Ayadi Houda, Frikha-Dammak Donyez, Fakhfakh Jawhar, Chamkha Mohamed, Hassairi Ilem, Allouche Noureddine, Sayadi Sami, Maalej Sami
Laboratoire de Biodiversité Marine et Environment (LR18ES/30), Université de Sfax, BP 1171, 3000 Sfax, Tunisia.
Laboratore de Chimie Organique (LR17ES/08), Unité des Substances Naturelles, Université de Sfax, BP 1171, 3000 Sfax, Tunisia.
3 Biotech. 2020 Dec;10(12):533. doi: 10.1007/s13205-020-02512-x. Epub 2020 Nov 13.
In the present study, the growth conditions and accumulation of ectoines (ectoine and hydroxyectoine) by DSM 102817 under salt stress conditions have been investigated. The productivity assay of this strain for ectoines revealed that the highest cellular content was reached in the minimal glucose sea water medium (SW-15) within 15% salinity. The addition of 0.1% (w/v) aspartic acid to the medium allowed an average of four times higher biomass production, and a dry mycelial biomass of 1.76 g L was obtained after 6 days of growth in shake flasks at 40 °C and 200 rpm. Among the inorganic cations supplemented to the glucose SW-15 medium, the addition of 1 mM Fe yielded the highest amount of mycelial biomass (3.45 g L) and total ectoines content (119 mg g), resulting in about 410 mg L of products at the end of exponential growth phase. After 1 h of incubation in an osmotic downshock solution containing 2% NaCl, 70% of this content was released by the mycelium, and recovering cells maintained a high survival, with a maximal growth rate ( ) of about 93% of the control population exposed to 15% NaCl. During growth at optimal salinity and temperature (15% NaCl and 40 °C), developed a compact and circular pellets that were easy to separate by simple decantation from both fermentation media and after hypoosmotic shock. Overall, the ectoines excreting could be a promising resource for ectoines production in a commercially valuable culture medium and at a large-scale fermentation process.
在本研究中,对DSM 102817在盐胁迫条件下的生长条件以及胞外菌素(四氢嘧啶和羟基四氢嘧啶)的积累情况进行了研究。该菌株对胞外菌素的生产力测定表明,在盐度为15%的最低葡萄糖海水培养基(SW - 15)中,细胞含量达到最高。向培养基中添加0.1%(w/v)的天冬氨酸可使生物量产量平均提高四倍,在40℃和200 rpm的摇瓶中培养6天后,获得了1.76 g/L的干菌丝体生物量。在添加到葡萄糖SW - 15培养基中的无机阳离子中,添加1 mM铁产生的菌丝体生物量最高(3.45 g/L),胞外菌素总含量最高(119 mg/g),在指数生长期结束时产生约410 mg/L的产物。在含有2% NaCl的渗透休克溶液中孵育1小时后,菌丝体释放出70%的该含量产物,复苏细胞保持高存活率,最大生长速率()约为暴露于15% NaCl的对照群体的93%。在最适盐度和温度(15% NaCl和40℃)下生长期间,形成了紧密的圆形颗粒,通过简单倾析法很容易从发酵培养基和低渗休克后分离出来。总体而言,分泌胞外菌素的菌株可能是在具有商业价值的培养基中大规模发酵生产胞外菌素的有前景的资源。