Growth, natural relationships, cellular fatty acids and metabolic adaptation of sulfate-reducing bacteria that utilize long-chain alkanes under anoxic conditions

详细信息    查看全文

• 作者：F. Aeckersberg ; F. A. Rainey and F. Widdel
• 关键词：Key words Anaerobic alkane oxidation ; Sulfate ; reducing bacteria ; Cyclodextrin ; Alkenes ; Fatty acids ; Alkane activation
• 刊名：Archives of Microbiology
• 出版年：1998
• 出版时间：September 1998
• 年：1998
• 卷：170
• 期：5
• 页码：361-369
• 全文大小：147 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Microbiology
  Microbial Ecology
  Biochemistry
  Cell Biology
  Biotechnology
  Ecology
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1432-072X

文摘

Natural relationships, improvement of anaerobic growth on hydrocarbons, and properties that may provide clues to an understanding of oxygen-independent alkane metabolism were studied with two mesophilic sulfate-reducing bacteria, strains Hxd3 and Pnd3. Strain Hxd3 had been formerly isolated from an oil tank; strain Pnd3 was isolated from marine sediment. Strains Hxd3 and Pnd3 grew under strictly anoxic conditions on n-alkanes in the range of C₁₂–C₂₀ and C₁₄–C₁₇, respectively, reducing sulfate to sulfide. Both strains shared 90% 16 S rRNA sequence similarity and clustered with classified species of completely oxidizing, sulfate-reducing bacteria within the δ-subclass of Proteobacteria. Anaerobic growth on alkanes was stimulated by α-cyclodextrin, which served as a non-degradable carrier for the hydrophobic substrate. Cells of strain Hxd3 grown on hydrocarbons and α-cyclodextrin were used to study the composition of cellular fatty acids and in vivo activities. When strain Hxd3 was grown on hexadecane (C₁₆H₃₄), cellular fatty acids with C-odd chains were dominant. Vice versa, cultures grown on heptadecane (C₁₇H₃₆) contained mainly fatty acids with C-even chains. In contrast, during growth on 1-alkenes or fatty acids, a C-even substrate yielded C-even fatty acids, and a C-odd substrate yielded C-odd fatty acids. These results suggest that anaerobic degradation of alkanes by strain Hxd3 does not occur via a desaturation to the corresponding 1-alkenes, a hypothetical reaction formerly discussed in the literature. Rather an alteration of the carbon chain by a C-odd carbon unit is likely to occur during activation; one hypothetical reaction is a terminal addition of a C₁ unit. In contrast, fatty acid analyses of strain Pnd3 after growth on alkanes did not indicate an alteration of the carbon chain by a C-odd carbon unit, suggesting that the initial reaction differed from that in strain Hxd3. When hexadecane-grown cells of strain Hxd3 were resuspended in medium with 1-hexadecene, an adaptation period of 2 days was observed. Also this result is not in favor of an anaerobic alkane degradation via the corresponding 1-alkene.