Development and Application of a Novel Bioreactor with Loofa (Luffa cylindrica) Sponge as a Carrier For Cell Immobilization.

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Efficient immobilization of flocculating cells can be achieved by simply inoculating a reactor containing a bed of the loofa sponge with the cell suspension. The cells were trapped inside the lattice of the sponge and grew to high cell densities. In the case of non-flocculating cells, flocculation was induced by addition of flocculating agent (chitosan) and the flocculated cells were efficiently immobilized as described above. Fungi was immobilized by inoculating either spores or homogenized hyphae into a reactor containing a bed of the loofa sponge. The spores germinated inside the lattice structure of the sponge and the resulting hyphae were entangled (immobilized) on the sponge.Although mass transfer was better in a fixed bed made of a single cylindrical sponge, the amounts of sponge per unit reactor volume and the immobilized cells per unit sponge were higher when sliced loofa sponges were used for bed construction. Thus cylindrical or sliced loofa sponges should be used for aerobi … More c or anaerobic fermentation processes, respectively.As examplex of application to anaerobic fermentation, immobilized flocculating (Saccharomyces cerevisiae) or non-flocculating (Candida brassicae) was used for continuous ethanol production from molasses and sucrose medium. The processes were stable for long periods of time. In the case of aerobic processes, long term continuous glucoamylase production by Aspergillus awamori immobilized on loofa sponge was possible. Furthermore, continuous direct ethanol production from starch was achieved by using a combination of immobilized Aspergillus awamori and Saccharomyces cerevisiae.The above results have shown that representative flocculating and non-flocculating fermentation microorganisms (yeast, bacteria and fungi) can be efficiently immobilized on loofa sponge. Furthermore, by using either the cylindrical or sliced loofa sponge, suitable fixed beds for aerobic or anaerobic fermentation processes can be constructed. It can be thus concluded that bioreactor with loofa sponges has great potential for application in a wide range of fermentation processes. Less