An antiviral subtance extracted from Streptococcus faecalis

In Vitro Screening of Antiviral Activity of Lactic Acid Bacteria Isolated from Traditional Fermented Foods

Studies of newly isolated strains of lactic acid bacteria (LAB) are a good basis for expanding the potential for their applications in functional foods, probiotic food supplements, and other probiotic products. They exhibit various functional properties, including such with antiviral activity. Probiotic strains can manifest their antiviral effects by various mechanisms, including direct interaction with viruses, production of antiviral compounds, or immune system modulation. Ten newly isolated LAB strains from traditional fermented food products have been tested for the determination of their antiviral activity. This study was performed to evaluate the effect of cell-free supernatants (CFSs) from the studied strains for the effect on viral replication of Human alphaherpesvirus—HHV-1 and HHV-2 as well as for direct virucidal activity. The CFSs of the LAB strains were used in non-toxic concentrations of 25%, 6.25%, and 1.6%. No direct virucidal activity was observed in tested CFSs, but five of the strains observed a well-defined effect of viral replication inhibition with the selective index (SI) from 4.40 to >54. For two of these five strains, Lactobacillus delbrueckii subsp. bulgaricus KZM 2-11-3 and Lactiplantibacillus plantarum KC 5-12 strong activity against HHV-2 with a selective index (SI) over 45 was detected, which is a good basis for further research.

Effect of bacterial cell-free supernatants on infectivity of norovirus surrogates

Bacterial metabolic products were evaluated for inhibitory effects on viral propagation in cell culture. Cell-free supernatants (CFS) were prepared from growth of Enterococcus faecalis ATCC 19433, Pseudomonas fluorescens ATCC 13525, Escherichia coli 08, Staphylococcus epidermidis ATCC 12228, Bacillus subtilis 168, Bacillus coagulans 185A, B. coagulans 7050, Clostridium sporogenes PA3679, and a commercial probiotic mixture of Lactobacillus acidophilus, Lactobacillus rhamnosus, Bifidobacterium bifidum, Lactobacillus salivarius, and Streptococcus thermophilus in microbiological medium or milk. The inhibitory effects of CFS on the propagation of murine norovirus 1 and Tulane virus in RAW 264.7 and LLCMK2 cells, respectively, were evaluated in the continuous presence of CFS or after exposure of host cells to CFS. Slight inhibition of viral propagation was observed for murine norovirus and Tulane virus in the continuous presence of CFS of B. subtilis 168 and E. faecalis 19433, respectively. CFS cytotoxicity was also determined by microscopic examination. Virus persisted in the CFS that demonstrated cytotoxic effects, suggesting a lack of direct effect of CFS on virions. The viral propagation indicates a general lack of competitive inhibition by bacterial extracellular products and bears significance in understanding the persistence of virus in food and human systems shared by bacteria that are recognized for their colonization and competitive capabilities.

Inhibition of aging changes by lyophilized Streptococcus faecalis in diet

Effects of dietary Streptococcus faecalis (SF) on aging were evaluated using 1-week, 6-month, and 27-month-old Wistar and SHR rats. SF was lyophilized and added to commercial pellets at 1%. SF inhibited hypertension in aging SHR. SF inhibited aging-related changes in a wide variety of tissues. These changes were a disarray of hepatic cords, portal fibrosis; calcification of cartilage matrix, dominance of chondroitin sulfate B, and keratosulfate over chondroitin sulfates A and C; aortic endothelial damage, segmental thickening, calcification, and chondroid cells in the intima; atrophy of epidermis and appendages, and increase in amorphous dermal matrix; waxy degeneration and atrophy of psoas muscles; increase in lipoperoxides in the serum, liver, and brain; and reduction of cyclic AMP and GMP in the serum. Histological changes of the xyphoid cartilage, aorta, mesenteric artery, liver, dorsal skin, and psoas muscles in 27-month-old SF rats were much less severe than those in controls.