Understanding the physiological roles of polyhydroxybutyrate (PHB) in Rhodospirillum rubrum S1 under aerobic chemoheterotrophic conditions
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- 作者：Tanja Narancic ; Elisa Scollica ; Shane T. Kenny…
- 关键词：Rhodospirillum rubrum S1 ; Aerobic growth ; Polyhydroxybutyrate (PHB) ; Ribulose 1 ; 5 ; bisphosphate carboxylase (RuBisCO) ; Crotonyl ; CoA carboxylase/reductase ; Ethylmalonyl ; CoA pathway
- 刊名：Applied Microbiology and Biotechnology
- 出版年：2016
- 出版时间：October 2016
- 年：2016
- 卷：100
- 期：20
- 页码：8901-8912
- 全文大小：738 KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Chemistry
Biotechnology
Microbiology
Microbial Genetics and Genomics - 出版者：Springer Berlin / Heidelberg
- ISSN：1432-0614
- 卷排序：100
文摘
Polyhydroxybutyrate (PHB) is an important biopolymer accumulated by bacteria and associated with cell survival and stress response. Here, we make two surprising findings in the PHB-accumulating species Rhodospirillum rubrum S1. We first show that the presence of PHB promotes the increased assimilation of acetate preferentially into biomass rather than PHB. When R. rubrum is supplied with 13C-acetate as a PHB precursor, 83.5 % of the carbon in PHB comes from acetate. However, only 15 % of the acetate ends up in PHB with the remainder assimilated as bacterial biomass. The PHB-negative mutant of R. rubrum assimilates 2-fold less acetate into biomass compared to the wild-type strain. Acetate assimilation proceeds via the ethylmalonyl-CoA pathway with (R)-3-hydroxybutyrate as a common intermediate with the PHB pathway. Secondly, we show that R. rubrum cells accumulating PHB have reduced ribulose 1,5-bisphosphate carboxylase (RuBisCO) activity. RuBisCO activity reduces 5-fold over a 36-h period after the onset of PHB. In contrast, a PHB-negative mutant maintains the same level of RuBisCO activity over the growth period. Since RuBisCO controls the redox potential in R. rubrum, PHB likely replaces RuBisCO in this role. R. rubrum is the first bacterium found to express RuBisCO under aerobic chemoheterotrophic conditions.