Molecular Identification Of Some Microalgae From South China Sea And Screening Of Oil-rich Microalgae

The vast waters of South China Sea possess very complex climatological andgeological environmental conditions, they are also important sources of energyproducing microalgae. This study was based on microalgae isolated from South ChinaSea. Indentification of these microalgae were proceed by using molecular biologymethods. The screening of microalgae with growth fast and high oil content wascarried out by measuring the growth index and oil content. This study provided moreraw materials for microalgae biodiesel production.Main work contents and results are as follows:1. Through the interactive use of macromanipulation, the96-well plate dilutionmethod, water droplets, tablet,73strains of microalgae were separated and purifiedfrom141water samples, and provided a wealth of resources algae species. The effectof dilution is best, but the obtained species were relatively single, and they weregenerally the species with superiority.2. Fifty seven strains of purebred algae cells were identified by moleculartechniques using18s ribosomal RNA gene (rDNA), and11different species of algaecells were identified. Eight species were specified to genus,1species was specified tofamily,2species were specified to order. Identification results were as follows: NO.1,5,7,11,21,29,59and72algae strains were respectively genus Bodo, genusPavlova、genus Cafeteria、genus Paraphysomonas、genus Chlamydomonas、genusPycnococcus、genus Psammodictyon、genus Caecitellus, NO.55algae strain belongedto family Bacillariaceae，NO.54algae strain belonged to order Chlorellales, NO.109algae strain belonged to order Chromulinales. The results proved that the molecularidentification was efficient in the classification and identification of microalgae.3. Physiological and biochemical analyses of11strains of identified algae werecarried out. Algal cell density was determined through the optical density method. Thegrowth curve of these strains of identified algae show that: for54and109algae strains, they grew significantly faster than those of other algae strains from enteringthe exponential growth phase to the end of the exponential phase. The specific growthrates of NO.54,55,109and1algal strains were relatively higher, and the specificgrowth rate of NO.54algae strain is highest, it was0.4415/d. The results ofmeasuring biomass by freeze-dried and weighed method showed that: the biomass ofNO.59,72algae strains were relatively higher, and the biomass of NO.59algae strainwas the highest, reaching167.33g/mL. The results of determinating total fat contentby weight method showed that: the total fat contents of NO.54,109,59algae strainswere relatively higher, and the total fat content of NO.54algae strain was the highest,reaching40.42%. The oil productivity of NO.54,109,59algae strains were relativelyhigher, and the oil productivity of NO.59algae strain was the highest, reaching46.46g/mL. Considering various aspects, NO.54,59and109algae strains grew morerapidly, and the oil contents of them were higher. Therefore the three algae strainswere more suitable to be used as raw materials of microalgae biodiesel.