• Journal of Microbiology and Biotechnology
• /
• v.13 no.6
• /
• pp.937-941
• /
• 2003

Microbiologically influenced corrosion (MIC) is an electrochemical process where the participation of microorganisms initiates, facilitates, or accelerates the corrosion reaction. Sulfate-reducing bacteria (SRB) reduce sulfate to sulfide and are known to be the most destructive microorganisms in anaerobic MIC. Accordingly, the current study attempted to elucidate the mechanisms involved and the relative importance of the corrosive products in SRB-induced corrosion. The measured rate of anaerobic corrosion of iron coupons by Desulfovibrio desulfuricans was $89.9{\;}\mu\textrm{g}{\;}\textrm{m}^{-2}{\;}d^{-1}$. Direct contact between the cells and the iron coupon did not seem to be necessary for corrosion to occur, since the corrosion rate was similar ($100.8{\;}\mu\textrm{g}{\;}\textrm{m}^{-2}{\;}d^{-1}$) when the coupon was enclosed in a dialysis bag. The participation of sulfide in the corrosion process was only marginal, as the specific corrosion rate was 2.5 times higher in a sulfate-free pyruvate medium than in an $H_2S-producing$ lactate medium. Acetate (18.8-22.1 mM), the end-product of pyruvate and lactate metabolism, was identified in the culture medium and thus presumed to play a major role in the corrosion process involving Desulfovibrio desulfuricans.

• Journal of Korean Society of Environmental Engineers
• /
• v.27 no.9
• /
• pp.958-964
• /
• 2005

Experiment was conducted to investigate the amount of hydrogen gas and the characteristics of organic acids production from various carbohydrates by anaerobic bacteria. The variation characteristics of organic acids and hydrogen gas production at the fermentative culture were also studied in the presence of heavy metals such as cadmium or lopper. 3.43 mole hydrogen per mole of hexose was produced when sucrose was used as a carbon source. Acetic acid and butyric acid were main products by the anaerobic fermentation. Hydrogen production rate was decreased and formation of acetic acid was increased as the concentration of heavy metals was increased in the medium. The inhibition of hydrogen production by the copper was more serious than the cadmium.

• Transactions of the Korean hydrogen and new energy society
• /
• v.17 no.3
• /
• pp.286-292
• /
• 2006

Chlamydomonas reinhardtii is a green algae that can use light energy and water to produce hydrogen under anaerobic condition. This work reports the effect of limiting factors on hydrogen production in sulfur deprived anaerobic C. reinhardtii culture. In order to confirm the relationship between hydrogen production and limiting factors such as residual PSII activity and endogenic substrate degradation, the increase in chlorophyll concentration and the decrease in starch concentration was investigated during sulfur deprivation. The overall hydrogen production increased depending on cell density in range of $0.4{\sim}0.96\;g$ DCW/l. At this time, the increase in chlorophyll concentration during 24 h after sulfur deprivation increased in proportion to hydrogen production, however, the decrease in starch concentration was not proportional to that. Therefore, hydrogen production under sulfur deprivation using green alga was closely associated with the residual PSII activity than the endogenic substrate degradation.

• Journal of Microbiology
• /
• v.40 no.3
• /
• pp.193-198
• /
• 2002

Several 2,4,6-trinitrotoluene (TNT) degrading bacteria were isolated from an activated sludge by an enrichment culture technique, and their TNT removal activities were examined. Among the isolates, strain C1 showed the highest degrading capability, and completely removed 100 or 200 mg I$\^$-1/ of TNT within 6 hours of incubation. This bacterium was identified as Klebsiella sp. The effects of different carbon sources on the removal of the parent TNT by Klebsiella sp. C1 were negligible, but the transformation rates of TNT metabolites such as amino-dinitrotoluenes and diamino-nitrotoluenes were higher with fructose addition compared to glucose addition. When nitrate was used as the nitrogen source, the degradation rates of TNT and hydroxylamino-dinitrotoluenes were higher than those with the ammonium addition. Although the TNT removal rate of Klebsiella sp. C1 was slightly higher in anaerobic conditions, the further transformations of TNT metabolites were more favorable in aerobic conditions.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.3
• /
• pp.609-614
• /
• 2010

The effluent from anaerobic digestion contains organic nitrogen and phosphorus, which are both required for growth of Spirulina platensis. Effluent (20%) from the upflow anaerobic sludge blanket (UASB) from a pig farm, supplemented with 4.5 g/l sodium bicarbonate ($NaHCO_3$) and 0.2 g/l urea fertilizer (46:0:0, N:P:K), was found to be not only a suitable medium for the growth of Spirulina platensis but also a low-cost alternative. Cost calculation showed that this medium is 4.4 times cheaper than modifized Zarrouk's medium. The average productivities of a semi-continuous culture grown under outdoor conditions in a 6-1 scale and a 100-1 pilot scale were 19.9 $g/m^2/d$ and 12 $g/m^2/d$, respectively. In addition, the biomass of organisms grown in UASB effluent contained approximately 57.9% protein, 1.12% $\gamma$-linolenic acid, and 19.5% phycocyanin. The average rates of bicarbonate, total nitrogen, and phosphorus removal were 380 mg/l/d, 34 mg/l/d, and 4 mg/l/d, respectively.

• Korean Journal of Microbiology
• /
• v.12 no.3
• /
• pp.131-137
• /
• 1974

It is a well-known fact that an isolation of non-sporeforming anaerobes, considered normal flora in man ordinarily but causes serious infections sometimes, is a dificult procedure because of their great oxygen sensitivity. Among the many techniques employed in clinical laboratories, despite of its high expenses, the GasPak method has been most widely used because of its relative simplicity. On the other hand, the steel wool method has gained a good reputation recently. This technique makes it possible to treat individual plate so that any single specimen can be promptly cultured anaerobically. The procedure is quite simple and the expenses are negligible. In the present study it is to compare these two methods as to their efficiency of anaerobic cultivation using 13 VPI strains of non-sporeforming amaerobic bacteria. Among the 13 species the following 11, Bacteroides fragilis ss. fragilis, B. fragilis ss. thetaiotaomicron, propionibacterium acnes, Eubacterium limosum, E. lentum, peptococcus asaccharolyticus, Pc. prevotii, Pc. magnus, peptostreptococcus anaerobius, Ps. intermedius nad Veillonella parvula, grew well with the steel wool method whose colony numbers reaching 57 to 119% of those with GasPak method. The remaining two species, Fusobacterium nucleatum and F.necrophorum, did not grow well with the steel wool method showing the colony numbers were only 0.4% of those with GasPak method in the case of Fusobacterium nucleatum. In the case of Fusobacterium necrophorum, very few colonies developed even with a heavy inoculation. As to the size of colonies, there were no significant difference between these two methods.

• Restorative Dentistry and Endodontics
• /
• v.16 no.1
• /
• pp.226-235
• /
• 1991

Therapeutic use of antibiotics in the pulpal disease should reduce the clinical symptoms and pathogenic microflora in the pulp. The purpose of this study was focused on local drug delivery into the root canal in endodontic therapy. Monolithic films from polycaprolactone and polyethylene glycol preparations with minocycline were prepared, and then the antimicrobial effect of these films on necrotic canal was tested. A total 17 necrotized pulp teeth were sampled before and 1 week after insertion of film into the pulp. Bacterial culture were performed with anaerobical condition and seeded in the 5 selective and non - selective media for 7 days in $37^{\circ}C$ of anaerobic chamber. Bacterial identification were performed with Gram staining, biochemical test, and API kit There was significantly decreased of anaerobic and aerobic microflora of 13 among 17 patients after therapy. Among the identified microflora, Streptococcus species, black - pigmented species and Fusobacterium species were significantly reduced 1 week after treatment with local delivery antibiotics. Furthermore, clinical symptoms included in pain and local swelling were continuousely reduced after therapy. These results suggest that local drug delivery with minocycline is effeicient to treat the endodontic involved teeth for releasing clinical symptoms and microbiological shifting.

• Transactions of the Korean hydrogen and new energy society
• /
• v.25 no.4
• /
• pp.337-343
• /
• 2014

This study was conducted to evaluate the characteristics of dark fermentative $H_2$ production from microalgae (Chlorella vulgaris) using batch reactors under mesophilic (25, $35^{\circ}C$) and thermophilic (45, $55^{\circ}C$) conditions. The $H_2$ yield and $H_2$ production rate increased with increasing temperature. The maximum $H_2$ yield and $H_2$ production rate were 56.77 mL $H_2/g$ dcw, 3.33 mL $H_2/g\;dcw{\cdot}h$ at $55^{\circ}C$, respectively. The activation energy calculated using Arrhenius equation was 36.24 kcal/mol, which was higher than that of dark $H_2$ fermentation of glucose by anaerobic mixed culture. Although the concentration of butyrate was maintained, the concentrations of lactate and acetate increased with increasing temperature. The $H_2$ yield was linearly proportional to acetate/ butyrate ratio.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.398-401
• /
• 2003

Bacillus species predominantly outgrown in a night soil treatment system were isolated and characterized. Cell interactions took place among them and cell population changed under various culture conditions. Maximum removal of $NH_4\;^+-N$ and cell production occurred under the conditions of 30% DO and C/N ratio of 8. Additions of 0.8% peptone and 0.3% yeast extract to a basal medium influenced the growth of isolates and the removal of $NH_4\;^+-N$ in flask culture, and metal ions such as Ca, Fe and Mg also did. During the flask experiment of nitrogen removal under an aerobic condition, active nitrification by the isolates occurred largely in 1 h with the decrease of COD and alkalinity destructed was only 74.6% of theoretical value. From the nitrogen balance, the percentage of nitrogen lost in the flask culture was estimated to be 29.0%. This conversion of ammonia to $N_2$ under an aerobic condition was confirmed by GC analysis. The B3 process using the Bacillus species seemed to have some economic advantage.

• Journal of environmental and Sanitary engineering
• /
• v.11 no.2
• /
• pp.27-31
• /
• 1996

2,4,6-Trinitrotoluene(TNT) was reduced into intermediate products by mixed culture incubated in anaerobic condition. To test the effects of extracellular material to electron transfer between sulfide and TNT, filtered medium of mixed culture was loaded in the test tubes with TNT and sulfide. The transformation rate was measured under four different conditions. The rate under microbial activity was the fastest among under different conditions. With sulfide or filtrate alone and TNT, the reactions were measured as the slowest reactions or no reactions occured, respectively. The reaction rate coefficient were calculated by linear regression and the first order kinetic was fitted best. Also, the plot of rate coefficients (K$_{f}$) showed linear relationships when at time zero TNT and sulfide concentration were 20 mg/1 and 6.0 mM, respectively. By extrapolation, reaction rate coefficient of 100% filtrate could be calculated as 0.0054/minute. However, reaction rate was affected by different concentration of sulfide, so it is a dependent of sulfide concentration. The results of this test showed TNT reduction rate can be limited more by microbial reaction than by mediation of filtrate or sulfide and filtrate alone.