• Journal of the Korean Society of Safety
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• v.27 no.4
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• pp.68-75
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• 2012

The biogenic corrosion of mortars adopted in sewage repair by sulfuric acid-producing bacteria was considered in this paper. Calcium aluminate cement (CAC) was known to resist microbiologically-induced corrosion significantly better than portland and blended portland cement.In this study, CAC as well portland cement mortars were tested as main binder to evaluate the corrosion resistance by the chemical immersion test. Replacement ratios of CAC were changed as 0, 20, 40, 50, 60% of OPC binder and 0, 2, 4, 6% of EVA(Ethylene Vinyl Acetate) were also adopted to increase properties of CAC repair mortars in sewage application. Setting time, compressive strength, acid resistance and adhesive strength were measured for various experiments. As a results of the experiments, the proper formulation of repair mortars was found at 40% of CAC and 4% of EVA. Finally, the CAC mortars adopted in field sewer pipe and were demonstrated to superior in adhesion and workability.

• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1035-1043
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• 2012

The ammonia-oxidizing bacterial (AOB) communities in three membrane bioreactors (MBRs) were monitored for 2 months after an acclimation period in order to investigate the influence of sludge age and medium type on AOB changeability and its connection with nitrification effectiveness. One MBR with a sludge age of 4 days was fed with a synthetic medium, whereas the other two with sludge ages of 8 and 32 days were fed with landfill leachate. The research revealed that landfill leachate can be effectively treated in an MBR with a higher sludge age for longer periods of time and that this improvement in performance was correlated with an increase in AOB biodiversity. Interestingly, the medium type has a stronger influence on AOB biocenosis formation than the sludge age.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.585-595
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• 2019

Analysis of bacterial communities based on their 16S rDNA sequences revealed the predominance of Proteobacteria (Aeromonas sp., Acinetobacter sp. and Thaueraamino aromatica sp.) and uncultured bacterium in activated sludge from the effluent treatment plant (ETP) of Mother Dairy, Calcutta (India). Each isolate was used for bioremediation of dairy wastewater with simultaneous conversion of nitrogenous pollutants into ammonia. A consortium developed using seven of these isolates and three Bacillus strains from different environmental origins could reduce 93% nitrate with simultaneous production of ammonia (626 ㎍/100 ml) within 20 h in non-aerated, immobilized conditions as compared to 82% nitrate reduction producing 2.4 ㎍/100 ml ammonia in 96 h with extensive aeration in a conventional ETP. The treated ammonia-rich effluent could be used instead of freshwater and fertilizer during cultivation of mung bean with 1.6-fold increase in grain yield. The ETP with the surrounding agricultural land makes this process a zero liquid discharge technology for using the biofertilizer generated. In addition, the process requires minimal energy supporting sustained environmental health. This method is thus proposed as an alternative approach for small-scale dairy ETPs.

• Journal of Microbiology and Biotechnology
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• v.20 no.7
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• pp.1140-1151
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• 2010

Differences in DNA banding patterns, obtained by ribosomal intergenic spacer analysis (RISA), and nitrification were followed in a moving-bed biofilm reactor (MBBR) receiving municipal landfill leachate. Complete nitrification (>99%) to nitrate was obtained in the two-stage MBBR system with an ammonium load of 1.09 g N-$NH_4/m^2{\cdot}d$. Increasing the ammonium load to 2.03 g N-$NH_4/m^2{\cdot}d$or more caused a decline in process efficiency to 70-86%. Moreover, at the highest ammonium load (3.76 g N-$NH_4/m^2{\cdot}d$), nitrite was the predominant product of nitrification. Community succession was evident in both compartments in response to changes in ammonium load. Nonmetric multidimensional scaling (NMDS) supported by similarity analysis (ANOSIM) showed that microbial biofilm communities differed between compartments. The microbial biofilm was composed mainly of ammonia-oxidizing bacteria (AOB), with Nitrosomonas europeae and N. eutropha being most abundant. These results suggest that high ammonium concentrations suit particular AOB strains.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.244-251
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• 2005

The induction of growth promotion on numerous crops by rhizobacteria is a well documented phenomenon. In case of tomato (Lycopersicon esculentum), fruit yield is higher in replant soil than that in fresh soil. To investigate what kind of rhizobacterium is involved, microbial community in rhizosphere and on rhizoplane of tomato plants from each soil was analyzed by dilution plating on selective media. Many Gram-negative bacteria and actinomycetes were isolated from tomato in replant soil. One Gram-negative rhizobacterium isolated was identified as Pseudomonas putida based on its biochemical characteristics, fatty acid methyl ester analysis and 16S rDNA sequence. This bacterium designated strain 17 inhibited the growth of Pseudomonas corrugata, and increased growth of tomato seedlings. In addition, its culture filtrate inhibited conidial germination of plant-pathogenic fungi such as Fusarium oxysporum f. sp. radicis-lycopersici, F. oxysporum f. sp. cucumerinum, and Nectria radicicola. Scanning electron microscopy revealed strain 17 colonized and persisted on the epidermal surfaces of tomato radicles and roots. These results suggest that P. putida strain 17 may serve as a biological control agent to suppress multiple soil-borne diseases for tomato plants. Increased microbial populations that suppress deleterious microorganisms including pathogens could be one of the major factors in increased tomato yield in replant soil.

• The Korean Journal of Ecology
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• v.22 no.5
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• pp.305-309
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• 1999

The occurrence of tetQ and aacC2 genes encoding tetracycline and gentamicin resistance determinant, respectively, was assessed in total bacterial community DNA isolated from Dongchon stream of Sunchon area. To examine the resistance potential of bacteria that were not cultured, total DNA from 1 liter of stream water was extracted by freeze-thaw method. The PCR technique was employed to determine the abundance of the target genes. The highest frequency of tetQ gene was obtained from site 1, located near the animal farms area, whereas the incidence of aacC2 was highest in site 5, the downstream area. These results showed that the occurrence of antibiotic resistance gene may be used as a convenient marker of water quality related to source.

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.22-26
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• 2002

There are a number of ways in which environmental microbiology and microbial ecology will benefit from DNA micro array technology. These include community genome arrays, SSU rDNA arrays, environmental functional gene arrays, population biology arrays, and there are clearly more different applications of microarray technology that can be applied to relevant problems in environmental microbiology. Two types of the applications, bacterial identification chip and functional gene detection chip, will be presented. For the bacterial identification chip, a new approach employing random genome fragments that eliminates the disadvantages of traditional DNA-DNA hybridization is proposed to identify and type bacteria based on genomic DNA-DNA similarity. Bacterial genomes are fragmented randomly, and representative fragments are spotted on a glass slide and then hybridized to test genomes. Resulting hybridization profiles are used in statistical procedures to identify test strains. Second, the direct binding version of microarray with a different array design and hybridization scheme is proposed to quantify target genes in environmental samples. Reference DNA was employed to normalize variations in spot size and hybridization. The approach for designing quantitative microarrays and the inferred equation from this study provide a simple and convenient way to estimate the target gene concentration from the hybridization signal ratio.

• 한국해양학회지
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• v.28 no.2
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• pp.107-113
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• 1993

Interrelationship between bacterial and phytoplankton variables and associations of this relationship with phytoplankton community structure were studied from July, 1990 to October, 1991 in the estuarine system of Mankyung and dongjin Rivers where estuarine mixing is very active. During the study period only bacterial production and chlorophyll were always significantly correlated (r$^2$>0.36, p<0.02), suggesting that phytoplankton-biomass related process seemed to be related to bacterial production in the estuarine waters. However, bacterial production comprised only a small fraction (on average<2.6) of primary production throughout the study period, suggesting that those parameters were uncoupled. this might be partly due that phytoplankton, food particles for zooplankton, food particles for zooplankton, were mostly composed of large and/or chain-forming diatoms.

• Journal of Navigation and Port Research
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• v.33 no.2
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• pp.161-166
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• 2009

Lactobacillus sp., Acetobacter sp. and yeast were the most dominant organisms in the EM stock culture and subculture product. Lactic acid bacteria and yeast were able to grow in the fermentation process utilizing seawater. EM treatment of higher concentrations using EM stock culture and EM clay balls (1% or 4%) contributed to an early removal of malodor and an increase of DO in the polluted sediments, indicating an odor-removing activity of EM. The EM treatment of higher concentrations (1% or 4%) somewhat appeared to modify the microbial communities within the sediments, which was confirmed by existence of a few unique fragments from the stock culture based on PCR-DGGE. It still remains to be elucidated that EM cultures were directly involved in the malodor removal and potential sediment bioremediation.

• Journal of Korean Neurosurgical Society
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• v.60 no.4
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• pp.481-483
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• 2017

Sphingomonas paucimobilis (S. paucimobilis) is a gram negative bacillus. It has existed in soil, drinking water and plants. It has been isolated from distilled water tanks, respirators, and hemodialysis devices at the hospital setting. Patients with chronic disorders or immune suppression may be susceptible to infections with it. This microorganism has also been reported to infect healthy persons. Both nosocomial and community-acquired infections have been reported. So far, a variety of infections have been reported, including sepsis, septic pulmonary embolism, septic arthritis, peritonitis, and endophthalmitis. Only 2 cases of meningitis have been reported so far in the literature. So far, no previous reports of culture proliferation have been reported in patients with external ventricular drains, as was the case in our patient. Therefore, our case is the first to have S. paucimobilis proliferation in cerebrospinal fluid culture during intensive care unit stay for an external ventricular drain.