| In order to obtain the conditions of high density cultivation and induction of high astaxanthin productivity of Haematococcus pluvialis,the culturing and inducing conditions were observed through single-factor experiments.The optimal basic culture media were determined,firstly.And then three plant growth regulators,indole-butyric acid(3-IBA),naphthyl acetic acid(NAA)and gibberellin(GA3),and three low toxicity herbicide S-Metolachlor,Butachlor and MCPA-Na,were applied to test their potential effect on cell growth and astaxanthin production in the green-cell stage and astaxanthin-induction stage,respectively.The results are as follows:(1)The modified BG-11 medium,24-26°C,Na HCO3 1.0g/L were the optimal conditions for H.pluvialis cell growth,and the maximum cell concentration reached to 160×104 cell/m L at the those conditions.(2)Plant regulators,3-IBA,NAA and GA3,were added into the cultivation media at different concentration to determine the effect on the algal growth and astaxanthin production.For 3-IBA,10 μg/m L in green-cell stage and 25 μg/m L in astaxanthin-induction stage were the optimal comditions for cell growth and antaxanthin production,and the maximum cell concentration and astaxanthin content reached 153×104 cell/m L and 13.77 mg/L at these concentrations;For NAA,the optimal conditions were 5μg/m L in green-cell stage and 25μg/m L in astaxanthin-induction stage,and the maximum cell concentration and astaxanthin content reached 140×104 cell/m L and 13.91 mg/L at these conditions;For GA3 5 μg/m L in green-cell stage and 25 μg/m L in astaxanthin-induction stages were the optimal concentration conditions for cell growth and astaxanthin accumulation,and the maximum cell concentration and astaxanthin content reached 115×104 cell/m L and 12.75 mg/L at these conditions.(3)Several low toxicity herbicide,S-Metolachlor,Butachlor and MCPA-Na,were added into the cultivation media at different concentration to determine the effect on the algal growth and astaxanthin production.For S-Metolachlor,2 μg/m L in green-cell stage and 5 μg/m L in induction stage were the optimal concentration for cell growth and astaxanthin accumulation,and the maximum cell concentration and astaxanthin content reached 194×104 cell/m L and 15.99 mg/L at these conditions.As for Butachlor,no catalytic role were observed in the study,the cells growth were inhibited at low concentration.For MCPA-Na,3 μg/m L in green-cell stage and 5 μg/m Lin induction stage were the optimal concentration for cell growth and astaxanthin accumulation,and the maximum cell concentration and astaxanthin content reached 190×104 cell/m L and 12.79 mg/L at these conditions. |
