We aimed to determine the effects of Lactobacillus strains against rotaviral infections. Rotaviruses are the major causative agent of acute gastroenteritis in infants and children worldwide. However, to date, no specific antiviral drugs for the treatment of rotavirus infection have been developed. We identified 263 Lactobacillus strains from 35 samples of the traditional Korean fermented vegetable food kimchi. Among them, Lactobacillus plantarum LRCC5310, more specifically the exopolysaccharides produced by these cells, were shown to have an antiviral effect against human rotavirus Wa strain in vitro. In vivo, the oral administration of exopolysaccharides for 2 d before and 5 d after mouse infection with the murine rotavirus epidemic diarrhea of infant mice strain led to a decrease in the duration of diarrhea and viral shedding and prevented the destruction of enteric epithelium integrity in the infected mice. We demonstrated here that the exopolysaccharides extracted from L. plantarum LRCC5310 can be used for the effective control of rotavirus infection.

Several enzymes are involved in the process of converting milk to lactic acid and coagulated milk to curd and, therefore, are important in dairy fermented products. Amylase, proteinase, and lipase are enzymes that play an important role in degrading milk into monomeric molecules such as oligosaccharides, amino acids, and fatty acids, which are the main molecules responsible for flavors in cheese. In the current study, we determined the amylase, proteinase, and lipase activities of Lactococcus chungangensis CAU 28(T), a bacterial strain of nondairy origin, and compared them with those of the reference strain, Lactococcus lactis ssp. lactis KCTC 3769(T), which is commonly used in the dairy industry. Lactococcus chungangensis CAU 28(T) and L. lactis ssp. lactis KCTC 3769(T) were both found to have amylase, proteinase, and lipase activities in broth culture, cream cheese, and yogurt. Notably, the proteinase and lipase activities of L. chungangensis CAU 28(T) were higher than those of L. lactis ssp. lactis KCTC 3769(T), with proteinase activity of 10.50 U/mL in tryptic soy broth and 8.64 U/mL in cream cheese, and lipase activity of 100 U/mL of tryptic soy broth, and 100 U/mL of cream cheese. In contrast, the amylase activity was low, with 5.28 U/mL in tryptic soy broth and 8.86 U/mL in cream cheese. These enzyme activities in L. chungangensis CAU 28(T) suggest that this strain has potential to be used for manufacturing dairy fermented products, even though the strain is of nondairy origin.

Interest is increasing in the potentially beneficial role of probiotics in the prevention and treatment of atopic diseases. In this study, we investigated the protective effects of Lactococcus chungangensis CAU 28(T) against atopic dermatitis using murine macrophage RAW 264.7 cells, human keratinocyte HaCaT cells, human mast cell line HMC-1 cells, and a 2,4-dinitrochlorobenzene-induced atopic dermatitis model (NC/Nga mice). The results showed that L. chungangensis CAU 28(T) exhibited potent antiinflammatory activity by inhibiting the production of the proinflammatory mediators nitric oxide and prostaglandin E2 in lipopolysaccharide-stimulated RAW 264.7 cells. Treatment with L. chungangensis CAU 28(T) reduced the release of β-hexosaminidase and histamine in HMC-1 cells stimulated with mast cell activator compound 48/80. In addition, the back skin and ears of NC/Nga mice exhibited reduced histological manifestations of atopic skin lesions such as erosion, hyperplasia of the epidermis and dermis, and inflammatory cell infiltration. Oral administration of L. chungangensis CAU 28(T) suppressed the production of IL-4, IL-5, IL-12, IFN-γ, tumor necrosis factor-α, and thymus- and activation-regulated chemokine (TARC) in skin lesions, indicating that it strongly drives the local immune system with efficacy comparable to that of tacrolimus, a topical immunomodulatory drug used for the treatment of atopic dermatitis. The findings indicate that L. chungangensis CAU 28(T) could be a novel probiotic candidate for controlling the symptoms of atopic dermatitis.

Lactococcus lactis has a played a prominent role in food industry from traditional milk fermentations to industrial scale processes. Extensive studies on the biochemical, physiological, and genetic aspects of L. lactis are evident from published literature. Recently, another novel species, Lactococcus chungangensis, was isolated from activated sludge as the sixth member of the genus to be discovered. To date, no study has been conducted to explore the functional aspects of L. chungangensis to identify features similar to those in L. lactis that are relevant to the dairy industry. Hence, the present study was undertaken to identify functional genes relevant to dairy application through comparative transcriptomic analysis of L. chungangensis with L. lactis. In expression microarray data, 415 genes were upregulated and 1,500 were downregulated of the total 1,915 probes analyzed. Interesting findings from this study were the identification of functional genes such as aminohydrolase and S-adenosylmethionine in L. chungangensis, which are useful in flavor production in cheese making. Probing these genes by PCR and analyzing the sequence confirmed the presence of these genes. Phenotypic analysis of these genes was also investigated by growing the strain in different concentrations of skim milk media to confirm the ability of L. chungangensis to degrade casein in milk, which is the major precursor for flavor enhancing compounds. Other adaptive and stress-response genes such as cold shock and heat shock proteins were also revealed. All experimental investigations at the functional level suggest that L. chungangensis possesses some interesting genes which are of commercial significance, especially in cheese production.

Many human gastrointestinal facultative anaerobic and aerobic bacteria possess alcohol dehydrogenase (ADH) activity and are therefore capable of oxidizing ethanol to acetaldehyde. However, the ADH activity of Lactococcus spp., except Lactococcus lactis ssp. lactis, has not been widely determined, though they play an important role as the starter for most cheesemaking technologies. Cheese is a functional food recognized as an aid to digestion. In the current study, the ADH activity of Lactococcus chungangensis CAU 28(T) and 11 reference strains from the genus Lactococcus was determined. Only 5 strains, 3 of dairy origin, L. lactis ssp. lactis KCTC 3769(T), L. lactis ssp. cremoris KCCM 40699(T), and Lactococcus raffinolactis DSM 20443(T), and 2 of nondairy origin, Lactococcus fujiensis NJ317(T) and Lactococcus chungangensis CAU 28(T) KCTC 13185(T), showed ADH activity and possessed the ADH gene. All these strains were capable of making cheese, but the highest level of ADH activity was found in L. chungangensis, with 45.9nmol/min per gram in tryptic soy broth and 65.8nmol/min per gram in cream cheese. The extent that consumption of cheese, following imbibing alcohol, reduced alcohol uptake was observed by following the level of alcohol in the serum of mice. The results show a potential novel benefit of cheese as a dairy functional food.