AUTHOR=Evivie Smith Etareri , Abdelazez Amro , Li Bailiang , Lu Shijia , Liu Fei , Huo Guicheng 

TITLE=Lactobacillus delbrueckii subsp. bulgaricus KLDS 1.0207 Exerts Antimicrobial and Cytotoxic Effects in vitro and Improves Blood Biochemical Parameters in vivo Against Notable Foodborne Pathogens

JOURNAL=Frontiers in Microbiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2020.583070

DOI=10.3389/fmicb.2020.583070

ISSN=1664-302X

ABSTRACT=<p>Globally, foodborne diseases (FBDs) result in millions of sicknesses and deaths annually. Cumulative evidence suggests that the use of probiotic lactic acid bacteria (LAB) strains could be a viable alternative in inhibiting the activities of foodborne pathogens. This study aims to evaluate the <italic>in vitro</italic> antimicrobial, cytotoxic, and tolerance levels of <italic>Lactobacillus bulgaricus</italic> KLDS 1.0207 against two notable foodborne pathogens – <italic>Escherichia coli</italic> ATCC25922 and <italic>Staphylococcus aureus</italic> ATCC25923. Afterward, a 48 BALB/c mice-trial was used to assess its ameliorative effects on weight and serum biochemical parameters. Results showed that the cell-free supernatant (CFS) of this strain significantly inhibited both pathogens, but these effects were abolished at pH 6.5 and 7.0 (<italic>P</italic> &lt; 0.05). Also, 6.96 ± 0.02 log CFU mL<sup>–1</sup> of <italic>L. bulgaricus</italic> KLDS 1.0207 was still viable after three hours in simulated gastric juice and at pH 3.0, indicating that this strain was a potential probiotic candidate. Also, inflammatory activities in RAW264.7 cells were significantly inhibited using 10<sup>9</sup> CFU mL<sup>–1</sup> of <italic>L. bulgaricus</italic> KLDS 1.0207 cells (<italic>P</italic> &lt; 0.05). Significant weight losses were also prevented in the T<sub><italic>LBSA</italic></sub> (from 19.42 ± 1.04 to 19.55 ± 0.55 g) and T<sub><italic>LBEC</italic></sub> (from 22.86 ± 0.90 to 14.77 ± 9.86 g) groups compared to their respective model groups (T<sub><italic>SA</italic></sub> – from 21.65 ± 1.80 to 20.14 ± 1.84, and T<sub><italic>EC</italic></sub> – from 21.45 ± 0.82 to 14.45 ± 9.70 g). Besides, there was a slight weight gain in the <italic>S. aureus</italic> prevention group (T<sub><italic>LBSA</italic></sub>) compared to the model group (T<sub><italic>SA</italic></sub>). Serum biochemical analyses revealed that the total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), and some mineral levels were markedly increased by <italic>S. aureus</italic> and <italic>E. coli</italic> administrations but were reversed to normalcy in both prevention groups (T<sub><italic>LBSA</italic></sub> and T<sub><italic>LBEC</italic></sub>). Interestingly, high-density lipoprotein (HDL) levels, which were initially disrupted in the model groups, were restored in the prevention groups (T<sub><italic>LBSA</italic></sub> and T<sub><italic>LBEC</italic></sub>). This study presents <italic>L. bulgaricus</italic> KLDS 1.0207 as a promising probiotic candidate with antimicrobial, anti-inflammatory, acid, and bile tolerant and lipid-regulating applications. It also gives valuable insights for targeted future <italic>in vivo</italic> treatment and prevention studies involving other probiotic LAB candidates. Future <italic>in vivo</italic> studies elucidating specific mechanisms behind the <italic>in vitro</italic> antimicrobial, cytotoxic, and <italic>in vivo</italic> ameliorative effects are warranted.</p>