222047519
Miso is a fermented soybean paste that originated in China but made its way to Japan by Buddhist priests. It's made with salt, soybeans and fermented soybeans called Koji. It was first used to preserve food during warmer months, but it's now used as an important flavor enhancer and preservative in a wide array of dishes from across the world. The bacteria responsible for the fermentation process to produce miso is Tetragenococcus halophilus, which is a halophilic lactic acid bacterium. Let's take a closer look at this interesting bacterium and it's contribution to fermented foods.
Here is a picture of miso paste. It's a traditional Japanese seasoning that is described as having a salty and concentrated soy flavor with hints tanginess due to the fermentation process. It's a rich source of probiotics and bacteria that promote good gut health as well as vitamins and minerals. Typically, it's used as seasoning in traditional soups, but it can also be used as an alternative to salt in baked goods and adds savory and earthy flavor.
Now for the star of the show!!!!
Tetragenococcus halophilus is the bacteria used in the fermentation of soybeans to form miso.
Here is an image of T. halophilus under a scanning electron microscope at a) 50 00x and b)150 00x magnification.
T. halophilus are gram-positive, cocci shaped bacteria found in high salinity environments. This high salt tolerance, it's production of acidic metabolites and it's ability to increase the level of unsaturated fatty acids and decrease the level of saturated fatty acids make it an ideal starter bacteria for the production of miso.
Here is a link to an article for more information:
https://ift.onlinelibrary.wiley.com/doi/full/10.1111/1750-3841.15773
Miso preparation involves 2 fermentations. The first is the preparation of Koji using a Mould and the second fermentation which involves bacteria occurs after the Koji has been mixed with salt and soybean mash. Please note that Pediococcus halophilus has been assigned to the new genus Tetragenococcus halophilus.
This article has more information on the production of Miso.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9731531/#:~:text=Miso%20is%20formed%20by%20combining,et%20al.%2C%202021
Although the consumption of T. halophilus can have many health benefits, they still produce biogenic amines such as histamine and tyramine which in high amounts are associated with neurotoxicity. Please note that although the article uses bacteria isolated from fish sauce it is similar to miso production in the presence of T. halophilus and the particular biogenic amines present.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8621993/
Certain strains of T. halophilus are shown to display acquired resistance to antibiotics such as chloramphenicol and gentamicin by acquiring transmissible determinants.
This article has more information on the safety risks associated with T. halophilus:
https://www.sciencedirect.com/science/article/abs/pii/S0740002016302040?via%3Dihub
T. halophilus _ has been a staple in Japanese cuisine for centuries. It's long-term consumption has been found to improve immune activation and tolerance by increasing the production of certain subsets of CD4 T cells and even diminish autoimmunity in a recent study carried out on rats. This is believed to be evidence that the consumption of foods fermented with _T. halophilus have contributed to Japan's high life expectancy.
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0267473
