Production of a selective antibacterial fatty acid against Staphylococcus aureus by Bifidobacterium strains

Hiroshi Kikukawa; Toshihiro Nagao; Mitsuki Ota; Shigeo Takashima; Kohji Kitaguchi; Emiko Yanase; Sadatoshi Maeda; Kiyotaka Y Hara

doi:10.20517/mrr.2022.24

Production of a selective antibacterial fatty acid against Staphylococcus aureus by Bifidobacterium strains

Microbiome Res Rep. 2023 Feb 22;2(1):4. doi: 10.20517/mrr.2022.24. eCollection 2023.

Authors

Hiroshi Kikukawa^{1

2}, Toshihiro Nagao³, Mitsuki Ota⁴, Shigeo Takashima⁵, Kohji Kitaguchi⁶, Emiko Yanase⁶, Sadatoshi Maeda⁷, Kiyotaka Y Hara^{1

2}

Affiliations

¹ Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
² School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526, Japan.
³ Research Division of Biomaterials and Commodity Chemicals, Osaka Research Institute of Industrial Science and Technology, Osaka 536-8553, Japan.
⁴ Graduate School of Natural Science and Technology, Gifu University, Gifu 501-1193, Japan.
⁵ Institute for Glyco-core Research (iGCORE), Gifu University, Gifu 501-1193, Japan.
⁶ Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan.
⁷ The United Graduate School of Veterinary Sciences, Gifu University, Gifu 501-1193, Japan.

Abstract

Aims: C16 monounsaturated fatty acid (C16:1) show antibacterial activity against Staphylococcus aureus, a pathogen associated with various diseases such as atopic dermatitis and bacteremia, while the compound does not exhibit antibacterial activity against Staphylococcus epidermidis, an epidermal commensal that inhibits the growth of S. aureus. In this study, we aimed to find bifidobacterial strains with the ability to produce C16:1 and to find a practical manner to utilize C16:1-producing strains in industry. Methods: Various Bifidobacterium strains were screened for their content of C16:1. The chemical identity of C16:1 produced by a selected strain was analyzed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Medium components that affect the C16:1 content of the selected strain were investigated. Antibacterial activity against staphylococci was compared between the authentic C16:1 isomers and total fatty acids (TFA) extracted from the selected strain. Results: B. adolescentis 12451, B. adolescentis 12-111, B. boum JCM 1211, and Bifidobacterium sp. JCM 7042 showed high C16:1 content among the tested strains. TFA extracted from Bifidobacterium sp. JCM 7042 contained C16:1 at 2.3% as the fatty acid constituent (2.4 mg/L of broth). Through GC-MS and LC-MS analyses, the C16:1 synthesized by Bifidobacterium sp. JCM 7042 was identified as 7-cis-hexadecenoic acid (7-cis-C16:1). The authentic 7-cis-C16:1 showed strong and selective antibacterial activity against S. aureus, similar to 6-cis-C16:1, with a minimum inhibitory concentration (MIC) of < 10 µg/mL. Components that increase C16:1 productivity were not found in the MRS and TOS media; however, Tween 80 was shown to considerably reduce the C16:1 ratio in TFA. Antibacterial activity against S. aureus was observed when the TFA extracted from Bifidobacterium sp. JCM 7042 contained high level of 7-cis-C16:1 (6.1% in TFA) but not when it contained low level of 7-cis-C16:1 (0.1% in TFA). Conclusion: The fatty acid, 7-cis-C16:1, which can selectively inhibit the S. aureus growth, is accumulated in TFA of several bifidobacteria. The TFA extracted from cultured cells of Bifidobacterium sp. JCM 7042 demonstrated antibacterial activity. From a practical viewpoint, our findings are important for developing an efficient method to produce novel skin care cosmetics, functional dairy foods, and other commodities.

Keywords: Bifidobacterium; Staphylococcus aureus; Staphylococcus epidermidis; hexadecenoic acid; screening; selective antibacterial activity.