Production of 10-Ketostearic Acid from Oleic Acid by Flavobacterium sp. Strain DS5 (NRRL B-14859)

A microbial isolate, Flavobacterium sp. strain DS5, produces 10-ketostearic acid (10-KSA) from oleic acid in 85% yield. This is the first report on this type of reaction catalyzed by a Flavobacterium strain. The product was purified to give white, plate-like crystals melting at 79.2°C. The optimum time, pH, and temperature for the production of 10-KSA are 36 h, 7.5, and 30°C, respectively. A small amount of 10-hydroxystearic acid (10-HSA) (about 10% of the amount of the main product, 10-KSA) is also produced during the bioconversion. 10-KSA is not further metabolized by strain DS5 and accumulates in the medium. In contrast to growing cells, a resting-cell suspension of strain DS5 produces 10-HSA and 10-KSA in a ratio of 1:3. The crude cell extract obtained from ultrasonic disruption of the cells converts oleic acid mainly to 10-HSA (10-HSA/10-KSA ratio, 97:3). This result strongly suggested that oleic acid is converted to 10-KSA via 10-HSA. Enzymes catalyzing the hydration and secondary alcohol dehydrogenation are cell associated. Product 10-HSA from strain DS5 is 66% enantiomeric excess in the 10(R) form. The oleic acid conversion enzyme(s) reacts with unsaturated fatty acids in the order oleic acid > palmitoleic acid > linoleic acid > linolenic acid > γ-linolenic acid > myristoleic acid.     

Conversion of fatty acids by Bacillus sphaericus-like organisms

Bacillus sphaericus species are mesophilic round-spored organisms that readily utilize fatty acid-based surfactants during growth, but their ability to modify fatty acids is unknown. Among 57 B. sphaericus-like strains tested for fatty acid transformation activity in Wallen fermentation (WF) medium, ten converted oleic acid to a new product determined by gas chromatography – mass spectrometry (GC-MS) to be 10-ketostearic acid (10-KSA). Additionally, a few other strains converted ricinoleic acid and linoleic acid to new products that remain to be characterized. Unlike most microbial hydrations of oleic acid, which produce a mixture of 10-KSA and 10-hydroxystearic acid, the conversion of oleic acid by B. sphaericus strains was unique in that 10-KSA was the sole reaction product. By replacing dextrose with sodium pyruvate in WF and adjusting to pH 6.5, conversion of oleic acid to 10-KSA by strain NRRL NRS-732 was improved from about 11% to more than 60%. Using the defined optimal conditions, the conversion reaction was scaled up in a stirred-batch reactor by using technical-grade oleic acid as substrate. This is the first report on the characterization of fatty acid conversions by B. sphaericus species. Received: 17 December 2001 / Accepted: 17 January 2002     

Oleic acid transformations by selected strains of Sphingobacterium thalpophilum and Bacillus cereus from composted manure

In a survey of 186 randomly selected microbial strains isolated from composted manure, 63 transformed oleic acid into three types of products: hydroxy fatty acid, fatty amide, and less polar oleyl lipid. Selection of oleic acid-transforming microorganisms was enhanced in nutrient agar supplemented with 0.1% (vol/vol) oleic acid at pH 7.2. Most of the 63 diverse isolates elicited inconsistent and poorly reproduced transformations. However, strains 142b (NRRL B-14797) transformed oleic acid to 10-hydroxystearic acid consistently, and strain 229b (NRRL B-14812) produced an octadecenamide. Taxonomic studies indicated that NRRL strain B-14797, possessing 1,3-dihydroxy-2-amino-15-methylhexadecane and sphinganine bases, was closely related to Sphingobacterium thalpophilum, and NRRL B-14812 was identified as Bacillus cereus.     

Oleyl Oleate and Homologous Wax Esters Synthesized Coordinately from Oleic Acid by Acinetobacter and Coryneform Strains

Newly isolated Acinetobacter (NRRL B-14920, B-14921, B-14923) and coryneform (NRRL B-14922) strains accumulated oleyl oleate and homologous liquid wax esters (C_30:2–C_36:2) in culture broths. Diunsaturated oleyl oleate preponderated in 75 mg liquid wax esters (280 mg lipid extract) recovered from 100-ml cultures of Acinetobacter B-14920 supplemented with 810 mg oleic acid–oleyl alcohol. With soybean oil instead of oleic acid, wax esters (260 mg) were increased to approximately 50% of the lipid extract. Production of wax esters by cultures supplemented with combined fatty (C₈–C₁₈) alcohols and acids suggests a coordinated synthesis whereby the exogenous alcohol remains unaltered, and the fatty acid is partially oxidized with removal of C₂ units before esterification. Consequently, C₈–C₁₈ primary alcohols control chain lengths of the wax esters. Exogenous fatty acids are presumed to enter an intracellular oxidation pool from which is produced a homologous series of liquid wax esters.     

Screening for marine nanoplanktic microalgae from Greek coastal lagoons (Ionian Sea) for use in mariculture

Mediterranean mariculture uses imported strains of marine phytoplankton, raising questions of ecological risk and ability to adapt to local conditions for mass culture outdoors. In this context, we report here on the mass-culture potential and chemical composition of six strains of Prasinophyceae (five strains of Tetraselmis sp. and one Pyramimonas sp.) isolated from a Greek coastal lagoon. Proximate composition had a pattern of 10–20% ash, 35–65% protein, 6–10% lipids, and 25–45% other organics including carbohydrates. The amino acid profiles were typical for the marine representatives of the class. All strains had a high PUFA content with dominant the ω3 fraction in four of them. The fatty acid profiles indicated a Tetraselmis strain with high EPA (14%) and a Pyramimonas strain with high DHA (6%). These strains might be a good alternative for the common commercial strains used in Mediterranean aquaculture.     

Isolation and Characterization of Taiwanese Heterotrophic Microalgae: Screening of Strains for Docosahexaenoic Acid (DHA) Production

Marine heterotrophic microalgal species which are potentially rich in docosahexaenoic acid (DHA, C22:6n−3) have been found in Taiwan; however, there was a lack of detailed analysis and characterization of these indigenous algae which is needed for the development of commercial applications. Hence, the objective of this study was to screen DHA-rich heterotrophic microalgae species indigenous to Taiwan for commercial purposes. Heterotrophic microalgae from a variety of marine habitats were isolated, cultivated, and then identified according to their 18S rRNA gene sequences and morphological characteristics. A comparison was made of their fatty acid profiles, fatty acid content, and amount of biomass. For the strain with highest DHA yield, the optimal growth conditions were determined in order to establish the best fermentation conditions for scale-up. In this study, 25 heterotrophic microalgal strains were successfully isolated from marine habitats around Taiwan. All of the isolated strains showed a close phylogenic relationship with the Thraustochytriaceae family according to their 18S rRNA gene sequences. GC/MS analysis discerned seven distinctive fatty acid profiles of these strains, with the production of eicosapentaenoic acid (C20:5n−3) ranging from 0.02 to 2.61 mg L⁻¹, and DHA ranging from 0.8 to 18.0 mg L⁻¹. An Aurantiochytrium strain BL10 with high DHA production was subsequently chosen for further manipulation. Under optimal growth conditions it could produce up to 59.0 g of dry biomass per liter of culture, with dry biomass containing 73% total fatty acid and 29% DHA, revealing BL10 as an excellent source of microbial DHA.     

Screening of antioxidative activity of<Emphasis Type="Italic">Bifidobacterium</Emphasis> species isolated from Korean infant feces and their identification

Among 59 Korean isolated, 20 were confirmed as members of the genusBifidobacterium species based on gram staining, microscopic examination of cell morphology and the TLC method. The oxygen tolerance and antioxidative activities of these 20Bifidobacterium strains and 5 standardBifidobacterium strains were tested. All the strains demonstrated antioxidative activities as regards inhibiting linoleic acid peroxidation. The antioxidative activities of isolated and standard strains were found to range from 10.7–46.4% and from 10.7–22.2%, respectively. In addition, all tested strains exhibited a scavenging ability on DPPH free radicals, range from 15–41% for the isolated strains and 8.3–22% for the standard strain. Accordingly, the isolatedBifidobacterium strains demonstrated higher antioxidative activities than the 5 standardBifidobacterium strains. On the base of grades for each test, HJL 7511 was identified as the best strain, followed by HJL 7501. 2 strains were identified with Polymerase Chain Reaction (PCR) assay using group-specific primers designed from the nucleotide sequences of the 16S rRNA and internal transcribed spacer (ITS) regions of the Bifidobacteria. Based on the sequencing results, HJL 7511 and HJL 7501 were identified asBifidobacterium infantis.     

Production of 10-Hydroxy-8(E)-Octadecenoic Acid from Oleic Acid Conversion by Strains of Pseudomonas aeruginosa

Eighteen Pseudomonas aeruginosa strains were examined for their ability to convert oleic acid to produce 10-hydroxy-8(E)-octadecenoic acid (HOD), which was structurally confirmed by GC-MS, NMR, and FTIR. There were no substantial amounts of other new compounds found in the fermentation broths in addition to HOD and 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). The results demonstrated that P. aeruginosa strains possessed varying levels of activity for producing HOD. Under the experimental conditions, strain NRRL B-14938 isolated from sheep manure was the best HOD producer exhibiting the highest HOD to DOD product ratio in the medium most suitable for purifying HOD. Using strain B-14938 as a model system for further characterization, optimum conditions for producing HOD were found to be at 26°C and pH 7.0 after 60 h of reaction time using a medium containing EDTA as a chelating agent. This study has identified a high-yielding P. aeruginosa strain and provided the reaction characteristics needed to develop a scale-up production process of HOD for testing its properties and potential new uses.     

Seasonal changes in fatty acid composition associated with cold-hardening in third instar larvae of Eurosta solidaginis

Third-instar larvae of the goldenrod gall fly Eurosta solidaginis (Diptera: Tephritidae) survive extended periods in winter during which tissue water is frozen. Both low temperature and reduced water activity during freezing present challenges for the structural integrity of cellular lipids. Fatty acids of both phospholipids and triacylglycerols from fat body cells of E. solidaginis were analyzed throughout fall and early winter, a period that encompasses the acquisition of freeze-tolerance, to determine if adaptations to freezing include changes in fatty acid unsaturation. The five most abundant fatty acids from both fractions were (in decreasing order) oleic (40–65%), palmitoleic (18–20%), palmitic (12–17%), linoleic (5–10%), and stearic acids (4 –7%). This represents a typical complement of Dipteran fatty acids, although oleic acid levels were higher in E. solidaginis than those reported from other Dipterans (˜28%; Downer 1985). From September to November, monounsaturates increased from 59 to 70% in phospholipids at the expense of saturated fatty acids (25% –20%) suggesting activation of a Δ⁹-desaturase enzyme. These changes resulted in an increase in the ratio of unsaturated to saturated fatty acids (U/S) from 3.0 to 4.2, although there was no change in the average number of double bonds per fatty acid (unsaturation index, UI ≈ 1.2 in phospholipids and 0.9 in triacylglycerols throughout the season). These changes were temporally correlated to decreasing ambient temperatures and increasing larval and fat body cell freeze-tolerance. Accepted: 31 October 1996     

Co-existence of physiologically similar sulfate-reducing bacteria in a full-scale sulfidogenic bioreactor fed with a single organic electron donor

A combination of culture-dependent and independent methods was used to study the co-existence of different sulfate-reducing bacteria (SRB) in an upflow anaerobic sludge bed reactor treating sulfate-rich wastewater. The wastewater was fed with ethanol as an external electron donor. Twenty six strains of SRB were randomly picked and isolated from the highest serial dilution that showed growth (i.e. 10⁸). Repetitive enterobacterial palindromic polymerase chain reaction and whole cell protein profiling revealed a low genetic diversity, with only two genotypes among the 26 strains obtained in the pure culture. The low genetic diversity suggests the absence of micro-niches within the reactor, which might be due to a low spatial and temporal micro-heterogeneity. The total 16S rDNA sequencing of two representative strains L3 and L7 indicated a close relatedness to the genus Desulfovibrio. The two strains differed in as many as five physiological traits, which might allow them to occupy distinct niches and thus co-exist within the same habitat. Whole cell hybridisation with fluorescently labeled oligonucleotide probes was performed to characterise the SRB community in the reactor. The isolated strains Desulfovibrio L3 and Desulfovibrio L7 were the most dominant SRB, representing 30–35% and 25–35%, respectively, of the total SRB community. Desulfobulbus-like bacteria contributed for 20–25%, and the Desulfobacca acetoxidans-specific probe targeted approximately 15–20% of the total SRB. The whole cell hybridisation results thus revealed a consortium of four different species of SRB that can be enriched and maintained on a single energy source in a full-scale sulfidogenic reactor.     

Biodiscovery of new Australian thraustochytrids for production of biodiesel and long-chain omega-3 oils

Heterotrophic growth of thraustochytrids has potential in co-producing a feedstock for biodiesel and long-chain (LC, ≥C₂₀) omega-3 oils. Biodiscovery of thraustochytrids from Tasmania (temperate) and Queensland (tropical), Australia, covered a biogeographic range of habitats including fresh, brackish, and marine waters. A total of 36 thraustochytrid strains were isolated and separated into eight chemotaxonomic groups (A–H) based on fatty acid (FA) and sterol composition which clustered closely with four different genera obtained by 18S rDNA molecular identification. Differences in the relative proportions (%FA) of long-chain C₂₀, C₂₂, omega-3, and omega-6 polyunsaturated fatty acids (PUFA), including docosahexaenoic acid (DHA), docosapentaenoic acid, arachidonic acid, eicosapentaenoic acid (EPA), and saturated FA, as well as the presence of odd-chain PUFA (OC-PUFA) were the major factors influencing the separation of these groups. OC-PUFA were detected in temperate strains of groups A, B, and C (Schizochytrium and Thraustochytrium). Group D (Ulkenia) had high omega-3 LC-PUFA (53% total fatty acids (TFA)) and EPA up to 11.2% TFA. Strains from groups E and F (Aurantiochytrium) contained DHA levels of 50–61% TFA after 7 days of growth in basal medium at 20 °C. Groups G and H (Aurantiochytrium) strains had high levels of 15:0 (20–30% TFA) and the sum of saturated FA was in the range of 32–51%. β,β-Carotene, canthaxanthin, and astaxanthin were identified in selected strains. Phylogenetic and chemotaxonomic groupings demonstrated similar patterns for the majority of strains. Our results demonstrate the potential of these new Australian thraustochytrids for the production of biodiesel in addition to omega-3 LC-PUFA-rich oils.     

Identification and production of 3-hydroxy-Δ9-cis-1,18-octadecenedioic acid by mutants of Candida tropicalis

 The transformation of oleic acid by mutants of Candida tropicalis was studied in fed-batch cultures. Besides Δ⁹-cis–1,18-octadecenedioic acid, 3-hydroxy-Δ⁹-cis–1,18-octadecenedioic acid was detected as the main fermentation product. Here we describe the production, isolation and the complete chemical characterization of the purified 3-hydroxy-Δ⁹-cis–1,18-octadecenedioic acid. The geometric configuration of the double bond was not changed during bioconversion. The enantiomeric excess of the compound was 76%. Mutagenesis of C. tropicalis DSM 3152 with N-methyl-N-nitro-N′-nitrosoguanidine and selection with oleic acid as the sole carbon source led to mutant M 25, which produced the 3-hydroxy-Δ⁹-cis–1,18-octadecenedioic acid at a 1.8-fold higher concentration in the medium as compared to the parent strain. The maximum concentration of the hydroxy dioic acid was 19.4 g/l after 223 h fermentation. Received: 24 August 1995/Received revision: 21 September 1995/Accepted: 4 October 1995     

Screening and Identification of Endomannanase-Producing Microfungi from Hypersaline Environments

A culture-dependent enrichment technique was used to isolate endo-1,4-β-mannanase–producing fungi from a hypersaline environment. Galactomannan was used as carbon source and resulted in isolation of strains of Scopulariopsis brevicaulis, S. candida, and Verticillium dahliae. The Scopulariopsis isolates were found to be more dominant and could be isolated from consecutive evaporation ponds, whereas Verticillium was only isolated from one pond. The Scopulariopsis strains exhibited only endomannanase activity, whereas Verticillium displayed broad-activity spectrum by secreting endoxylanases and cellulases in addition to endomannanases. S. candida LMK004 and LMK008 produced 7420 and 14750 nkat g⁻¹ biomass, respectively. Endomannanase production in these strains increased with an increase in NaCl concentration up to 10% (w/v), after which both growth and enzyme production was decreased. V. dahliae LMK006 grew and produced up to 5000 nkat g⁻¹ biomass endomannanase in the absence of NaCl. Increased NaCl concentration had a negative effect on this strain. S. brevicaulis LMK002 showed poor endomannanase production but a similar growth trend as the other Scopulariopsis strains. In general, the Scopulariopsis strains exhibited better halotolerance than V. dahliae and could grow in the presence of 20% NaCl on solid medium.     

Conversion of oleic acid to 10-hydroxystearic acid by two species of ruminal bacteria

Bacteria able to convert oleic acid to 10-hydroxystearic acid were isolated from the ovine rumen. The solid hydroxy fatty acid produced from bacterial fermentations containing oleic acid was recovered by filtration, extraction into ether and crystallisation. The identity of the product was confirmed by HPLC and gas chromatography/mass spectrometry. One 10-hydroxystearic-acid-producing bacterial group was represented by two strains of an anaerobic gram-negative curved rod with tufts of flagella on the concave surface of the cell. The morphology and other characteristics enabled the strains to be tentatively identified as Selenomonas ruminantium. Another bacterium capable of the same transformation, represented by two strains of a facultatively anaerobic gram positive chain-forming coccus, was identified as Enterococcus faecalis. Since unsaturated fatty acids entering the rumen are normally hydrogenated, hydration of oleic acid represents an alternative fate of unknown significance in vivo.     

Conversion of Unsaturated Fatty Acids by Bacteria Isolated from Compost

A compost mixture amended with soybean oil was enriched in microorganisms that transformed unsaturated fatty acids (UFAs). When oleic acid or 10-ketostearic acid was the selective fatty acid, Sphingobacterium thalpophilum (NRRL B-23206, NRRL B-23208, NRRL B-23209, NRRL B-23210, NRRL B-23211, NRRL B-23212), Acinetobacter spp. (NRRL B-23207, NRRL B-23213), and Enterobacter cloacae (NRRL B-23264, NRRL B-23265, NRRL B-23266) represented isolates that produced either hydroxystearic acid, ketostearic acid, or incomplete decarboxylations. When ricinoleic (12-hydroxy-9-octadecenoic) acid was the selective UFA, Enterobacter cloacae (NRRL B-23257, NRRL B-23267) and Escherichia sp. (NRRL B-23259) produced 12-C and 14-C homologous compounds, and Pseudomonas aeruginosa (NRRL B-23256, NRRL B-23260) converted ricinoleate to a trihydroxyoctadecenoate product. Also, various Enterobacter, Pseudomonas, and Serratia spp. appeared to decarboxylate linoleate substrate incompletely. These saprophytic, compost bacteria were aerobic or facultative anaerobic Gram-negative and decomposed UFAs through decarboxylation, hydroxylation, and hydroperoxidation mechanisms. Received: 3 November 1998 / Accepted: 30 November 1998     

Biosynthesis of poly-β-hydroxyalkanoates by Sphingopyxis chilensis S37 and Wautersia sp. PZK cultured in cellulose pulp mill effluents containing 2,4,6-trichlorophenol

Poly-β-hydroxyalkanoates (PHA) polymer is synthesized by different bacterial species. There has been considerable interest in the development and production of biodegradable polymers; however, the high cost of PHA production has restricted its applications. Kraft cellulose industry effluents containing 2,4,6-trichlorophenol (10 or 20 μg ml⁻¹) were used by the bacteria Sphingopyxis chilensis S37 and Wautersia sp. PZK to synthesize PHA. In this condition, S. chilensis S37 was able to grow and degrade 2,4,6-trichlorophenol (ca. 60%) and 80% of these cells accumulated PHA. Wautersia PZK completely degraded 2,4,6-TCP and more than 90% of the cells accumulated PHA in 72 h. The PHA detection was performed by flow cytometry and polyester composition was characterized by gas chromatography-mass spectroscopy (GC-MS), indicating that these polymers are made by 3-hydroxybutyric acid and 3-hydroxyhexadecanoic acid for S37 and PZK strains, respectively. Results demonstrated that strains’ growth and PHA production and composition are not modified in cellulose effluents with or without 2,4,6-TCP (10–20 μg ml⁻¹). Therefore, our results indicate that S. chilensis S37 and Wautersia sp. PZK are able to degrade a toxic compound such as a 2,4,6-TCP and simultaneously produce a valuable biopolymer using low-value substrates.     

Diversity of Oleic Acid,Ricinoleic Acid and Linoleic Acid Conversions Among <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> Strains*

Sixteen Pseudomonas aeruginosa strains, including patent strain NRRL B-18602, three recent isolates from composted materials amended with ricinoleic acid, and 12 randomly selected from the holdings of the ARS Culture Collection, were examined for their fatty acid converting abilities. The study examined the bioconversion of oleic acid to 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) and ricinoleic acid to 7,10,12-trihydroxy-8(E)-octadecenoic acid (TOD). A new DOD-like compound from linoleic acid was observed. All strains except NRRL B-247 exhibited varying levels of DOD production. NRRL B-1000, NRRL B-18602 and NRRL B-23258 with yields up to 84% were among the best DOD producers. TOD production generally paralleled DOD production at a relatively lower yield of up to 15%. Strains NRRL B-1000 and NRRL B-23260 were the best TOD producers. A DOD-like product in low yields was obtained from linoleic acid. The fatty acid bioconversion capability was related neither to growth rate nor to variation in the greenish pigmentation of the strains. Production of significant quantities of DOD and TOD from oleic and ricinoleic acids, respectively, appeared to be a characteristic trait of P. aeruginosa strains. A number of highly effective strains for DOD production were identified.     

Anomalies in the growth kinetics of Saccharomyces cerevisiae strains in aerobic chemostat cultures

Aerobic glucose-limited chemostat cultivations were conducted with Saccharomyces cerevisiae strains NRRL Y132, ATCC 4126 and CBS 8066, using a complex medium. At low dilution rates all three strains utilised glucose oxidatively with high biomass yield coefficients, no ethanol production and very low steady-state residual glucose concentrations in the culture. Above a threshold dilution rate, respiro-fermentative (oxido-reductive) metabolism commenced, with simultaneous respiration and fermentation occurring, which is typical of Crabtree-positive yeasts. However, at high dilution rates the three strains responded differently. At high dilution rates S. cerevisiae CBS 8066 produced 7–8 g ethanol L⁻¹ from 20 g glucose L⁻¹ with concomitant low levels of residual glucose, which increased markedly only close to the wash-out dilution rate. By contrast, in the respiro-fermentative region both S. cerevisiae ATCC 4126 and NRRL Y132 produced much lower levels of ethanol (3–4 g L⁻¹) than S. cerevisiae CBS 8066, concomitant with very high residual sugar concentrations, which was a significant deviation from Monod kinetics and appeared to be associated either with high growth rates or with a fermentative (or respiro-fermentative) metabolism. Supplementation of the cultures with inorganic or organic nutrients failed to improve ethanol production or glucose assimilation. Journal of Industrial Microbiology & Biotechnology (2000) 24, 231–236. Received 09 August 1999/ Accepted in revised form 18 December 1999     

Isolation and characterization of two novel ethanol-tolerant facultative-anaerobic thermophilic bacteria strains from waste compost

In a search for potential ethanologens, waste compost was screened for ethanol-tolerant thermophilic microorganisms. Two thermophilic bacterial strains, M5EXG and M10EXG, with tolerance of 5 and 10% (v/v) ethanol, respectively, were isolated. Both isolates are facultative anaerobic, non-spore forming, non-motile, catalase-positive, oxidase-negative, Gram-negative rods that are capable of utilizing a range of carbon sources including arabinose, galactose, mannose, glucose and xylose and produce low amounts of ethanol, acetate and lactate. Growth of both isolates was observed in fully defined minimal media within the temperature range 50–80°C and pH 6.0–8.0. Phylogenetic analysis of the 16S rDNA sequences revealed that both isolates clustered with members of subgroup 5 of the genus Bacillus. G+C contents and DNA–DNA relatedness of M5EXG and M10EXG revealed that they are strains belonging to Geobacillus thermoglucosidasius. However, physiological and biochemical differences were evident when isolates M5EXG and M10EXG were compared with G. thermoglucosidasius type strain (DSM 2542^T). The new thermophilic, ethanol-tolerant strains of G. thermoglucosidasius may be candidates for ethanol production at elevated temperatures.     

Eicosapentaenoic and docosahexaenoic acids production by and okara-utilizing potential of thraustochytrids

Nine thraustochytrid strains isolated from subtropical mangroves were screened for their eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) production potential in a glucose yeast extract medium. Their ability to utilize okara (soymilk residue) for growth and EPA and DHA production was also evaluated. EPA yield was low in most strains, while DHA level was high on glucose yeast extract medium, producing 28.1–41.1% of total fatty acids, for all strains, with the exception of Ulkenia sp. KF13. The DHA yield of Schizochytrium mangrovei strains ranged from 747.7 to 2778.9 mg/l after 52 h of fermentation at 25°C. All strains utilized okara as a substrate for growth, but DHA yield was lower when compared with fermentation in a glucose yeast extract medium. Journal of Industrial Microbiology & Biotechnology (2001) 27, 199–202. Received 11 December 2000/ Accepted in revised form 29 June 2001