Phenotypic Traits and Immunomodulatory Properties of Leuconostoc carnosum Isolated From Meat Products

Abstract

Twelve strains of Leuconostoc carnosum from meat products were investigated in terms of biochemical, physiological, and functional properties. The spectrum of sugars fermented by L. carnosum strains was limited to few mono- and disaccharides, consistently with the natural habitats of the species, including meat and fermented vegetables. The strains were able to grow from 4 to 37°C with an optimum of approximately 32.5°C. The ability to grow at temperatures compatible with refrigeration and in presence of up to 60 g/L NaCl explains the high loads of L. carnosum frequently described in many meat-based products. Six strains produced exopolysaccharides, causing a ropy phenotype of colonies, according to the potential involvement on L. carnosum in the appearance of slime in packed meat products. On the other side, the study provides evidence of a potential protective role of L. carnosum WC0321 and L. carnosum WC0323 against Listeria monocytogenes, consistently with the presence in these strains of the genes encoding leucocin B. Some meat-based products intended to be consumed without cooking may harbor up to 108 CFU/g of L. carnosum; therefore, we investigated the potential impact of this load on health. No strains survived the treatment with simulated gastric juice. Three selected strains were challenged for the capability to colonize a mouse model and their immunomodulatory properties were investigated. The strains did not colonize the intestine of mice during 10 days of daily dietary administration. Intriguingly, despite the loss of viability during the gastrointestinal transit, the strains exhibited different immunomodulatory effect on the maturation of dendritic cells in vivo, the extent of which correlated to the production of exopolysaccharides. The ability to stimulate the mucosal associated immune system in such probiotic-like manner, the general absence of antibiotic resistance genes, and the lack of the biosynthetic pathways for biogenic amines should reassure on the safety of this species, with potential for exploitation of selected starters.

Influence of Isolation Temperature on Isolating Diverse Lactic Acid Bacteria from Kimchi and Cultural Characteristics of Psychrotrophs

“…miyukkimchii , and Leu. carnosum growth, despite the known optimum cultural temperature being approximately 30°C [ 23 - 25 ]. In a previous study, the appropriate cultural temperature of Leu.…”

Characterization of Leuconostoc carnosum and Latilactobacillus sakei during Cooked Pork Ham Processing

“…and Latilactobacillus sp. strains isolated from various sources, including dairy-related products, modified atmosphere packaged sausage, and cooked ham [ 10 , 36 , 37 ]. These findings align with our observations.…”

Microbiota Survey of Sliced Cooked Ham During the Secondary Shelf Life

“…In these samples, a similar role was exerted by several Latilactobacillus , Leuconostoc , and Carnobacterium species, among which the most frequently detected were L. sakei , L. carnosum , L. mesenteroides , and C. divergens . Generally, the low temperatures of storage made L. carnosum and L. mesenteroides the species best adapted to cooked ham ( Vasilopoulos et al, 2008 ; Raimondi et al, 2021 ). Besides their preservative effect, LAB can also be involved in spoilage ( Comi et al, 2016 ; Raimondi et al, 2019 ).…”

“…LAB may concur with meat preservation due to the production of organic acids and hydrogen peroxide, which exert an intrinsic antimicrobial effect. Furthermore, selected strains produce bacteriocins specifically inhibiting certain contaminating pathogen bacteria, such as Listeria ( Raimondi et al, 2021 ). On the other hand, LAB may contribute to spoilage of MAP cooked ham, inducing discoloration, changes in odor, flavor, and texture, and slime formation, negatively affecting the shelf life ( Samelis et al, 2000 ; Kreyenschmidt et al, 2010 ; Raimondi et al, 2019 ).…”