Weissella hellenica SKkimchi3 produces the higher exopolysaccharide (EPS) on sucrose than lactose, glucose, and fructose at pH 5 and 20 degrees C. Sucrose was exclusively used to cultivate SKkimchi3 in all experiments base on the EPS production tests. The molecular mass of EPS, as determined by gel permeation chroma-tography, was 203,000. (1)H and (13)C NMR analysis indicated that the identity of EPS may be a glucan. When EPS, starch, and cellulose was treated with a-amylase, glucoamylase, glucosidase, and cellulase, glucose was produced from starch and cellulose but was not produced from EPS. Based on HPLC analysis, elemental analysis, (1)H and (13)C NMR analysis, and enzymatic hydrolysis tests, EPS was estimated to be a glucan. EPS suspension was not precipitated even by centrifugation at 10,000xg for 60 min, and EPS made the fermented milk and bacterial culture viscous.

A bacterium growing inside yeast cytoplasm was observed by light microscope without staining. The bacterium was separately stained from yeast cell by a fluorescent dye, 4',6-diamidino-2-phenylindole (DAPI). The bacterium actively moved inside yeast cytoplasm and propagated in company with the yeast growth. The bacterium was separated from the yeast cytoplasm by selective disruption of yeast cells and the yeast without the intracellular bacterium (YWOB) was obtained by selective inactivation of bacterial cells. The yeast and the intracellular bacterium were identified as Candida tropicalis and Microbacterium sp., respectively. The length of Microbacterium sp. and C. tropicalis measured with SEM image was smaller than 0.5 microm and was larger than 5 microm, respectively. The yeast with the intracellular bacterium (YWIB) grew in a starch-based medium but the YWOB was not C. tropicalis has neither extracellular nor intracellular saccharification enzyme. Glucose was produced from starch by the extracellular crude enzyme (culture fluid) of Microbacterium sp. YWIB produced significantly more ethanol from glucose than YWOB but did not from starch. Conclusively, C. tropicalis is thought to catabolize starch dependent upon Microbacterium sp. growing in its cytoplasm and furnish stable habitat for the Microbacterium sp.

In this study, a novel three-compartmented electrochemical bioreactor (3-CEB) was designed in an effort to overcome the disadvantages of the two-compartmented electrochemical bioreactor (2-CEB) separated with a cation-selective membrane for enrichment of strict anaerobes. The 3-CEB was comprised of an anode, outlet, and a cathode compartment. The outlet compartment was positioned between the anode and cathode compartment, and it was separated with the anode side by a rubber plate and with the cathode side by a porous glass membrane. A platinum wire bridging the anode and outlet compartment operated as a redox passage, however, through which no material could permeate. Butyrate fermentation bacteria were enriched on the basis of the metabolite production. Butyrate generated by strict anaerobes was significantly more abundant in the 3-CEB than in the 2-CEB. Acetic acid and lactic acid generated by facultative anaerobes was relatively higher in the 2-CEB than in the 3-CEB. Meanwhile, butyrate was not generated in the bioreactor utilized for the control test, to which the electrochemical potential was not charged. In a continuous culture using the 3-CEB, the majority of the glucose was fermented to butyrate, and the acetate additionally supplied to the bacterial culture was metabolically reduced to butyrate. More lactate than butyrate was generated from glucose in the 2-CEB. © KSBB

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