Antimicrobial Activities And Chemical Compositions Of Liposoluble Compounds In Some Microalgae

Methanol-toluene(3:1) extracts from 12 species of marine and fresh microalgae was screened for antimicrobial activities by using the agar disc diffusion method.The results indicated that most species screened showed antibacterial and antifungal activities and extracts from Pyramidomonas delicatula and Synechocystis aquetilis had stronger antimicrobial activities than orther species. 6 species of microalgae were also extracted by methanol-toluene(3:1), ether and acetone in order to compare their extract efficiency. Of the three solvents, the methanol- toluene(3:1) had the best extract efficiency in antimicrobiaol activity.Crude grease and different elution fractions after the separation of the silica gel column chromatography from chlorella pyrenoidosa, Pyramidononas delicatula, Synechocystis aquatilies and Porphyridium purpureum were tested for the antimicrobial activities. The crude grease form chlorella pyrenoidosa had stronger antimicrobial activities than each elution fraction, while the benzene fractions from Pyramidonanas delicatula and Synechocystis aquatilies had the strongest antimicrobial activities. The ethanol fractions from Porphyridium purpureum had strong activities against Fasarium oxyssporam, Staphylococcus aureus and Piricularia oryzae cav A15. The petroleum ether fractions from 4 pecies of microalgae almost had no antimicrobial activities. The liposoluble compounds of microalgae had strong activities against plant pathogenic bacteria and fungi.Further separation and identification of the petroleum ether fractions and benzene fractions from 4 species of microalgae were made by GC-MS. The petroleum ether fractions were dominanted by hydrocarbon which did not exhibit anticrobial activities. The benzene fractions had complicated composition, so further separation and identification were needed to confirm active compound. The ethanol fractions which had strong antimicrobial activities had rich fatty acid assayed by GC.The liposoluble pigments from 4 species of microalgae included the chlorophyll a, 3 -carotene and a specie of orange-red pigment. Their antimicrobial activities needed further research.These 4 species of microalgae had rich PUFA, so they had highly pharmaceutical and health care value.