Mouafo Hippolyte T, Mbawala Augustin, Somashekar Devappa, Tchougang Hervé M, Harohally Nanishankar V, Ndjouenkeu Robert
Department of Food Sciences and Nutrition, National School of Agro-Industrial Sciences, University of Ngaoundéré, Ngaoundéré, Cameroon.
Centre for Food and Nutrition Research, Institute of Medical Research and Medicinal Plants Studies, Yaoundé, Cameroon.
Biotechnol Appl Biochem. 2021 Jun;68(3):585-596. doi: 10.1002/bab.1966. Epub 2020 Jun 25.
Biosurfactants are microbial surface-active compounds with antimicrobial and antioxidant activities that display a range of physiological functions. In this study, a strain isolated from a Cameroonian fermented milk "pendidam" and identified as Lactobacillus casei subsp. casei TM1B was used for biosurfactants production. The biosurfactants produced by L. casei TM1B with molasses as the substrate had a good surface (40.77 mN/m) and emulsifying (84.50%) activities. The scavenging of the ABTS radical (IC value of 0.60 ± 0.03 mg/mL) by the biosurfactants was found to be higher than that of DPPH radical (IC value of 0.97 ± 0.13 mg/mL). The maximum chelating activity of biosurfactants (82.29%) was observed at 3.5 mg/mL. The biologically active compound of the biosurfactants produced by L. casei TM1B was identified as 2,5-O-methylrhamnofuranosyl-palmitate, a novel rhamnolipid-like biosurfactant by using chemical, Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and NMR analysis. The biosurfactants were bactericidal against several Gram-negative and Gram-positive pathogens (minimum inhibitory concentration values ranged from 3.22 to 12.83 mg/mL), and scanning electron microscope analysis revealed bacterial cell walls and membranes as main targets.
生物表面活性剂是具有抗菌和抗氧化活性的微生物表面活性化合物，具有一系列生理功能。在本研究中，从喀麦隆发酵乳“pendidam”中分离出的一株菌株，经鉴定为干酪乳杆菌干酪亚种TM1B，用于生产生物表面活性剂。以糖蜜为底物，干酪乳杆菌TM1B产生的生物表面活性剂具有良好的表面活性（40.77 mN/m）和乳化活性（84.50%）。发现该生物表面活性剂对ABTS自由基的清除能力（IC值为0.60±0.03 mg/mL）高于对DPPH自由基的清除能力（IC值为0.97±0.13 mg/mL）。在3.5 mg/mL时观察到生物表面活性剂的最大螯合活性为82.29%。通过化学、傅里叶变换红外光谱、气相色谱-质谱和核磁共振分析，将干酪乳杆菌TM1B产生的生物表面活性剂的生物活性化合物鉴定为2,5-O-甲基鼠李糖呋喃基-棕榈酸酯，一种新型鼠李糖脂样生物表面活性剂。该生物表面活性剂对几种革兰氏阴性和革兰氏阳性病原体具有杀菌作用（最低抑菌浓度值范围为3.22至12.83 mg/mL），扫描电子显微镜分析表明细菌细胞壁和细胞膜是主要靶点。
