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Engineering sucrose metabolism in Pseudomonas putida highlights the importance of porins.
Microbial Biotechnology ( IF 4.8 ) Pub Date : 2018-05-28 , DOI: 10.1111/1751-7915.13283
Hannes Löwe 1 , Peter Sinner 1 , Andreas Kremling 1 , Katharina Pflüger-Grau 1
Affiliation  

Using agricultural wastes as a substrate for biotechnological processes is of great interest in industrial biotechnology. A prerequisite for using these wastes is the ability of the industrially relevant microorganisms to metabolize the sugars present therein. Therefore, many metabolic engineering approaches are directed towards widening the substrate spectrum of the workhorses of industrial biotechnology like Escherichia coli, yeast or Pseudomonas putida. For instance, neither xylose or arabinose from cellulosic residues, nor sucrose, the main sugar in waste molasses, can be metabolized by most E. coli and P. putida wild types. We evaluated a new, so far uncharacterized gene cluster for sucrose metabolism from Pseudomonas protegens Pf‐5 and showed that it enables P. putida to grow on sucrose as the sole carbon and energy source. Even when integrated into the genome of P. putida, the resulting strain grew on sucrose at rates similar to the rate of the wild type on glucose – making it the fastest growing, plasmid‐free P. putida strain known so far using sucrose as substrate. Next, we elucidated the role of the porin, an orthologue of the sucrose porin ScrY, in the gene cluster and found that in P. putida, a porin is needed for sucrose transport across the outer membrane. Consequently, native porins were not sufficient to allow unlimited growth on sucrose. Therefore, we concluded that the outer membrane can be a considerable barrier for substrate transport, depending on strain, genotype and culture conditions, all of which should be taken into account in metabolic engineering approaches. We additionally showed the potential of the engineered P. putida strains by growing them on molasses with efficiencies twice as high as obtained with the wild‐type P. putida. This can be seen as a further step towards the production of low‐value chemicals and biofuels with P. putida from alternative and more affordable substrates in the future.

中文翻译:

恶臭假单胞菌中的工程蔗糖代谢突出了孔蛋白的重要性。

在工业生物技术中,使用农业废弃物作为生物技术过程的基质非常重要。使用这些废物的先决条件是工业相关微生物代谢其中存在的糖的能力。因此,许多代谢工程学方法旨在扩大工业生物技术如大肠杆菌,酵母菌或恶臭假单胞菌(Pseudomonas putida)的底物谱。例如,纤维素残渣中的木糖或阿拉伯糖,或废糖蜜中的主要糖蔗糖都不能被大多数大肠杆菌恶臭假单胞菌的野生型代谢。我们评估了迄今为止尚未鉴定的蔗糖代谢的新特性基因簇假单胞菌可产生Pf-5,并表明它可使恶臭假单胞菌以蔗糖为唯一碳和能源生长。即使将其整合到恶臭假单胞菌的基因组中,所得菌株在蔗糖上的生长速率也与野生型葡萄糖的生长速率相似,从而使其成为迄今为止已知的以蔗糖为底物的生长最快,无质粒的恶臭假单胞菌菌株。 。接下来,我们阐明了孔蛋白(蔗糖孔蛋白ScrY的直向同源物)在基因簇中的作用,并发现在恶臭假单胞菌中,需要一种孔蛋白来使蔗糖穿过外膜运输。因此,天然孔蛋白不足以使蔗糖无限生长。因此,我们得出结论,根据菌株,基因型和培养条件,外膜可能是基质运输的重要障碍,在代谢工程方法中应考虑所有这些因素。我们还通过在糖蜜中生长经过改造的恶臭假单胞菌菌株,显示了其潜力,其效率是野生型恶臭假单胞菌的两倍。 这可以看作是未来使用替代和价格更可承受的底物,利用恶臭假单胞菌生产低价值化学品和生物燃料的又一步。
更新日期:2018-05-28
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