Effects Of L-Carnitine Enrichment On Population Growth,Photosynthesis Capacity And Antioxidative Capacity In Two Species Of Microalgae

The object of this study was to identify the influence of L-Carnitine enrichment on population growth, absorptivity rate of nitrogen(N), phosphorus(P) and ferrum(Fe), photosynthesis capacity, antioxidant capacity and bacterial bopulations in Chlorella vulgaris and Duanliella salina. This would provide support and reference for the usage of L-carnitine in microalgae cultivation. Chlorella vulgaris and Duanliella salina were cultured with f/2 formulations for 14 days and enriched by 4 levels(with 3 replicates) of L-carnitine: 50, 100 and 200 and 0 mg/L(control). The results are shown as follows:1. L-carnitine enrichment had a significant(P<0.05) effect on the population growth in Chlorella vulgaris. The population growth of the 50 mg/L groups were significantly higher than the control(P<0.05). The population growth of 200 mg/L groups were significantly lower than the control(P<0.05) in the 4-6 days, however, there was no significant difference at other times(P>0.05). The effects of L-carnitine were significant on the absorptivity rate of N, P and Fe. The absorptivity rate of P and Fe of Chlorella vulgaris supplied 50 mg/L were higher than those supplied other three concentrations, and the Chlorella vulgaris supplied 200 mg/L had the highest absorptivity rate of N. In addition, the effects of L-carnitine were significant on the photosynthesis ability. The chlorophyll a concentration and productivity of Chlorella vulgaris supplied 200 mg/L were higher than those in the control, and the Chlorella vulgaris supplied 100 mg/ L had the highest photosynthesis rate. The catalase(CAT), glutathione peroxidase(GSH-Px), superoxide dismutase(T-SOD) and the peroxidase(POD) activities of Chlorella vulgaris in 200 mg/L groups were significantly higher than the control(P<0.05). The T-AOC in 50 and 100 mg/L groups had no significant difference(P<0.05), and they were significantly higher than that in the control. L-carnitine supplementation had a significant influence on the populations of bacterial(P<0.05). The treated groups were significantly different from the control(P<0.05), and 200 mg/L groups were significantly higher than those in other groups(P<0.05).2. L-carnitine enrichment had a significant effect on the population growth in Duanliella salina(P<0.05). The population growth of the 50 mg/L groups were significantly higher than that in the other groups(P <0.05), and the 200 mg/L groups inhibited the growth of the Duanliella salina in the 4-5 days, but there was no significant difference at other times(P>0.05). The effects of L-carnitine were significant on the absorptivity rate of N, P and Fe. The absorptivity rate of P and Fe of Duanliella salina supplied 50 mg/L were higher than those supplied other three concentrations, and the Duanliella salina supplied 200 mg/L had the highest absorptivity rate of N. The chlorophyll a concentration and productivity of Duanliella salina supplied 200 mg/L were higher than those supplied other three concentrations, and the group supplied 100 mg/ L had the highest photosynthesis rate. The T-SOD, CAT and the GSH-Px activities of Duanliella salina in 200 mg/L groups were significantly higher than the control groups(P<0.05). The POD in 50 mg/L groups were significantly higher than the control(P<0.05). The T-AOC in 100 and 200 mg/L groups had no significant difference(P>0.05), and they were significantly higher than the 0 and 50 mg/L groups(p<0.05). L-carnitine supplementation had a significant influence on the populations of symbiotic bacterial(P<0.05). The treated groups were significantly different from the control(P<0.05), 200 mg/L groups were significantly higher than those in other groups(P<0.05).Comprehensive research results as follows: The 50 mg/L L-carnitine could improve the population growth and absorptivity rate of N, P and Fe of Chlorella vulgaris and Duanliella salina; 100 mg/L could improve photosynthetic ability; 200 mg/L could improve antioxidant capacity and the population growth of symbiotic bacterial.