Advantageous characteristics of the diatom Chaetoceros gracilis as a sustainable biofuel producer

Table 7 Use of liquid fertilizer as the nutrient source in culture media

	2% supernatant of liquid fertilizer		0.5% liquid fertilizer		1% liquid fertilizer		2% liquid fertilizer
	1st subculture	2nd subculture	1st subculture	2nd subculture	1st subculture	2nd subculture	1st subculture	2nd subculture
Doubling time (h)	17.6 ± 0.5	12.5 ± 0.3	10.7 ± 0.1	14.5 ± 0.1	11.8 ± 0.1	11.6 ± 0.3	15.9 ± 0.7	15.8 ± 0.5
Cell density on 4th day (10⁶ cells/mL)	3.69 ± 0.06	4.87 ± 0.10	4.73 ± 0.12	4.61 ± 0.06	5.19 ± 0.08	6.65 ± 0.16	6.12 ± 0.09	6.88 ± 0.11
Cell density on 10th day (10⁶ cells/mL)	6.06 ± 0.37	6.69 ± 0.27	5.38 ± 0.05	5.59 ± 0.10	7.71 ± 0.01	8.75 ± 0.08	11.6 ± 0.1	9.88 ± 0.05
TAG on 10th day (mg/L)	220 ± 5	181 ± 3	94.9 ± 3.4	93.1 ± 3.8	165 ± 4	217 ± 15	213 ± 2	270 ± 15

Liquid fertilizer diluted tenfold (10% by vol) with pure water; resulting 10% solution, with or without removing suspended materials, diluted further to 5, 10, and 20% (v/v) with seawater to obtain indicated amounts of liquid fertilizer culture media; cells cultured in resulting medium; cells used to inoculate liquid fertilizer medium cultivated in F/2-enriched seawater (1st subculture) or subcultured once in same liquid fertilizer medium (2nd subculture); and n = 3

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