Maximizing the productivity of catalytic biofilms on solid supports in membrane aerated reactors

Abstract

A new solid support membrane aerated biofilm reactor was designed for the synthesis of enantiopure (S)-styrene oxide utilizing Pseudomonas sp. strain VLB120DeltaC growing in a biofilm as biocatalyst. In analogy to traditional packed bed systems, maximizing the volumetric oxygen mass transfer capability (k(L)a) was identified as the most critical issue enabling a consistent productivity, as this parameter was shown to directly influence biofilm growth and biotransformation performance. A microporous ceramic unit was identified as an ideal microenvironment for biofilm growth and for efficient oxygen transfer. A uniform and dense biofilm developed on this matrix. Due to this dual function, the reactor configuration could be significantly simplified by eliminating additional packing materials, as used in traditional packed bed reactors. Up to now, a maximum productivity of 28 g L(ab) (-1) day(-1) was achieved by integrating an in situ substrate feed and an in situ product recovery technique based on a silicone membrane. The system was stable for more than 30 days before it was actively terminated.

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

“…strain VLB120⌬C made it possible to directly monitor live cells in the biofilm. Biofilms were cultivated in a custommade flow-cell system, which allowed the real-time fluorescence-based optical analysis of cell physiology and the direct addition of the solvent styrene to the biofilm based on a diffusion-controlled substrate delivery mechanism using a permeable silicone membrane (12). A schematic view of the setup is shown in the figure in the supplemental material.…”

“…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.…”

Disruption of Putrescine Biosynthesis in Shewanella oneidensis Enhances Biofilm Cohesiveness and Performance in Cr(VI) Immobilization

“…However, controlling biofilm-based bioprocesses is very challenging because of the intrinsic heterogeneous and dynamic properties of biofilms (10,11). Previous studies have shown that either unfavorable environmental conditions (e.g., exposure to toxic contaminants) or variations in nutrient supply (e.g., dissolved O 2 availability) could cause cell dispersal from biofilms (12)(13)(14)(15), resulting in a decrease in the performance of the biofilm-based bioprocesses.…”