• Journal of Microbiology and Biotechnology
• /
• v.20 no.3
• /
• pp.615-621
• /
• 2010

The viability of low-temperature sulfate reduction with hydrogen as electron donor was studied with a bench-scale gas-lift bioreactor (GLB) operated at $9^{\circ}C$. Prior to the GLB experiment, the temperature range of sulfate reduction of the inoculum was assayed. The results of the temperature gradient assay indicated that the inoculum was a psychrotolerant mesophilic enrichment culture that had an optimal temperature for sulfate reduction of $31^{\circ}C$, and minimum and maximum temperatures of $7^{\circ}C$ and $41^{\circ}C$, respectively. In the GLB experiment at $9^{\circ}C$, a sulfate reduction rate of 500-600 mg $l^{-1}d^{-1}$, corresponding to a specific activity of 173 mg ${SO_4}^{2-}g\;VSS^{-1}d^{-1}$, was obtained. The electron flow from the consumed $H_2$-gas to sulfate reduction varied between 27% and 52%, whereas the electron flow to acetate production decreased steadily from 15% to 5%. No methane was produced. Acetate was produced from $CO_2$ and $H_2$ by homoacetogenic bacteria. Acetate supported the growth of some heterotrophic sulfate-reducing bacteria. The sulfate reduction rate in the GLB was limited by the slow biomass growth rate at $9^{\circ}C$ and low biomass retention in the reactor. Nevertheless, this study demonstrated the potential sulfate reduction rate of psychrotolerant sulfate-reducing mesophiles at suboptimal temperature.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.56 no.1
• /
• pp.89-98
• /
• 2023

We evaluated the effects of prebiotic (mannan oligosaccharides, Mos) and probiotic diet supplements on growth performance, innate immunity, antioxidant activity, and intestinal changes in the microbial flora of red seabream Pagrus major. A basal diet (Con) was formulated to meet the nutrient requirement of red seabream. The dietary starch in Con was replaced with 0.6% Mos, Lactobacillus plantarum, Bacillus subtilis, B. licheniformis and probiotic mixture (labeled as Mos, Pro-LP, Pro-BS, Pro-BL and Pro-Mix, respectively). We stocked 450 fish in 18 polypropylene tanks (400 L) in triplicate groups per dietary treatment. The fish were fed one of the diets twice (08:30, 18:30 h) a day for 63 days. Lysozyme activity was significantly higher in all the supplemented groups than that of the Con group. The immunoglobulin level of Pro-Mix, anti-protease activity of Pro-BL, and glutathione peroxidase and superoxide dismutase activity of Pro-BS, Pro-BL and Pro-Mix groups were significantly higher than those of the Con group. The ratio of total Vibrio/heterotrophic marine bacteria counts was significantly lower in Pro-LP, Pro-BL and Pro-Mix groups than that of the Con group. Therefore, dietary supplementation of Mos and probiotics to improves immune response and antioxidant enzyme activity and inhibits Vibrio bacteria in the intestine.

• Journal of Environmental Science International
• /
• v.12 no.8
• /
• pp.847-852
• /
• 2003

It was examined carefully that the bacterial die-off between Chlorella vulgaris and E. coli. W3110 was tested through adding TOC (total organic carbon) with the lab-scaled continuous river water flow system (CRWFS). Artificial synthetic wastewater was applied at two levels of organic carbon concentration; 1,335 mg/l in treatment type 1 and 267 mg/l in type 2. In both types, the population densities of Chlorella vulgaris were similar in a maximum 8.25 ${\times}$ 10$\^$6/ cells/ml (type 1) and 6.925 ${\times}$ 10$\^$6/ cells/ml (type 2). The maximum densities of E. coli. W3110 were 2.0 ${\times}$ 10$\^$8/ colony forming unit (CFU)/ml in type 1 and 3.9 ${\times}$ 10$\^$8/ CFU/ml in type 2. The densities increased for 11 days in type 1 and 4 days in type 2, then decreased rapidly till the 35th day, then slightly increased again. This trend was prominent in type 2. It implied that a wider range of nutrients was required in the growth of heterotrophic bacteria in type 2 than in type 1. We could not expect successful bacterial die-off if the wastewater retention time was not furnished sufficiently.

• ALGAE
• /
• v.17 no.3
• /
• pp.195-199
• /
• 2002

We investigated the association of Chlorella vulgaris and E. coli W9110 in removal of total organic carbon with the lab-scaled continuous river water flow system (CRWFS). Artificial wastewater was applied at two levels of organic carbon concentration; 1,335 $mg{\cdot}l^{-1}$ in the treatment (T)-1 and 267 $mg{\cdot}l^{-1}$ in T-2. The highest densities of C. vulgaris were $8.3{\times10^6\;cells{\cdot}ml^{-1}$ in T-1 and $6.9{\times}10^6\;cells{\cdot}ml^{-1}$ in T-2. The maximum densities of E. coli W3110 were $2.0{\times}10^8$ clony forming unit (CFU)${\cdot}ml^{-1}$ in T-1 and $3.9{\times}10^8\;CFU{\cdot}ml^{-1}$ in T-2. The densities increased during the first 11 days in T-q and 4 days in T-2, and decreased rapidly till 35th day, then increased slightly afterwards. This trend was prominent in T-2. It was inplied that wider range of nutrients was required in the growth of heterotrophic bacteria in T-2 than in T-1. The algal biomass should be increased effectively for the successful removal of organic carbon.

• ALGAE
• /
• v.25 no.2
• /
• pp.99-104
• /
• 2010

A psychrotolerant cyanobacterium, Nodularia spumigena KNUA005, was isolated from a cyanobacterial bloom sample collected near Dasan Station in Ny-${\AA}lesund$, Svalbard Islands during the Arctic summer season. To generate an axenic culture, the isolate was subjected to three purification steps: centrifugation, antibiotic treatment and streaking. The broad antibacterial spectrum of imipenem killed a wide range of heterotrophic bacteria, while the cyanobacterium was capable of enduring both antibiotics, the remaining contaminants that survived after treatment with imipenem were eliminated by the application of an aminoglycoside antibiotic, kanamycin. Physical separation by centrifugation and streaking techniques also aided axenic culture production. According to the cold-tolerance test, this mat-forming cyanobacterium was able to proliferate at low temperatures ranging between 15 and $20^{\circ}C$ which indicates the presence of cold-tolerance related genes in N. spumigena KNUA005. This suggests the possibility of incorporating cold-resistance genes into indigenous cyanobacterial strains for the consistent production of algae-based biofuel during the low-temperature seasons. Therefore, it is needed to determine the cold-tolerance mechanisms in the Arctic cyanobacterium in the next research stage.

• Korean Journal of Microbiology
• /
• v.35 no.1
• /
• pp.72-77
• /
• 1999

To investigate soil bacterial diversity according to vegelalioo types, utilizing ability of sole carbon sources and restriction enzyme patterns of 16s rDNA were analyzed. From the both results; five kinds of soil microbial communities were grouped as forest soil (Quercus mongolica and Pinus densi&ra vegetation), grass-agricultured soil and microbial communities of naked soil. But, both soil microbial communities of directily exlracted from ths soil and indirectly extracted from heterotrophic bacteria that cultured soil in LB medium showed very different similarity.

• Journal of Environmental Health Sciences
• /
• v.9 no.1
• /
• pp.49-62
• /
• 1983

Evaluation of water quality of Yeong San river and Seomjin river by using of newly simplified MBOD method was performed. Of course, thought that there is some differences between nutrient demands of heterotrophic bacteria and those of Algae which obtain it by photosynthesis, but it has little influence on evaluation of Algae Growth potential. The result of this study were as follows: 1) In both river, the value of Chemical analysis and MBOD method of inorganic salts reveals as nearly same result. 2) Though organic pollution of Seomjin river is less than that of Yeongsan but inorganic contamination is somewhat advanced BOD 2.8 ppm. and MBOD 340 ppm. in Seomjin river but BOD 22 ppm. and MBOD 480 ppm. in Yeongsan river. 3) Both river have tendency to reveal higher Nitrogen value is MBOD=MBOD -P

• Journal of Korean Society on Water Environment
• /
• v.18 no.2
• /
• pp.113-122
• /
• 2002

A bench-scale anoxic membrane bioreactor (MBR) system, consisting of a bioreactor coupled to a ceramic crossflow ultrafiltration module, was evaluated to treat a synthetic wastewater containing alkaline hydrolysis byproducts (hydrolysates) of RDX, The wastewater was formulated the same as RDX hydrolysates, and consisted of acetate, formate, formaldehyde as carbon sources and nitrite, nitrate as electron accepters. The MBR system removed 80 to 90% of these carbon sources, and approximately 90% of the stoichiometric amount of nitrate, 60% of nitrite. The reactor was also operated over a range of transmembrane pressures, temperatures, suspended solids concentration, and organic loading rate in order to maximize treatment efficiency and permeate flux. Increasing transmembrane pressure and temperature did not improve membrane flux significantly. Increasing biomass concentration in the bioreactor decreased the permeate flux significantly. The maximum volumetric organic loading rate was $0.72kg\;COD/m^3/day$, and the maximum F/M ratio was 0.50 kg N/kg MLSS/day and 1.82 kg COD/kg MLSS/day. Membrane permeate was clear and essentially free of bacteria, as indicated by heterotrophic plate count. Permeate flux ranged between 0.15 and $2.0m^3/m^2/day$ and was maintained by routine backwashing every 3 to 4 day. Backwashing with 2% NaOCl solution every fourth or fifth backwashing cycle was able to restore membrane flux to its original value.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.58 no.1
• /
• pp.59-67
• /
• 2022

This study assessed the levels of water qualities and microbials contamination of inland olive flounder farms in Jeju in the summers from 2015 to 2017. Three farms (A-C) located in a concentrated area using mixing coastal seawater and underground seawater and one farm (D) located in an independent area using only coastal seawater were selected. Total ammonia nitrogen (TAN) reached a maximum of 0.898 ± 1.024 mg/L as N in the coastal seawater of A-C, which was close to the limit of the water quality management goal of the fish farm. TAN in the influent from A-C was up to three times higher than that of D, so that the discharged water did not spread to a wide range area along the coast and continued to affect the influent. TAN of the effluent in A-C increased by 2.7-4.6 times compared to the influent, resulting in serious self-pollution in the flounder farm. Heterotrophic marine bacteria in the influent of A-C was about 600 times higher than D, and the discharge of A-C was increased by about 30 times compared to the influent.

• Korean Journal of Environmental Biology
• /
• v.35 no.2
• /
• pp.198-206
• /
• 2017

From June 2007 to May 2008, seasonal variations of bacterial abundance and heterotrophic nanoflagellate (HNF), together with environmental factors, were investigated at weekly and monthly intervals in Kyeonggi Bay. During the study period, the water temperature and salinity varied from $1.9^{\circ}C{\sim}29.0^{\circ}C$ and 31~35.1 psu, respectively. The concentration of ammonia, nitrate+nitrite, phosphate, and silicate ranged from 0.01 to $3.22{\mu}M$, 2.03 to $15.34{\mu}M$, 0.06 to $1.82{\mu}M$, and 0.03 to $18.3{\mu}M$, respectively. The annual average concentration of Chl. a varied from $0.86{\mu}g\;L^{-1}$ to $37.70{\mu}g\;L^{-1}$; the concentration was twice as much at the surface than at the deeper layers. The abundance of bacteria and HNF ranged from $0.29{\times}10^6$ to $7.62{\times}10^6cells\;mL^{-1}$ and $1.00{\times}10^2$ to $1.26{\times}10^3cells\;mL^{-1}$, respectively. In particular, there were significant correlations between bacteria and HNF abundance (p<0.05), and then the high abundance of HNF was frequently observed with an increase of bacterial abundance in summer (p<0.001). Our results therefore indicate that bacterial abundance in the bay was mainly controlled by resources supplied as organic and inorganic substances from Lake Shihwa due to the daily water exchange after dike construction. Also, the bacterial abundance was significantly controlled by HNF grazing pressure (top-down) in the warm seasons, i.e. excluding winter, in the Kyeonggi Bay.