In vitro characterization of lactic acid bacterial strains isolated from fermented foods with anti-inflammatory and dipeptidyl peptidase-IV inhibition potential

Microbial dipeptidyl peptidases of the S9B family as host-microbe isozymes

Human dipeptidyl peptidase 4 (hDPP-4) has been a pharmacological target for metabolic diseases, particularly diabetes, since the early 2000s. As a ubiquitous enzyme found in both prokaryotic and eukaryotic organisms, hDPP-4 plays crucial roles in host homeostasis and disease progression. While many studies have explored hDPP-4's properties, research on gut microbially derived DPP-4 (mDPP-4) remains limited. This review discusses the significance of mDPP-4 and its health implications, analyzing crystal structures of mDPP-4 in comparison to human counterparts. We examine how hDPP-4 inhibitors could influence gut microbiome composition and mDPP-4 activity. Additionally, this review connects ongoing discussions regarding DPP-4 substrate specificity and potential access routes for mDPP-4, emphasizing the urgent need for further research on mDPP-4's role in health and improve the precision of DPP-4 inhibitor therapies.

GABA synthesizing lactic acid bacteria and genomic analysis of Levilactobacillus brevis LAB6

This study was conducted to investigate the γ-aminobutyric acid (GABA) production ability of 20 Lactobacillus and 25 Bifidobacterium strains which were previously isolated in our laboratory. Effect of initial pH, incubation time, monosodium glutamate (MSG), and pyridoxal-5'-phosphate (PLP) concentration for highest GABA production by two potent bacterial strains, Levilactobacillus brevis LAB6 and Limosilactobacillus fermentum LAB19 were optimized in the MRS media. A threefold increase in GABA production at an initial pH 4.0, incubation time of 120 h in medium supplemented with 3% MSG and 400 μM of PLP for LAB6 and 300 μM for LAB19 lead to the production of 19.67 ± 0.28 and 20.77 ± 0.14 g/L of GABA, respectively. Coculturing both strains under optimized conditions led to a GABA yield of 20.02 ± 0.17 g/L. Owing to potent anti-inflammatory activity in-vitro, as reported previously, and highest GABA production ability of LAB6 (MTCC 25662), its whole-genome sequencing and bioinformatics analysis was carried out for mining genes related to GABA metabolism. LAB6 harbored a complete glutamate decarboxylase (GAD) gene system comprising gadA, gadB, and gadC as well as genes responsible for the beneficial probiotic traits, such as for acid and bile tolerance and host adhesion. Comparative genomic analysis of LAB6 with 28 completely sequenced Levilactobacillus brevis strains revealed the presence of 95 strain-specific genes-families that was significantly higher than most other L. brevis strains.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03918-7.

Anti-inflammatory effects of a naturally lacto-fermented cucumber product on RAW 264.7 macrophages in association with increased functional ingredients

A naturally lacto-fermented cucumber product was developed for use as anti-inflammatory functional foods. To explore the anti-inflammatory characteristics, water (CWE) and ethanol extracts (CEE) from this product were selected to assess their anti-inflammatory potential on RAW 264.7 macrophages in the absence or presence of lipopolysaccharide (LPS), using four different inflammatory models. Changes in pro- (IL-1β, IL-6 and TNF-α) and anti-inflammatory (IL-10) cytokine secretions by treated macrophages were measured using ELISA. The results showed that both CWE and CEE had strong potential to inhibit LPS-stimulated inflammation in macrophages in a repair manner. CWE had a better effect than CEE. The total phenolic, flavonoid and saponin contents in CEE were significantly (P < 0.05) correlated with IL-10 (r = 0.384, P = 0.036*) and TNF-α (r = 0.371, P = 0.043*) levels, but slightly correlated with TNF-α/IL-10 secretion ratios (r = -0.184, P = 0.359) by treated RAW 264.7 cells, respectively.