Tetragenococcus halophilus

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Photograph of a collection of Tetragenococcus halophilus cells. Image credit: Noda Institute for Scientific Research

Classification

Bacteria; bacilotta; Bacili; Lactobacillales; Enterococcaceae; Tetragenococcus

Species

NCBI: [1]

Tetragenococcus halophilusenus species

Description and Significance

Tetragenococcus halophilus is a gram positive, spherical lactic acid bacteria that lives in extreme salt environments and was originally isolated in Miso (Kumazawa et. al. 2018). Since then, it has been observed in other halophilic fermented foods such as soy sauce, fish sauce, and salted anchovies (Guindo et. al. 2022). The bacteria contributes to fermentation by introducing organic acids and degrading unfavored sugars (Link 2021).

Genome Structure

The bacteria possesses a single circular chromosome. The median length of the genome is 2.42 Mb with a GC content of 35.7% and a median protein count of 2254. There are 42 known genomes for the species, with 6 complete genomes, 2 scaffolds, and the rest contig.

Accumulation/Deletion events in spacers and repeated insertion of the CRISPR 1 loci have created resistances to bacteriophages targeting Tetragenococcus halophilus, resulting in strains with different levels of resistance (Matsutani, et. al. 2021).

Cell Structure, Metabolism and Life Cycle

Tetragenococcus halophilus is spherical, and like other Tetragenococcus it is a facultative aerobe, gram positive, non-motile, and non-sporulating.

The bacteria optimally grows in salt concentration ranges of about 12-16% and, like other gram positive halophiles, is chloride dependent and grows optimally in media containing .5-3.0 M NaCl (Licui 2015). It is known for producing organic acids like aspartic acid, glutamic acid, dipeptide N-succinyl-glutamic acid, and alanine along with volatile compounds like benzeneacetaldehyde and 2-methyl-propanal (Kim 2022).

Ecology and Human Impact

The organic acids and volatile compounds it produces contribute to the flavor and smell of halophilic fermented foods. When manufacturing these foods, it is commonly used as a starter to both improve the flavor and consistency of the finished product (Matsutani 2021). Recent research has revealed that T. halophilus is found within the gut microbiota in some individuals, although its role in human health is unknown (Guindo, et. al. 2022).

T. halophilus has been credited for some beneficial health on humans, particularly in regards to regulating the immune system in response to atopic disease, although more study needs to be done on this particular matter (Guindo, et. al. 2022).

References

Kumazawa, T., Nishimura, A., Asai, N., & Adachi, T. (2018). Isolation of immune-regulatory Tetragenococcus halophilus from miso. PloS one, 13(12), e0208821. https://doi.org/10.1371/journal.pone.0208821

Guindo, C. O., Morsli, M., Bellali, S., Drancourt, M., & Grine, G. (2022). A Tetragenococcus halophilus human gut isolate. Current research in microbial sciences, 3, 100112. https://doi.org/10.1016/j.crmicr.2022.100112

Schoch CL, et al. NCBI Taxonomy: a comprehensive update on curation, resources and tools. Database (Oxford). 2020: baaa062. PubMed: 32761142 PMC: PMC7408187.

Link, T., Vogel, R. F., & Ehrmann, M. A. (2021). The diversity among the species Tetragenococcus halophilus including new isolates from a lupine seed fermentation. BMC microbiology, 21(1), 320. https://doi.org/10.1186/s12866-021-02381-1 Licui Liu, Lifang Si, Xin Meng, Lixin Luo, Comparative transcriptomic analysis reveals novel genes and regulatory mechanisms of Tetragenococcus halophilus in response to salt stress, Journal of Industrial Microbiology and Biotechnology, Volume 42, Issue 4, 1 April 2015, Pages 601–616, https://doi.org/10.1007/s10295-014-1579-0

Kim, D.H., Kim, SA., Jo, Y.M. et al. Probiotic potential of Tetragenococcus halophilus EFEL7002 isolated from Korean soy Meju. BMC Microbiol 22, 149 (2022). https://doi.org/10.1186/s12866-022-02561-7

Matsutani M, Wakinaka T, Watanabe J, Tokuoka M, Ohnishi A. Comparative Genomics of Closely Related Tetragenococcus halophilus Strains Elucidate the Diversity and Microevolution of CRISPR Elements. Front Microbiol. 2021 Jun 18;12:687985. doi: 10.3389/fmicb.2021.687985. PMID: 34220781; PMCID: PMC8249745.

Author

Page authored by Jeremy Rezek, student of Prof. Bradley Tolar at UNC Wilmington.