Hvidsten Ina, Mjøs Svein Are, Holmelid Bjarte, Bødtker Gunhild, Barth Tanja
Department of Chemistry, University of Bergen, Allégaten 41, 5007 Bergen, Norway.
Department of Chemistry, University of Bergen, Allégaten 41, 5007 Bergen, Norway.
Chem Phys Lipids. 2017 Nov;208:19-30. doi: 10.1016/j.chemphyslip.2017.08.006. Epub 2017 Sep 1.
Dietzia sp. A14101 belonging to the genus Dietzia (Gram-positive bacteria, Actinomycetes, high G+C content of DNA) was isolated from an oil reservoir model column inoculated with oil-field bacteria (Bødtker et al., 2009). Low interfacial tension (IFT) values were obtained by studying intact strain cells grown on water-immiscible hydrocarbons (HC) (Kowalewski et al. (2004), Kowalewski et al. (2005). Further investigations showed that the adaptation mechanism of Dietzia sp. A14101 to toxic water-immiscible HC involved changes both on the level of fatty acids content and in the physical properties of the cellular surface (development of the negative cellular surface charge and an increased in hydrophobicity) (Hvidsten et al., 2015b). However, these changes could not explain the low IFT values observed in earlier studies of this strain. Generally, low IFT imply a production of surface active compounds of low MW that are lipids by structure (Rosenberg and Ron, 1999). In this paper, it is shown that Dietzia sp. A14101 produces a range of glycolipids on all substrates. The amount of trehalose-containing lipids increases when the strain is grown on hydrocarbons. The production peak seems to coincide with the exponential growth phase, and such increased glycolipid synthesis continues throughout the stationary phase. The results indicate that only low amounts of the hydrocarbon substrate is incorporated directly into the glycolipids produced. Most of the hydrocarbon substrate seems to be employed for the biosynthesis of the neutral lipids and higher amounts of biomass were generated on HC substrates compared to incubations on non-HC substrates. The lipid content of the cell was determined as the total lipid extract (TLE), and was further fractionated (SPE). The hydrophobic and hydrophilic moieties of the isolated surface active compounds were determined (GC-MS, TLC, DART, LC-MS). The changes in the lipid content during the culture development were monitored by 1D and 2D TLC, emulsification and oil-spreading tests.
Dietzia属的Dietzia sp. A14101（革兰氏阳性菌，放线菌，DNA的G+C含量高）是从接种了油田细菌的油藏模型柱中分离得到的（Bødtker等人，2009年）。通过研究在与水不混溶的碳氢化合物（HC）上生长的完整菌株细胞，获得了低界面张力（IFT）值（Kowalewski等人，2004年；Kowalewski等人，2005年）。进一步的研究表明，Dietzia sp. A14101对有毒的与水不混溶的HC的适应机制涉及脂肪酸含量水平和细胞表面物理性质的变化（细胞表面负电荷的产生和疏水性的增加）（Hvidsten等人，2015b）。然而，这些变化无法解释在该菌株早期研究中观察到的低IFT值。一般来说，低IFT意味着产生了结构上为脂质的低分子量表面活性化合物（Rosenberg和Ron，1999年）。本文表明，Dietzia sp. A14101在所有底物上都能产生一系列糖脂。当该菌株在碳氢化合物上生长时，含海藻糖的脂质数量会增加。产量峰值似乎与指数生长期一致，并且这种糖脂合成的增加在整个稳定期都会持续。结果表明，只有少量的碳氢化合物底物直接掺入所产生的糖脂中。大多数碳氢化合物底物似乎用于中性脂质的生物合成，与在非HC底物上培养相比，在HC底物上产生了更多的生物量。细胞的脂质含量被测定为总脂质提取物（TLE），并进一步进行了分馏（SPE）。测定了分离出的表面活性化合物的疏水和亲水部分（GC-MS、TLC、DART、LC-MS）。通过一维和二维TLC、乳化和铺油试验监测了培养过程中脂质含量的变化。
