Development of hydrogel microtubes for microbe culture in open environment

Abstract

This paper describes a microbe culture system in an open environment using hydrogel microtubes. In recent years, oil production microbes, such as Aurantiochytrium, have been found and are studied to produce fuels of new age instead of fossil fuels. Biomass production by microbes is promising, where scale-up, collection of the products and competition against other microbes are the most important challenges. Here, we propose to use hydrogel microtubes to encapsulate, culture, and protect microbes. The tubes can be micro- and mass-fabricated. They allow oxygen and nutrition to go through while they prevent competitive microbes from intruding inside. The microbes and byproducts can be collected together with the tubes. In this paper, we demonstrate the proof-of-concepts experiments: we fabricated hydrogel micro tubes and cultured Coryne glutamicum which produce lactic acid inside the tubes. The microbes were increased inside the tubes and protected even when competitive microbes existed in the culture media. Furthermore, we demonstrated how to collect microbes inside the tubes.

Microfluidic mass production system for hydrogel microtubes for microbial culture

“…Sodium alginate and calcium chloride were purchased from Wako Pure Chemical Industries, and isotonic sodium chloride solution was purchased from Otsuka Pharmaceutical Factory. On the basis of our previous research, 15) we prepared 1.5 w=v% sodium alginate solution by mixing 7.5 g of sodium alginate and 492.5 mL of deionized water (DI water) and 16.65 w=v% calcium chloride solution by mixing 16.65 g of calcium chloride and 983.35 ml of DI water. Using these solutions, hydrogel microtubes suitable for microbial culture were formed.…”

“…Using these solutions, hydrogel microtubes suitable for microbial culture were formed. 15) V. alginolyticus was purchased from the National Institute of Technology and Evaluation and used as the target microorganism. The microbial suspension was composed of hipolypepton, yeast extract, MgSO 4 1 7H 2 O, Daigo's artificial seawater SP, and DI water, all of which were purchased from Wako Pure Chemical Industries.…”

“…1. 15,16) The microtubes made of calcium alginate, which is a commonly used hydrogel for encapsulation, have a network structure and nanopores approximately 200 nm in diameter. [17][18][19][20][21] The nanopores are small enough to block the competing microorganisms outside but sufficiently large for oxygen, carbon dioxide, nutrition, and byproducts to diffuse through.…”

Development of a Triple-Coaxial Flow Device for Fabricating a Hydrogel Microtube and Its Application to Bioremediation

“…Moreover, the microbes can be easily collected along with the tubes without contaminating the surrounding environment. We previously developed a microfluidic device to produce the microtubes that encapsulate microbes using double-coaxial flow [ 11 , 12 , 13 ]. The double-coaxial flow comprises a sodium alginate solution as the outer flow and a microbial suspension as the inner flow.…”

Hollow Hydrogel Microfiber Encapsulating Microorganisms for Mass-Cultivation in Open Systems

“…We previously introduced a concept for a new cultivation technique using hollow hydrogel microfibers to cultivate microorganisms in open cultivation systems [ 16 ]. In the present study, we conduct detailed analyses of the method, including enhancement of the mechanical toughness utilizing a double-network hydrogel.…”