by Bruno Pot, Food microbiologist, Vrije Universiteit Brussel. Brussels, Belgium
Does the name Lactobacillus ring a bell?
Did you think you knew what lactobacilli were? Yes? Sorry, as of today you might need to study again! No?, then please read this message too.
What happened today/recently may have a future impact on what you can read on the labels of many fermented food products, like your favoured yoghurt or probiotic. It is likely that the name of the bacteria which is on the label will change. How is that?
Lesson 1: Taxonomy and nomenclature are important aspects of biology. They allow us to communicate about all living things: not to confuse dogs with cats, spiders with insects, palm trees with oaks. This is indispensable in our daily lives, but also has medical, nutritional, environmental, and why not, even academic importance.
Lesson 2: Bacteria also get a name. The Lactobacillus bulgaricus and Streptococcus thermophilus from your yoghurt are perfect examples. Lactobacillus and Streptococcus tell you the bugs’ “genus” name (no “o” in the word, sorry), while the names bulgaricus and thermophilus reflect the species names. It compares to our Latin name as humans: Homo sapiens. So, you see, biology can be simple.
Lesson 3: We think of a species in biology terms, if two members can produce offspring. For bacteria this is a problem, as they have no gender: they simply divide in two, over and over again, whenever the conditions are suitable to do so. But: how then define a species? In the past, scientists used to use specific properties like the shape and size (length, diameter), the colour when grown in the lab, the chemical reactions they can perform (e.g. produce yoghurt), etc… to group bacteria into species. This turned out to be very practical, but not always very correct.
Lesson 4: Nowadays scientists can use the genetic information of bacteria (their complete genome actually) to compare them and to decide if they belong to the same genus and species, or not! Now guess what! When this was done on all 255 Lactobacillus species, it turned out that huge mistakes were made in the past. Mistakes that would have put humans in the same species as cats, dogs, even as frogs…
In short: the “species” names of the old genus Lactobacillus have not been changed, the genus name Lactobacillus, however, has now been blessed with 23 additional names! If you want to know the new genus name of your old bug, you can do it here, or here and here.
But what does it mean for you? In the coming months and years some of these new names will gradually replace the name Lactobacillus. Don’t worry, they are still the same micro-organisms and their products will still taste as nice. Also, we will still be able to talk about the lactobacilli as good bugs, but if we want to be very specific about e.g. good bugs that live in bees, such as the Lactobacillus bombi, you might be tempted to call them… (try one of these links here, or here and here).
Right you got it!
End of biology lesson.