낙동강의 조류 및 방선균에 의한 이취 특성 연구 = Studies on odor characteristics of Nackdong river by algae and actinomycetes

다국어 초록 (Multilingual Abstract)

Water serves human and living organisms as a basic constituent. It is also essential material in agricultural, industrial as well as in service areas. Besides, as a key element for the maintenance of biological activity, we cannot think of life without water.
Daily average consumption of water in Korea was estimated as 360ℓ per day per person. Common criteria for the water quality standards are color, turbidity, taste and odor. Especially for drinking water, odor criterion should be strictly maintained to eliminate public distrust to drinking water.
Some of the biological source of odor from water are algae, actinomycetes, decaying organic matter, and secretion of metabolites. Among them, odors related to the growth of algae has been known for long times.
Nackdong river is rich in nutrients which support growth of algae. Therefore, diatom and cyanobacterial bloom recur every year in the Nakdong river. Moreover, there is also potentiality of natural actinomycetes odor which also needs microbiological investigation.
In this study, water quality, dominant algae, actinomycetes, geosmin and 2-MIB, the major known odor materials were investigated from January to December 2003 at 6 sites in the Nackdong river which serves as an important source of drinking water around the Youngnam region. Besides, odor producing actinomycetes were isolated from the Nackdong river, identified and their growth and production of geosmin and 2-MIB were characterized.
Conclusions derived from the results of the investigation are summarized as follows.
1. Among the algae occurred in the Nackdong river, major species of diatom were in the genus Stephanodiscus, Aulacoseira, Synedra Nitschia, major green algae was Actinastrum, major blue green algae were Microcystis and Lyngbya, and dominant flagellate algae was Cryptomonas. Especially, diatom in the genus Stephanodiscus was dominant during the low temperature drought season in the down stream stations.
2. Counts of actinomycetes in the Pungji site (upstream) were 22 CFU/㎖ on average with maximum value of 60 CFU/㎖. The counts in the Waekwan site (midstream) were 22 CFU/㎖ on average with maximum value of 70 CFU/㎖. As a whole the counts of actinomycetes in the up-and midstreams were higher than those in the downstream sites. In April, June, and September, counts of actinomycetes were increased presumably due to the rainfall which may have washed the soil inhabiting actinomycetes off to the river Little relationship were found between the counts and environmental factors such as temperature, pH, DO, COD, Chlorophyll-a, and nutrients (nitrate, TN, soluble phosphate, TP).
3. The odor materials, geosmin and 2-MIB were mainly detected in mid-and downstream sites, Koryoung, Namji, Mulkeum, and westnackdong-river during summer and autumn seasons along with the occurrence of odor producing algae such as Anabaena, Lyngbya and Oscijlatoria. Highest concentration of geosmin was found at Mulkeum site in September (202.3 ng/ℓ) and highest concentration of 2-MIB was found at Namji site in July(425.2 ng/ℓ). However both compounds were not detected from January to March when the diatom Stephanodiscus was dominant.
4. Odor producing microorganisms were isolated from the Nackdong river and identified according to their morphological (mycelium, spore),biochemical (carbon source assimilation), chemotaxonomical (structure of diaminopimelic acid, cell membrane fatty acid composition) and molecular biological (sequence of 16SrDNA) characteristics. Results of the tests for the taxonomic identification indicate that all 18 isolates belongs to the genus Streptomyces. The isolates were named as Streptomyces sp. YSY01~ YSY18.
5. Optimal pH for the growth of isolates was 7.0~7.9 and optimal temperature for growth was 20~25℃. Growth were severely retarded at temperatures higher than 30℃ and lower than 10℃.
6. When water sampled from Nackdong and Keumho river was inoculated with washed mycelia of the isolates such as Streptomyces sp. YSY01, small amount of geosmin and 2-MIB were detected temporarily. However, the conditions did not support the growth of mycelium. On the contrary, when starch was added to the filtrates of water from Nackdong river, Keumho river and Seungse stream and inoculated with the spores of the isolates, growth of the culture and production of geosmin and 2-MIB were increased in proportion to the amount of added starch.
7. Control solution of geosmin and 2-MIB (1,000 ng/ℓ) did not inhibit the luminescence of luminescent bacteria (Vibrio fischerii NRRL-B-1177). However, culture solution of the isolated actinomycetes exerted inhibition to the luminescent bacteria according to the increase in the amount of the mycelium. The results indicate that the luminescence inhibition toxicity of the Streptomyces culture to Vibrio fischerii NRRL-B-1177 may be caused by unknown metabolites rather than the effect of geosmin or 2-MIB.

목차 (Table of Contents)

• 목차 = ⅰ
• List of Tables = ⅲ
• List of Figures = ⅴ
• ABSTRACT = ⅸ
• Ⅰ. 서론 = 1
• Ⅱ. 연구사 = 3
• Ⅲ 재료 및 방법 = 8
• 1. 조사대상 낙동강의 개황 = 8
• 2. 조사지점 및 시료채취 = 9
• 3. 수질 분석 = 9
• 4. Geosmin, 2-MIB 분석 = 11
• 5. 식물성플랑크톤과 방선균 조사 = 13
• 6. 방선균의 분리·동정 = 13
• 7. 분리 방선균의 이취 생성 특성 조사 = 20
• 8. 발광세균을 이용한 발광저해도 조사 = 23
• Ⅳ. 결과 및 고찰 = 24
• 1. 낙동강의 수환경 = 24
• 가. 수질오염도(수온, pH, DO, BOD, COD, TOC) = 24
• 나. 영양염류농도 = 25
• 2. 조류의 계절변화 = 28
• 3. 낙동강의 방선균수 = 35
• 4. 낙동강의 geosmin 및 2-MIB = 39
• 5. 방선균의 분리 동정 = 45
• 가. 분리 방선균 균주의 형태 = 45
• 나. 생화학적 특성 = 53
• 다. 16SrRNA 분석 (Phylogenetic analysis) = 63
• 5. 분리 방선균의 이취 생성 특성 = 67
• 가. 분리 방선균의 최적 성장 = 67
• 나. 분리 방선균주의 배지종류별 이취 생성 = 69
• 다. 낙동강 수질과 분리 방선균주의 이취생성 특성 = 73
• 6. 발광세균에 의한 발광저해도 평가 = 84
• Ⅴ. 종합고찰 = 87
• Ⅵ. 결론 = 89
• 참고문헌 = 91
• Appendix = 99