An Interview with Manuel F. Varela and Ann F. Varela: Ruth Ella Moore: First African American to earn the doctorate in the Natural Sciences

Dec 5, 2021 by

Photograph of Ruth Ella Moore
Ruth Ella Moore

Michael F. Shaughnessy

Yet the grit and perseverance of women like Ruth Ella Moore, the  first African American woman to receive a Ph.D. in natural science from Ohio State University, as well as civil rights legislation and the women’s movement, help to overcome these obstacles.”

—Congressional Record Volume 151, Number 52 (Tuesday, April 26, 2005), House of Representatives, Pages H2488-H2489, From the Congressional Record.

Women obtain approximatively 50% of all doctorates in biology, yet only 36% of Assistant Professors are women, a number that drops to 18% for Full Professors.”

—Alain Touwaide

1) Ruth E. Moore led a very distinguished career—when and where was she born, and what do we know about her early life?

Ruth Ella Moore was born in Columbus, Ohio, in 1903, to William E. and Margaret Moore. Her mother was a talented artist and seamstress who had graduated from the Columbus State College of Art and Design. She had inspired Moore from a young age to be creative and pursue a degree in higher education. Moore had two older brothers, Donovan L. and William E. Moore.

2) Where did Moore go to school, and what did she study?

Moore and her two older brothers were educated in the Columbus, Ohio, public school system. Later, she earned a Bachelor of Science degree in 1925, and she acquired her Masters of Science Degree two years later in 1927, both at Ohio State University.

Being nearly depleted of funds to continue her higher education degree program in Ohio, Moore accepted a position at Tennessee State College in Nashville teaching Hygiene and English. Shortly after that, she returned to Ohio and ultimately attained her Ph.D. in 1933 from Ohio State University in bacteriology and wrote her dissertations focused on tuberculosis bacteria.

After receiving her doctorate, she formally became the first African American woman to earn a graduate degree in the natural sciences. In 1940, Howard University hired her as an assistant professor in the medical college, where she would remain until her retirement in 1973. Through the course of her employment at Howard, Moore was promoted to the chairperson for the Bacteriology Department, which she later renamed to the Department of Microbiology. She became an associate professor and directed and participated in research relating to bacteriology.

Moore was the first woman to lead any department at Howard University. She remained the head of the department until 1960. The research she performed on African-American blood types and the reaction of different gut microorganisms to antibiotics has had substantial bearings on public health.

3) Tuberculosis and immunology seem to be the leading research thrusts for Moore. What did she find, and can you briefly describe what tuberculosis is precisely and how it affects humans?

During the late 1920s and early 1930s, Moore, a graduate student, studied the causative agent of the disease called consumption, a bacillus-shaped bacterium called Mycobacterium tuberculosis, for her Ph.D. dissertation project. See Figure 1. The final version encompassing her complete thesis was broken down into two separate chapters. The first chapter of her work dealt with “Studies on Dissociation of Mycobacterium Tuberculosis.” The second chapter of her Ph.D. project was titled “A New Method of Concentration of the Tubercle Bacilli as Applied to Sputum and Urine Examination.”

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Figure 1. Scanning electron micrograph of Mycobacterium tuberculosis bacteria.

Surprisingly, Moore’s Ph.D. thesis data were not published in a dedicated scientific journal. The reasons for this disparity are unclear. Frequently, Ph.D. dissertation projects are bound and housed in a university library of the Ph.D. granting institution but are also published separately in external peer-reviewed journals devoted to the particular scientific discipline of study. Thus, the primary source of Moore’s work on TB-causing bacteria can be found in her unpublished dissertation.

During Moore’s first chapter of her graduate studies on the Mycobacterium tuberculosis microbe, she focused on a bacteriological phenomenon known then as dissociation. This so-called dissociative process of the tuberculosis pathogen involved the cleavage of an avirulent form of the microbe from the parental pathogenic, virulent form—the dissociated non-pathogenic strain of the bacterium presented with new features and properties. Later investigators followed up the groundbreaking work conducted by Moore eventually. The dissociative character of Mycobacterium tuberculosis is now known to involve biological changes in the cell wall components and phenotypes of the bacterial colonies on culture media. These new dissociative features permitted investigators and clinicians to identify pathogenic versus avirulent strains of the microbes in tuberculosis patients.

In the second chapter of Moore’s graduate dissertation, she focused on developing a new method for preparing clinical sputum smears and culturing the microbe from urine specimens. In Moore’s time, a variety of methods was invoked to prepare sputum smears, some early methods dating back to the period of Robert Koch, who had taken the Nobel Prize for his work demonstrating that the Mycobacterium tuberculosis bacterium was the causative agent of the disease tuberculosis. However, many of the methods for specimen processing suffered from diluted clinical preparations, which made a clinical examination of many specimens cumbersome and inefficient. Thus, new laboratory methods were continually developing to concentrate the microorganisms in the sputum or urine samples to more closely identify and characterize the bacteria. Moore’s graduate studies were directly related to these issues regarding concentrating Mycobacterium tuberculosis organisms in clinical specimens to sort them out more readily for diagnosis.

Tuberculosis is a dreadful disease that has afflicted countless millions throughout recorded history. The ailment is so severe within the human victims that it seems to “consume” them, hence, the moniker consumption. These consumptives, the human patients, exhibit severe spasmodic coughing episodes in which they spew large quantities of sputum that is laden with infectious new microbial agents.

The affliction of tuberculosis (TB) upon a patient by Mycobacterium tuberculosis can be severe and last a lifetime. When inhaled, the microbe enters the lung, where alveolar macrophages phagocytose it. However, instead of being killed by the phagocytes, the bacteria escape certain death by preventing phagocytosis, permitting the bacteria to escape death by oxidative disintegration from the patient’s immune system. The escaped TB bacteria grow and are potent stimulators of inflammation. Thus, the lungs fill up with recruited T-cells and natural killer cells. Both cell types can secrete a protein called interferon-gamma (IFN-γ). See Figure 2.

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Figure 2. 1 HIG Interferon-Gamma.

The secreted IFN-γ activates new lung macrophages, which can kill the consumptive tubercular bacilli. However, in patients who cannot produce the IFN-γ, the TB bacilli can flourish. Eventually, the infection can progress into a chronic inflammatory state, producing granulomatous lung lesions called tubercles. These tubercular lung lesions can become necrotic, producing caseous granulomas, from which the bacilli bacteria escape, and can produce additional complications in TB patients.

In modern times, TB treatment involves long courses of multiple anti-bacterial medicines, like isoniazid, ethambutol, pyrazinamide, rifampin, and clofazimine. In many cases, treatment may last two to six months, or perhaps a year, depending on the severity of the illness in the individual patient and the level of drug resistance in the TB-causing microbe. Prevention by an attenuated form of the Mycobacterium bovis bacterium to produce a vaccine called Bacille Calmette-Guérin (BCG) is routinely followed in areas where TB is endemic.

Although the incidence numbers in the U.S. have been in a steady decline, tuberculosis has remained a serious public health concern in large cities and on a worldwide basis. Approximately nine million cases of TB occur every year, with more than a million deaths occurring annually from the affliction. The high morbidity and mortality rates involved with TB can be attributed to multidrug-resistant and, in some cases, extensively drug-resistant strains of the Mycobacterium tuberculosis microbe. These strains are recalcitrant to the medicines and can effectively confound treatment of clinical TB cases.

4) Apparently, Moore was also interested in dentistry—studying cavities and the immune system.

In 1938, when Moore was an instructor of bacteriology at Howard University’s medical college, she published an influential review article dealing with the immune response to dental caries, a condition known as tooth decay or teeth cavities. Moore provided an overview of the etiological factors involved in the predisposition of dental caries, such as age, diet, oral hygienic practices, general health status, and genetic inheritance. In particular, Moore was interested in the relationship of a bacterial species called Bacillus acidophilus, as it was known then. In modern times, we know this microbe as Lactobacillus acidophilus. See Figure 3. During the late 1930s, it was widely thought that Lactobacillus acidophilus was the etiological agent for dental caries.

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Figure 3. SEM image of Lactobacillus acidophilus.

While we know nowadays that Streptococcus mutans is more commonly thought to be the leading cause of dental caries, such a case was not so evident in the mid-20th century. During the time of Moore, the notion that the Lactobacillus acidophilus microbe was a causative agent of tooth decay was considered seriously by many investigators because the bacterium was found in the mouth microbiome of all or most cases of dental caries. Indeed, even in modern times, several species of the Lactobacillus genus, including Lactobacillus acidophilus, can be found amongst dozens of microbial species that constitute the dental plaque, a biofilm consisting of hundreds of layers of microbes that exist in an anaerobic condition.

In her article, Moore had considered the notion that dental caries could be due to an allergic reaction against mouth bacteria like the Lactobacillus acidophilus. Another notion considered by Moore involved the possibility that the Lactobacillus acidophilus fermented sugars in the mouth, converting the sugars into acids, a process well documented in many locales, such as in specific fermented foods, on moist skin, and in the vagina. When Moore pondered the relationship between Lactobacillus acidophilus and the immune system, she speculated whether the propensity to suffer from dental caries might be measured by a skin reaction test. The test involved the administration of a bacterial filtrate consisting of secreted cellular material taken from mouth isolates of Lactobacillus acidophilus in patients with dental caries.

When the Lactobacillus acidophilus filtrates were injected into the skin of human test subjects, producing an immune reaction to the injected antigens, Moore and her colleague, Raymond L. Hayes, an instructor of dentistry, observed that in persons with Lactobacillus acidophilus already in their mouths, the skin test showed more pronounced swelling, a positive result in their experimental system.

Interestingly, in the discussion section of her paper, Moore thought about the potential for a vaccine directed against the causative agent of dental caries. While she especially considered Lactobacillus acidophilus as a putative antigenic target for a dental caries vaccine, in modern times, there have been tremendous efforts directed in developing a vaccine against Streptococcus mutans. A dental vaccine may be of considerable value in mitigating the dental caries epidemic in developed countries.

Within the oxygen-deprived layers of the oral biofilm matrix, i.e., dental plaque, Streptococcus mutans can be protected by these biofilm bacteria from the growth inhibitory effects of the immune system and anti-bacterial agents, like antibiotics. In unchecked dental plaque biofilm, the numbers of bacteria can reach into the tens of billions. At the gum line, biofilm bacteria, like Lactobacillus acidophilus, Actinomyces, Veillonella, and Fusobacterium can help protect the Streptococcus mutans. Under these protective conditions, the Streptococcus mutans can ferment sugars like fructose into corrosive acids by glycolysis and lactic acid fermentation metabolic pathways.

The lactic acid produced is strong enough in its acidity to dissolve the tooth enamel, which is considered the most rigid structure in the human body. Once the enamel is compromised, its structure can be readily digested by proteolytic enzymes in the mouth. If left unchecked, dental caries can lead to additional decay in the layers below the enamel, such as dentin material, or into the pulp cavity, possibly leading to an abscess in the bone tissue that supports the teeth. The best preventative measures include regular teeth brushing and flossing daily.

Frequently, the unchecked dental plaque at the gum line transforms into a hardened material called tartar, known in clinical circles as dental calculus, that can facilitate gum tissue inflammation, leading to bleeding, abscesses, and eventually the loss of the teeth. See Figure 4. This pathological process is known as periodontal illness and, if untreated, includes conditions known as gingivitis (gum inflammation) and the more severe form called acute necrotizing ulcerative gingivitis, known as trench mouth. Periodontal disease can progress to chronic periodontitis, characterized by tissue loss and irreversible bone loss in the mouth.

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Figure 4. Dental plaque is seen at the bottom of the tooth.

5) Blood types of African Americans were another realm of her investigation. What insights did Moore have? (I know anemia may be one area.)

During the early to mid-1950s, while holding the rank of assistant professor of bacteriology at Howard University, Moore conducted a series of studies focusing on the distribution of blood types that occur in African Americans. In her study, Moore noted that previous studies of blood type groupings suffered from several problems, such as inadequate sample sizes, limited geographical locations from which human test subjects were sampled (only New York City), and close relatives of the humans tested had been neglected. Moore set out to circumvent these prior limitations from other laboratories by studying the blood types from a much larger number of human beings in a population sampled from much of the United States and including siblings of the leading human test subjects.

Moore focused on the known ABO and Rh blood groups that Karl Landsteiner had discovered. See Figure 5. She likewise studied the so-called MN blood groups, which had also been discovered by Landsteiner and colleagues in the late 1920s and were widely known at the time. The MN system is no longer considered in modern blood studies. Moore had observed that among the several thousand African Americans she studied, the majority (about 52%) had type O blood, while 27% had blood type A, and 17% were typed B. Only about 3% of the sampled human beings were blood typed as having both A and B antigens. These blood grouping data collected by Moore were consistent with a previous study showing that African Americans had primarily higher blood type O and B incidences.


Figure 5. Blood groups.

Interestingly, Moore discovered that amongst the type A blood subjects, the incidence numbers of the sub-types A-1 and A-2 did not significantly differ between African Americans and the non-African Americans sampled throughout the rest of the U.S. Lastly, Moore made the exciting observation that slightly more African Americans had Rh factor blood type (about 91%) than the rest of the U.S. population, of which 85% were Rh+. Strikingly, these early ABO and Rh blood type groups are remarkably consistent with present-day numbers collected in modern times. These scientific studies by Moore are a testament to her stellar investigative talent.

In another study, conducted later, Moore was interested in specific Rh blood group subtypes. One of these types, called blood factor U, was discovered in 1953 by A.S. Weiner, J. Unger, L. Cohen, and E.B. Gordon in an African American woman who had died from severe anemia after suffering from a bleeding peptic ulcer and who had gone into a fever, chills, and shock after having undergone two blood transfusions. The fatal blood transfusion in the patient was attributed to an incompatible factor U.

In this same study, Moore had also been curious about blood factor V, another Rh subtype. This factor V blood type antigen had been discovered by A. DeNatale, A. Cahan, J.A. Jack, R.R. Race, and R. Sanger in 1955. They had observed the V antigen factor in a non-African American male patient who had suffered from anemia but had received an incompatible transfusion from an African American blood donor. These investigators had noted that the factor V antigen was common in African Americans but rare in the vast majority of the non-African American population.

As before, Moore had conducted an extensive study of the U and V factors in the blood of a large group of human test subjects. She had grouped the cohorts into Howard University students representing a geographically wide distribution of human beings and African Americans from New York. Moore collected the blood samples and placed them in a solution of oxalate. Next, Moore conducted a serological analysis to determine whether the U and V blood factors were present and compared her two groups with the data collected by DeNatale and colleagues. In short, Moore observed that these two blood antigens, factors U and V, occurred with high frequencies in African Americans, compared to the non-African Americans she tested. This groundbreaking study formed the biological basis for the death of the anemic female patient and the incompatible blood transfusion in the male patient with anemia.

6) In a sense, Moore was somewhat one of the first people to study the impact of antibiotics and gut microorganisms specifically. What did she learn in this realm?

In the early 1960s, while still an associate professor and chair at Howard University’s bacteriology department, Moore conducted a study of antimicrobial susceptibility in gut bacteria from the Enterobacteriaceae family. First, Moore and her laboratory colleagues M.S. Briscoe and D.E. Puckett had isolated in their pure forms a collection of bacterial clones from the gut of the so-called Death’s Head cockroach. These insect gut bacterial isolates were identified as Escherichia freundii (now called Citrobacter freundii), Paracolobactrum intermedium, Aerobacter aerogenes (known in modern times as Enterobacter aerogenes), Aerobacter cloacae (now Enterobacter cloacae), Salmonella choleraesuis (now called Salmonella enterica, serotype Choleraesuis), and various species of the bacterial genus called Klebsiella. The investigators published their preliminary findings in the Journal of Insect Pathology in 1961. Moore and her co-authors had noted that no pathological conditions had been observed in the guts of the adult cockroaches.

Next, Moore and colleagues conducted a follow-up project involving a so-called Kirby-Bauer test to measure the extent of bacterial susceptibility to growth inhibition by various antimicrobial agents. In the Kirby-Bauer method, flat circular discs were impregnated with specific concentrations of various antibiotics. For each antibiotic, two discs were used—one containing a low drug concentration and the second one with a higher drug amount. These antibiotic discs were then sterilely placed onto Petri plates containing a culture medium called trypticase soy agar (TSA). Before the disc addition, the TSA plates had been inoculated with each bacterial isolate that Moore had retrieved from the Death’s Head insects. The bacterial inoculants on the TSA Petri dishes were then incubated overnight in an incubator, permitting the bacteria to grow and the antibiotics in the Kirby-Bauer to diffuse from the discs and move into the TSA medium.

If an antimicrobial agent from the disc inhibits the growth of bacteria, a so-called zone of inhibition forms around the disc on the plate’s agar. Based on the size of the growth inhibition zone, the nature of the antibiotics’ activities can be determined for each drug and each species of bacteria.

Moore and her fellow laboratory investigators could then discern how susceptible the bacteria were to the antibiotics. If the bacteria were sensitive to an antibiotic, the inhibition zone’s size would be relatively larger in diameter. Conversely, if the bacteria were antimicrobial-resistant, the disc’s zone sizes would be relatively smaller in their diameters. Moore and her colleagues could determine whether the various bacterial species were sensitive or resistant to the antimicrobial agents tested based on their diameter measurements of the inhibition zones around the antibiotic discs. See Figure 6. After the Petri dishes were incubated, Moore measured the bacterial growth inhibition zone diameters about the Kirby-Bauer discs and concluded whether the bacteria were antibiotic susceptible or resistant.

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Figure 6. Antibiotic susceptibility testing by disk diffusion using the Kirby Bauer method.

Moore found that while the gut bacteria from the cockroaches differed widely in their antimicrobial susceptibility profiles, virtually all of the isolates were multidrug-resistant! Enterobacter aerogenes was resistant to three drugs, and the remaining isolates were resistant to at least five of the antibiotics tested. Shockingly, Salmonella Choleraesuis was resistant to 10 anti-bacterial drugs, and the Klebsiella species were resistant to eight antibiotics. In Moore’s study, Citrobacter freundii was resistant to the most antibiotics, holding the study’s record at resistance to 12 of the antimicrobial agents tested.

7) Again, Moore was way ahead of her time—studying the reactions of particular pathogens to very different classes of antimicrobial agents. What were her contributions here?

In a second part of the cockroach gut bacteria project, Moore wanted to understand whether a given susceptibility to an antibiotic was due to a so-called bacteriostatic effect or a bactericidal one. In bacteriostatic inhibition, the bacteria do not die from the antibiotic—instead, they stop growing. Thus, if the antibiotic is taken away, the bacteria will resume its growth as before. On the other hand, if the growth inhibition by the drug is bactericidal, the bacteria die. Therefore, the removal of the drug would not bring the bacteria back to life. Moore analyzed the type of growth inhibition for the bacteria that had been susceptible to antibiotics.

She conducted the following experiments to determine whether the cockroach gut bacteria had succumbed to growth by the antibiotics in a bacteriostatic or bactericidal manner. She cut out samples of the agar containing bacteria from the growth inhibition zones of the Kirby-Bauer TSA plates and placed the agar pieces in test tubes containing liquid nutrient broth without antibiotics.

Then Moore incubated the nutrient broth cultures overnight in an incubator. If the bacteria had experienced a bacteriostatic effect by the antibiotic in the discs from the previous Kirby-Bauer tests, the new inoculants would continue their growth patterns and turn the nutrient broth into a cloudy solution of saturated bacterial cultures. Thus, bacterial growth in the liquid broth tubes indicated that the antimicrobial growth inhibition effect had been of a bacteriostatic nature.

On the other hand, if the bacteria had experienced a bactericidal killing effect, the new inoculants would have failed to thrive in the nutrient both test tubes, and the culture media would remain clear, filled with dead bacteria. By performing this additional follow-up experiment, Moore was able to discern whether the antibiotics had been bacteriostatic or bactericidal in their growth suppressing properties.

Overall, Moore observed that the vast majority of the gut bacteria that had been susceptible to the various antibiotics had indeed been killed by the antimicrobial agents tested in the end. In December of 1963, Moore, Briscoe, and Puckett published their new findings in the journal called the American Institute of Biological Sciences Bulletin (AIBS), known as BioScience in modern times.

8) In a sense, we all need hobbies—interestingly enough, what was one of her hobbies?

In addition to being a distinguished scientist, Ruth Ella Moore was also a brilliant seamstress. She inherited a love of fashion design and a chic, timeless quality from her mother. Moore was notorious for sewing much of what she wore. Indeed, she made a great majority of her entire wardrobe without having any degree in clothing construction or design. Remaining in step with the latest trends in fashion, she picked out her patterns and materials for designing the outfits conscientiously. In 2009, selections of her apparel were featured in The Sewer’s Art: Quality, Fashion, and Economy. Among those outfits selected were a two-piece woman’s suit with an off-white long sleeve jacket and black skirt, a floor-length red-violet evening dress made of velvet, and a long floral-patterned taffeta dress with short sleeves.

9) What kinds of awards did she garner, and at what prestigious universities did Moore teach?

While a graduate student enrolled at The Ohio State University, Moore was an instructor at a smaller college in Nashville, an institution known today as Tennessee State University, where she had taught courses in English and Hygiene. As mentioned above, Moore became a faculty member at the prestigious Historically Black Howard University in the institution’s Medical College.

In addition to Moore being the first African American female in the U.S. to be awarded the coveted doctorate in the natural sciences field of microbiology in 1933, she was also the first female to become head of an academic department at Howard University. As chair of the Bacteriology Department at Howard’s Medical College, Moore held the post for over six years, retiring from the position in 1957 to teach and concentrate on her research program.

During her life, Moore was bestowed with several honorary doctorates. One, in particular, was given to her in literature by Oberlin College and another in philosophy from Gettysburg College.

Moore had received official congressional recognition for her scientific contributions in 2005. In a congressional bill titled “The Significance of African American Women in the U.S. Community,” sponsored by U.S. House Representative Eddie Bernice Johnson of Texas, Moore was included as one of several scientists acknowledged for their many varied contributions to scientific research and society. The Johnson-sponsored bill passed the House of Representatives floor in April of 2005.

In 2021, Dr. Moore was inducted into the Hall of Fame sponsored by the Office of Diversity at The Ohio State University, her alma mater. She had been nominated for the prestigious inclusion by the University’s Public Health Alumni Society. In her honor, The Ohio State College of Public Health also established the Moore Scholarship for first-generation higher education students, a trailblazing endeavor in the education of undergraduate college students.

10) What have I neglected to ask regarding this outstanding female scientist?

Dr. Ruth Ella Moore was the first African American of either gender to become a member of the American Society for Microbiology (ASM). She participated and presented at the ASM scientific conferences even though she was barred from staying at the conference’s hotels. Moore was also barred from participating in the society’s banquet meals with her fellow ASM conference attendees.

It is noteworthy that Moore was able to secure a faculty position amid an era rife with discrimination against women and minorities in which academic positions at higher educational institutions in the U.S. were quite limited. It seems apparent that landing a tenure track professorship was out of reach for Moore at the great majority of the colleges and universities throughout the U.S.

Interestingly, Moore was never promoted to full professor, retiring as an emeritus associate professor in 1973, holding the emeritus status for 17 years. Moreover, Moore appears to have never been granted tenure, although she spent several decades conducting research and teaching medical students medical bacteriology.

In 1994, professor Ruth Ella Moore passed away at the National Lutheran Home for the Aged in Rockville, Maryland, due to cardiac-related issues on the 19th of July at 91 years.

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