• Journal of The Korean Society of Grassland and Forage Science
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• v.39 no.4
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• pp.227-234
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• 2019

This study was performed to investigate the effect of heat-stressed environment on rumen microbial diversity in Holstein cows. Rectal temperature and respiration rate were measured and rumen fluid was collected under normal environment (NE; Temperature humidity index (THI)=64.6) and heat-stressed environment (HE; THI=87.2) from 10 Holstein cows (60±17.7 months, 717±64.4 kg) fed on the basis of dairy feeding management in National Institute of Animal Science. The rumen bacteria diversity was analyzed by using the Illumina HiSeq^TM 4000 platform. The rectal temperature and respiratory rate were increased by 1.5℃ and 53 breaths/min in HE compared to that in NE, respectively. In this study, HE exposure induced significant changes of ruminal microbe. At phylum level, Fibrobacteres were increased in HE. At genus level, Ruminococcaceae bacterium P7 and YAD3003, Butyrivibrio sp. AE2032, Erysipelotrichaceae bacterium NK3D112, Bifidobacterium pseudolongum, Lachnospiraceae bacterium FE2018, XBB2008, and AC2029, Eubacterium celulosolvens, Clostridium hathewayi, and Butyrivibrio hungatei were decreased in HE, while Choristoneura murinana nucleopolyhedrovirus, Calothrix parasitica, Nostoc sp. KVJ20, Anabaena sp. ATCC 33047, Fibrobacter sp. UWB13 and sp. UWB5, Lachnospiraceae bacterium G41, and Xanthomonas arboricola were increased in HE. In conclusion, HE might have an effect to change the rumen microbial community in Holstein cows.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.1
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• pp.70-75
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• 1986

The population and kinds of algae causing the waterbloom on the rice seedling bed and the damage of young rice plant by the nuisance green phytoplanktonic algae in rice field were studied to find out the efficiency of fertilizers and the effect of methods of fertilizers application in the rice field, laboratory, pot and green house. pot and green house. The results obtained were summarized as follows; 1. In the rice seedling bed, the kinds of algae causing waterblooms were identified mainly photosynthetic bluegreen algae as the Anabaena, Ulothrix and Oscillatoria spp. in reclaimed saline soil. Micromonospora, Oscillatoria, and Chlamydomonas spp. were habitated mainly in plain. Whereas, Spyrogyra, Oscillatoria and Navicula spp. were identified mainly in mauntainous area. 2. In the rice field, the nuisance phytoplanktonic green algae were identified mainly Scenedesmus, Chlamidospora, and Micromonospora spp. in Gimjae plain, in Namweon mountainous area and Gangjin costal plain, respectively. 3. The algal biomass has been havily habitated in which rice field were constituted with high pH value and high concentration of $NH^+_4-N$ and $NO^-_3-N$ in surface water and in soil with the optimum temperature for the algal growth ($22-30^{\circ}C$). 4. In the laboratory experiment, maximum algal biomass were obtained at levels of 80 ppm for the nitrogen and 20 ppm for the phosphorus. And were obtained of the levels of 40 ppm in the case of joint application of N and $P_2O_5$. 5. From the pot experiment, compare of the control plot, an addition of nitrogen alone or nitrogen+phosphorus enhanced algal biomass while the phosphorus alone did not. 6. Surface application of fertilizer was remarkably increased of algal biomass than did the whole layer or deep layer application.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.640-651
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• 2019

The study analyzed the relationship between harmful cyanobacteria and physicochemical factors in Lake Juam from 2005 to 2018. The research locations were designated St. 1 (Juam-Dam) and St. 2 (Sinpyong). Harmful cyanobacteria was found in four genera (Microcystis sp., Anabaena sp., Aphanizomenon sp., Oscillatoria sp.). The average standing crops of harmful cyanobacteria in both locations were 2,575 cells mL^-1 and 2,557 cells mL^-1 from 2005 to 2011. Since 2012, there has been a significant decrease that the measurements were 42 cells mL^-1 and 82 cells mL^-1 from 2012 to 2018. To analyze the reason for the decrease in harmful cyanobacteria, Pearson's correlation and t-tests were performed on data collected during the summer period (June-September). Pearson's correlation showed a significantly positive correlation with total nitrogen(TN), outflow, and storage and a negative correlation with electrical conductivity. T-tests were conducted in two different periods and showed decreases in total nitrogen, electrical conductivity, and residence time. The average rainfall was decreased from 263.3 mm (2005-2011) to 219.9 mm (2012-2018) and total nitrogen was decreased from 0.912 mg L^-1 (2005-2011) to 0.811 mg L^-1 (2012-2018) and the same variability was seen in TP (total phosphorus). Therefore, it seems that the low-rainfall decreased the nutrients (TN) and variability in the TP, resulting in a decrease in harmful cyanobacteria in Lake Juam.