Characterization of a biofilm membrane reactor and its prospects for fine chemical synthesis

Abstract

Biofilms are known to be robust biocatalysts. Conventionally, they have been mainly applied for wastewater treatment, however recent reports about their employment for chemical synthesis are increasingly attracting attention. Engineered Pseudomonas sp. strain VLB120DC biofilm growing in a tubular membrane reactor was utilized for the continuous production of (S)-styrene oxide. A biofilm specific morphotype appeared in the effluent during cultivation, accounting for 60-80% of the total biofilm irrespective of inoculation conditions but with similar specific activities as the original morphotype. Mass transfer of the substrate styrene and the product styrene oxide was found to be dependent on the flow rate but was not limiting the epoxidation rate. Oxygen was identified as one of the main parameters influencing the biotransformation rate. Productivity was linearly dependent on the specific membrane area and on the tube wall thickness. On average volumetric productivities of 24 g L À1 aq day À1 with a maximum of 70 g L À1 aq day À1 and biomass concentrations of 45 g BDW L À1 aq have been achieved over long continuous process periods (!50 days) without reactor downtimes.

Real-Time Solvent Tolerance Analysis ofPseudomonassp. Strain VLB120ΔC Catalytic Biofilms

“…These results were similar to those of earlier studies conducted in other biofilm reactor formats for styrene oxide synthesis, such as tubular, solid support membrane aerated reactors. These experiments also showed that the styrene oxide formation rate increased concomitantly with the biofilm biomass and was not hampered by either substrate or product (10,11).…”

“…than their planktonic or freely swimming counterparts (7,9,16,19,29,40). There has been growing interest in recent years in the exploitation of these robust catalysts for biotechnological applications (e.g., biotransformations) to produce value-added chemicals (10,11,12,27). These studies have shown that the use of biofilms may overcome major bottlenecks in classical biocatalysis processes, such as substrate/product toxicity and short-term biocatalytic stability.…”

“…In previous studies, it has been shown that Pseudomonas sp. strain VLB120⌬C biofilms are promising catalysts for the long-term conversions of the toxic substrate styrene to (S)-styrene oxide in a continuous process (10,11,12). However, biofilm cellular integrity, spatial distributions of live and dead cells, inactivation, adaptation, and enhanced solvent tolerance mechanisms have not been studied, characterized, or elucidated so far.…”

“…strain VLB120⌬C, a promising catalyst for the synthesis of (S)-styrene oxide. This strain has been studied extensively in conventional stirred-tank reactors (31) and also has been used in novel biofilm reactors (10,11,12). To address the question of how catalytic biofilms adapt to toxic environments and to explore its ability as an alternative biocatalyst to its planktonic counterparts, this study presents a time-resolved, noninvasive, quantitative approach to investigate biofilm development and its response to the toxic solvent styrene.…”

Outer Membrane Protein AlkL Boosts Biocatalytic Oxyfunctionalization of Hydrophobic Substrates in Escherichia coli

“…Glucose and organic acid concentrations in the aqueous phase were determined by high-performance liquid chromatography (HPLC) as described before (23).…”