Antagonistic Effects of Conjugated Linoleic Acids of Lactobacillus casei against Foodborne Enterohemorrhagic Escherichia coli

Abstract

Probiotics in fermented foods or commercially available supplements benefit the host by providing metabolites and peptides. The production of these metabolites varies with the available substrates or prebiotics present in the system and their concentration. In this study, 0.5% peanut flour (PF) was used to stimulate the growth and production of metabolites of wild-type Lactobacillus casei (LCwt) and compare with an engineered L. casei (LCCLA) capable of converting a higher amount of conjugated linoleic acid (CLA). The total extracellular metabolites present in the cell-free cultural supernatant (CFCS) of LCwt (without peanut), LCwt+PF (with peanut), and LCCLA were collected after 24 and 48 h of incubation, and their antagonistic activities against enterohemorrhagic Escherichia coli (EHEC EDL933) growth and pathogenesis were evaluated. All collected metabolites exhibited varying efficiency in restraining EHEC EDL933 growth, whereas supplementing a low concentration of CLA to the 48-h CFCS from LCwt showed augmented antagonism toward EHEC EDL933. A downregulation of key virulence genes was observed from metabolites collected at the 48-h time point. These observations indicate that the presence of metabolites in CFCSs—including CLA, which is produced by Lactobacillus and was identified by gas chromatography–mass spectrometry—plays a critical role. This study demonstrates the potential applicability of Lactobacillus-originated CLA in the prevention of EHEC EDL933–mediated illnesses. HIGHLIGHTS

Combined effect of metabolites produced by a modified Lactobacillus casei and berry phenolic extract on Campylobacter and microbiome in chicken cecum contents

“…CFCS of LC +mcra was found to be stable at a wide pH and temperature and was enriched in metabolites, including short chain fatty acids, poly unsaturated fatty acids, and polypeptides (Aditya et al., 2022; Peng et al., 2015, 2018). Multiple isomers of linoleic acids (LAs), which are short chain fatty acid, were found in abundance within the CFCSs of LC +mcra as bioactive compound when analyzed by GC‐mass spectrometry (Aditya et al., 2020, 2022; Peng et al., 2018, 2019). The mixtures of the LA isomers, often named CLA from CFCS, were proven to be effective in anti‐pathogenic activity against enteric pathogens (Aditya et al., 2020, 2022; Peng et al., 2018, 2019).…”

“…Multiple isomers of linoleic acids (LAs), which are short chain fatty acid, were found in abundance within the CFCSs of LC +mcra as bioactive compound when analyzed by GC‐mass spectrometry (Aditya et al., 2020, 2022; Peng et al., 2018, 2019). The mixtures of the LA isomers, often named CLA from CFCS, were proven to be effective in anti‐pathogenic activity against enteric pathogens (Aditya et al., 2020, 2022; Peng et al., 2018, 2019). The prebiotic used in this study was combination of blackberry and blueberry phenolic extract at 1:1 (v/v) ratio was also previously investigated in multiple in vitro and in vivo studies.…”

“…In this study, we used the CFCSs from LC +mcra which was characterized previously for physicochemical properties to evaluate the stability and also analyzed for active metabolites. CFCS of LC +mcra was found to be stable at a wide pH and temperature and was enriched in metabolites, including short chain fatty acids, poly unsaturated fatty acids, and polypeptides (Aditya et al., 2022; Peng et al., 2015, 2018). Multiple isomers of linoleic acids (LAs), which are short chain fatty acid, were found in abundance within the CFCSs of LC +mcra as bioactive compound when analyzed by GC‐mass spectrometry (Aditya et al., 2020, 2022; Peng et al., 2018, 2019).…”