綠球藻屬

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綠球藻屬
Chlorella vulgaris NIES2170.jpg
Chlorella vulgaris
科学分类 编辑
界: 植物界 Plantae
门: 绿藻门 Chlorophyta
纲: 共球藻綱 Trebouxiophyceae
目: 小球藻目 Chlorellales
属: 綠球藻屬 Chlorella
M.Beijerinck, 1890
物種

部分物種,見內文

綠球藻屬(學名:Chlorella)是共球藻綱小球藻科之下的一個單細胞绿藻[1][2],是一種於水面浮生的植物。綠球藻屬物種能夠在簡單環境裡通過光合作用迅速繁殖,只需要提供足夠的二氧化碳陽光和少量礦物質[3]

本屬物種為常見營養補充品「綠藻」常用的物種。現時全球規模最大的綠球藻養殖基地位於琉球八重山群島。 另外,本屬物種過往及現在亦同時用於治理污水、以及試圖利用人類的小便來培養本屬物種(包括Chlorella sorokiniana[4]Chlorella vulgaris[5][6]

語源[编辑]

綠球藻的學名Chlorella來自於希臘語字根 χλώροςchloros,綠色)和拉丁語的後綴ella(小)。

發現與研究歷史[编辑]

綠球藻是由荷蘭微生物學者马丁努斯·威廉·拜耶林克於1890年間在河流湖泊中發現[1];而1931年獲诺贝尔生理学或医学奖的癌症研究權威的德國生物化學家細胞生理學家奥托·海因里希·瓦尔堡是第一個以綠藻進行生物學研究的學者[1]。 1961年,美國加州大學梅尔文·卡尔文以綠球藻研究植物中二氧化碳同化的途徑而榮獲诺贝尔化学奖

型態與特徵[编辑]

綠球藻顧名思義有着球形的外型,直徑約2到10微米,沒有鞭毛,但有細胞壁,由多層纖維素框架組成。綠球藻屬物種細胞有葉綠體和和散落在細胞質線粒體。葉綠體含有綠色光合色素葉綠素-a-b,其比例與一般高等植物相同[7]

分類學[编辑]

綠球藻屬物種的單系性仍然存疑:儘管其父系分類單元已不斷將關係較遠的物種分出去,現時的綠球藻仍然被認為是一個並系群,包含不少因為趨同效應而有着相似型態的物種。

部分物種[编辑]

目前普遍同意為本屬成員的物種有24個,以下為當中部分物種:

食用[编辑]

許多人認為綠球藻可以作為食物和能源的潛在來源,因為它的光合效率英语photosynthetic efficiency理論上可以達到8%[8],超過其他諸如甘蔗之類的高效作物。

早在1960年代,《人民日报》引述中國科學院水生所的研究,發現綠球藻屬物種的蛋白质含量高達30%以上,可治療當時中國國民因為长期营养不良而导致的浮肿病[9]。1960年10月,秘书胡喬木呈書毛澤東稱,推廣綠球藻,既可治浮腫,又能“保證不餓死人”。1960年10月27日毛将胡乔木的信批转全國,開始大力推廣,大规模用人尿来培植綠球藻。 事實上,乾燥的綠球藻屬物種的蛋白質含量可高達45%,還有20%脂肪酸,20%碳水化合物,5%食用纖維,10%礦物質及維生素。因此現時已有健康食品生產商在大型的人造圓塘大量生產綠球藻以供食用。

當科學家首次大規模的收穫養殖的綠球藻時,認為這些綠球藻將會是人類飲食中廉價的蛋白質補充劑的來源。一些倡導者有時專注於藻類的其他假定的健康益處,例如體重控制癌症預防免疫系統支持英语immune system enhancer[10]。據美國癌症協會聲稱:「可用的科學研究不支持其預防或治療癌症或任何其他人類疾病的有效性。」[11]

在某些生長條件下, 小球藻能夠產生多元不飽和脂肪含量高的油—小綠球藻Chlorella minutissima)可生產二十碳五烯酸,而且比例還佔總脂質的39.9%[12]

歷史[编辑]

在全球擔心在1940年代末到1950年代初期的「嬰兒潮」人口爆炸期,由於擔心人口不受控的增長會引發糧食危機,綠球藻被視為新的和有前途的主要食物來源,並且是當前世界飢餓危機的可能解決方案。在此期間許多人認為飢餓將是一個壓倒性的問題,並認為小球藻通過以相對較低的成本提供大量優質食物來結束這場危機[10]

許多機構開始研究藻類,包括卡內基研究所英语Carnegie Institution of Washington洛克菲勒基金會美國國立衛生研究院加州大學伯克利分校原子能委員會斯坦福大學第二次世界大戰之後 ,許多歐洲人正在挨餓,而不少馬爾薩斯主義者英语Malthusianism認為戰爭不是發生饑荒的主因。他們認為:全球糧食生產無法追上人口的增加,才是饑荒的主要成因。根據1946年一份FAO的報告,預期在1960年將要生產出比1939年的糧食產量多25到35%,才能趕上人口上的增長;而若要確所有人的健康,這個比例更要上調至90到100%[10]。Because meat was costly and energy-intensive to produce, protein shortages were also an issue. Increasing cultivated area alone would go only so far in providing adequate nutrition to the population. The USDA calculated that, to feed the U.S. population by 1975, it would have to add 200 million acres (800,000 km²) of land, but only 45 million were available. One way to combat national food shortages was to increase the land available for farmers, yet the American frontier and farm land had long since been extinguished in trade for expansion and urban life. Hopes rested solely on new agricultural techniques and technologies. Because of these circumstances, an alternative solution was needed.

To cope with the upcoming postwar population boom in the United States and elsewhere, researchers decided to tap into the unexploited sea resources. Initial testing by the Stanford Research Institute showed Chlorella (when growing in warm, sunny, shallow conditions) could convert 20% of solar energy into a plant that, when dried, contains 50% protein.[10] In addition, Chlorella contains fat and vitamins. The plant's photosynthetic efficiency allows it to yield more protein per unit area than any plant—one scientist predicted 10,000 tons of protein a year could be produced with just 20 workers staffing a 1000-acre (4-km2) Chlorella farm.[10] The pilot research performed at Stanford and elsewhere led to immense press from journalists and newspapers, yet did not lead to large-scale algae production. Chlorella seemed like a viable option because of the technological advances in agriculture at the time and the widespread acclaim it got from experts and scientists who studied it. Algae researchers had even hoped to add a neutralized Chlorella powder to conventional food products, as a way to fortify them with vitamins and minerals.[10]

When the preliminary laboratory results were published, the scientific community at first backed the possibilities of Chlorella. Science News Letter praised the optimistic results in an article entitled "Algae to Feed the Starving". John Burlew, the editor of the Carnegie Institution of Washington book Algal Culture-from Laboratory to Pilot Plant, stated, "the algae culture may fill a very real need,"[13] which Science News Letter turned into "future populations of the world will be kept from starving by the production of improved or educated algae related to the green scum on ponds." The cover of the magazine also featured Arthur D. Little's Cambridge laboratory, which was a supposed future food factory. A few years later, the magazine published an article entitled "Tomorrow's Dinner", which stated, "There is no doubt in the mind of scientists that the farms of the future will actually be factories." Science Digest also reported, "common pond scum would soon become the world's most important agricultural crop." However, in the decades since those claims were made, algae have not been cultivated on that large of a scale.

Current status[编辑]

Since the growing world food problem of the 1940s was solved by better crop efficiency and other advances in traditional agriculture, Chlorella has not seen the kind of public and scientific interest that it had in the 1940s. Chlorella has only a niche market for companies promoting it as a dietary supplement.[10]

Production difficulties[编辑]

The experimental research was carried out in laboratories, rather than in the field, and scientists discovered that Chlorella would be much more difficult to produce than previously thought. To be practical, the algae grown would have to be placed either in artificial light or in shade to produce at its maximum photosynthetic efficiency. Also, for the Chlorella to be as productive as the world would require, it would have to be grown in carbonated water, which would have added millions to the production cost. A sophisticated process, and additional cost, was required to harvest the crop, and, for Chlorella to be a viable food source, its cell walls would have to be pulverized. The plant could reach its nutritional potential only in highly modified artificial situations. Another problem was developing sufficiently palatable food products from Chlorella.[14]

Although the production of Chlorella looked promising and involved creative technology, it has not to date been cultivated on the scale some had predicted. It has not been sold on the scale of Spirulina, soybean products, or whole grains. Costs have remained high, and Chlorella has for the most part been sold as a health food, for cosmetics, or as animal feed.[14] After a decade of experimentation, studies showed that following exposure to sunlight, Chlorella captured just 2.5% of the solar energy, not much better than conventional crops.[10] Chlorella, too, was found by scientists in the 1960s to be impossible for humans and other animals to digest in its natural state due to the tough cell walls encapsulating the nutrients, which presented further problems for its use in American food production.[10]

用於二氧化碳還原和氧氣生產[编辑]

1965年,前蘇聯俄羅斯CELSS英语Controlled Ecological Life Support System實驗場所BIOS-3以大桶在人造光下養殖綠球藻,以去除實驗場所內的二氧化碳,並為內裡的人提供氧氣。實驗確定,只要有8平方米的暴露綠球藻面積,就可以為一個在密封環境內的成人去除其排出的二氧化碳,並替代以其所需的氧氣[15]

替代醫學[编辑]

一顆被壓成藥丸狀的綠球藻錠

綠球藻在美國和加拿大主要被作為健康補充劑銷售,而在日本則作為食品補充劑[16] 綠球藻有一些聲稱的健康影響[17],包括:治療癌症的能力[18]。 然而,根據美國癌症協會英语American Cancer Society的報告,“現有的科學研究不支持其預防或治療癌症或任何其他人類疾病的有效性”[18]

健康問題[编辑]

2002年曾有一項研究發現認為:綠球藻的細胞壁含有脂多醣,是一種在革蘭氏陰性菌中發現的內毒素,會影響免疫系統、並可能導致炎症[19][20][21] 。然而,較近期的研究認為:在革蘭氏陰性菌以外的生物體發現的脂多醣 ,例如在藍綠菌中的脂多醣與革蘭氏陰性菌中的脂多醣明顯不同[22]

水族箱[编辑]

當水族箱內有綠球藻,可令水的顏色變綠、降低水的透光度。這是由於在水族箱內其他生物排出的高濃度硝酸鹽磷酸鹽,在陽光直接照射下有助綠球藻生長。通過不斷補充新水,逐步替換水族箱內的水,有助減低水族箱內硝酸鹽和磷酸鹽的濃度;為水族箱遮光,亦能幫助緩解問題。

參看[编辑]

參考文獻[编辑]

  1. ^ 1.0 1.1 1.2 沈曉瑄. 綠球藻(Chlorella)的發現. [2018-03-20]. (原始内容存档于2011-12-31) (中文(繁體)‎). 
  2. ^ WoRMS. Chlorella M.Beijerinck, 1890. World Register of Marine Species. [2018-03-22]. 
  3. ^ Scheffler, John. Underwater Habitats. Illumin. 2007-09-03, 9 (4). 
  4. ^ Zhang, Shanshan; Lim, Chun Yong; Chen, Chia-Lung; Liu, He; Wang, Jing-Yuan. Urban nutrient recovery from fresh human urine through cultivation of Chlorella sorokiniana. Journal of Environmental Management. 2014-12-01, 145: 129–136 [2018-03-22]. doi:10.1016/j.jenvman.2014.06.013 (英语). 
  5. ^ Li, Ming; Liu, Hong; Tong, Ling; Fu, Yuming; He, Wenting; Hu, Enzhu; Hu, Dawei. The culture of Chlorella vulgaris with human urine in multibiological life support system experiments. COSPAR Scientific Assembly (Bremen, Germany). 18-15 July 2010, 38th: p.8 (英语). 
  6. ^ Jaatinen, S; Lakaniemi, AM; Rintala, J. Use of diluted urine for cultivation of Chlorella vulgaris. Environ Technol.. 2015-11-07, 37 (9): 1159–1170 [2018-03-22]. doi:10.1080/09593330.2015.1105300 (英语). 
  7. ^ http://formosa.ntm.gov.tw/seaweeds/b/b3_01.asp
  8. ^ Zelitch, I. Photosynthesis, Photorespiration and Plant Productivity. Academic Press. 1971: 275. 
  9. ^ 1960年7月6日《人民日报》刊出〈大量生产小球藻〉一文:“小球藻是单细胞水生植物。体积很小,一万个单体连起来,也只有三寸左右长。过去,它自然生长在池沼河渠中.在水面上泛起绿色泡沫,人们认为这是污水,是废物。现在,经过培养化验,证明它不是废物,而是宝物;一百斤小球藻干粉巾,含有四十五斤蛋白质,比大米的蛋白质含量高五倍半,比小麦高三倍多;含有脂肪约十五斤,比大米多十几倍,比小麦多六倍以上;此外,它还含有大量碳水化公物和各种维生素。根据对比试验证明,经常吃小球藻的猪,体重增加的速度约比不吃小球藻的猪快一倍左右。小球藻含有重要的药料和抗生素,有催生和防治疫病的作用,能帮助母猪受孕并多生猪仔,帮助乳牛增加产奶量,帮助病畜恢复健康。在小球藻培育成功并开始大量利用以后,各地陆续发现了和利用了大球藻、莲孢霉菌和金霉素菌等作饲料,也都具有很高的营养价值。”
  10. ^ 10.0 10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 Belasco, Warren. Algae Burgers for a Hungry World? The Rise and Fall of Chlorella Cuisine. Technology and Culture. 1997-07, 38 (3): 608–34. JSTOR 3106856. doi:10.2307/3106856 (英语). 
  11. ^ Chlorella. American Cancer Society. 2011-04-29 [2013-08]. (原始内容存档于2013-09-05) (英语). 
  12. ^ Yongmanitchai, W; Ward, OP. Growth of and omega-3 fatty acid production by Phaeodactylum tricornutum under different culture conditions. Applied and Environmental Microbiology. 1991, 57 (2): 419–25. PMC 182726. PMID 2014989. 
  13. ^ Burlew, John (编). Algal Culture-from Laboratory to Pilot Plant. Carnegie Institution of Washington. 1953: 6. ISBN 0-87279-611-6. 
  14. ^ 14.0 14.1 Becker, E.W. Micro-algae as a source of protein. Biotechnology Advances. 2007, 25 (2): 207–10. PMID 17196357. doi:10.1016/j.biotechadv.2006.11.002. 
  15. ^ Russian CELSS Studies. Space Colonies. Permanent. [3 November 2012]. 
  16. ^ Chlorella
  17. ^ Sun Chlorella, Going Green from the Inside Out – LA Sentinel
  18. ^ 18.0 18.1 Chlorella. American Cancer Society. 29 April 2011 [13 September 2013]. (原始内容存档于5 September 2013).  已忽略未知参数|df= (帮助)
  19. ^ Sasik, Roman. Trojan horses of Chlorella 'superfood'. Robb Wolf. 19 January 2012. 
  20. ^ Armstrong, PB; Armstrong, MT; Pardy, RL; Child, A; Wainwright, N. Immunohistochemical demonstration of a lipopolysaccharide in the cell wall of a eukaryote, the green alga, Chlorella. The Biological Bulletin. 2002, 203 (2): 203–4. PMID 12414578. doi:10.2307/1543397. 
  21. ^ Qin, Liya; Wu, Xuefei; Block, Michelle L.; Liu, Yuxin; Breese, George R.; Hong, Jau-Shyong; Knapp, Darin J.; Crews, Fulton T. Systemic LPS causes chronic neuroinflammation and progressive neurodegeneration. Glia. 2007, 55 (5): 453–62. PMC 2871685. PMID 17203472. doi:10.1002/glia.20467. 
  22. ^ Stewart, Ian; Schluter, Philip J; Shaw, Glen R. Cyanobacterial lipopolysaccharides and human health - a review. Environmental Health: A Global Access Science Source. 2006, 5: 7. PMC 1489932. PMID 16563160. doi:10.1186/1476-069X-5-7. 
  • 高華. 大饑荒中的「糧食食用增量法」與代食品 (中文). 

外部連結[编辑]