• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.71-78
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• 2002

Seasonal change of total bacterial numbers were estimated in Daechung Reservoir from September, 1998 to August, 1999 and environmental factors which affects total bacterial numbers were estimated. Total bacterial numbers ranged between 1.2 and $19.0{\times}10^6\;cells/ml$ and averaged $6.9{\times}10^6\;cells/ml$. Bacterial numbers changed dynamically with season. The bacterial numbers were highest in July and showed peaks in April and July in sites studied except for the HOE (Hoenam site), In the HOE (Hoenam site), total bacterial numbers increased eve the period of March${\sim}$August. The correlation coefficient between bacterial number and chlorophyll a (<$200\;{\mu}m$) was r = 0.72(p< 0.05) at the MAN (man site). Total bacterial numbers in Daechung Reservoir was diversely changed by the seasonal variation of several environmental quality parameters.

• Korean Journal of Microbiology
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• v.37 no.2
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• pp.124-129
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• 2001

For elucidating the effect of salinity to the effect of wastewater treatment, the heterotrophic bacterial numbers, total bacterial numbers, and the bacterial community structure by FISH method were analyzed. The total bacterial numbers were not significantly changed by the salinity. But the heterotrophic bacterial numbers and bacterial community structures were drastically changed by the increase of salinity. In case of 1% salinity, the heterotrophic bacterial numbers and structure were slightly changed comparing to those of contol. In case of 2% and higher salinities, the numbers of heterotrophic bacteria and the proportions of Eubacteria, Proteobacteria $\alpha$-group, $\rho$-group and Cytophaga-Flavobacterium groups were deceasing. By these results, the salinity stress to bacterial community in waste water treatment was unveiled, and for sustaining the waste water treatment system, the salinity should be lower than 1%.

• Journal of Microbiology
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• v.34 no.4
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• pp.300-304
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• 1996

To define the effects of zooplankton and phytoplankton to bacteria, bacterial numbers, frequency of dividing cells (FDC) and size distribution were performed with image analysis in the surface layer of Lake Soyang. In August 1992, when Anabaena was blooming, the bacterial number increased at daytime. Bacterial numbers and FDC value had a negative correlation (r = 0.83, P < 0.01). Bacterial size spectrums were dynamically changed during the day and night, especially the small bacteria less than $0.5\;{\mu}m^3$. Meanwhile, in October, after the bloom, the bacterial number was only one third of that in August, even though the FDC was higher than that in August. The bacterial numbers of small size class dropped at 13:00. But the size spectrums were relatively constant during the night time. These results suggest that the bacterial growth was tightly coupled with phytoplankton during Anabaena bloom. And after the bloom, the bacterial number was controlled grazing activity of zooplankton at daytime.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.329-334
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• 2009

Bacterial numbers, such as endospore-formers, and treatment efficiencies were investigated for Rotating Activated Bacillus Contactors (RABC) and other advanced wastewater treatment processes including anaerobic-anoxic-oxic (A2O), sequencing batch reactor (SBR) and biological aerated filter (BAF). Endospore-forming bacterial numbers in the RABC showed 129-fold higher levels than those of the existing advanced systems. RABC process demonstrated the highest bacterial numbers in its bioreactors (paired t-test, p<0.01). RBC biofilms and aeration tanks of the RABC system showed 131- and 476-fold higher than other existing advanced processes, respectively. Mean treatment efficiencies of the existing systems were 83.5% for chemical oxygen demand (COD), 59.1% for total nitrogen (TN) and 76.8% for total phosphorus (TP). However, RABC process removed 96.9% for COD, 96.9% for TN and 91.9% for TP for highly concentrated food wastewater (COD>1,500 mg/L, TN>150 mg/L, TP>50 mg/L). Treatment efficiency was significantly reduced when the numbers of Bacillus genus in the bioreactors decreased below $10^6CFU/mL$. The automated RABC (A-RABC), in which dissolved oxygen concentrations are automatically controlled, showed higher treatment efficiencies compared to the RABC process. The RABC system maintained sufficient bacterial numbers for the effective treatment of highly concentrated food wastewater. Moreover, final effluent was in agreement to water quality standards.

• Korean Journal of Veterinary Service
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• v.20 no.2
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• pp.169-175
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• 1997

This study was carried out to assess the effect of the chlorine treatment into water for processing chicken products in each stage of slaughtering, with a special viewpoint related with reducing the viable number of microorganisms by which the water and the chicken body were contaminated. The mean bacterial number on chicken samples after picking process was log5.37$\pm$0.20~5.84$\pm$0.160CFU/$\textrm{cm}^2$. When assessed by standard plate count method, it was the higher one than any other processing stage in which eviscerating, pinning, packaging, and chilling was followed in order of the mean bacterial number. The coliform bacterial numbers on carcasses after sampling from different processing stages were log2.11$\pm$0.63~2.88$\pm$0.25MPN/$\textrm{cm}^2, which show almost similar numbers in each processing stage. But, after chilling process the number was decreased slightly. The bacterial counts in the water for scalding and chilling showed log3.43 $\pm$ 0.59~5.06$\pm$0.21 and log4.30$\pm$0.21~6.62$\pm$0.33CFU/$m\ell$, respectively. In the coliform counts for the water taken out from the 2nd chilling tank, the number was log1.97$\pm$0.35~2.91$\pm$0.22MPN/$m\ell$ which showed higher than those of the 1st and the 3rd chilling tank water. The effect of chlorination in reducing the bacterial numbers was accepted at the residual chlorine concentration of 1$m\ell$/$\ell$by showing the reduction from $10^8$ to $10^4$CFU level and the numbers were decreased less than 10CFU at the concentration of 5mg/$\ell$, when assessed by viable cell counts. In conclusion, these results suggested that chlorination In chilling water with final concentration of 5mg/$\ell$was strongly recommended to reduce the bacterial numbers on final chicken products.

• Journal of Microbiology
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• v.41 no.3
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• pp.262-265
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• 2003

Although enumerating bacterial cells is a fundamental step in understanding microbial ecosystems in marine environments, substantial decrease in bacterial counts with increasing sample storage time hampers the accurate estimation of bacterial biomass. We compared the variations in bacterial cell numbers caused by freezing and thawing of sample bottles or slides. Bacterial counts of seawater samples frozen only once in a sampling bottle yielded approximately 95％ of the original numbers after 90 days, whereas 80％ of the original count was obtained for samples prepared on slides. Only 67％ and 58％ of the original counts were recovered in samples repeatedly frozen and thawed in bottles or on slides, respectively. The results indicated that freezing a seawater sample in a bottle increased the consistency of the epifluorescence microscopic enumeration of bacterial cells.

• The Journal of Natural Sciences
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• v.16 no.1
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• pp.143-154
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• 2005

To define the ecological roles of bacterial community in Daechung Reservoir. Vertical variation of total bacterial numbers were estimated at MAN site for one year with DAPI staining. The bacterial numbers were counted, environmental factors were monitored at the surface, -5m, -10m, -15m and -25 m of MAN sited and tried to explain the vertical bacterial numbers with environmental factors. The bacterial number was $1.6-1.7.0 x10^6$ cells/ml at the surface, $2.3-11.0x10^6$ cells/ml at 5 m depth, $1.2-1.4.0x10^6$ cells/ml at 10 m depth, $1.4-15.0x10^6$ cells/ml at 15 m depth and $1.4-1.3.0x10^6$ cells/ml at 25 m depth. The Mean bacterial number at the surface was more that those at any other depth. The explanation of the vertical total bacterial numbers with environmental factors were suggested.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.283-288
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• 2008

Plant leaf surface is an important niche for diverse epiphytic microbes, including bacteria and fungi. Plant leaf surface plays a critical frontline defense against pathogen infections. The objective of our study was to evaluate the effectiveness of a starch-based super-absorbent polymer(SAP) combination, which enhances water potential and nutrient availability to plant leaves. We evaluated the effect of SAP on the maintenance of bacterial populations. In order to monitor bacterial populations in situ, a SAP mixture containing Pseudomonas syringae pv. tabaci that expressed recombinant green fluorescent protein(GFPuv) was spray-challenged onto whole leaves of Nicotiana benthamiana. The SAP combination treatment enhanced bacterial robustness, as indicated by disease severity and incidence. Unexpectedly, bacterial numbers were not significantly different between leaves treated with the SAP combination and those treated with water alone. Furthermore, young leaves treated with the SAP combination had more severe symptoms and a greater number of bacterial spots caused by primary and secondary infections compared to young leaves treated with the water control. In contrast, bacterial cell numbers did not statistically differ between the two groups, which indicated that measurement of viable GFP-based bacterial spots may provide a more sensitive methodology for assessing virulence of bacterial pathogens than methods that require dilution plating following maceration of bacterial-inoculated leaf tissue. Our study suggests that the SAP combination successfully increased bacterial aggressiveness, which could either be used to promote the ability of biological agents to control weedy plants or increase the robustness of saprophytic epiphytes against competition from potentially harmful microbes.

• Journal of Microbiology
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• v.37 no.1
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• pp.10-13
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• 1999

The bacterial abundance, proportion of respiring bacteria, and bacterial community of southern Lake Baikal were analyzed at 1 m and 400m depths during winter. The total bacterial numbers were 5.1${\times}$105 cells ml-1 at 1 m and 2.5${\times}$105 cells ml-1 at 400 m depth, which are about half and quarter of the numbers of other lakes. The proportion of respiring bacteria was as low as 2.5% at 1 m and 1.4% at 400 m depth. Considering the amount of organic carbon which need to be degraded and low proportion of respiring bacteria, the bacteria could be assumed to have high activities. The EUB/DAPI ratios were 77 and 89% at 1 m and 400 m depths, respectively. Of the bacterial community, the other group was dominant at both depths, and gamma group of protebacteria followed next. But the beta group of proteobacteria and Cytophaga-Flavobacterium groups occupied very small proportions.

• Journal of Microbiology
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• v.44 no.5
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• pp.572-576
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• 2006

To obtain primary idea on oral bacterium species that are generally present in periodotally healthy Koreans, the oral bacterial flora in the saliva of four periodontally healthy Koreans at different ages (5, 32, 35, 65) was investigated in this study. For this investigation, 16S rRNA gene clone libraries were generated from the saliva of the four healthy Koreans, and 50 clones were randomly selected from each saliva clone library and sequenced. Totally, 37 different kinds of bacterial 16S rRNA gene sequences were identified based on sequence homology search through GenBank database. The 37 kinds of saliva clone sequences were classified to 14 genera and 2 uncultured and 1 unidentified bacteria. Among the 14 identified genera, Streptococcus, Prevotella, and Veillollella were common genera, and Streptococcus was dominant genus that accounted for 7 different species. Among the seven Streptococcus species, S. salivarius appeared as the most common species. More numbers of species belonging to the genera Streptococcus and Prevotella was present in saliva from ages 32 and 35. While saliva from ages 5 and 65 showed more numbers of species belonging to the genera Rothia, including potential pathogenic species. Overall, saliva of a young child and a senior showed higher bacterial diversity than that of young adults.