Microbial biofilms: New catalysts for maximizing productivity of long-term biotransformations
Microbial biofilms: New catalysts for maximizing productivity of long-term biotransformations
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DOI：
10.1002/bit.21547
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发表时间：
2007-12-15
影响因子：
3.8
通讯作者：
Schmid, Andreas
中科院分区：
文献类型：
--
作者：
Gross, Rainer;Hauer, Bernhard;Schmid, Andreas
由于生物催化剂的不稳定，生物催化反应的性能常常受到产物和/或底物毒性以及短期反应时间的限制。生物膜中的微生物对杀菌剂表现出显著的抗性，并形成稳定的群落。在自然界中，特别是在以严重污染场地等恶劣条件为特征的环境中，细胞主要在生物膜中生长，这使它们能够应对生理压力。这种稳健性被用来设计一种基于催化生物膜的生物工艺概念，用于有毒反应物的长期稳定转化。已经对69株细菌进行了筛选，以找到适合生物膜生物转化的微生物。这包括对重组酶表达重要的宿主菌株和从生物过滤器或受污染土壤中分离的菌株。几乎所有具有生物修复潜力的生物都表现出良好的生物被膜形成能力。假单胞菌属菌株VLB120 Delta C因其良好的生物被膜形成能力和对不对称环氧化的催化能力而被选为模式生物。以管式反应器为模型反应装置，研究了苯乙烯生物转化为(S)-环氧苯乙烷的反应过程。该工艺至少稳定55d，最大体积产率为16g/(L-AQ天)，收率为9摩尔%。原位产物抽提防止了催化剂对产物的抑制。对生物转化过程中生物膜的生理学和动力学进行了表征，并讨论了该反应概念的局限性和优点。
The performance of biocatalytic reactions is often hampered by product and/or substrate toxicity and short-term reaction times due to instable biocatalysts. Microbes in biofilms show a remarkable resistance against biocides and form stable communities. In nature, especially in environments characterized by harsh conditions such as heavily contaminated sites, cells grow pre-dominantly in biofilms, which enable them to cope with physiological stress. This robustness was utilized to design a bioprocess concept based on catalytic biofilms for stable long-term transformations of toxic reactants. Sixty-nine bacterial strains have been screened to find organisms suitable for biofilm-based biotransformations. This included host strains important for recombinant enzyme expression and strains isolated from biofilters or contaminated soils. Nearly all organisms with bioremediation potential showed good biofilm forming capacities. Pseudomonas sp. strain VLB120 Delta C was chosen as a model organism due to its excellent biofilm forming capacity and its well-studied capability of catalyzing asymmetric epoxidations. A tubular reactor was used for the biotransformation of styrene to (S)-styrene oxide as a model reaction. The process was stable for at least 55 days at a maximal volumetric productivity of 16 g/(L-aq day) and a yield of 9 mol%. In situ product extraction prevented product inhibition of the catalyst. Biofilm physiology and dynamics are characterized during the biotransformation and limitations and advantages of this reaction concept are discussed.