, interest continued to grow after it was found to be a common contaminant of nearly all dairy and margarine products.^6,7 In a series of articles in the late 1940s, researchers identified, isolated, and produced at scale the enzymes (lipases) responsible for the “fat-splitting” phenotype Rogers’ had observed 40 years earlier.^8,9 Then, in the 1950s and 60s, it was revealed that strains of Y. lipolytica could metabolize a diverse range of hydrocarbons and waste products from the petroleum industry. One strain of Y. lipolytica was even isolated from inside the fuselage of a jet plane, using the jet-fuel as a food source.^10,11

Simultaneously, Y. lipolytica was reported to be a safe alternative food product for human consumption, even if it had been grown on industrial petrochemical waste products.¹² In the 1970s, Amoco and British Petroleum (BP) developed and sold commercial food products consisting of high-protein strains of Y. lipolytica produced in large scale bioreactors that used petroleum refinery waste as a feed stock.¹³ Although these products met significant regulatory and market resistance, interest in using Y. lipolytica as a platform organism for biomanufacturing has only continued to grow in the decades that followed.¹⁴ For example, in 2014 three strains of Y. lipolytica in ATCC’s collection (ATCC® 76861™, ATCC® 201249™, and ATCC® 76982™) were used in creating the strain that received the U.S. FDA’s Generally Recognized as Safe (GRAS) status¹⁵ for recombinant production of rebaudioside A, the zero-calorie sweetener known commercially as Stevia.¹⁶

So, what began as a problem in wooden butter tubs has become a powerful solution for the future of the industrial biotechnology sector. Today, ATCC has one of the largest public collections of Y. lipolytica in the world as well as the most diverse collection of whole-genome sequencing data for the species on the ATCC Genome Portal.

Item 62/100: The Current Pandemic…Cholera, Not COVID
James Budnick, PhD, Senior Scientist
ATCC® 14035™ – Vibrio cholerae Pacini

We are currently in a pandemic—the seventh cholera pandemic since 1817.¹⁷ Cholera is caused by the ingestion of water/food contaminated with the bacterium Vibrio cholerae and symptoms include watery diarrhea, vomiting, leg cramps, and restlessness.¹⁸ Worldwide, there are an estimated 1-4 million cases and 21-143 thousand deaths from cholera each year.¹⁹

V. cholerae is a gram-negative motile bacterium with a distinctive curved morphology and a single polar flagellum. The bacterium expresses multiple virulence factors, most notably Cholera toxin, toxin-coregulated pilus (TCP), multiple secretion systems, flagella, and accessory toxins. Interestingly, the predominant strain in the seventh pandemic is a V. cholerae biotype called “El Tor,” which is genetically distinct from the “Classical” biotypes that caused pandemics 1-6; these distinctions are the focus of much of the research today.²⁰

Despite its prevalence, cholera is a preventable and highly treatable disease. Prevention relies on access to safe drinking water, early detection and treatment, and improved health care infrastructure. A majority of people infected will show no or mild symptoms, but severe infections can be treated with rehydration solutions and antibiotics.²⁰

The prevention of cholera within London in the 19^th century significantly contributed to the understanding and acceptance of Germ Theory. There was an outbreak of cholera in London in 1854 during the third cholera pandemic and Dr. John Snow thought that instead of the Miasma Theory (bad air), the spread of infection was caused by contaminated water sources (Germ Theory). As the story goes, he convinced the authorities to remove the handle of the Broad Street pump, which stopped the residents from consuming water from the suspected source of the infection. Within a few days the spread of the disease stopped, and Dr. Snow would continue to study and decrease the spread of cholera in subsequent outbreaks throughout the city.  These studies led to the development of modern epidemiology, and the broad street pump map is still used in classrooms today.²¹

ATCC contains >65 strains of V. cholerae, including “Classical” biotypes, “El Tor” biotypes, knock-out strains, and more to help further study and create mitigation strategies to combat this organism.

Item 63/100: Tracking Down H5
Travis Farley, BS, Technical Manager
ATCC® VR-3436SD™ – Quantitative Synthetic Avian Influenza Virus (H5N1) RNA

The CDC reports that since 1997, more than 890 sporadic human infections with highly pathogenic avian influenza (HPAI) H5N1 have been reported globally.²² These cases, often linked to direct contact with infected poultry, highlight the zoonotic potential of avian influenza viruses. In the U.S., the 2014–2015 outbreaks of H5N2 and H5N8 led to the largest poultry epidemic in national history.²³

For over a century, ATCC has been a trusted global resource for authenticated biological materials, playing a critical role in pandemic preparedness and infectious disease research. To support research and response efforts, ATCC provides high-quality strains, molecular standards—such as Quantitative Synthetic Avian Influenza Virus (H5N1) RNA(ATCC® VR-3436SD™)—and human cell lines like Calu-3, which are essential for studying viral replication, host-pathogen interactions, and transmissibility. These tools have enabled scientists to conduct reproducible studies that inform vaccine development, antiviral testing, and public health strategies. As H5N1 continues to circulate in wild birds, poultry, and even spill over into mammals, ATCC remains a cornerstone of global health infrastructure—empowering researchers to detect, understand, and respond to emerging threats with speed and scientific rigor.²⁴

Item 64/100: Reclassifying Tuberculosis
Marco Riojas, PhD, Senior Scientist
ATCC® 35743™ – Mycobacterium tuberculosis var. BCG Riojas et al.

Tuberculosis (TB), caused by the bacterium Mycobacterium tuberculosis, remains the leading cause of death from infectious diseases worldwide, responsible for nearly 1.5 million fatalities each year. While TB primarily affects humans, several closely related bacterial species cause similar diseases in animals; these include M. africanum, M. bovis, M. caprae, M. microti, and M. pinnipedii. Collectively, these organisms are classified within the Mycobacterium tuberculosis Complex (MTBC), a group historically thought to consist of distinct species based on host range and subtle phenotypic differences.

However, ATCC scientists, led by Dr. Marco Riojas, recently challenged this long-standing classification. By applying advanced genomic tools—specifically whole-genome sequencing (WGS), digital DNA-DNA hybridization (dDDH), and comprehensive phylogenomic analysis—the team examined the type strains of each MTBC member. Their findings revealed that these so-called species are not genetically distinct enough to warrant separate species status. Instead, they are best understood as closely related host-adapted variants of Mycobacterium tuberculosis.

To validate this conclusion, the researchers extended their analysis to over 3,700 non-type MTBC genome sequences available in GenBank. The results were consistent: all strains fell within the genetic boundaries of M. tuberculosis. This discovery not only resolved a long-standing taxonomic ambiguity but also underscored the importance of genome-based classification in modern microbiology.

The findings were published in the International Journal of Systematic and Evolutionary Microbiology,²⁵ officially unifying the previously separate members of the MTBC under a single species name: Mycobacterium tuberculosis. The previous species name or lineage is not lost, however, as we recommended that this be used as the variant name, e.g., Mycobacterium tuberculosis var. BCG (ATCC® 35743™). ATCC also hosted a webinar describing these research findings. This reclassification has significant implications for diagnostics, epidemiology, and our broader understanding of TB evolution and host adaptation.

Item 65/100: Yellow Fever – the Only Nobel Prize for a Virus Vaccine
Sujatha Rashid, PhD, PMP, Principal Investigator
ATCC® VR-1506™ – Yellow fever virus

Yellow fever, a lethal disease with a propensity to occur as epidemics, has fascinated many intrepid scientists, spurring research for over two centuries. This led to great scientific discoveries like identifying the role of a mosquito vector, discovering the causative viral agent and virus propagation methods, and developing a vaccine nearly a century ago that is still used today. The successful isolation of the virus in 1927 from a Ghanian patient (strain Asibi) by Rockefeller Foundation researchers working in Africa paved the way for the cascading events leading to a live attenuated vaccine. In the early 1930s, the Asibi strain was adapted to grow in mouse embryonic tissue.²⁶

After 17 passages, the virus, named 17D, was further attenuated by numerous passages of the culture in chicken embryo cells and then in embryonated eggs until the resulting virus was no longer lethal in animals. The 17D vaccine received licensing approval in 1938, and it is the only one still in use, capable of inducing strong and prolonged immunity with just a single dose.²⁷ In 1951, Max Theiler was awarded the Nobel Prize in Physiology or Medicine for “discoveries concerning yellow fever and how to combat it.” The 17D vaccine strain is considered to be one of the most effective and safe, live attenuated viruses developed to date. It continues to be relevant as vaccine manufacturers currently use one of the three 17D sub-strains (17DD, 17D-204, and 7D-213) to produce the life-saving vaccine, which is much needed in nearly 50 yellow fever endemic countries in Africa and in Central and South America.²⁸

Item 66/100: From Smallpox Eradication to Viral Vector Vaccine Candidate
Angela Robertson, PMP, Program Manager I
ATCC® VR-1566™ – Vaccina virus

Smallpox, caused by the variola virus, is an ancient infectious disease that was thought to have existed for at least 3,000 years until it was declared officially eradicated in 1980. Eradication was achieved through a global smallpox vaccination campaign led by the World Health Organization using vaccinia virus (VACV)-based vaccines.²⁹ The first- and second-generation VACV vaccines, which utilized live animals and replication-competent cell- and tissue-derived strains, were immunoprotective but carried safety risks. Modified vaccinia virus Ankara (MVA) was developed through serial tissue culture passaging of Chorioallantois vaccinia virus Ankara (CVA) in chicken embryo fibroblasts. In the 1970s, MVA was used as part of the two-step smallpox vaccination program. It demonstrates an excellent safety profile and is replication-deficient in humans and mammalian cell lines while still being immunoprotective.

Through recombinant DNA technology, numerous studies have looked at utilizing a recombinant MVA that expresses other viral genes as vaccine candidates. Although MVA cannot replicate in humans and many other mammalian cells, expression of many viral genes in the recombinant model is not impaired by this replication deficiency. This model’s advantages include an excellent safety profile, supported by extensive clinical experience during the smallpox vaccination campaign, and high gene expression and immunogenicity.^30,31 A recombinant MVA vaccine is approved for mpox and Ebola virus. Other virus targets studied include herpes simplex virus, HIV-1, hepatitis C virus, SARS-CoV-2, MERS, RSV, and the equine encephalitis viruses.

Item 67/100: EMEM: Minimal Ingredients, Maximum Impact
Tamilore Akinde, BS, Associate Biologist Intern (SPARC Program)
ATCC® 30-2003™ – Eagle’s Minimum Essential Medium (EMEM)

In 1955, Dr. Harry Eagle developed Basal Medium Eagle (BME) to support the growth of HeLa and mouse L cells using the minimum necessary low–molecular-weight substances. He discovered that both normal and malignant cells required a balanced mix of 13 amino acids and 8 vitamins.³² Designed for long-term in vitro growth, BME helped redefine mammalian cell culture. By 1959, Eagle expanded his work to meet the needs of more cell lines, leading to the creation of Eagle’s Minimum Essential Medium (EMEM).³³

EMEM quickly became a cornerstone of classical media thanks to its simplicity and compatibility with a broad range of cell lines. Unlike BME, it also contains glucose and six inorganic salts that support biosynthetic activity.³⁴

Over 60 years later, EMEM remains one of the most widely used media in cell culture research. Its balanced formulation provides a reliable foundation for scientific discovery, enabling everything from basic research to biopharmaceutical manufacturing and development.³⁵ ATCC's formulation of EMEM builds on this legacy, offering a high-quality, tested medium optimized for consistency and performance. We use our own version for cell lines that respond best to EMEM, providing optimal growth.

Did you know?

ATCC maintains one of the world’s largest and most diverse collections of biological materials, including some that have been to space, lived in jet fuel, or helped win Nobel Prizes!

References

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2. Slater NG, Cameron JS, Lessof MH. The Crithidia luciliae kinetoplast immunofluorescence test in systemic lupus erythematosus. Clin Exp Immunol 25(3): 480–486, 1976. PubMed: 786521
3. Ameer MA, et al. An Overview of Systemic Lupus Erythematosus (SLE) Pathogenesis, Classification, and Management. Cureus 14(10): e30330, 2022. PubMed: 36407159
4. Rogers LA. 1904. Studies upon the keeping quality of butter. I. Canned butter. Govt. print. off, Washington, 1904. Accessed June 30, 2025.  https://www.biodiversitylibrary.org/bibliography/48941.
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6. Jacobsen H. Researches on and means to prevent rancidity of vegetable margarine. Folia Microbiol (Delft) 5: 94–102, 1919.
7. Long HF. A study of some lipolytic microorganisms isolated from dairy products. Doctor of Philosophy. Iowa State University, Digital Repository, Ames, 1936.
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9. Peters II, Nelson FE. Factors Influencing the Production of Lipase by Mycotorula lipolytica. J Bacteriol 55: 581–591, 1948. PubMed: 16561495
10. Iizuka H, Iida M, Unami Y. Microbiological Studies on Petroleum and Natural Gas. J Gen Appl Microbiol 12:119–126, 1966.
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