Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental, and Natural Resources Engineering, Luleå University of Technology, SE-971 87 Luleå, Sweden.
Biomolecules. 2020 Apr 29;10(5):694. doi: 10.3390/biom10050694.
Thraustochytrids are considered natural producers of omega-3 fatty acids as they can synthesize up to 70% docosahexaenoic acids (DHA) of total lipids. However, commercial and sustainable production of microbial DHA is limited by elevated cost of carbon substrates for thraustochytrids cultivation. This problem can be addressed by utilizing low-cost renewable substrates. In the present study, growth, lipid accumulation and fatty acid profiles of the marine thraustochytrid sp (ATCC-PRA-276) cultivated on volatile fatty acids (C1, formic acid; C2, acetic acid; C3, propionic acid; C4, butyric acid; C5, valeric acid and C6, caproic acid) and glucose as control were evaluated for the first time. This strain showed an inability to utilize C3, C5 and C6 as a substrate when provided at >2 g/L, while efficiently utilizing C2 and C4 up to 40 g/L. The highest cell dry weight (12.35 g/L) and total lipid concentration (6.59 g/L) were attained when this strain was cultivated on 40 g/L of butyric acid, followed by cultivation on glucose (11.87 g/L and 5.34 g/L, respectively) and acetic acid (8.70 g/L and 3.43 g/L, respectively). With 40 g/L butyric acid, the maximum docosahexaenoic acid content was 2.81 g/L, corresponding to 42.63% w/w of total lipids and a yield of 0.23 g/g. This marine oleaginous microorganism showed an elevated potential for polyunsaturated fatty acids production at higher acetic and butyric acid concentrations than previously reported. Moreover, fluorescence microscopy revealed that growth on butyric acid caused cell size to increase to 45 µm, one of the largest values reported for oleaginous microorganisms, as well as the presence of numerous tiny lipid droplets.
厚壳贻贝被认为是 ω-3 脂肪酸的天然生产者，因为它们可以合成高达总脂质的 70%的二十二碳六烯酸 (DHA)。然而，由于用于厚壳贻贝培养的碳底物成本高昂，商业和可持续生产微生物 DHA 受到限制。这个问题可以通过利用低成本可再生底物来解决。在本研究中，首次评估了海洋硫球藻属（ATCC-PRA-276）在挥发性脂肪酸（C1，甲酸；C2，乙酸；C3，丙酸；C4，丁酸；C5，戊酸和 C6，己酸）和葡萄糖上的生长、脂质积累和脂肪酸谱，作为对照。当提供大于 2 g/L 时，该菌株无法利用 C3、C5 和 C6 作为底物，而当提供高达 40 g/L 时，可有效利用 C2 和 C4。当该菌株在 40 g/L 丁酸上培养时，可获得最高的细胞干重（12.35 g/L）和总脂质浓度（6.59 g/L），其次是在葡萄糖（分别为 11.87 g/L 和 5.34 g/L）和乙酸（分别为 8.70 g/L 和 3.43 g/L）上培养。当使用 40 g/L 丁酸时，二十二碳六烯酸的含量最高为 2.81 g/L，占总脂质的 42.63%w/w，产率为 0.23 g/g。与之前报道的相比，这种海洋油脂微生物在较高的乙酸和丁酸浓度下显示出更高的多不饱和脂肪酸生产潜力。此外，荧光显微镜显示，在丁酸上生长会导致细胞大小增加到 45 µm，这是报道的油脂微生物中最大的细胞之一，并且存在许多微小的脂质滴。
