• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.763-769
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• 1995

As a mean to recover photosynthetic bacterial(PSB) cells and its practical uses in food industrial wastewater treatment, various biodegradable polyelectrolytes were first investigated for flocculation of suspended colloids in the PSB treatment process of soybean curd wastewater. Anionic polyelectrolytes such as sodium alginate and carrageenan were not effective but a cationic polyelectrolyte chitosan isolated from Portunus trituberclatus showed very effective flocculation activity. The concentration of chitosan, pH and temperature of wastewater for maximal flocculation were 40 mg/l, pH 7 and room temperature, respectively. Test using deacetylated chitosan to various degree showed higher flocculating activities in samples deacetylated over 75% and time for maximum flocculation was 40 min by stirring slowly under the above optimal conditions. Chitosan was not only effective to flocculate cells but also removed COD and MLSS of the wastewater. COD of 42% and MLSS of 87% were removed by addition of chitosan to the soybean curd wastewater treated with PSB.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.556-560
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• 1997

The removal efficiency of COD and the production of ${\delta}-aminolevulinic$ acid (ALA) were concurrently investigated for both purifying the soybean curd wastewater of high BOD and utilizing the wastewater as a renewable substrate of ALA production using Rhodobacter capsulatus KK-10. Its wastewater was a favorable media for the growth of photosynthetic bacteria in terms of its environmental characteristics having COD/BOD rate of 0.98, ratio of BOD : N : P=100 : 6 : 4, BOD/N ratio of 17.2, lactic acid of 1,080 ppm. Its COD value wastewater was decreased to 94% and dry cell weight was approached to about 1.2 g/l after cultivation of the photosynthetic bacteria for 4 days. By the addition of 15 mM levulinic acid (LA) into the wastewater at the middle log phase of cell growth, the amount of ALA secreted was 55 mg/l. The ALA production was considerably increased to 114 mg/l under the cultural condition of 15 mM supplementations of glycine and succinate with LA at the same period. Furthermore the maximum ALA production of 120 mg/l and COD removal efficiency of 92% were accomplished in the soybean curd wastewater enriched with one addition of 15 mM LA and three serial additions 15 mM ALA precursors.

• Microbiology and Biotechnology Letters
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• v.23 no.6
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• pp.770-776
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• 1995

For the purpose of development of non-toxic and biodegradable flocculant, chitosan complex was isolated from Ganoderma lucidum wastes. The isolated complex was identified as the expected chitosan-glucan complex by IR specta. The complex was extracted by treatment of 50% NaOH solution at 120$\circ$C for 5 hrs, namely optimal condition and solubilized with 2% acetic acid for fur-ther use as flocculant. Preliminary experiments showed that the solubilized complex had higher flocculation activity of 1.3 fold than commercial chitosan at 400 mg/l concentration in soybean curd wastewater. Also the solubilized complex removed 83% of MLSS and 60% of COD in the soybean curd wastewater treated by photosynthetic bacteria, 50% of turbidity and 21% of MLSS in sugar industry wastewater, and 90% of turbidity and 89% of MLSS in alcohol fermentation wastewater. Bacterial cell flocculation activities of the solubilized chitosan-glucan complex were 89% in Bacillus subtilis broth, 81% in Streptococcus lactis broth, and more than 90% in Escherichia coli broth after standing for 2 days. The results reveal that chitosan-glucan complex from Ganoderma lucidum wastes can substitute for commercial chitosan as non-toxic and biodegradable flocculant.

• Journal of Microbiology and Biotechnology
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• v.12 no.4
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• pp.643-648
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• 2002

For wastewater treatment and utilization of the biomass, a photosynthetic bacterium was isolated based on its cell growth rate, cell mass, and assimilating ability of organic acids. The isolate was a Gram-negative rod-shaped bacterium that contained a single polar flagellum and formed a lamellar intracytoplasmic membrane (ICM) system, including bacteriochlorophyll $\alpha$. The major isoprenoid quinone component was identified as ubiquinone Q-10, and the fatty acid composition was characterized as to contain relatively large amount of C-16:0 (18.74%) and C-18:1 (59.23%). Based on its morphology, phototrophic properties, quinone component, and fatty acid composition, the isolate appeared to be closely related to the Rhodopseudomonas subgroup of purple nonsulfur bacteria. A phylogenetic analysis of the isolate using its 16S rRNA gene sequence data also supported the phenotypic findings, and classified the isolate closely related to Rhodopseudomonas palustris. Accordingly, the nomenclature of the isolate was proposed as Rhodopseudomonas palustris KUGB306. A bench-scale photosynthetic bacteria (PSB) reactor using the isolate was designed and operated for the treatment of soybean curd wastewater.