Streak plate isolation showing colonial morphology of Bacillus subtilis on trypticase soy agar (TSA) incubated for 24 hours at 37oC. Note the rough and dry/matte texture characteristic of this organism’s growth. Read More
Scanning electromicrograph of Staphylococcus aureus bacteria. Credit: National Institutes of Health/Department of Health and Human Services (NIAID). Read More
Please help me! I am planning to identify this microorganism by API but I can not identify the shape (rod or cocci). This microorganism has positive oxidase. Its colony is red, irregular, flat.
Please teach me. Thanks so much! Nhu Thuy from Vietnam
We celebrated the 200th episode of TWiV by visiting the National Emerging Infectious Diseases Laboratories at Boston University Medical Center, where we met with Elke, Paul, and Ron to talk about building and working in a BSL4 facility. It was an amazing visit that will be fully documented in an... Read More
Some holiday fun from last winter composed of different collected plate contaminants. Based on colony morphology and wet mounts, these bacteria are likely to be: Staphylococcus sp. (white), Serratia marcescens (dark orange), and Micrococcus luteus (creamy yellow). The design was incubated for 5-... Read More
This confocal micrograph, taken as part of a synthetic biology project, shows Bacillus subtilis, a Gram-positive, rod-shaped bacterium that is commonly found in soil. Distinct lineages of bacteria expressing different fluorescent proteins were initially mixed randomly on a petri dish. As the bac... Read More
Starch agar contains high molecular weight starch molecules (soluable starch). When Iodine is added it reacts with starch to produces a dark brown/purple color. A zone of clearing forms around organisms that produce the exoenzyme amylase after addition of iodine. This plate was incubated for ... Read More
The following picture shows the isolated black colonies of Salmonella on Salmonella-Shigella (S-S) Agar. S-S Agar is used as a selective and differential medium for the isolation of Salmonella and some Shigella species. The inclusion of bile salts is to inhibit gram-positive organisms. Ferric ci... Read More
Many air travelers are concerned about the risks of catching a disease from other passengers given the long time spent in crowded air cabins. New research shows disease-causing bacteria can linger on surfaces commonly found in airplane cabins for days, even up to a week. Participants discuss ... Read More
Mannitol Salt Agar (MSA)
•Important Ingredients: Phenol red, mannitol (sugar), 7.5% NaCl
•Differential: between pathogenic S. aureus and S. epidermidis
•Selective: NaCl inhibits non-halophilic organisms. Organism that can grow are halophilic.
•Mannitol Fermentors: fermentation of acid cau... Read More
A colorized electron microscope image captures delicate chains of streptococcus in a laboratory sample. Though some strep infections can be deadly, many strains are harmless—among the thousands of benign beings that make their home in our bodies.
Photograph by Martin Oeggerli, with support fr... Read More
Bioluminescent art blends science and creativity to create images that can only be seen in the dark. What do you get when you add a chemical engineer, a graphic designer and a research scientist? Beautiful art. In a wondrous combination of nature and design, bioluminescent art involves using nat... Read More
Germaphobes, maybe you're on to something.
Sickness-causing bacteria and viruses can lurk on surfaces long after they're expelled in an infected person's sneeze or snot. Some can even stay on a surface for months, given the right conditions. While the ability of these microorganisms to actual... Read More
Artist Sonja Bäumel explores the skin microbiome in her project Cartography of the Human Body. Bacteria isolated from Bäumel’s skin were characterized and grown individually, then used to reconstruct an artificial microbiome with many layers of differently-colored species. Giant petri dishes gre... Read More
Bacitracin test done on a lawn of Streptococcus pyogenes grown on blood agar. The zone of inhibition around the bacitracin disc, approx 14mm measuring the entire length of the zone, indicates sensitivity. The zone of inhibition is red because the red blood cells did not lyse. Grown for 24 hr... Read More
Serratia marcesens is a Gram-negative, rod-shaped bacterium that is commonly found in soil, water, on plants and in animals and thrives in damp conditions. This organism is well known for its production of the blood red pigment, prodigiosin. Production of prodigiosin can be influenced by several... Read More
Three organisms inoculated in TSB to look at tube morphology. From left to right:
Staphylococcus aureus: flocculent growth/turbid, growth throughout the tube.
Mycobacterium smegmatis: pellicle, growth at the top of the tube. M. smegmatis tends to stick to the tube and grow up the side.
Ba... Read More
It's Friday and I can finally enjoy the beach! So I thought it would be nice to reflect my excitement at work growing this happy Listeria monocytogenes ;) Read More
Unknown organism isolated from a swab taken off the bottom of a shoe. Students were asked to swab something in the classroom. One swab was done on the bottom of a shoe and incubated on a TSA plate for 48 hrs at 37 degree’s C. The organism was difficult to scrape so a small chunk of the organis... Read More