Immobilization of Enterobacter aerogenes by a Trimeric Autotransporter Adhesin, AtaA, and Its Application to Biohydrogen Production

Abstract

Biological hydrogen production by microbial cells has been extensively researched as an energy-efficient and environmentally-friendly process. In this study, we propose a fast, easy method for immobilizing Enterobacter aerogenes by expressing ataA, which encodes the adhesive protein of Acinetobacter sp. Tol 5. AtaA protein on the E. aerogenes cells carrying the ataA gene was demonstrated by immunoblotting and flow cytometry. The AtaA-producing cells exhibited stronger adherence and auto-agglutination characteristics than wild-type cells, and were successfully immobilized (at approximately 2.5 mg/cm 3 ) on polyurethane foam. Hydrogen production from the cell-immobilized polyurethane foams was monitored in repetitive batch reactions and flow reactor studies. The total hydrogen production in triple-repetitive batch reactions reached 0.6 mol/mol glucose, and the hydrogen production rate in the flow reactor was 42 mL·h −1 ·L −1 . The AtaA production achieved simple and immediate immobilization of E. aerogenes on the foam, enabling repetitive and continuous hydrogen production. This report newly demonstrates the production of AtaA on the cell surfaces of bacterial genera other than Acinetobacter, and can simplify and accelerate the immobilization of whole-cell catalysts.

Single-Cell Adhesion Force Mapping of a Highly Sticky Bacterium in Liquid

“…The adhesiveness of AtaA can be conferred to other non-adhesive bacteria by heterologous expression of the ataA gene [16,21,38,39]. We have developed a new cell immobilization method using AtaA and have demonstrated its effectiveness in microbial green production processes [38][39][40][41].…”

“…The adhesiveness of AtaA can be conferred to other non-adhesive bacteria by heterologous expression of the ataA gene [16,21,38,39]. We have developed a new cell immobilization method using AtaA and have demonstrated its effectiveness in microbial green production processes [38][39][40][41]. Furthermore, cells immobilized with AtaA can be detached using liquids that inhibit cell adhesion, that is, washing with DW or the addition of casamino acids, and the detached cells can be re-immobilized in a salt medium or in a buffer solution [21,22].…”

A Review of the Enhancement of Bio-Hydrogen Generation by Chemicals Addition

“…Apart from the immobilization approach, the conditions of operation are also found to be effective in enhancing BHP. For example, the hydrogen production yield was higher in continuous BHP, compared with the batch operation [129,131]. This is possibly due to the effective removal of inhibitory metabolic intermediates, which creates a favorable chemical environment for hydrogenase to catalyze the hydrogen formation reaction [132,133].…”

Functional Autodisplay of Phenolic Acid Decarboxylase using a GDSL Autotransporter on Escherichia coli for Efficient Catalysis of 4-Hydroxycinnamic Acids to Vinylphenol Derivatives

“…So, neither substrate nor product needs to be internalized or excreted through the cell membrane; therefore, cytotoxicity of the end product to the cell is alleviated, and biocatalysis is favored [16]. These systems have a wide range of biotechnological applications in many areas such as whole-cell biocatalysis for bioconversion, biosensing, biosorption, and immobilization [17][18][19][20][21][22][23]. The GDSL autotransporter is a distinctive autotransporter that consists of a lipolytic enzyme of the GDSL family of lipases or esterases as a passenger domain at the N-terminus and a β-barrel domain at C-terminus, which is necessary for secretion of the passenger protein to the outer membrane [24].…”