Biocatalysis in seawater: Investigating a halotolerant ω‐transaminase capable of converting furfural in a seawater reaction medium

Abstract

The increasing demand for freshwater and the continued depletion of available resources has led to a deepening global water crisis. Significant water consumption required by many biotechnological processes contributes to both the environmental and economic cost of this problem. Relatively few biocatalytic processes have been developed to utilize the more abundant supply of seawater, with seawater composition and salinity limiting its use with many mesophilic enzymes. We recently reported a salt tolerant ω‐transaminase enzyme, Ad2‐TAm, isolated from the genome of a halophilic bacterium, Halomonas sp. CSM‐2, from a Triassic period salt mine. In this study we aimed to demonstrate its applicability to biocatalytic reactions carried out in a seawater‐based medium. Ad2‐TAm was examined for its ability to aminate the industrially relevant substrate, furfural, in both seawater and freshwater‐based reaction systems. Furfural was aminated with 53.6% conversion in a buffered seawater system, displaying improved function versus freshwater. Ad2‐TAm outperformed the commonly employed commercial ω‐TAms from Chromobacterium violaceum and Vibrio fluvialis, both of which showed decreased conversion in seawater. Given the increasingly precarious availability of global freshwater, such applications of enzymes from halophiles have the ability to reduce demand for freshwater in large‐scale industrial processes, delivering considerable environmental and economic benefits.

Transaminases for industrial biocatalysis: novel enzyme discovery

“…CSM-2, a moderately halophilic bacterium isolated from a Triassic period salt mine. Ad2-TAm displayed no loss of function up to 1.5 M NaCl and organic solvent tolerance, as well as the ability to function in a seawater reaction medium (Kelly et al 2017(Kelly et al , 2019b.…”

Whole‐Cell Biocatalysis in Seawater: New Halotolerant Yeast Strains for the Regio‐ and Stereoselectivity Reduction of 1‐Phenylpropane‐1,2‐Dione in Saline‐Rich Media

“…However, the low solubility of hydrophobic substrates in water entails using large quantities of this liquid, which is another problem in industrial processes, and an important one to analyze and solve . Seawater has been proposed as a bio‐sustainable alternative to using freshwater . Seawater is a widely available inexpensive resource; in fact, 71 % of the Earth's surface is covered by oceans.…”

“…Seawater is a widely available inexpensive resource; in fact, 71 % of the Earth's surface is covered by oceans. Recent reports have demonstrated the possibility of using seawater as an alternative to freshwater in biocatalytic processes …”

Novel Routes in Transformation of Lignocellulosic Biomass to Furan Platform Chemicals: From Pretreatment to Enzyme Catalysis

“…In another study, a transaminase from Vibrio fluvialis was employed for the reduction amination of HMF with alanine as an amine donor, while an alanine dehydrogenase was added in order to shift the equilibrium [107]. A salt-tolerant ω-transaminase capable of catalyzing the amination of FA in salt water was studied [114]. The enzyme, produced by a halophilic bacterium Halomonas sp.…”