Biofilm bioreactor
CA3172356A1
Abstract
Described herein are biofilm bioreactors for synthesis at the interface between two liquids, and methods of using such bioreactors for the biotransformation of feedstocks into chemical products. Also contemplated is the extraction of such products.
Description (excerpt)
TITLE Biofilm Bioreactor CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This Application claims the benefit of U.S. Provisional Application 62/978,428 filed on February 19, 2020, the entirety of which is incorporated herein by reference. FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT [0002] The United States Government has certain ownership rights in this invention. Licensing inquiries may be directed to Office of Technology Transfer, US Naval Research Laboratory, Code 1004, Washington, DC 20375, USA; +1.202.767.7230; techtran@nrl.navy.mil, referencing NC 112,479. BACKGROUND [0003] Fermentation and algae bioreactors are used to produce bioethanol, biodiesel and other products. In industrial scale biomanufacturing, typically a product is produced in a suspended cell reactor during so-called log-scale growth where biomass is undergoing periodic doublings. To extract the final product, downstream processing such as distillation or dehydration followed by solvent phase extraction can be required. [0004] Biofilm bioreactors are a type of bioreactor that uses cells that are immobilized on a solid scaffold for the synthesis of a product. A variety of biofilm bioreactors have been developed for different applications, particularly for wastewater treatment. These include packed bed reactors (Holliday et al., 1978), which use a granular matrix packed within a column as a scaffold; two-phase partitioning bioreactors (Daugulis et al., 1997), wherein a non-aqueous phase is added to a microorganism-containing aqueous phase to facilitate the continual and gradual transfer of hydrophobic substrates into the aqueous phase; and extractive membrane bioreactors (Livingston, 1998), where a membrane separates an aerated biomedium and a feedstock (typically wastewater). Volatile organic compounds diffuse across the membrane and are degraded by a biofilm growing on the biomedium side of the reactor. [0005] Biofilm bioreactors have utilized naturally-forming consortia of organisms and been applied for applications such as the removal of toxic materials from wastewater, or the production of products from gaseous sources such as carbon monoxide. [0006] Hydrocarbonoclastic organisms such as Marinobacter spp. form biofilms and are able to uptake alkanes and aromatics (Gauthier et al., 1992; Lattuati et al., 2002; Ennouri et al., 2017; Mournier et al., 2018, Arroyo et al., 2013) and convert them into products such as wax esters, which have commercial value as lubricants. Organisms capable of accumulating lipids such as wax esters are commonly referred to as oleaginous. Evidence of extracellular neutral lipids produced by Marinobacter spp. have been reported by Nakano et al., 2012. These pathways can also be diverted to produce other products such as phloroglucinol (Meyer et al., 2019). [0007] Additionally, organic solvents have been utilized as a means to periodically extract products from planktonically grown algae such as B. brunaii or D. sauna in a process termed milking (Hejazi et al, 2004; Jackson et al., 2018; Hejazi et al., 2005; Sayre, 2009). The milking approach enables the non-destructive removal of hydrocarbons from a bioreactor into a solvent phase, which can dramatically reduce required downstream processing. Several systems have been developed for product extraction from milking. One, a mixer-settler system, operates in a continuous single stage. In a mixing segment, solvent and the culture medium are stirred to provide contact between the solvent and cells. The solvent culture mixture then transfers into a settling segment where a top solvent phase containing the product, and a bottom aqueous phase containing the cell fraction are separated. A second system, the column extractor, passes droplets of organic solution through a media solution to extract product. In both cases, the cells are planktonic, cultured in a separate vessel, and periodically transferred into the extraction system for removal. [0008] The key challenges of biofilm-based processing include mass transfer limitations, control over biofilm formation, and challenges with product extraction. BRIEF SUMMARY [0009] In a first embodiment, a bioreactor includes a vessel comprising a solid support suitable for the growth of a biofilm; containment for a feedstock solution in contact with the biofilm; and a container for extraction solution configured to be delivered to the vessel containing the biofilm. The bioreactor is configured to host a biofilm-forming microorganism that is tolerant of both solutions and can carry out biotransformations. The feedstock provides a chemical source that can be biologically transformed into a desired product. The extraction solution, when in contact with the biofilm, enables the removal of the desired product. The biofilm-forming microorganism should be tolerant of both solutions and can carry out biotransformation of feedstock into the product. The microorganism preferably enjoys stable growth in the biofilm. The product can be extracted in a continuous or periodic (or batched) manner through exposure to the extraction solution. [0010] For example, a bioreactor system might include a column comprising a substrate coated with a biofilm comprising hydrocarbonoclastic and/or oleaginous organisms; a first reservoir operably connected to deliver to the column a first liquid comprising a feedstock; a second
Filing details
- Inventors
- Sarah Glaven
- Assignee
- The Government Of The United States Of America, As Represented By The Secretary …
- Filed
- Feb 18, 2021
- Granted
- Application pending
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