Long-duration effect of multi-factor stresses on the cellular biochemistry, oil-yielding performance and morphology of Nannochloropsis oculata

Abstract

Microalga Nannochloropsis oculata is a promising alternative feedstock for biodiesel. Elevating its oil-yielding capacity is conducive to cost-saving biodiesel production. However, the regulatory processes of multi-factor collaborative stresses (MFCS) on the oil-yielding performance of N. oculata are unclear. The duration effects of MFCS (high irradiation, nitrogen deficiency and elevated iron supplementation) on N. oculata were investigated in an 18-d batch culture. Despite the reduction in cell division, the biomass concentration increased, resulting from the large accumulation of the carbon/energy-reservoir. However, different storage forms were found in different cellular storage compounds, and both the protein content and pigment composition swiftly and drastically changed. The analysis of four biodiesel properties using pertinent empirical equations indicated their progressive effective improvement in lipid classes and fatty acid composition. The variation curve of neutral lipid productivity was monitored with fluorescent Nile red and was closely correlated to the results from conventional methods. In addition, a series of changes in the organelles (e.g., chloroplast, lipid body and vacuole) and cell shape, dependent on the stress duration, were observed by TEM and LSCM. These changes presumably played an important role in the acclimation of N. oculata to MFCS and accordingly improved its oil-yielding performance.

Biomass Fatty Acid Profile and Fuel Property Prediction of Bagasse Waste Grown Nannochloropsis oculata

“…In particular, the proportion (% total FA, Table 2) of 16:0 increased, as well as that of 18:1n 9 , which suggests that they played a conspicuous role in the course of TAG reserve. Almost all of our results are similar to the findings of [43] for the fatty acid profile of N. oculata under stressed conditions (high irradiation, nitrogen deficiency, and elevated iron supplementation). They reported that, under stressed conditions, the SFA and MUFA proportions increased accordingly, with their sum increasing from 63.56% to 92.18%.…”

Comparative Proteomics Reveals Evidence of Enhanced EPA Trafficking in a Mutant Strain of Nannochloropsis oculata

“…The percentage of neutral lipids gradually increased for both wild-type and M1 mutant strain and reached the highest (35 and 27%, respectively) on day 12. Nutrient limitation is known to induce TAG accumulation as a stress response, and a previous study showed that C16:0 reached the maximum of around 40% of TFA under these conditions ( Wei and Huang, 2017 ). In order to further investigate the increase in EPA content, two time-points were chosen based on the FAs profiles between TAG and EPA, EPA percentages, and absolute EPA quantifications.…”

Extracción e identificación de lípidos polares de las microalgas Nannochloropsis oceanica y Desmodesmus asymmetricus

“…Además, los lípidos en la microalga Np se concentran en pocas gotas La Tabla 7 muestra que, para Np, los porcentajes de lípidos neutros (F4) y lípidos polares (F3) son aproximadamente 37 y 3%. Al comparar estos resultados con los de Y. Ma y colaboradores [16], en estudios realizados de tres cepas de microalgas Nannochloropsis oceanica, en condiciones controladas de laboratorio, cuyos resultados de lípidos neutros y polares fueron 23-32 y 21-26%, respectivamente, puede inferirse que la microalga Np estudiada ha sufrido estrés por las condiciones de cultivo en el invernadero, pues incrementaron sus niveles de lípidos neutros y disminuyeron los niveles de lípidos polares, efecto similar al reportado por Wei y su equipo [17].…”