Botany and Microbiology Department, Faculty of Science, Alexandria University, Moharam Bek, Alexandria, 21511, Egypt.
Alexandria Company for Petroleum Additives (ACPA), Alexandria, Egypt.
Microb Cell Fact. 2023 Sep 7;22(1):176. doi: 10.1186/s12934-023-02186-z.
Bioemulsifiers are natural or microbial-based products with the ability to emulsify hydrophobic compounds in water. These compounds are biodegradable, eco-friendly, and find applications in various industries.
Thirteen yeasts were isolated from different sources in Alexandria, Egypt, and evaluated for their potential to produce intracellular bioemulsifiers. One yeast, isolated from a local market in Egypt, showed the highest emulsification index (EI) value. Through 26S rRNA sequencing, this yeast was identified as Saccharomyces cerevisiae strain MYN04. The growth kinetics of the isolate were studied, and after 36 h of incubation, the highest yield of cell dry weight (CDW) was obtained at 3.17 g/L, with an EI of 55.6%. Experimental designs were used to investigate the effects of culture parameters on maximizing bioemulsifier SC04 production and CDW. The study achieved a maximum EI of 79.0 ± 2.0%. Furthermore, the crude bioemulsifier was precipitated with 50% ethanol and purified using Sephadex G-75 gel filtration chromatography. Bioemulsifier SC04 was found to consist of 27.1% carbohydrates and 72.9% proteins. Structural determination of purified bioemulsifier SC04 was carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), high-performance liquid chromatography (HPLC), and nuclear magnetic resonance spectroscopy (NMR). FTIR spectroscopy revealed characteristic bands associated with carboxyl and hydroxyl groups of carbohydrates, as well as amine groups of proteins. HPLC analysis of monosaccharide composition detected the presence of mannose, galactose, and glucose. Physicochemical characterization of the fraction after gel filtration indicated that bioemulsifier SC04 is a high molecular weight protein-oligosaccharide complex. This bioemulsifier demonstrated stability at different pH values, temperatures, and salinities. At a concentration of 0.5 mg/mL, it exhibited 51.8% scavenging of DPPH radicals. Furthermore, in vitro cytotoxicity evaluation using the MTT assay revealed a noncytotoxic effect of SC04 against normal epithelial kidney cell lines.
This study presents a new eco-friendly bioemulsifier, named SC04, which exhibits significant emulsifying ability, antioxidant and anticancer properties, and stabilizing properties. These findings suggest that SC04 is a promising candidate for applications in the food, pharmaceutical, and industrial sectors.
生物乳化剂是具有将疏水性化合物乳化在水中的能力的天然或微生物基产品。这些化合物是可生物降解的、环保的，并且在各个行业中有应用。
从埃及亚历山大的不同来源分离出 13 株酵母，并评估其产生细胞内生物乳化剂的潜力。从埃及当地市场分离出的一株酵母表现出最高的乳化指数（EI）值。通过 26S rRNA 测序，该酵母被鉴定为酿酒酵母菌株 MYN04。研究了该分离株的生长动力学，在孵育 36 小时后，在 3.17 g/L 时获得最高的细胞干重（CDW）产量，EI 为 55.6%。使用实验设计来研究培养参数对最大程度地提高生物乳化剂 SC04 产量和 CDW 的影响。研究达到了 79.0±2.0%的最大 EI。此外，用 50%乙醇沉淀粗生物乳化剂，并使用 Sephadex G-75 凝胶过滤层析进行纯化。发现生物乳化剂 SC04 由 27.1%碳水化合物和 72.9%蛋白质组成。使用傅里叶变换红外光谱（FTIR）、扫描电子显微镜-能量色散 X 射线光谱（SEM-EDX）、高效液相色谱（HPLC）和核磁共振光谱（NMR）对纯化的生物乳化剂 SC04 进行结构测定。FTIR 光谱显示与碳水化合物的羧基和羟基以及蛋白质的胺基相关的特征带。单糖组成的 HPLC 分析检测到甘露糖、半乳糖和葡萄糖的存在。凝胶过滤后的理化特性表明，生物乳化剂 SC04 是一种高分子量的蛋白-寡糖复合物。该生物乳化剂在不同的 pH 值、温度和盐度下表现出稳定性。在 0.5mg/mL 浓度下，它对 DPPH 自由基的清除率达到 51.8%。此外，使用 MTT 测定法进行的体外细胞毒性评估表明，SC04 对正常上皮肾细胞系没有细胞毒性作用。
本研究提出了一种新的环保型生物乳化剂，命名为 SC04，它具有显著的乳化能力、抗氧化和抗癌特性以及稳定特性。这些发现表明，SC04 是食品、制药和工业领域应用的有前途的候选物。
