The effect of immunoregulation of Streptococcus lactis L16 strain upon Staphylococcus aureus infection

Effect of Staphylococcus aureus Contamination on the Microbial Diversity and Metabolites in Wholewheat Sourdough

Wholewheat sourdough products are becoming increasingly more popular, and Staphylococcus aureus is a common opportunistic pathogen in dough products. The effects of S. aureus contamination (102 cfu/g) on metabolites as well as titratable acidity (TTA), pH, and microbial diversity of sourdough were investigated. S. aureus contamination significantly decreased the content of mannose while increasing the sorbitol in sourdough (p < 0.05). The S. aureus contamination significantly reduced the number of lactic acid bacteria (LAB), such as Lactobacillus curvatus, and the TTA values (p < 0.05). Furthermore, S. aureus contamination significantly reduced the content of most esters and acid flavor compounds while significantly increasing the content of 2,4-decadienal (p < 0.05), which is a compound that could have a negative impact on the flavor of sourdough. The PCA model developed based on volatile metabolites data could be used to distinguish contamination of S. aureus in sourdough cultured for 4 h. Sorbitol, 2,3-dimethylundecane, 1-pentanol, and 3-methylbutanoic acid were newly found to be the characteristic metabolites in S. aureus-contaminated sourdough.

Contrasting Vaginal Bacterial Communities Between Estrus and Non-estrus of Giant Pandas (Ailuropoda melanoleuca)

Bacterial infection and imbalance of bacterial community in the genitourinary system of giant panda could affect the reproductive health. In severe cases, it can also lead to abortion. In this study, 13 of vaginal secretions in the estrue (E) group and seven of vaginal secretions in the non-estrue (NE) group were used to study the composition and diversity of vaginal bacterial communities between estrus and non-estrus by 16S rRNA gene sequencing analysis. The results showed that the vaginal microbiome in giant pandas shared the same top five abundant species between estrus and non-estrus at the phylum level. However, the vaginal microbiome changed significantly during estrus at the genus level. In top 10 genera, the abundance of Escherichia, Streptococcus, and Bacteroides in the E group was significantly higher than that in the NE group (p<0.05); Azomonas, Porphyromonas, Prevotella, Campylobacter, and Peptoniphilus in the NE group was significantly higher than that in the E group (p<0.05). The richness and diversity of vaginal microbiome in giant panda on estrus were significantly lower than those on non-estrus (p<0.05). It is noteworthy that the abundance of Streptococcus, Escherichia, and Bacteroides of vagina in giant pandas maintained low abundance in the daily. Whereas, they increased significantly during estrus period, which may play an important role in female giant pandas during estrus period. It was hypothesized that hormones may be responsible for the changes in the vaginal microbiome of giant pandas between estrus and no-estrus stages.

Immunological responses and evaluation of the protection in dairy cows vaccinated with staphylococcal surface proteins

Bovine mastitis is a significant cause of economic losses in the dairy industry. Staphylococcus aureus is one of the most common contagious mastitis pathogens, whereas Staphylococcus chromogenes increasingly became a significant cause of subclinical mastitis in dairy cows. Current mastitis control measures are not effective on all mastitis pathogens. There is no effective vaccine to control Staphylococcal mastitis in dairy cows. The objective of this study was to evaluate the immune responses and protection in dairy cows vaccinated with S. aureus surface proteins (SASP) or S. chromogenes surface proteins (SCSP). We divided eighteen Holstein dairy cows randomly into three groups of 6 animals each. We vaccinated group 1 and 2 animals with SASP and SCSP with Emulsigen-D adjuvant, respectively. We injected control (group 3) animals with PBS (pH 7.2) in Emulsigen®-D. We vaccinated animals three times at 28 and 14 days before drying off, and at dry off. Two weeks after the third vaccination, we challenged each animal by dipping all teats in S. aureus culture suspension once daily for 14 consecutive days. We evaluated milk or mammary secretion and serum antibody titers during vaccination and challenge periods. We evaluated milk samples for the number of bacteria shedding and somatic cell counts (SCC). Out of six cows vaccinated with SASP, one cow was removed from the study due to injury, two were infected clinically, another two were infected subclinically, and the remaining cow was not infected. No SCSP vaccinated cows developed clinical or subclinical mastitis. Out of six control cows, two developed clinical mastitis whereas four were infected subclinically. The SCSP vaccine cross-protected against S. aureus mastitis and reduced number of S. aureus shedding in milk. We concluded that the SCSP is a promising vaccine to control Staphylococcal mastitis in dairy cows.

Oral administration of Lactobacillus plantarum attenuates inflammatory damage in mice challenged with two pathogens

This study aimed to determine the immunomodulatory effect of Lactobacillus plantarum on Salmonella typhimurium and Staphylococcus aureus infection. A mouse inflammation model was established using S. aureus and S. typhimurium. The infected mice were treated with low, medium, and high doses (2 × 108, 4 × 108, and 8 × 108 colony forming units (CFU)/mL, respectively) of three antibacterial L. plantarum strains. The body weight changes, spleen and thymus indexes, cytokines (interleukin (IL)-4 and interferon (IFN)-γ), and secreted immunoglobulin A levels were measured. Compared with the model group, all the L. plantarum-treated groups show increased body weight, reduced spleen swelling, decreased IFN-γ content, significantly increased IL-4 content, and significantly decreased ratio of IFN-γ to IL-4. sIgA levels increased at the end of the experiment. The three L. plantarum strains can effectively attenuate the symptoms of S. typhimurium and S. aureus infection by regulating the Th1/Th2 response and enhancing sIgA secretion.

The effect of immune modulation of Streptococcus constellatus SC10 strain upon Acinetobactor baumannii infection

Acinetobacter baumannii is a tiny, plump and rod-shaped Gram-negative coccobacillus, notorious as an opportunistic pathogen, which is now being considered by CDC as a serious public health threat. Preventing colonization may be a better therapeutic choice using microbiota to protect against A. baumannii transmission. Human microbiota not only regulates immune homeostasis as well provides essential health benefits therefore discovering the interface due microbiota in host immune system will allow to recognise novel immuno- or microbe-based therapies. Streptococcus constellatus frequently isolated from oral cavity was selected for this study to check if its guards against A. baumannii by improving the immune response and the immune signalling pathway. In a mouse model we explored various parameters which include mouse body weight, internal organ weight, level of sIgA and different cytokine changes to evaluate its prophylactic effect against A. baumannii. Administration of S. constellatus SC10 was able to control the weight lose induced by A. bumannii infection in both the protected and treated groups. Particularly resistant against infection was more in treated group where the different cytokine following administration of SC10 strain remarkably controlled the infection and induced more sIgA production. The level of different interleukins IL-4, IL-10, IL-12 and IFN-γ was suppressed in treatment and protected group after exposure of S. constellatus. The excretion of sIgA following infection was many folds high in both group treated and protected groups Study suggests that SC10 L16 have potential immunomodulating effect which is able to regulate cytokines and sIgA response at the early phase of infection and modulate the further progress of clinical symptoms during infection.