Abstract

The economic feasibility of microalgae biomass production for biofuels is evaluated based on biomass concentration and productivity, and accumulation of pigments, lipid, carbohydrate, and protein. These parametric indicators are commonly promoted in microalgae cultures by manipulating the growth conditions, such as altering the growth nutrients, temperature, salinity, and mixing intensity. In view of this, the current study evaluated the potential of Dunaliella salina, Nannochloropsis oculata, Oocystis minuta, and Neochloris conjuncta to accumulate biomass, pigments, lipid, carbohydrate, and protein under different mechanical agitation conditions of the culture systems. The results show that the maximum biomass concentration (2423 mg/L) and productivity (544 mg/L/d) were observed in D. salina at a stirring speed of 1400 rpm and an aeration rate of 0.15 vvm. Also, the maximum total lipid content (23%) was recorded for N. oculata at a shaking speed of 200 rpm. The highest protein (49%) and carbohydrate (45%) contents were recorded for D salina and O. minuta at shaking speeds of 125 and 200 rpm, respectively. The higher proportions of protein and carbohydrate over lipid in all of the cultured microalgae species under the evaluated mechanical agitation conditions indicate that the microalgae species are better candidates for bioethanol production, and use as a protein source for animal feed, compared with biodiesel production.

摘要

基于生物质浓度和生产力，以及色素、脂质、碳水化合物和蛋白质的积累，评估用于生物燃料的微藻生物质生产的经济可行性。这些参数指标通常在微藻培养中通过操纵生长条件来促进，例如改变生长养分、温度、盐度和混合强度。有鉴于此，目前的研究评估了盐生杜氏藻、Nannochloropsis oculata、Oocystis minuta和Neochloris conjuncta的潜力。在培养系统的不同机械搅拌条件下积累生物量、色素、脂质、碳水化合物和蛋白质。结果表明，在1400 rpm 的搅拌速度和 0.15 vvm 的曝气速率下，盐藻中的最大生物量浓度 (2423 mg/L) 和生产力 (544 mg/L/d)。此外，在200 rpm 的摇动速度下， N. oculata的最大总脂质含量 (23%) 被记录下来。D salina和O. minuta的蛋白质 (49%) 和碳水化合物 (45%) 含量最高振动速度分别为 125 和 200 rpm。在评估的机械搅拌条件下，所有培养的微藻物种中蛋白质和碳水化合物的比例高于脂质，这表明与生物柴油生产相比，微藻物种更适合生产生物乙醇，并用作动物饲料的蛋白质来源。