Record Details
Growth of Aphanizomenon flos-aquae in defined media
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Growth of Aphanizomenon flos-aquae in defined media |
| Names |
O'Flaherty, Larrance Michael Arthur, 1941-
(creator) Phinney, Harry K. (advisor) |
| Date Issued | 1968-07-25 (iso8601) |
| Note | Graduation date: 1969 |
| Abstract | A strain of Aphanizomenon flos-aquae Born. et Flah. has been introduced into culture and maintained since August of 1964 in completely defined media. It exhibits the planktonic, colonial flake form found in nature, and both heterocysts and akinetes are present. The color and size of the flake and general appearance of the cells is substantially improved over that found at the time of collection in Upper Klamath Lake, Klamath County, Oregon. Initially, A. flos-aquae was isolated and cultured in a medium designated ASMT No, 8, a modification of the ASM of McLachlan and Gorham. ASMT No. 8 contained no organic substances other than disodium ethylenedinitrilotetra-acetate (Na₂EDTA) and Tris(hydroxymethyl) aminomethane (Tris). Experiments demonstrated that Tris was not essential for the growth of Aphanizomenon and the medium minus Tris was designated ASM No. 8. Factorial experiments indicated that better growth and morphological condition of the alga were obtained in media containing combinations of ferric chloride, Na₂EDTA and a new iron source, hydrogen ferric ethylenediamine di-o-hydroxyphenylacetate (EDDHA) than that obtained in ASMT No. 8. Best growth and condition of the alga was obtained in a medium designated ASM No. 8a which contained 0. 54 mg of ferric chloride, 3. 0 mg Na₂EDTA and 0, 07 mg of iron as EDDHA per liter. A. flos-aquae has been grown in ASM No. 8a for a year and a half. Factorial experiments gave evidence that there were significant interactions between the various mineral ions of ASM No. 8a, between the mineral ions and light intensity, light intensity and temperature, between different media, temperature and culture location, between culture location, temperature and light intensity and between different media, temperature and the quality of light used for the culture of the alga, Growth rate experiments and an analysis of covariance demonstrated that there was no significant difference between the growth rates of A. flos-aquae at different pH, temperatures or light intensities. The alga exhibited the same growth and morphological condition at pH from 6. 9 to 9. 2, and there was no significant difference in the growth rate or condition of Aphanizomenon cultured at temperatures of approximately 15 C and 20 C. The alga also exhibited the same response to culture under light from artificial sources at illumination intensities of 40, and approximately 70 or 110 ft-c. At light intensities above 140 ft-c, the alga exhibited chlorosis, loss of the colonial flake form or lysis. The alga showed both growth and good maintenance of condition in a north facing window at light intensities up to 300 ft-c supplied by natural daylight supplemented with light from fluorescent tubes. These light intensities were of variable magnitude and duration resulting from changes in cloud cover and day length. Preliminary experiments have shown that A. flos-aquae reduces acetylene and that the contaminant bacteria apparently do not. In addition, there was an indication that the rate of acetylene reduction was increased in relation to increasing concentrations of Vitamin B₁₂ (cobalamin). Further experiments need to be conducted using both acetylene reduction and N¹⁵ enriched nitrogen before a definitestatement can be made that Aphanizomenon does fix nitrogen. The growth of A. flos-aquae was definitely related to the concentration of nitrate nitrogen. There was a significant reduction in the mean yield of the alga when nitrate was omitted from ASM No. 8a, but the condition and morphology of the alga was unchanged. Nitrite nitrogen was not a suitable substitute for nitrate in the metabolism of the alga and higher concentrations of nitrite were toxic to Aphanizomenon. Bacteria-free cultures of Aphanizomenon were not obtained despite attempts at purification using pasteurization of akinetes contained in bottom sediments, ultraviolet irradiation and chlorine treatment of culture material. A screening test using antibiotics on both the alga and contaminant bacteria exhibited some promise that treatment with one or two antibiotics inhibited the bacteria without apparently killing the alga. |
| Genre | Thesis/Dissertation |
| Topic | Aphanizomenon |
| Identifier | http://hdl.handle.net/1957/46320 |
