Topic: anaerobes

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...

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