species: bacteria

Fermentation of the Future

Fermentation of the Future

Using populations of bacteria or yeasts to change dairy product composition doesn’t sound like a wholesome idea, but that is what lies behind the production of cheese, mango lassi and, despite its name, crème fraîche. Some fermented dairy products such as these have been shown to be healthy in ways beyond providing nutrition. Consequentially, food scientists are asking whether the processes that conjure up greater amounts of certain health-promoting ingredients in fermented dairy could be applied more widely and effectively. Read More...

Bacterial Count

Bacterial Count

A new study scans breast milk for the different bacterial species found in it. Species that can grow whether or not there is air around them colonize a baby’s intestine first, but are then overrun by other species that flourish in the absence of oxygen, like Bifidobacterium infantis. The class Clostridia can be found in breast milk, and probably travels there from mom’s gut.   Milk enthusiasts probably all share a favorite bacterium: Bifidobacterium infantis, the species that coevolved with humans and promotes a healthy infant gut. Breast milk contains many other kinds of bacteria, but recording the full species register is a surprisingly tricky task. Recently, a team of Swiss researchers did the most complete job yet.   Ted Jost and others1 in the Zurich-based group took milk samples from seven women at three intervals after giving birth, cultured the milk in various ways, and then sequenced the DNA in the milk using multiple techniques. That should cover all the bases. Their culture methods, numbering nine, catered for bacteria of every lifestyle choice. They laced agar jelly with all manner of nutrient mixtures and provided airy compartments for species that like to grow in oxygen. Meanwhile species that flourish despite an absence of oxygen (facultative anaerobes) or can’t handle life in its presence (obligate anaerobes) were given the chance to grow in an anaerobic chamber. Usually, the first kinds of bacteria to set up camp in a baby’s intestine are facultative anaerobes like Escherichia coli species. As expected, Streptococci, another facultative anaerobe, was one of the most common categories identified in Jost et al.’s study. Then, after a few days, when the facultative anaerobes have used up the oxygen in a baby’s gut lumen, populations of obligate anaerobes, like Bifido species, start to take off2. And Bifidobacterium infantis, by far […] Read More...

Tales from an often-ignored community

Tales from an often-ignored community

Breast milk contains bacteria. That much is known. Some studies (although not, alas, the Human Microbiome Project) have even characterized the bacterial community found in milk. But how does the composition of such a community vary among women? And how might it change over the course of lactation? Read More...

Milk-fed bacteria’s secret weapon

Milk-fed bacteria's secret weapon

If a bacterium walks into a Bar & Grill, what does he order to eat? If there are any simple sugar molecules on the menu, such as glucose, galactose, or mannose, then he’ll order a plate of them. But given these simple sugars are the first choice of pretty much any type of bacteria, the Bacteria’s Bar & Grill is likely to run out quickly. Read More...

The Many Faces of Lactoferrin

Fresh out of the womb, a newborn baby is challenged with armies of disease-causing microbes. How does he survive this onslaught? In some parts of the world, he doesn't. Millions of babies die each year in the first few months of life from common infections. A recent publication by Barboza and colleagues unfolds how a major milk protein, lactoferrin, displays different "faces", depending on which pathogens are present. Read More...

Dinosaur aunts, bacterial stowaways, and insect milk

Dinosaur aunts, bacterial stowaways, and insect milk

Milk is everywhere. From the dairy aisle at the grocery store to the explosive cover of the Mother's Day issue of Time magazine, the ubiquity of milk makes it easy to take for granted. But surprisingly, milk synthesis is evolutionarily older than mammals. Milk is even older than dinosaurs. Read More...

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