A Novel Lactobacillus casei LP1 Producing 1,4-Dihydroxy-2-Naphthoic Acid, a Bifidogenic Growth Stimulator

Abstract

1,4-Dihydroxy-2-naphthoic acid (DHNA) is a bifidogenic growth stimulator (BGS) and could be a functional food ingredient since bifidobacteria are beneficial for human health. For that reason, lactic acid bacteria producing DHNA have been screened. A lactic acid bacterium LP1 strain isolated from a natural cheese was confirmed to produce DHNA, analyzed by a HPLC method. The strain was identified as Lactobacillus casei by 16S rRNA gene sequence analysis. The cell-free supernatant of fermented whey produced by L. casei LP1 presented the BGS activity for three bifidobacterial strains such as Bifidobacterium longum subsp. infantis KCTC 3127, Bifidobacterium bifidum KCTC 3202, and Bifidobacterium breve KCTC 3220 which were human-originated. To the best of our knowledge, a L. casei strain which can produce DHNA was firstly identified in this study.

Keywords: 1,4-dihydroxy-2-naphthoic acid; Lactobacillus casei LP1; bifidogenic growth stimulator.

Fig. 1

Chromatogram of 1,4-dihydroxy-2-naphthoic acid in fermented whey with Lactobacillus casei LP1. (A) DHNA standard, (B) whey, and (C) fermented whey. The arrows indicate DHNA peaks. HPLC condition: column, Agilent HC-C18 (4.6×150 mm); column temperature, 45°C; flow rate, 1 mL/min; injection volume, 20 μL; detection wavelength, 254 nm; mobile phase, acetonitrile: methanol: water: acetic acid (15:25:225:0.1; pH 5.5).

Fig. 2

Bifidogenic growth stimulator activity of fermented whey with Lactobacillus casei LP1. (A) Bifidobacterium longum subsp. infantis KCTC 3127, (B) Bifidobacterium bifidum KCTC 3202, and (C) Bifidobacterium breve KCTC 3220. No addition, only bifidobacterial strain was inoculated into 1/10 RCM broth; Whey, bifidobacterial strain plus whey broth adjusted to pH 4.5 with lactic acid; Fermented whey, bifidobacterial strain plus fermented whey with L. casei LP1.