• Ocean and Polar Research
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• v.39 no.4
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• pp.245-255
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• 2017

There are a number of pieces of evidences that suggest a link between marine diatoms and microorganisms, but knowledge about related microbial communities is greatly lacking. The present study investigated the microbial community structures related to the growth of the marine diatom Cyclotella meneghiniana. We collected free-living bacteria (FLB) and particle-associated bacteria (PAB) at each growth stage (e.g., lag, exponential, stationary and death) of the diatom, and analyzed their bacterial 16S rDNA using pyrosequencing. Metagenomics analysis showed that community structures of FLB and PAB differed considerably with the progress of growth stages. FLB showed higher diversity than PAB, but variation in the different growth stages of C. meneghiniana was more evident in PAB. The proportion of the genus Hoeflea, belonging to the order Rhizobiales, was dominant in both FLB and PAB, and it gradually increased with the growth of C. meneghiniana. However, Enhydrobacter clade tended to considerably decrease in PAB. In addition, Marinobacter decreased steadily in FLB, but first increased and then decreased in PAB. These results suggest that Hoeflea, Enhydrobacter, and Marinobacter may be closely related to the growth of diatom C. meneghiniana.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.692-699
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• 2003

The changes of physicochemical and microbiological states of Myeolchi-jeot, a Korean salted and fermented anchovy, were investigated during 20 days of storage at $4^{\circ}C,\;15^{\circ}C,\;and\;30^{\circ}C$. A total of 314 bacterial strains isolated from Myeolchi-jeot samples at different time intervals were identified, and their abilities to produce biogenic amines were determined by both decarboxylating agar media and HPLC analysis. The salinity and water activity of Myeolchi-jeot changed little, while the pH increased slightly over 20 days at the tested temperatures. A significant increase of total plate count was observed in the sample stored at $30^{\circ}C$. Staphylococcus spp. were dominant in Myeolchi-jeot, and its amine productivity was very weak. Bacillus spp. appeared increasingly with the progress of storage at all temperatures tested, and the increase was considerably dependent on the increase of storage temperature. Also, 58-73%, 83-90%, 81-90%, and 83-93% of Bacillus strains had the ability to produce histamine, tyramine, putrescine, and cadaverine, respectively. Therefore, the main amine producer in Myeolchi-jeot stored for a long period seems to be the genus Bacillus, especially B. licheniformis.

• ALGAE
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• v.22 no.3
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• pp.185-192
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• 2007

A study was carried out in nine fertilized fish ponds under three treatments (T-I, T-II and T-III) at Bangladesh Agricultural University, Mymensingh to see the bloom of euglenophytes with the intention of observing its impact on the growth of fish in culture condition. Some water quality parameters viz., temperature, dissolved oxygen, pH, PO4-P and NO3-N concentration and some biological parameters viz., phytoplankton population and growth of fish were monitored at fixed intervals. Euglenophytes showed a heavy bloom in late August in the ponds of T-II. The bloom was occurred by the genera, Euglena, Phacus and Trachelomonas of which Euglena was the most dominant genus. In relation of water quality parameters with euglenophytes bloom, it was hypothesized that euglenophytes prefers higher temperature and acidic environment with higher nutrient concentrations. Acidic environment and nutrient enrichment enhanced the bloom of euglenophytes which hampered the growth of other beneficial algal groups (chlorophytes and bacillariophytes) and fish. Due to heavy bloom, the fishes breathed with difficulty at the surface. The fishes in the heavy bloom ponds presented the weight values were lower than verified for those in the ponds where the bloom did not occur. Total production (calculated) of fish in different treatments ranged from 1355.89 to1760.63 kg ha–1 with significantly (p < 0.05) lowest in the ponds of T-II.

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.76-84
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• 2014

This study was performed to monitor the effects of water level change on changes of landscape, vegetation community, and species diversity of riparian forest. Hantan river dam, study area, has been constructed in the area of Chansoo-myeon, Pocheon-si and Yeoncheon-eup, Yeoncheon-gun, Gyeonggi-do, which is a dam for flood control only in flooding season. Landscape changes were notable after the construction of coffer dam, and the changes were caused by water level increase in areas of riparian forests which consisted of mainly withered willow as a dominant species in the flooding season. It changed vegetation communities of riparian forest from Phragmites japonica and Salix koreensis to Phragmites japonica. Species diversity index was lowest in 2010 when the coffer dam was constructed and showed an increasing trend later. Thus, this study is well in agreement with a previous report that plants of the genus Salix wither by muddy water during flooding and also suggests, controlling water level of river and prediction of water level change's effects should be considered when any facilities are planned.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.48 no.2
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• pp.113-119
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• 2003

Soybean sprout pathogenic bacteria were isolated from the large, deep containers of a commercial factory. Over a period of one year, 40 pathogenic-like bacteria were isolated among a total of 732 isolates. In addition to bacteria previously reported to be associated with rotting, such as Pseudomonas putida and Erwinia carotovora, several other genera were also identified: Acinetobacter spp., Chryseobacterium spp., Klebsiella sp., Pantoea agglomerans, Bacillus sp. Fatty acid methyl ester (FAME) analysis using the Microbial ID (MIDI) system, and 16s rRNA sequence analysis, yielded identical results, confirming the identities of these microorganisms. Several types of selective media were not good for identification and determination of population structure in commercial environments, as colony type was not specific to the genus. There was no dominant bacterium, and we were not able to find the main bacterium responsible for soybean spout rot. Even though we did not identify a major target for controlling rot or screening for resistant cultivars, the results of this study indicated that bacterial rot of soybean sprout is endemic. In addition, it emerged that factory epidemics in summer are not caused by the bacteria isolated in this study.

• Journal of Life Science
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• v.14 no.1
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• pp.163-166
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• 2004

To investigate the bacterial growth on granular activated carbon (GAC) for the purification of tap water, fixed bed columns with GAC were installed and operated at an empty bed contact time (EBCT) of 1 min$\pm$0.08 min. There was no bacterial breakthrough in the spring. However, the bacterial concentrations of effluent (($10^3$ CFU/ml) were higher than that of the influent ($10^2$ CFU/ml) after 10 day operation in summer. More bacteria were enumerated near the entering point of the tap water, while the bacterial activities were similar throughout the columns. Different bacterial species were detected on coal- and plant-based GAC, although the dominant genus was the same as Acinetobacter.

• The Korean Journal of Mycology
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• v.20 no.4
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• pp.302-308
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• 1992

Seven genera and 15 species of fungi were isolated from 50 samples of then different steps of dried onion (5 samples of each step) collected from an onion factory in Sohag Governorate, Egypt, and grown on glucose-Czapek's agar (7 genera and 15 species) and 10% NaCl glucose-Czapek's (2 genera and 6 species). The average total counts of fungi were gradually decreased throughout the different steps of drying from 2090 to zero and 152 to zero colonies/g on glucose-Czapek's agar and 10% NaCl glucose-Czapek's agar media, respectively. Aspergillus was the most common genus on the two types of media used. The dominant species were Aspergillus niger, A. flavus, A. terreus, Penicillium chrysogenum and Fusarium of oxysporum on glucose-Czapek's agar and A. terreus and A. niger on 10% NaCl glucose-Czapek's agar. The chloroform extracts of different samples were tested for the presence of mycotoxins using thin layer chromatographic analysis. The results indicated that aflatoxin was present at concentrations decreased throughout the different steps of the drying from step No. 1, onion bulbs, $120\;{\mu}g/kg$; to step No. 8, standard A, $20\;{\mu}g/kg$ while step Nos. 9 & 10 (completely dry powdered onion) were free from aflatoxin. Citrinin was also present in the first three steps at concentrations gradually decreased from 30 to 10 mg/kg.

• Weed & Turfgrass Science
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• v.3 no.3
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• pp.190-195
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• 2014

Echinochloa (L.) P. Beauv. includes some of the noxious weeds, causing a serious yield loss when they are dominant in the fields. Identification of the Echinochloa is very difficult because many interspecific and intraspecific forms of the species are found. However, it is important to identify the species exactly and to know the genetic diversity of the species for effective weed management. This study was conducted to identify and summarize the Echinochloa species by comparing the genetic variation and relationship among Korean Echinochloa species using SSR. The genetic diversity of 107 individuals, including seven species were assessed using five SSR markers. UPGMA dendrogram generated two clades (I and II) and clade II divided again into two subclades (II-1 and II-2) whereas the model based genetic structure proposed four subpopulations. The two subpopulations were corresponded to clades I and II-1 and the other two were arranged to clade II-2 of the UPGMA dendrogram. We have concluded that E. colona and E. glabrescens might have not distributed in Korea. The biological varieties, praticola and echinata, of E. crus-galli should be treated as E. crus-galli. Korean Echinochloa should be summarized with four species, i.e., E. oryzicola, E. crus-galli, E. esculenta, and E. oryzoides.

• Environmental Engineering Research
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• v.23 no.4
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• pp.420-429
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• 2018

Soil stabilization is a soil remediation technique that reduces the mobility of heavy metals in soils. Although it is a well-established technique, it is nonetheless essential to perform a follow-up chemical assessment via a leaching test to evaluate the immobilization of heavy metals in the soil matrix. Unfortunately, a standard chemical assessment is not sufficient for evaluation of the biological functional state of stabilized soils slated for agricultural use. Therefore, it is useful to employ a pyrosequencing-based microbial community analysis for the purpose. In this study, a recently stabilized site in the proximity of an exhausted mine was analyzed for bacterial diversity, richness, and relative abundance as well as the effect of environmental factors. Based on the Shannon and Chao1 indices and rarefaction curves, the results showed that the stabilized layer exhibited lower bacterial diversity than control soils. The prevalence of dominant bacterial populations was examined in a hierarchical manner. Relatively high abundances of Proteobacteria and Methylobacter tundripaludum were observed in the stabilized soil. In particular, there was substantial abundance of the Methylobacter genus, which is known for its association with heavy metal contamination. The study demonstrated the efficacy of (micro)biological assessment for aiding in the understanding and post-management of stabilized soils.

• The Plant Pathology Journal
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• v.35 no.4
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• pp.362-371
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• 2019

Plant phenotype is affected by a community of associated microorganisms which requires dissection of the functional fraction. In this study, we aimed to culture the functionally active fraction of an upland soil microbiome, which can suppress tomato bacterial wilt. The microbiome fraction (MF) from the rhizosphere of Hawaii 7996 treated with an upland soil or forest soil MF was successively cultured in a designed modified M9 (MM9) medium partially mimicking the nutrient composition of tomato root exudates. Bacterial cells were harvested to amplify V3 and V4 regions of 16S rRNA gene for QIIME based sequence analysis and were also treated to Hawaii 7996 prior to Ralstonia solanacearum inoculation. The disease progress indicated that the upland MM9 $1^{st}$ transfer suppressed the bacterial wilt. Community analysis revealed that species richness was declined by successive cultivation of the MF. The upland MM9 $1^{st}$ transfer harbored population of phylum Proteobacteria (98.12%), Bacteriodetes (0.69%), Firmicutes (0.51%), Actinobacteria (0.08%), unidentified (0.54%), Cyanobacteria (0.01%), FBP (0.001%), OD1 (0.001%), Acidobacteria (0.005%). The family Enterobacteriaceae of Proteobacteria was the dominant member (86.76%) of the total population of which genus Enterobacter composed 86.76% making it a potential candidate to suppress bacterial wilt. The results suggest that this mixed culture approach is feasible to harvest microorganisms which may function as biocontrol agents.