Leuconostoc mesenteroides

Leuconostoc mesenteroides, is a bacterial species sometimes associated with fermentation, under conditions of salinity and low temperatures (such as lactic acid production in fermented sausages).[2] In some cases, for instance vegetables and food storage, it was associated with pathogenicity (causing soft rot, slime production and bad odor).[3] L. mesenteroides is approximately 0.5-0.7 µm in diameter and has a length of 0.7-1.2 µm,[2] producing small grayish colonies that are typically less than 1.0 mm in diameter. It is facultatively anaerobic, Gram-positive, non-motile, non-sporogenous, and spherical. It often forms lenticular coccoid cells in pairs and chains, however, it can occasionally forms short rods with rounded ends in long chains, as its shape can differ depending on what media the species is grown on.[2][3] L. mesenteroides grows best at 30 °C, but can survive in temperatures ranging from 10 °C to 30 °C. It's optimum pH is 5.5, but can still show growth in pH of 4.5-7.0.[3]

Leuconostoc mesenteroides
Scientific classification
Kingdom:
Bacteria
Division:
Firmicutes
Class:
Bacilli
Order:
Lactobacillales
Family:
Leuconostocaceae
Genus:
Leuconostoc
Species:
L. mesenteroides
Binomial name
Leuconostoc mesenteroides
(Tsenkovskii 1878) van Tieghem 1878 [1]
Synonyms

Ascococcus mesenteroides Tsenkovskii 1878
Betacoccus arabinosaceus Orla-Jensen 1919

Microbiological Characteristics

L. mesenteroides is an obligate heterolactic fermentative lactic acid bacterium that is mostly used in industrial dairy fermentation, playing various roles, such as production of dextran, gas, and flavor compounds.[3] It is approximately 0.5-0.7 µm by 0.7-1.2 µm, and produces small grayish colonies that are usually less than 1.0 mm in diameter.[2] L. mesenteroides is a facultative anaerobe and will undergo heterolactic fermentation under microaerophilic conditions.[3] Taking this into consideration, it is important to note that L. mesenteroides utilizes sugar glucose as its primary source of metabolism, also well as other sugars such as sucrose and fructose.[3] Then, it creates ethanol, lactate, and CO2 as products of fermentation.[3] When grown in sucrose solution, it converts the sugar to dextrans having mostly alpha 1,6 linkages, but 1,2, 1,3, and 1,4 linkages are also present.[2][3]

Environment

L. mesenteroides is typically found on the skin of a large variety of fleshy fruits and vegetables,[3] and can be cultured using MRS agar, tomato juice agar, MRS broth, and skim milk.[3] This microbe is commonly used for souring vegetables like cucumbers and cabbage, producing fermented foods such as kim chi, sauerkraut, and pickles.[3] L. mesenteroides does best in temperatures ranging between 10 °C to 30 °C,[2][3] but has an optimum temperature of 30 °C. Additionally, it can survive in a pH range of 4.5-7.0, with an optima of 5.5. L. mesenteroides also has a doubling time of 0.6 h−1 under aerobic conditions.[2][3]

Genetics

The genome of L. mesenteroides has been successfully mapped, having an average genome size of 1.90138 Mbp and 1762 protein genes.[2] It also has a G+C content of 37.7683%[2] L. mesenteroides is from the phylum Firmicutes, and is a member of the lactic bacteria family. This is important as it has the ability to produce lactic acid which lowers the pH of the surrounding environment and, in turn, inhibits other competing food spoilage organism's growth as they cannot tolerate the acidic environment.[2][3]

Taxonomy

L. mesenteroides is divided into several subspecies.

L. m. subsp. cremoris (Knudsen and Sørensen 1929) Garvie 1983
L. m. subsp. dextranicum (Beijerinck 1912) Garvie 1983
L. m. subsp. mesenteroides (Tsenkovskii 1878) Garvie 1983
L. m. subsp. suionicum Gu et al. 2012

References
  1. Page Leuconostoc on Bacterio.net
  2. Özcan, E., Selvi, S., Nikerel, E., Teusink, B., Öner, E. T., Çakır, T. (2019). "A genome-scale metabolic network of the aroma bacterium Leuconostoc mesenteroides subsp. cremoris". Applied Microbiology and Biotechnology. 103 (7): 3153–3165. doi:10.1007/s00253-019-09630-4. PMID 30712128.CS1 maint: multiple names: authors list (link)
  3. Dols, M., Chraibi, W., Remaud-Simeon, M., Lindley, N. D., & Monsan, P. F. (1997). "Growth and energetics of Leuconostoc mesenteroides NRRL B-1299 during metabolism of various sugars and their consequences for dextransucrase production". Applied and Environmental Microbiology. 63 (6): 2159–2165.CS1 maint: multiple names: authors list (link)
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