【摘要】：隨著全球經(jīng)濟的快速發(fā)展,各國普遍存在的水體富營養(yǎng)化現(xiàn)象日趨嚴重,藻類作為水生生態(tài)系統(tǒng)中重要的初級生產(chǎn)力,藻類水華的頻繁爆發(fā)已成為嚴重危害生態(tài)平衡,影響人類生產(chǎn)生活的重大環(huán)境污染問題[1]。也是現(xiàn)階段影響較大,危害范圍遍及全世界每一個水域的世界性問題[2]。因此,對于藻類水華及其引起的災害問題展開控制技術研究是極其迫切的。2015年,我國的115個湖泊中,處于富營養(yǎng)狀態(tài)的湖泊有90個,占比高達78.3%[3],不但嚴重破壞了水生態(tài)平衡,同時水體富營養(yǎng)狀態(tài)下,水華藻類的爆發(fā)使藻類代謝產(chǎn)生的藻毒素急劇增加,給人類健康和正常的生產(chǎn)生活帶來巨大威脅[4]。溶藻細菌等微生物是水生態(tài)系統(tǒng)中的重要組成部分之一,還具有天然易得、經(jīng)濟、環(huán)境友好、作用明顯等特點,在控制藻類生長,維持其數(shù)量平衡上起重要作用[5],也受到越來越多的關注[6-7]。研究溶藻微生物對水華藻類的去除機理,篩選復配出高效溶藻細菌,研發(fā)溶藻微生物藥劑,對富營養(yǎng)化水體的預防和治理具有重要意義[8]。從本地富營養(yǎng)化水體中分離純化出7株細菌,編號S1～S7,其中3株(S4、S_5、S7)能使銅綠微囊藻液黃化,最后選擇溶藻效果最好,藻液黃化程度最顯著的S_5細菌作為本文的研究菌株。對S_5菌株進行初步鑒定和毒性檢測,然后將其作用于銅綠微囊藻,驗證其溶藻效果,繼而對其溶藻機理進行簡單探究,最后將其應用于人工采集的天然富養(yǎng)化水體中。對實驗數(shù)據(jù)進行總體歸納,得出以下幾項結(jié)論。1、結(jié)合細菌形態(tài)觀察、染色試驗和生理生化試驗等方法,對菌株S_5進行初步鑒定,依據(jù)《常見細菌系統(tǒng)鑒定手冊》和《伯杰氏細菌鑒定手冊》,初步鑒定S_5菌株為芽孢桿菌屬,具體種屬有待在分子水平上繼續(xù)研究。2、使溶藻細菌S_5作用于藍斑馬魚,對其進行生態(tài)毒理安全性檢測,檢測證實,溶藻細菌S_5對作用對象的生長無影響,且沒有遺傳毒性。3、將溶藻細菌S_5按3%、6%、9%和12%的體積比加入到銅綠微囊藻液中,結(jié)果表明,相比對照組,在菌液投加第7天時,9%組藻細胞數(shù)和葉綠素a含量分別降低82.65%和74.71%;第9天時,12%組兩指標分別降低82.56%和77.14%。且S_5細菌對藻細胞數(shù)量和葉綠素a含量的影響大致相同,一定濃度范圍內(nèi),菌液濃度越高,對銅綠微囊藻的溶解效果越明顯。但綜合考慮操作步驟及成本,建議實際處理中,使S_5菌液投加量為銅綠微囊藻液體積的9%,且第7天即可達明顯的除藻效果。4、分別向銅綠微囊藻中加入不同方式處理得到的菌懸液、高溫處理菌懸液、上清液、高溫處理上清液、細菌液體培養(yǎng)基及S_5原菌液,探究S_5細菌的溶藻方式,實驗證明S_5是通過釋放熱穩(wěn)定的胞外物質(zhì)來間接溶藻的。然后通過上清液的呈色反應對溶藻活性物質(zhì)進行研究,結(jié)果表明,S_5釋放的胞外物質(zhì)為熱穩(wěn)定的糖類物質(zhì)。5、向富營養(yǎng)狀態(tài)的天然采集水體中投加9%(v/v)的S_5菌液,15天后分析藻類群落結(jié)構(gòu)發(fā)現(xiàn),加入S_5后水體藻類的總密度由1.75×106個/L下降到1.09×106個/L,藻類去除率達62.29%。進一步分析藻類的組成:水體優(yōu)勢種由最初單一且絕對優(yōu)勢的斜生柵藻變?yōu)橛伤奈矕旁濉⑿鄙鷸旁搴筒欢ㄎ⒛以骞餐瑯?gòu)成優(yōu)勢種,三者共占藻類總量的56.61%,同時多樣性指數(shù)和均勻度指數(shù)均呈上升趨勢,而不加菌的反應池中兩個指數(shù)均有所下降,且優(yōu)勢種種類不變。
[Abstract]:With the rapid development of the global economy, the eutrophication of water bodies is becoming more and more serious. As an important primary productivity in aquatic ecosystem, algae blooms have become a serious ecological balance and a major environmental pollution problem affecting human production and life. In 2015, 90 of the 115 lakes in China were in eutrophic state, accounting for 78.3%[3], which not only seriously destroyed the water ecological balance, but also the water body. Under the eutrophic condition, algae blooms increase algae toxins produced by algae metabolism dramatically and pose a great threat to human health and normal production and life [4].Algolytic bacteria and other microorganisms are one of the important components of the aquatic ecosystem, and also have the characteristics of natural, economic, environment-friendly and obvious role in controlling algae. Growth and quantity balance play an important role [5], but also attracted more and more attention [6-7].To study the removal mechanism of algae by algae-lysing microorganisms, to screen and compound high-efficient algae-lysing bacteria, and to develop algae-lysing microbial agents are of great significance for the prevention and control of eutrophic water bodies [8]. Seven strains of bacteria were purified and numbered S1-S7. Among them, three strains (S4, S 5, S7) could cause the chlorosis of Microcystis aeruginosa. Finally, the S_5 bacterium with the best algal lysis effect and the most significant algal chlorosis degree was selected as the research strain. The algae-dissolving mechanism was explored and applied to the naturally enriched water. The experimental data were summarized and the following conclusions were drawn. 1. Strain S_5 was preliminarily identified by combining the methods of bacterial morphology observation, dyeing test and physiological and biochemical test. The results were in accordance with < Handbook for Identification of Common Bacterial Systems > and < Berger's Bacteria Identification Manual >, preliminary identification of Bacillus sp. S_5 strain, specific species to be further studied at the molecular level. 2, the algae-lysing bacteria S_5 acting on blue zebrafish, its ecological toxicological safety testing, detection confirmed that algae-lysing bacteria S_5 has no effect on the growth of the target, and no genetic toxicity. 3, the algae-lysing bacteria will be fine. The results showed that the number of algae cells and the content of chlorophyll a in 9% group decreased by 82.65% and 74.71% respectively on the 7th day, and that in 12% group decreased by 82.56% and 77.14% respectively on the 9th day. But considering the operation steps and cost, it is suggested that the dosage of S_5 should be 9% of the liquid volume of Microcystis aeruginosa, and the algae removal effect could be obvious on the 7th day. The results showed that S_5 could dissolve algae indirectly by releasing heat-stable extracellular substances. Then the algae-dissolving active substances were studied by color reaction of supernatant. The results showed that the extracellular substance released by S_5 was a heat-stable carbohydrate.5, and 9% (v/v) S_5 bacterial solution was added to the natural eutrophic water. After 15 days, the algae community structure was analyzed. The total algae density decreased from 1.75 106/L to 1.09 6550 The dominant species in the water body changed from single and absolute dominant species to four-tailed species. The dominant species consisted of two kinds of algae, namely, four-tailed species, oblique species and adventitious microcystis, accounting for 56.61% of the total algae. Meanwhile, the diversity index and evenness index increased, while the two indexes in the non-bacterial reaction pool decreased, and the dominant species were found. Unchanged.
【學位授予單位】：遼寧大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X52;X172

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