Blooms of Akashiwo sanguinea frequently break out around the world,causing huge economic losses to the aquaculture industry and seriously damaging coastal ecosystems.However,the formation mechanisms of A.sanguinea blo...Blooms of Akashiwo sanguinea frequently break out around the world,causing huge economic losses to the aquaculture industry and seriously damaging coastal ecosystems.However,the formation mechanisms of A.sanguinea blooms remain unclear.We investigated the allelopathic effects of A.sanguinea on multiple phytoplankton species,explored the mode of allelochemicals action and the way of nutrient factors regulation of the allelopathic activity.Results show that strains of A.sanguinea could inhibit the growth of co-occurring phytoplankton including Scrippsiella trochoidea,Phaeocystis globosa,and Rhodomonas salina,but inhibition of Prorocentrum micans was not obvious.The inhibition rates on phytoplankton were positively correlated with the cell densities of A.sanguinea.The highest inhibition rate of 94%on R.salina was for A.sanguinea CCMA256 culture of 2000 cells/mL at 72 h.We observed that cells of S.trochoidea,Ph.g lobosa,and R.sali na were lysed when co-cultured with A.sanguinea,with the shortest time for S.trochoidea.Additionally,the growth rates of A.sanguinea were promoted by coculturing with S.trochoidea,Ph.globosa,and R.salina.Four components of A.sanguinea culture were all able to inhibit growth of R.salina:the strongest inhibitory effect was found in the sonicated culture,followed by whole-cell culture,filtrates of sonicated culture,and filtrate culture.The crude extract of A.sanguinea culture also lysed cells of R.salina,and the inhibition rates on R.salina increased with the increasing dose of crude extract.It was shown that both nutrient enrichment and nitrogen:phosphorus ratio imbalance enhanced remarkably the allelopathic activity of A.sanguinea.The highest inhibition rate on R.salina of 70%occurred in A.sanguinea JX13 treatment at 2000 cells/mL under high nutrient condition in 48 h.In JX14 treatment at 2000 cells/mL for N:P of 10:1,the inhibition rate increased by 1.7 times of that for N:P of 20:1.In addition,the allelopathy of A.sanguinea could not only be a competitive strategy but also a nutrition strategy,playing an important role in formation and/or maintenance of blooms of the mixotrophic dinoflagellate A.sanguinea.展开更多
A possible source of biological material for the production of biodiesel is represented by microalgae, in particular by their lipid content. The aim of the present work was to optimize culture medium composition for i...A possible source of biological material for the production of biodiesel is represented by microalgae, in particular by their lipid content. The aim of the present work was to optimize culture medium composition for improving growth and lipid content of green microalgae Chlorella sorokiniana, Scenedesmus acuminatus and blue green Cyanobacterium aponicum. Lipids were quantitatively determined by spectrofluorometric method using Nile red flurometric stain. Initially, the effect of two different medium types, Bold’s and optimized culture medium (OCM), four types of carbon source (glucose and sodium acetate, molasses, glycerol, control) and four nitrogen concentrations (100%, -75%, -50%, -25%) on the enhancement of biomass and lipid content and lipid productivity were studied;indeed, optimized culture medium significantly improved growth, CDW for three microalgae, beside increasing lipid content and lipid productivity for S. acuminatus and C. aponicum by 7.5 and 5 folds respectively at 25th day compared to Bold’s medium. Moreover, 25% nitrogen deficient medium significantly increased lipid content and lipid productivity for both C. sorokiniana and C. aponicum at 2nd week of re-propagation to 10.6 and 2.6 folds over control (100% nitrogen). While S. acuminatus recorded the significant lipid content & productivity at 2nd week under recommended nitrogen dose in medium (100% N) by 4.4 folds over 25% deficient medium. Meanwhile 0.3% glycerol medium enhanced CDW, lipid content of S. acuminatus to 1.68 gL-1. While C. sorokiniana and C. aponicum recorded significant CDW under 0.3% acetate medium 1.37 and 0.76 gL-1. C. aponicum exhibited no growth under glycerol medium. The highest lipid content and lipid productivity were obtained under glycerol medium for C. sorokiniana and S. acuminatus (64.3 and 52.8 mg·g·gǃ·dǃ).展开更多
基金Supported by the National Natural Science Foundation of China(NSFC)(Nos.41576159,41676099)。
文摘Blooms of Akashiwo sanguinea frequently break out around the world,causing huge economic losses to the aquaculture industry and seriously damaging coastal ecosystems.However,the formation mechanisms of A.sanguinea blooms remain unclear.We investigated the allelopathic effects of A.sanguinea on multiple phytoplankton species,explored the mode of allelochemicals action and the way of nutrient factors regulation of the allelopathic activity.Results show that strains of A.sanguinea could inhibit the growth of co-occurring phytoplankton including Scrippsiella trochoidea,Phaeocystis globosa,and Rhodomonas salina,but inhibition of Prorocentrum micans was not obvious.The inhibition rates on phytoplankton were positively correlated with the cell densities of A.sanguinea.The highest inhibition rate of 94%on R.salina was for A.sanguinea CCMA256 culture of 2000 cells/mL at 72 h.We observed that cells of S.trochoidea,Ph.g lobosa,and R.sali na were lysed when co-cultured with A.sanguinea,with the shortest time for S.trochoidea.Additionally,the growth rates of A.sanguinea were promoted by coculturing with S.trochoidea,Ph.globosa,and R.salina.Four components of A.sanguinea culture were all able to inhibit growth of R.salina:the strongest inhibitory effect was found in the sonicated culture,followed by whole-cell culture,filtrates of sonicated culture,and filtrate culture.The crude extract of A.sanguinea culture also lysed cells of R.salina,and the inhibition rates on R.salina increased with the increasing dose of crude extract.It was shown that both nutrient enrichment and nitrogen:phosphorus ratio imbalance enhanced remarkably the allelopathic activity of A.sanguinea.The highest inhibition rate on R.salina of 70%occurred in A.sanguinea JX13 treatment at 2000 cells/mL under high nutrient condition in 48 h.In JX14 treatment at 2000 cells/mL for N:P of 10:1,the inhibition rate increased by 1.7 times of that for N:P of 20:1.In addition,the allelopathy of A.sanguinea could not only be a competitive strategy but also a nutrition strategy,playing an important role in formation and/or maintenance of blooms of the mixotrophic dinoflagellate A.sanguinea.
文摘A possible source of biological material for the production of biodiesel is represented by microalgae, in particular by their lipid content. The aim of the present work was to optimize culture medium composition for improving growth and lipid content of green microalgae Chlorella sorokiniana, Scenedesmus acuminatus and blue green Cyanobacterium aponicum. Lipids were quantitatively determined by spectrofluorometric method using Nile red flurometric stain. Initially, the effect of two different medium types, Bold’s and optimized culture medium (OCM), four types of carbon source (glucose and sodium acetate, molasses, glycerol, control) and four nitrogen concentrations (100%, -75%, -50%, -25%) on the enhancement of biomass and lipid content and lipid productivity were studied;indeed, optimized culture medium significantly improved growth, CDW for three microalgae, beside increasing lipid content and lipid productivity for S. acuminatus and C. aponicum by 7.5 and 5 folds respectively at 25th day compared to Bold’s medium. Moreover, 25% nitrogen deficient medium significantly increased lipid content and lipid productivity for both C. sorokiniana and C. aponicum at 2nd week of re-propagation to 10.6 and 2.6 folds over control (100% nitrogen). While S. acuminatus recorded the significant lipid content & productivity at 2nd week under recommended nitrogen dose in medium (100% N) by 4.4 folds over 25% deficient medium. Meanwhile 0.3% glycerol medium enhanced CDW, lipid content of S. acuminatus to 1.68 gL-1. While C. sorokiniana and C. aponicum recorded significant CDW under 0.3% acetate medium 1.37 and 0.76 gL-1. C. aponicum exhibited no growth under glycerol medium. The highest lipid content and lipid productivity were obtained under glycerol medium for C. sorokiniana and S. acuminatus (64.3 and 52.8 mg·g·gǃ·dǃ).
