Ibrahim Ibrahim M, Fedonenko Yuliya P, Sigida Elena N, Kokoulin Maxim S, Grinev Vyacheslav S, Mokrushin Ivan G, Burygin Gennady L, Zakharevich Andrey M, Shirokov Alexander A, Konnova Svetlana A
Department of Agricultural Microbiology, Faculty of Agriculture, Fayoum University, Fayoum, 63514, Egypt.
Chernyshevsky Saratov State University, 83 Ulitsa Astrakhanskaya, Saratov, 410012, Russia.
Extremophiles. 2023 Jan 30;27(1):4. doi: 10.1007/s00792-023-01289-0.
A strain, 3EQS1, was isolated from a salt sample taken from Lake Qarun (Fayoum Province, Egypt). On the basis of physiological, biochemical, and phylogenetic analyses, the strain was classified as Chromohalobacter salexigens. By 72 h of growth at 25 °C, strain 3EQS1 produced large amounts (15.1 g L) of exopolysaccharide (EPS) in a liquid mineral medium (initial pH 8.0) containing 10% sucrose and 10% NaCl. The EPS was precipitated from the cell-free culture medium with chilled ethanol and was purified by gel-permeation and anion-exchange chromatography. The molecular mass of the EPS was 0.9 × 10 Da. Chemical analyses, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy showed that the EPS was a linear β-D-(2 → 6)-linked fructan (levan). In aqueous solution, the EPS tended to form supramolecular aggregates with a critical aggregation concentration of 240 µg mL. The EPS had high emulsifying activity (E, %) against kerosene (31.2 ± 0.4%), sunflower oil (76.9 ± 1.3%), and crude oil (98.9 ± 0.8%), and it also had surfactant properties. A 0.1% (w/v) aqueous EPS solution reduced the surface tension of water by 11.9%. The levan of C. salexigens 3EQS1 may be useful in various biotechnological processes.
从取自卡伦湖（埃及法尤姆省）的盐样中分离出了一株菌株，3EQS1。基于生理、生化和系统发育分析，该菌株被归类为嗜盐嗜铬菌。在25℃下生长72小时后，菌株3EQS1在含有10%蔗糖和10%氯化钠的液体矿物培养基（初始pH 8.0）中产生了大量（15.1 g/L）的胞外多糖（EPS）。EPS通过用冷乙醇从无细胞培养基中沉淀出来，并通过凝胶渗透和阴离子交换色谱法进行纯化。EPS的分子量为0.9×10 Da。化学分析、傅里叶变换红外光谱和核磁共振光谱表明，EPS是一种线性的β-D-(2→6)-连接的果聚糖（左聚糖）。在水溶液中，EPS倾向于形成超分子聚集体，临界聚集浓度为240 μg/mL。EPS对煤油（31.2±0.4%）、向日葵油（76.9±1.3%）和原油（98.9±0.8%）具有高乳化活性（E，%），并且还具有表面活性剂特性。0.1%（w/v）的EPS水溶液使水的表面张力降低了11.9%。嗜盐嗜铬菌3EQS1的左聚糖可能在各种生物技术过程中有用。
