• Korean Journal of Microbiology
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• v.29 no.5
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• pp.339-343
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• 1991

Heterotrophic activity, total bacteria and salinity were determined seasonally in the estuary of Naktong River over half tidal cycle. Heterotrophic activity was determined by the uptake of [U- $^{14}$ C]glucose. Heterotrophic activity fluctuated with the tides and was decreased as salinity increased. Teh great activity occurred near low ebb tide at all seasons except summer. The main environmental factor affecting hetreotrophic activity was the salinity rather than water temperature in the estuary of Naktong River. In order to estimate the effect of salt, salt was added to estuarine water. Vmax for glucose of salt-added water was 17% and 77% of original estuarine water at station 1 and 2 respectively and slight increase was observed at station 3. Respiration rate and Kt+Sn for glucose of salt-added sample increased at all 3 stations. The increase of the Kt value implies the reduced affinity of bacterial population for glucose. The effects of salinity on the heterotrophic activity were more extensive in the upper region of estuary than at the mouth.

• Korean Journal of Microbiology
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• v.26 no.3
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• pp.256-261
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• 1988

Samples from Naktong Estuary had been taken for the characterization of heterotrophic bacterial communities and of the effects of environmental factors on their distribution in estuarine ecosystem. Bacterial communities isolated from seawater region were composed of more euryhalone groups than those from freshwater region, and the bacterial communities of summer were composed of more eurythermal groups than those of winter. Bacterial commnities became more diverse by the input of allochthonous bacteria from terrestrial and freshwater ecosystem, but less diverse by worse environmental conditions such as nutrient load, high salinity, low temperature, and so on.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.329-338
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• 1991

From July 1985 to December 1986, 28 variables of phycal-chemical factors, bacteria and heterotrophic activity were investigated 17 times at 3 stations in the estuary of Naktong River and the influences of environmental factors to bacterial population and heterotrophic activity were analyzed through multiple regression. The results of multiple regression were as follows. At station 1, total bacteria and heterotrophic bacteria(Z-25) could explain 57% of the variation of maximum uptake velocity for glucose and 54% of turnover time for glucose was explained by total coliform bacteria and MBOD, Sixty four percent of the variation of Kt+SN was accounted for salinity, MBOD-N and inorganic phosphate. Turnover rate for acetate was also accounted for the change of MBOD-P by 56%. At station 2 maximum uptake velocity for glucose depends on MBOD-N by 81%; turnover time on bacteria by 50%; Kt+Sn on avilable nutrient by 61%. More than 50% of maximum uptake velocity and turnover time for glucose were influenced by bacteria and that of Kt+Sn by the change of nutrient in the surface water of station 3. In the bottom water of station 3, the change of maximumuptake velocity, turnover time and Kt+Sn for glucose was controlled by total bacteria and available nutrient, bacteria, the change of nutrient salts respectively. On the whole, more than 50% of maximum uptake velocity and turnover time for glucose could be due to the change in the number of bacetria and the value of Kt+Sn was affected by the change of nutrient salts. Turnover rate for acetate was controlled by available phosphate at station 1 and by bacteria at station 2 and 3, which showed a distinct difference between the environmental factors which govern the rate of glucose and acetate uptake in the Naktong esturine ecosystem. And bacterial communities were controlled by available nutrients at station 1, by nutrient salts and salinity at station 2 and in the surface water of station 3 and by salinity in the bottom water of station 3.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.193-198
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• 1992

Environmental parameters and physiological characteristics of heterotrophic bacterial isolates were compared by factor analysis to investigate the influences of river barrage construction on the ecosystem of Naktong River Estuary. Aftcr the construction of river barrage, the influence of seawater was no longer significant. ant1 the influences of nutrients loading were increased from 50.7% to 77.1% of the environmental variances before and after the construction, respectively. The interpretations of features of bacterial physiological characteristics were closely related to environmental parameters as the results of factor analysis. But. differing from the environmental variances. it was found that the halophilic feature was the third factor of bacterial characteristics after the construction of river barrage. This suggests that the stability of Naktong estuarine ecosystem and heterotrophic bacterial characteristics are not established till now.

• Korean Journal of Microbiology
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• v.30 no.6
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• pp.444-449
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• 1992

A total of 858 heterotrohic bacteria were isolated and analyzed hy numerical method to investigate the heterotrophic hacterial community structure in Naktong Estuary. Although the values of H' (Shannon's diversity index). ranged between 1.54 and 3.49. were similar with those of the data hefore the construction of Naktong River barrage, however J' (evenness index. 0.31-0.80) was reduced. Physiological tolerance index for water temperature ($P_{s}$) was high at St.l and 2 whose depthes arc shallower than the other stations. and indices for pH ($P_{h}$) and salinity ($P_{s}$) were high at St. 2. 3. 4 where freshwater and seawater arc mixed. The predominant clusters were identified as Aeromonas. Vihrio. Pseudomonas. Acinelobacter-Morexella. Alcaligenes. Flavobacterium. Micrococcaccae. and Enterohacteriaceae. The kinds nf the isolates were similar with the previous result. hut the dominant genus was changed. These results suggest that the environmental changes in Naktong Estuary affect the hacterial physiological adaptation rather than the composition of heterotrophic hactcrial community.

• Korean Journal of Microbiology
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• v.26 no.3
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• pp.247-255
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• 1988

Using the numerical clustering method, 14 clusters (containing three or more strains) among 231 bacterial isolates from St. 1,17 clusters among 252 isolates from St.2,17 clusters among 301 isolates from St.3, and 15 clusters among 260isolates from St.4 were found at the 70% similarity value. The predominant organisms were identified as genera Aeromonas, Vibrio, and Alcaligenes at St.1, Alcaligenes at St.2, Aeromonas, Vibrio, and Moraxella-Acinetobacter group at St.3, and Pseudomonas at St.4.

• Korean Journal of Microbiology
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• v.27 no.4
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• pp.391-397
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• 1989

Population of Aeromonas and environmental parameters were investigated at three sites from August 1986, to December, 1986 in Naktong Estuary. The variation range of Aeromonas was $4.3\times10^{2}-4.6\times 10^{4}$ MPN/100ml. The result of ANOVA indicates significant differences among the populations of Aeromonas in each site. The highest population of Aeromonas occurred at site 2, and the lowest at site 3-B. To scrutinize the effects of environmental parameters on the distribution of Aeromonas spp, principal component analysis and multiple stepwise regression were used. The results showed that distribution of Aeromonas spp. was mainly influenced by outflow of freshwater and inflow of inorganic nutrients and correlated with heterotrophic bacteria, available nitrogen, fecal coliform bacteria, and temperature.