Meet The Microbiologist - The Scientists Behind The Microbiology

We pull back the curtain as former show hosts Merry Buckley and Carl Zimmer talk Meet the Scientist origins, favorite interviews and microbial topics. Julie’s Biggest Takeaways: Though the show started before podcasts were as popular as they are now, this didn’t pose a problem for Merry or Carl when soliciting guests - scientists were happy to have their work featured and to discuss their research. Inviting guests may involve bringing in a mix of experienced and early-career researchers, but both Merry and Carl agreed that the science is the major deciding factor when selecting guests. The ability to steer away from technical jargon and to use accessible, everyday analogies is one of the features shared by favorite guests. Carl uses the example of Bonnie Bassler, who explains bacterial quorum sensing as a communication mechanism. Delving into the personal motivations and experiences of guests can be tough, even when these experiences relate to science. Merry uses Abigail Salyers’ claim of the English teacher

How does an engineer approach microbial genetics? cworks with microbes of all kinds to optimize metabolic and agricultural systems. Here he discusses his work with Rhodobacter to make biofuels and for membrane protein expression, with Agrobacterium and plant pathogenic viruses to make drought-resistant plants, and with Clostridium and yeast cocultures for lignocellulose digestion. Take the listener survey at asm.org/mtmpoll Full shownotes at asm.org/mtm Links for this Episode: Wayne Curtis Lab site at Penn State University PLoS One: Molecular Cloning, Overexpression, and Characerization of a Novel Water Channel protein from Rhodobacter sphaeroides Protein Expression and Purification: Advancing Rhodobacter sphaeroides as a Platform for Expression of Functional Membrane Proteins Biotechnology for Biofuels: Consortia-Mediated Bioprocessing of Cellulose to Ethanol with a symbiotic Clostridium phytofermentans/Yeast Co-Culture HOM Tidbit: Genentech “Cloning Insulin” blog HOM Tidbit: Genentech press release annou

Over the course of a few decades, scientists have learned how insect endosymbiont bacteria affects insect reproduction and have used this understanding to control mosquito-born diseases. Seth Bordenstein talks about his research on the insect endosymbiont Wolbachia, human-microbiome interactions, and how the ecosystem of a host and its microbes can be refered to as a holobiont. Take the listener survey at asm.org/mtmpoll Links for this Episode: Bordenstein Lab at Vanderbilt University mSystems: Getting the hologenome concept right: an eco-evolutionary framwork for hosts and their microbiomes. PLoS Biology: Gut microbiota diversity across ethnicities in the United States. PNAS: One prophage WO gene rescues cytoplasmic incompatibility in Drosophila melanogaster. Discover the Microbes within! The Wolbachia Project HOM Tidbit: Studies on Rickettsia-Like Micro-Organisms in Insects (1924 paper from Hertig and Wolbach)  

Christine Foreman explains how microbes can survive and grow on glaciers, and what we can learn from microbes in glacier ice cores. Take the MTM listener (that's you!) survey asm.org/mtmpoll it only take 3 minutes. Thanks! Julie’s Biggest Takeaways Liquid inclusions between ice crystals create a vein-like network that allow microbes to survive between the ice crystals. Microbes living in glaciers have to adapt to a number of extreme environments: low water, low nutrients, extreme cold, and 6 months each of full sun or complete darkness mean there are many adaptive requirements to live in glaciers. Air bubbles trapped in ice cores provide data on the atmosphere 40,000 or 100,000 years ago. Using very old samples like these can inform scientists about the precipitation, temperature, and major cataclysmic events that occured at those time periods. Because so many researchers share ice core samples, a research group like Foreman’s will often get a very small sample, as low as 7 ml, for a particular time period. G

A very small proportion of people infected with HIV do not develop AIDS. Mark Connors talks about 2 patient populations that his lab studies, the elite controllers and the elite neutralizers, who control HIV infection with their respective T cell or B cell responses. Connors hopes his work on killer T cells and broadly neutralizing antibodies will help scientists develop better HIV therapies or an effective HIV vaccine. Links for This Episode: Mark Connors labsite at NIAID Immunity article: Identification of a CD4-binding-site antibody to HIV that evolved near-pan neutralization breadth. Immunity commentary: Class II-restricted CD8s: New lessons violate old paradigms. Science article: Trispecific broadly neutralizing HIV antibodies mediate potent SHIV protection in macaques. Imagining an HIV-Free Future (Smithsonian Worlds AIDS Day Event (Live Dec 4th at 6:45pm) HOM Tidbit: 12 Diseases that Changed Our World MTM Listener Survey

In the early 2000s, Andrew Read predicted that non-sterilizing vaccines would lead to more virulent disease. He was able to test his hypothesis with the real-world example of Marek’s disease, a disease of chickens. Read tells the story of his discovery, and talks about his work on myxoma virus. Take the MTM Listener Survey Subscribe (free) on Apple Podcasts, Google Podcasts, Android, RSS, or by email. Also available on the ASM Podcast Network app. Julie’s Biggest Takeaways: Every chicken on the market is vaccinated against Marek’s disease. Infection with Marek’s disease causes tumors on the bird and can lead to direct death, or condemnation of a flock requiring their culling. Birds are vaccinated with a live, attenuated virus, and there have been 3 vaccine iterations. The first used a related herpesvirus isolated from turkeys, while the second vaccine added a second virus strain. Each of these vaccines conferred protection for about 10 years, after which the disease began popping up again. The 3rd generation

A recent Nipah virus outbreak in Kerala, India, was halted due to improved detection capabilities. G. Arunkumar tells the story of his involvement. Host: Julie Wolf  Take the MTM Listener Survey Subscribe (free) on Apple Podcasts, Google Podcasts, Android, RSS, or by email. Also available on the ASM Podcast Network app. Julie’s Biggest Takeaways: Because bats are the normal reservoir, Nipah virus outbreaks appear to be seasonal, with an increase in cases coinciding with the spring, when the bat reproduction season is. Once a person is infected through direct contact with the virus, the virus is transmitted person-to-person through respiratory droplets. Family clusters combined with the right incubation time acted as a clue that a Nipah virus outbreak had begun. Molecular tests improved virus detection during the 2018 Nipah outbreak because patients presented symptoms within a few days, which was too short for them to have developed antibodies. Molecular tests allowed identification of infected patients withi

Robin Patel discusses her work on prosthetic joint infections and how metagenomics is changing infectious disease diagnostic procedures. Take the listener survey: asm.org/mtmpoll Julie’s Biggest Takeaways: The term antimicrobial resistance can mean many things. Although acquisition of genetic elements can lead to drug resistance, so can different growth lifestyles of bacteria; the same bacteria growing in liquid culture may be more susceptible to a drug than those bacteria growing on a biofilm. Lifestyle and genetics can intertwine, however, when bacteria growing as a biofilm exchange resistance genes through horizontal gene transfer. How do bacteria reach an implanted surface, such as on a prosthetic joint, to cause infection? It may rarely occur during surgery, if even a single bacterium reaches the joint surface despite the sterile conditions; alternatively, it could occur through hematogenous spread (through the blood) after the surgery is over. Most infections are believed to be seeded at the time of imp

To eliminate malaria, you have to stop transmission, and that’s what Carolina Barillas-Mury hopes to do. Her work on the interaction of the malaria parasite Plasmodium falciparum may lead to a transmission-blocking vaccine. She explains how, and discusses the co-evolution of malaria, mosquitos, and man.   Take the listener survey: asm.org/mtmpoll   Julie’s Biggest Takeaways: When born, babies carry antibodies from their mothers, which may protect them through passive immunity; additionally, babies are more easily protected from mosquito exposure by placing them under bed netting. As they grow, children become more active, and their passive immunity concurrently wanes. They may be exposed to mosquitoes carrying malaria parasites and their still-developing immune systems aren’t able to keep the parasites from replicating, leading to more severe disease, including cerebral malaria.   The Culicines and Anopholines are two major groups of mosquitoes that carry disease. The culicines have recently spread around the

How do researchers study a new pathogen? Stanley Perlman talks about how virus researchers studied SARS and MERS after they emerged, what they learned, and why there are no more cases of SARS. He also discusses his work on a coronavirus model of multiple sclerosis.   We want to hear from you! Please take our listener survey.   Julie’s Biggest Takeaways: Coronaviruses have the largest RNA genomes, with up to 40 kB of sequence, but why their genomes is so big is unclear - their genomes don’t seem to code for more genes than viruses with smaller genomes. Before the SARS coronavirus outbreak in 2002, few severe human infectious coronaviruses were known, but the several coronaviruses had been identified that cause serious disease in animals such as pigs, cats, and cows. Where did SARS go? SARS coronavirus had to cross into people and mutate for better infectivity, and when infecting people, it caused a lower respiratory disease. Quarantining SARS patients is extremely effective because the symptoms coincide with i

You may know that beer is fermented, but did you know making chocolate requires a fermentation step? Kevin Verstrepen discusses how his lab optimizes flavor profiles of the yeast used in this fermentation step, and explains how yeast was domesticated before microorganisms had been discovered. Take the MTM listener survey, we want to hear from you. Thanks! Julie’s Biggest Takeaways: Microbes are used to ferment foods, but they do more than just add ethanol or carbon dioxide: their metabolic byproducts add flavors and aromas that are an essential part of the fermented food. In cocoa bean fermentation, the yeast that are part of the initial fermentative microbial population control the development of the subsequent microbial populations and the quality of the final product. How the volatile flavor compounds generated during fermentation survive the roasting step remains unclear. Heat can destroy these labile compounds, but Kevin thinks the compounds were able to survive roasting because they become embedded in l

How can the humble zebrafish teach us about the human microbiome? John Rawls discusses the benefits of using animal models Take the MTM Listener Survey  Julie’s Biggest Takeaways:   Zebrafish and other model animals provide opportunities to understand host-microbe interactions. Zebrafish are particularly useful for imaging studies, due to their translucent skin and the ease of in vivo microscopy. This allows zebrafish to be used to in studies of spatial architecture or longitudinal studies (imaging the same fish specimen over time) in ways that other model organisms can’t be.   Zebrafish get their first microbes from their mother, just like mammals! The chorion, a protective coating that surrounds the zebrafish embryo, is seeded with microbes from passing through the cloaca of the female zebrafish. Surface-sterilizing this chorion allows researchers to generate germ-free animals that are very useful for microbiome studies.   A gut epithelial transcription factor is regulated by a signal from the gut microbiot

Gemma Reguera discusses her studies of Geobacter pili, which transfers electrons to iron oxide and other minerals, and can be used for new biotech applications. Host: Julie Wolf  Subscribe (free) on Apple Podcasts, Google Podcasts, Android, RSS, or by email. Also available on the ASM Podcast Network app. Julie’s Biggest Takeaways: Geobacter sulferreducans, a bacterium that “breathes” rust, is the lab representative of the genus Geobacter that dump electrons onto rust. These specialized microbes use minerals like manganese oxide and iron oxide (also known as rust) for respiration in both terrestrial and aquatic sediments. Although many species are strict anaerobes, a few species can grow under microaerophilic conditions, in which the bacteria will respire the oxygen to eliminate its toxic effects on the cell. Iron oxide respiration relies on the Geobacter pili, a simple structure composed of a single peptide repeat. The pili concentrate on one side of the bacterial cell, where they connect the cell with the i

Why do Legionnaire’s Disease outbreaks occur mostly in the summer? What is the connection of the Flint change in water source and Legionella outbreaks in the area? Michele Swanson discusses her work on Legionella pneumophila and her path from busy undergraduate to ASM President. Julie’s Biggest Takeaways: Legionella pneumophila is a waterborne microbe that lives in fresh water and can colonize water systems of the built environment. Colonization of cooling systems, like those used in air conditioning systems, can lead to contaminated water droplets that can cause disease. Legionella are very adaptable to different environment, but scientists don’t have great models to determine the exact preferences of the bacterium. After Flint switched water sources from lake to the Flint river, a chemical that prevents corrosion was omitted from the water treatment. This led to lead in the water, which was detected in pediatric patients. An increase of legionella cases in the two years also occurred, and the question was w

How is Toxoplasma gondii, a protozoan that causes neuro-invasive disease, transmitted as a foodborne pathogen? Why are cats important in transmitting Toxoplasma infection? Anita Koshy answer these questions and talks about her research on the latest Meet the Microbiologist. Julie’s Biggest Takeaways: The primary host for T. gondii is cats, in which the protozoan can undergo sexual reproduction. Why cats? No one knows, in part because there isn’t a good in vitro system to study cat epithelial cell interactions with T. gondii. Most warm-blooded animals, including birds, can be infected with Toxoplasma. Intermediate hosts can pass Toxoplasma from one to another if one eat these tissue cysts, explaining why Toxoplasma can be a foodborne pathogen. In healthy individuals, the immune response clears most fast-growing cells (tachyzoites) but some protozoans convert to a slow-growing cell form (bradyzoites). In people, these bradyzoites form cysts predominantly in the brain, the heart and the skeletal muscle. Some ser

Jennifer Gardy talks about whole-genome sequencing as a technique to address public health issues using genomic epidemiology. She talks about her research on TB and new DNA sequencing technologies, including her vision for microbial genetic sequencing as one piece of the puzzle in the future of public health. Julie’s Biggest Takeaways: Whole-genome sequencing technologies are replacing older DNA technologies to identify relatedness between microbial isolates. The genome sequences help to identify epidemiological questions such as the origins of an outbreak. A pathogen’s genome being passed person-to-person accrues small changes, similar to children playing telephone - except those children are scattered around the room, and you have to logically deduce the order in which the information was passed. DNA sequencing has moved forward faster than the upstream genomic preparation and downstream sequence analysis areas; Gardy expects advances in these ‘bookend’ areas to be breakthroughs of the future. The Ebola and

See the full shownotes at: asm.org/mtm Julie Pfeiffer tells the story of how she serendipitously found a role for the gut microbiota during polio virus infection, and how she and her lab discovered an important role for bacterial glycans in viral biology. She also talks about viral fitness strategies, and how RNA viruses and DNA viruses benefit from making different amounts of errors when copying their genomes. Julie's biggest takeaways: Determining the exact nature of the glycans that play these roles has been difficult because they are very complex. Aspects of lipopolysaccharide, chitin, and peptidoglycan are all sufficient to bind the viral capsid, but because of their structural complexity, it’s difficult to pinpoint the exact molecular interaction. Bacterial glycan interactions with viruses benefit the virus in two ways: the virus can be delivered to a host cell it will infect, and the viral capsid is stabilized. Whether there is a benefit to the bacterium during these interactions is unknown, but is an

Pete Greenberg tells how bacteria can communicate based on cell density, a phenomenon he helped name quorum sensing. He talks about therapeutics based on quorum-sensing discoveries, and how studying bacterial interactions can be used to test ecological principles like cooperation and social cheating. Julie's biggest takeaways: Quorum sensing can be likened to an old-fashioned smoking room, where a few cigar smokers don’t affect the air quality, but as more smokers enter the room, it becomes beneficial to the group to open the window: a changed behavior that benefits the group environment. Differentiating waste molecules from signaling molecules is important to define specific quorum sensing. The experimental evidence that shows that molecules serve as quorum sensing signals that allow bacteria to respond at high density comes from social engineering experiments to identify ‘cheaters.’ Quorum sensing results in changes in gene expression that benefit the community but not necessarily individual cells. An examp

Charlie Rice gives the history of learning to grow hepatitis C virus in culture, from pitfalls to hurdles and successes along the 20-year journey. He also talks about yellow fever virus, its vaccine, and the importance of curiosity-driven research

How are new diseases detected in a clinical microbiology lab? Melissa Miller talks about the time it takes to develop a test for a new disease (hint: it’s getting shorter). She also shares her definition of ‘point-of-care’ diagnostics and explains the major trends for clinical microbiology labs. Host: Julie Wolf  Subscribe (free) on iPhone, Android, RSS, or by email. You can also listen on your mobile device with the ASM Podcast app. Julie's biggest takeaways: Antibiograms are vital to understand the resistance characteristics of locally circulating disease strains. These help make empirical decisions for antibiotic therapy regimens before the susceptibility test results are available. New diseases require new diagnostic tests. How to determine how well new tests work once they’re developed? Clinical microbiologists look to the sensitivity (how well does a test detect if a patient has a disease) and specificity (how often is the test negative if the patients doesn’t have it) of the test. Having access t