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Marine Thraustochytrids: Biology and Biotechnology

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A special issue of Marine Drugs (ISSN 1660-3397). This special issue belongs to the section "Marine Biotechnology Related to Drug Discovery or Production".

Deadline for manuscript submissions: closed (15 September 2023) | Viewed by 9110

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Dr. Carolina Shene

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Department of Chemical Engineering and Center of Food Biotechnology and Bioseparations, BIOREN, Universidad de La Frontera, Casilla 54-D, Temuco 4811230, Chile
Interests: encapsulated; physical stability and antioxidant activity; marine microorganisms (isolation and culture); microbial lipidic compounds
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Dear Colleagues,

Thraustochytrids comprise a group of protists from at least 12 genera. However, only few strains have been studied to establish their role in the environment and/or their potential for the production of metabolites, mainly long-chain omega-3 polyunsaturated fatty acids. The ability of thraustochytrids to synthesize metabolites not found in terrestrial microorganisms make them a valuable resource for the biotechnological industry, and a source of genetic information and DNA for the development of improved strains.

This Special Issue invites articles on marine thraustochytrids, with a focus on the characterization of novel strains, metabolites and enzymes, and potential applications in the field of biotechnology (metabolic engineering, cultivation and downstream processing).

Dr. Carolina Shene
Guest Editor

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Keywords

lipids
long-chain polyunsaturated fatty acids
fermentation
metabolism
terpenoids
metabolic engineering
cell factories
antioxidant
lipid extraction
biorefinery

Published Papers (5 papers)

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Research

12 pages, 2414 KiB

Open AccessArticle

Harvesting Aurantiochytrium sp. SW1 via Flocculation Using Chitosan: Effects of Flocculation Parameters on Flocculation Efficiency and Zeta Potential

by Nadzirul Zamri, Nurul Nabila Suleiman, Norsyaqira Mohd Johar, Nur Syahidah Mohd Noor, Wei Lun Ang, Nazlina Haiza Mohd Yasin, Yusuf Nazir and Aidil Abdul Hamid

Mar. Drugs 2023, 21(4), 251; https://doi.org/10.3390/md21040251 - 19 Apr 2023

Cited by 1 | Viewed by 1712

Abstract

The use of chitosan as a flocculant has become a topic of interest over the years due to its positively charged polymer and biodegradable and non-toxic properties. However, most studies only focus on microalgae and wastewater treatment. This study provides crucial insight into the potential of using chitosan as an organic flocculant to harvest lipids and docosahexaenoic acid (DHA-rich Aurantiochytrium sp. SW1 cells by examining the correlation of flocculation parameters (chitosan concentration, molecular weight, medium pH, culture age, and cell density) toward the flocculation efficiency and zeta potential of the cells. A strong correlation between the pH and harvesting efficiency was observed as the pH increased from 3, with the optimal flocculation efficiency of >95% achieved at a chitosan concentration of 0.5 g/L at pH 6 where the zeta potential was almost zero (3.26 mV). The culture age and chitosan molecular weight have no effect on the flocculation efficiency but increasing the cell density decreases the flocculation efficiency. This is the first study to reveal the potential of chitosan to be used as a harvesting alternative for thraustochytrid cells. Full article

(This article belongs to the Special Issue Marine Thraustochytrids: Biology and Biotechnology)

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14 pages, 4547 KiB

Open AccessArticle

Identification and Functional Analysis of Two Novel Genes—Geranylgeranyl Pyrophosphate Synthase Gene (AlGGPPS) and Isopentenyl Pyrophosphate Isomerase Gene (AlIDI)—from Aurantiochytrium limacinum Significantly Enhance De Novo β-Carotene Biosynthesis in Escherichia coli

by Shitao Shi, Yi Chang, Jinhui Yu, Hui Chen, Qiang Wang and Yuping Bi

Mar. Drugs 2023, 21(4), 249; https://doi.org/10.3390/md21040249 - 17 Apr 2023

Cited by 3 | Viewed by 1586

Abstract

Precursor regulation has been an effective strategy to improve carotenoid production and the availability of novel precursor synthases facilitates engineering improvements. In this work, the putative geranylgeranyl pyrophosphate synthase encoding gene (AlGGPPS) and isopentenyl pyrophosphate isomerase encoding gene (AlIDI) from Aurantiochytrium limacinum MYA-1381 were isolated. We applied the excavated AlGGPPS and AlIDI to the de novo β-carotene biosynthetic pathway in Escherichia coli for functional identification and engineering application. Results showed that the two novel genes both functioned in the synthesis of β-carotene. Furthermore, AlGGPPS and AlIDI performed better than the original or endogenous one, with 39.7% and 80.9% increases in β-carotene production, respectively. Due to the coordinated expression of the 2 functional genes, β-carotene content of the modified carotenoid-producing E. coli accumulated a 2.99-fold yield of the initial EBIY strain in 12 h, reaching 10.99 mg/L in flask culture. This study helped to broaden current understanding of the carotenoid biosynthetic pathway in Aurantiochytrium and provided novel functional elements for carotenoid engineering improvements. Full article

(This article belongs to the Special Issue Marine Thraustochytrids: Biology and Biotechnology)

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13 pages, 1368 KiB

Open AccessArticle

Saturated and Polyunsaturated Fatty Acids Production by Aurantiochytrium limacinum PKU#Mn4 on Enteromorpha Hydrolysate

by Yaodong He, Xingyu Zhu, Yaodong Ning, Xiaohong Chen, Biswarup Sen and Guangyi Wang

Mar. Drugs 2023, 21(4), 198; https://doi.org/10.3390/md21040198 - 23 Mar 2023

Cited by 2 | Viewed by 1331

Abstract

Thraustochytrids are unicellular marine heterotrophic protists, which have recently shown a promising ability to produce omega-3 fatty acids from lignocellulosic hydrolysates and wastewaters. Here we studied the biorefinery potential of the dilute acid-pretreated marine macroalgae (Enteromorpha) in comparison with glucose via fermentation using a previously isolated thraustochytrid strain (Aurantiochytrium limacinum PKU#Mn4). The total reducing sugars in the Enteromorpha hydrolysate accounted for 43.93% of the dry cell weight (DCW). The strain was capable of producing the highest DCW (4.32 ± 0.09 g/L) and total fatty acids (TFA) content (0.65 ± 0.03 g/L) in the medium containing 100 g/L of hydrolysate. The maximum TFA yields of 0.164 ± 0.160 g/g DCW and 0.196 ± 0.010 g/g DCW were achieved at 80 g/L of hydrolysate and 40 g/L of glucose in the fermentation medium, respectively. Compositional analysis of TFA revealed the production of equivalent fractions (% TFA) of saturated and polyunsaturated fatty acids in hydrolysate or glucose medium. Furthermore, the strain yielded a much higher fraction (2.61–3.22%) of eicosapentaenoic acid (C20:5n-3) in the hydrolysate medium than that (0.25–0.49%) in the glucose medium. Overall, our findings suggest that Enteromorpha hydrolysate can be a potential natural substrate in the fermentative production of high-value fatty acids by thraustochytrids. Full article

(This article belongs to the Special Issue Marine Thraustochytrids: Biology and Biotechnology)

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18 pages, 2496 KiB

Open AccessArticle

Nitrogen Sources Affect the Long-Chain Polyunsaturated Fatty Acids Content in Thraustochytrium sp. RT2316-16

by Diego Valdebenito, Sebastián Urrutia, Allison Leyton, Yusuf Chisti, Juan A. Asenjo and Carolina Shene

Mar. Drugs 2023, 21(1), 15; https://doi.org/10.3390/md21010015 - 25 Dec 2022

Cited by 7 | Viewed by 1922

Abstract

The psychrophilic marine microorganism Thraustochytrium sp. RT2316-16 can produce carotenoids as well as lipids containing the omega-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid and docosahexaenoic acid. This work reports on the effects of the composition of the culture medium, including certain amino acids, on growth and lipid synthesis by RT2316-16. Compared with the culture on glutamate, the use of lysine, alanine, or serine, increased the content of the omega-3 PUFA in total lipids. In the media that contained yeast extract, glutamate, and glucose, lipid accumulation occurred when organic ammonium was exhausted earlier than glucose. In contrast, lipid mobilization was promoted if glucose was exhausted while organic ammonium (supplied by yeast extract and glutamate) remained in the medium. The total content of carotenoids in the lipid-free biomass decreased during the first 12 to 24 h of culture, simultaneously with a decrease in the total lipid content of the biomass. The experimental data suggested a possible interrelationship between the metabolism of carotenoids and lipids. A high content of omega-3 PUFA in the total lipids could be obtained by growing the thraustochytrid in a medium with a low glucose concentration (6 g L⁻¹) and a high concentration of organic nitrogen (yeast extract 12 g L⁻¹; glutamate 1.06 g L⁻¹), after glucose was exhausted. These observations may guide the development of a strategy to enhance omega-3 PUFA in the biomass. Full article

(This article belongs to the Special Issue Marine Thraustochytrids: Biology and Biotechnology)

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26 pages, 4838 KiB

Open AccessArticle

Characterization and Optimization of Culture Conditions for Aurantiochytrium sp. SC145 Isolated from Sand Cay (Son Ca) Island, Vietnam, and Antioxidative and Neuroprotective Activities of Its Polyunsaturated Fatty Acid Mixture

by Hoang Thi Minh Hien, Le Thi Thom, Nguyen Cam Ha, Luu Thi Tam, Ngo Thi Hoai Thu, Tru Van Nguyen, Vu Thi Loan, Nguyen Trong Dan and Dang Diem Hong

Mar. Drugs 2022, 20(12), 780; https://doi.org/10.3390/md20120780 - 14 Dec 2022

Cited by 5 | Viewed by 1948

Abstract

Aurantiochytrium is a heterotrophic marine microalga that has potential industrial applications. The main objectives of this study were to isolate an Aurantiochytrium strain from Sand Cay (Son Ca) Island, Vietnam, optimize its culture conditions, determine its nutritional composition, extract polyunsaturated fatty acids (PUFAs) in the free (FFA) and the alkyl ester (FAAE) forms, and evaluate the antioxidation and neuroprotection properties of the PUFAs. Aurantiochytrium sp. SC145 can be grown stably under laboratory conditions. Its culture conditions were optimized for a dry cell weight (DCW) of 31.18 g/L, with total lipids comprising 25.29%, proteins 7.93%, carbohydrates 15.21%, and carotenoid at 143.67 µg/L of DCW. The FAAEs and FFAs extracted from Aurantiochytrium sp. SC145 were rich in omega 3–6–9 fatty acids (40.73% and 44.00% of total fatty acids, respectively). No acute or subchronic oral toxicity was determined in mice fed with the PUFAs in FFA or FAAE forms at different doses over 90 days. Furthermore, the PUFAs in the FFA or FAAE forms and their main constituents of EPA, DHA, and ALA showed antioxidant and AChE inhibitory properties and neuroprotective activities against damage caused by H₂O₂- and amyloid-ß protein fragment 25–35 (Aβ_25-35)-induced C6 cells. These data suggest that PUFAs extracted from Aurantiochytrium sp. SC145 may be a potential therapeutic target for the treatment of neurodegenerative disorders. Full article

(This article belongs to the Special Issue Marine Thraustochytrids: Biology and Biotechnology)

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