Saprolegnia australis R. F. Elliott 1968 infection in Prussian carp Carassius gibelio (Bloch, 1782) eggs and its control with herb extracts

In order to control saprolegniosis in Prussian carp (Carassius gibelio (Bloch, 1782) eggs, it is important to screen herb extracts as potential anti‐Saprolegnia drugs in Prussian carp hatcheries. For this purpose, an oomycete water mould (strain SC) isolated from Prussian carp [Carassius gibelio (Bloch, 1782)] eggs suffering from saprolegniosis was characterised morphologically as well as from ITS rDNA sequence data. Initially identified as a Saprolegnia sp. based on its morphological features, the constructed phylogenetic tree using the neighbour joining method further indicated that the SC strain was closely related to Saprolegnia australis R. F. Elliott 1968 strain VI05733 (GenBank accession no. HE798564 ), and which could form biofilm communities as virulence factors. In addition, aqueous extracts from forty Chinese herbs were screened as possible anti‐Saprolegnia agents. Among them, a 1 g ml^?1 extract from Radix sanguisorbae was the most efficacious anti‐Saprolegnia agent, indicated by the minimum inhibitory concentration that was as low as 256 mg L^?1. Relative survival of 73 and 88% was obtained against the SC strain in fish eggs at concentrations of 256 and 1280 mg L^?1, respectively. This is the first known report of Saprolegnia australis R. F. Elliott 1968 infection in C. gibelio (Bloch, 1782) eggs involving the screening of R. sanguisorbae extracts as potential anti‐Saprolegnia agents.     

Nonlinear response of stream ecosystem structure to low‐level phosphorus enrichment

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Continuous multistep versus fed‐batch production of ethanol and xylitol in a simulated medium of sugarcane bagasse hydrolyzates

Co‐cultures for simultaneous production of ethanol and xylitol were studied under different operation bioreactor modes using Candida tropicalis IEC5‐ITV and Saccharomyces cerevisiae ITV01‐RD in a simulated medium of sugarcane bagasse hydrolyzates. Xylitol and ethanol tolerance by S. cerevisiae and C. tropicalis, respectively, was evaluated. The results showed that C. tropicalis was sensitive to ethanol concentrations up to 30 g/L, while xylitol had no effect on S. cerevisiae viability and metabolism. The best condition found for simultaneous culture was S. cerevisiae co‐culture and C. tropicalis sequential cultivation at 24 h. Under these conditions, productivity and yield for ethanol were Q_EtOH = 0.72 g L^?1 h^?1 and Y_EtOH/s = 0.37 g/g, and for xylitol, Q_XylOH = 0.10 g L^?1 h^?1 and Y_XylOH/S = 0.31 g/g, respectively; using fed‐batch culture, the results were Q_EtOH = 0.87 g L^?1 h^?1 and Y_EtOH/s = 0.44 g L^?1 h^?1, and Q_EtOH = 0.27 g L^?1 h^?1 and Y_EtOH/s = 0.57 g/g, respectively. Maximum volumetric productivity in continuous multistep cultures of ethanol and xylitol was at dilution rates of 0.131 and 0.074 h^?1, respectively. Continuous multistep production, Q_EtOH increased up to 50% more than in fed‐batch culture, even though xylitol yield remained unchanged.     

Effects of sodium chloride, formalin and iodine on the hatching success of common carp, Cyprinus carpio, eggs

Saprolegniales are ubiquitous in natural water supplies of fish hatcheries, and often cause serious disease problems. Sodium chloride, formalin and iodine, administered twice a day as a flush at different concentrations, were tested on infected eggs of common carp, Cyprinus carpio, to evaluate their antifungal activity and effect on hatching rates. Sodium chloride at 35 000 mg L^?1 and formalin at 400 mg L^?1 were found to be most effective in controlling Saprolegnia sp., with 85.4 and 91.8% hatching rates, respectively. Iodine increased the hatching rate by 27% at 200 mg L^?1 (P < 0.05). There were infections on eggs exposed to all levels of iodine, but not on eggs treated with sodium chloride and formalin. Sodium chloride and formalin were more effective than iodine in controlling Saprolegnia. Sodium chloride is a safe, efficacious and economical treatment of Saprolegniosis and is therefore recommended for treating common carp eggs.     

Enhancement of total lipid yield by nitrogen,carbon, and iron supplementation in isolated microalgae

The biochemical contents and biodiesel production ability of three microalgal strains grown under different sodium nitrate, sodium carbonate, and ferric ammonium citrate (iron) levels were investigated. The highest biomass and lipid contents were found in Scenedesmus sp., Chlorella sp., and Chlamydomonas sp. when grown in normal BG‐11 containing sodium carbonate concentration at 0.03 g · L^?1, and in normal BG‐11 containing iron concentration (IC) at 0.009 or 0.012 g · L^?1. Increasing the sodium nitrate level increased the biomass content, but decreased the lipid content in all three microalgae. Among the three microalgae, Scenedesmus sp. showed the highest total lipid yield of 0.69 g · L^?1 under the IC of 0.012 g · L^?1. Palmitic and oleic acids were the major fatty acids of Scenedesmus sp. and Chlamydomonas sp. lipids. On the other hand, Chlorella sp. lipids were rich in palmitic, oleic, and linolenic acids, and henceforth contributing to poor biodiesel properties below the standard limits. The three isolated strains had a potential for biodiesel production. Nevertheless, Scenedesmus sp. from stone quarry pond water was the most suitable source for biodiesel production with tolerance toward the high concentration of sodium carbonate without the loss of its biodiesel properties.     

Reference values for selected hematological and serum biochemical parameters of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles under intensive aquaculture conditions

This work aims to establish normal reference intervals for selected hemato‐biochemical parameters, based on their potential clinical relevance, and which may contribute to evaluating the health, nutritional and welfare status of Senegalese sole (Solea senegalensis Kaup, 1858) juveniles. Thirty‐one healthy Senegalese sole juveniles grown under intensive aquaculture conditions were used in the study. Based on the robust method with Box–Cox transformation data the established reference intervals for hematological parameters were: hematocrit 12–26%, hemoglobin 2.8–6 g dl^?1, erythrocytes 90–97.0% total, leucocytes 4–10% total; erythrocyte indices and differential leucocytes counts were also evaluated. Reference intervals for biochemical parameters were (g dl^?1) glucose 19–86 mg dl^?1, total protein 2.6–6.3, albumin 1–2.34, globulins 1.8–4.1, lipids 0.7–1.3, triglycerides 0.3–1.8, total cholesterol 0.1–0.9 g dl^?1, HDL‐cholesterol 4–65 mg dl^?1, LDL‐cholesterol 7–532 mg dl^?1, sodium 124–202 mmol L^?1), potassium 1.1–4.6 mmol L^?1, calcium 7.6–13.2 mg L^?1, magnesium 1.8–4.8 mg L^?1, inorganic phosphorus 3.4–9.5 mg L^?1, alkaline phosphatase 93–598 U L^?1, aspartate aminotransferase 118–605 U L^?1, lactate dehydrogenase 8.7–782 U L^?1, and creatine phosphokinase 31.5–552 U L^?1. This data is expected to provide a valuable tool to monitor the stress, health and nutritional conditions of Senegalese sole juveniles under aquaculture production.     

Isolation of anti-Saprolegnia lignans from Magnolia officinalis and SAR evaluation of honokiol/magnolol analogs

To control the fish fungal pathogen Saprolegnia, the effects of the petroleum ether extracts of Magnolia officinalis were evaluated by a rapeseed (Brassicanapus) microplate method in vitro. By loading on an open silica gel column and eluting with petroleum ether-ethyl acetate-methanol, honokiol (C₁₈H₁₈O₂) and magnolol (C₁₈H₁₈O₂) were isolated from Magnolia officinalis. Saprolegnia parasitica growth was inhibited significantly when honokiol concentration was >8.0?mg/L, and magnolol concentration was >9.0?mg/L, with EC₅₀ values of 4.38 and 4.92?mg/L, respectively. Six honokiol and magnolol derivatives were designed, synthesized and evaluated for their anti-Saprolegnia activity. According to the results, double bond and hydroxyl played an important role in inhibiting Saprolegnia. Mechanistically, through the scanning electron microscope observation, honokiol and magnolol could cause the Saprolegnia parasitica mycelium tegumental damage including intensive wrinkles and nodular structures. Moreover, compared to traditional drugs kresoxim-methyl (LC₅₀?=?0.66?mg/L) and azoxystrobin (LC₅₀?=?2.71?mg/L), honokiol and magnolol showed a lower detrimental effect on zebrafish, with the LC₅₀ values of 6.00 and 7.28?mg/L at 48?h, respectively. Overall, honokiol and magnolol were promising lead compounds for the development of commercial drugs anti-Saprolegnia.     

Microalgae for phosphorus removal and biomass production: a six species screen for dual‐purpose organisms

Microalgae biofuel production can be feasible when a second function is added, such as wastewater treatment. Microalgae differ in uptake of phosphorus (P) and growth, making top performer identification fundamental. The objective of this screen was to identify dual‐purpose candidates capable of high rates of P removal and growth. Three freshwater – Chlorella sp., Monoraphidium minutum sp., and Scenedesmus sp. – and three marine – Nannochloropsis sp., N. limnetica sp., and Tetraselmis suecica sp. – species were batch cultured in 250 mL flasks over 16 days to quantitate total phosphorus (TP) removal and growth as a function of P loads (control, and 5, 10, and 15 mg L^?1 enrichment of control). Experimental design used 100 μmol m^?2 s^?1 of light, a light/dark cycle of 14/10 h, and no CO₂ enrichment. Phosphorus uptake was dependent on species, duration of exposure, and treatment, with significant interaction effects. Growth was dependant on species and treatment. Not all species showed increased P removal with increasing P addition, and no species demonstrated higher growth. Nannochloropsis sp and N. limnetica sp. performed poorly across all treatments. Two dual‐purpose candidates were identified. At the 10 mg L^?1 treatment Monoraphidium minutum sp. removed 67.1% (6.66 mg L^?1 ± 0.60 SE) of TP at day 8, 79.3% (7.86 mg L^?1 ± 0.28 SE) at day 16, and biomass accumulation of 0.63 g L^?1 ± 0.06 SE at day 16. At the same treatment Tetraselmis suecica sp. removed 79.4% (6.98 mg L^?1 ± 0.24 SE) TP at day 8, 83.0% (7.30 mg L^?1 ± 0.60 SE) at day 16, and biomass of 0.55 g L^?1 ± 0.02 SE at day 16. These species merit further study using high‐density wastewater cultures and lipid profiling to assess suitability for a nutrient removal and biomass/biofuel production scheme.     

A simple <Emphasis Type="Italic">in vitro</Emphasis> screening method to determine the effects of drugs against growth of <Emphasis Type="Italic">Saprolegnia parasitica</Emphasis>

To screen the effect of possible antifungal chemicals against growth of fish pathogenic Saprolegnia spp., a simple and rapid in vitro screening method has been developed. Heat sterilized hemp seeds (Cannabis sativa) colonized by Saprolegnia parasitica are exposed to different concentrations of the test drugs diluted in water. One Saprolegnia colonized hemp seed is transferred into each well of a 48-well flat bottom tissue culture plate, after which 1 mL of each concentration of the test drugs is added per well. Subsequent to exposure and incubation, the plate is inspected and any Saprolegnia growth on the seeds is graded. The method described in the present paper proved to be simple, effective and reproducible in screening of fungistatic and fungicidal drugs against Saprolegnia growth.     

Bioaccumulation of Microcystins in Lettuce

The contamination of lettuce (Lactuca sativa L.) by water‐borne crude extracts of the cyanobacterium microcystin‐producing Microcystis aeruginosa (Kützing) Kützing was investigated. The aim of the study was to determine whether bioaccumulation of microcystins occurs in lettuce foliar tissue when sprayed with solutions containing microcystins at concentrations observed in aquatic systems (0.62 to 12.5 μg · L^?1). Microcystins were found in lettuce foliar tissues (8.31 to 177.8 μg per Kg of fresh weight) at all concentrations of crude extracts. Spraying with water containing microcystins and cyanobacteria may contaminate lettuce at levels higher than the daily intake of microcystins recommended by the World Health Organization (WHO), underscoring the need to monitor such food exposure pathways by public authorities.     

Pharmacokinetics of oxytetracycline in yellow catfish [Pelteobagrus fulvidraco (Richardson, 1846)] with a single and multiple‐dose oral administration

A pharmacokinetic study of oxytetracycline (OTC) following a single (100 mg kg^?1) or a multi‐dose (100 mg kg^?1 for 5 days) oral administration was carried out in yellow catfish, Pelteobagrus fulvidraco. After oral administration at 25°C, a one‐compartment model was developed. The absorption half‐life (t_1/2(ka)) was 3.92, 1.44, 2.75, and 3.34 h in plasma, muscle, liver, and kidney after the single dose, and 0.35, 0.22, 0.42, 0.32 h after the multi‐dose, respectively. The order of peak concentration (C_max) was liver > kidney > plasma > muscle, at 3.48 μg g^?1, 2.90 μg g^?1, 1.46 μg ml^?1, and 1.39 μg g^?1 after the single dose, and 14.02 μg g^?1, 8.51 μg g^?1, 4.17 μg ml^?1, and 3.84 μg g^?1 after the multi‐dose, respectively. The elimination half‐lives (t_1/2(ke)) of OTC in plasma, muscle, liver, and kidney were calculated to be 7.64, 26.29, 19.08, and 10.61 h after the single dose, and 47.54, 70.99, 49.87, and 47.73 h after the multi‐dose, respectively. The results suggest that OTC was absorbed faster after the multi‐dose than after the single dose, suggesting that OTC could be more efficacious after the multi‐dose and more effective in the control bacterial diseases in aquaculture, with the side effects of longer withdrawal periods.     

A comparison of isoprene and monoterpene emission rates from the perennial bioenergy crops short‐rotation coppice willow and Miscanthus and the annual arable crops wheat and oilseed rape

Biogenic volatile organic compounds (BVOC) emissions from bioenergy crops may differ from those of conventional crops. We compared emission rates of isoprene and a number of monoterpenes from the lignocellulosic bioenergy crops short‐rotation coppice (SRC) willow and Miscanthus, with the conventional crops wheat and oilseed rape. BVOC emission rates were measured via dynamic vegetation enclosure and GC‐MS analysis approximately monthly between April 2010 and August 2012 at a location in England and from SRC willow at two locations in Scotland. The largest BVOC emission rates were measured from willow in England and varied between years. Isoprene emission rates varied between μg g^?1 h^?1. Of the monoterpenes detected from willow, α‐pinene emission rates were highest (μg g^?1 h^?1), followed by μg g^?1 h^?1 for δ‐3‐carene, μg g^?1 h^?1 for β‐pinene and μg g^?1 h^?1 for limonene. BVOC emission rates measured in Scotland were much lower. Low emission rates of isoprene and α‐pinene were measured from Miscanthus in 2010 (μg g^?1 h^?1 and μg g^?1 h^?1, respectively) but were not detected in subsequent years. Emission rates from wheat of isoprene were negligible but relatively high for monoterpenes (μg g^?1 h^?1 and μg g^?1 h^?1 for α‐pinene and limonene, respectively). No significant emission rates of BVOCs were measured from oilseed rape. The measured emission rates followed a clear seasonal trend. Crude extrapolations based solely on data gathered here indicate that isoprene emissions from willow could correspond to 0.004–0.03% (UK) and 0.76–5.5% (Europe) of current global isoprene if 50% of all land potentially available for bioenergy crops is planted with willow.     

Determination of enalapril maleate and atenolol in their pharmaceutical products and in biological fluids by flow‐injection chemiluminescence

A chemiluminescent method using flow injection (FI) was investigated for rapid and sensitive determination of enalapril maleate and atenolol, which are used in the treatment of hypertension. The method is based on the sensitizing effect of these drugs on the Ce(IV)–sulfite reaction. The different experimental parameters affecting the chemiluminescence (CL) intensity were carefully studied and incorporated into the procedure. The method permitted the determination of 0.01–3.0 µg mL^?1 of enalapril maleate in bulk form with correlation coefficient r = 0.99993, lower limit of detection (LOD) 0.0025 µg mL^?1 (S/N = 2) and lower limit of quantitation (LOQ) 0.01 µg mL^?1. The linearity range of atenolol in bulk form was 0.01–2.0 µg mL^?1 (r = 0.99989) with LOD of 0.0003 µg mL^?1 (S/N = 2) and LOQ of 0.01 µg mL^?1. In biological fluids the linearity range of enalapril maleate was 0.1–2.0 µg mL^?1 in both urine and serum, and for atenolol the linearity range was 0.1–1.0 µg mL^?1 in both urine and serum. The method was also applied to the determination of the drugs in their pharmaceutical preparations. Copyright © 2009 John Wiley & Sons, Ltd.     

Triterpenoids from Euphorbia fischeriana

Nineteen triterpenoids including two new tirucallane ones, fisuphanins A and B, were isolated from the whole plant of Euphorbia fischeriana Steud. The new structures were elucidated on the basis of extensive spectroscopy techniques including infrared (IR), High Resolution Mass Spectrometry (HRMS), and Nuclear Magnetic Resonance (NMR). Some triterpenoids were evaluated for their cytotoxicity against A549 and MCF-7 cell lines.     

The influence of iron,siderophores and refractory DOM on cyanobacterial biomass in oligotrophic lakes

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Microbially enhanced dissolution of HgS in an acid mine drainage system in the California Coast Range

Mercury sulfides (cinnabar and metacinnabar) are the main ores of Hg and are relatively stable under oxic conditions (K_sp = 10^?54 and 10^?52, respectively). However, until now their stability in the presence of micro‐organisms inhabiting acid mine drainage (AMD) systems was unknown. We tested the effects of the AMD microbial community from the inoperative Hg mine at New Idria, CA, present in sediments of an AMD settling pond adjacent to the main waste pile and in a microbial biofilm on the surface of this pond, on the solubility of crystalline HgS. A 16S rRNA gene clone library revealed that the AMD microbial community was dominated by Fe‐oxidizing (orders Ferritrophicales and Gallionellas) and S‐oxidizing bacteria (Thiomonas sp.), with smaller amounts (≤6%) being comprised of the orders Xanthomondales and Rhodospirillales. Though the order Ferritrophicales dominate the 16S rRNA clones (>60%), qPCR results of the microbial community indicate that the Thiomonas sp. represents ~55% of the total micro‐organisms in the top 1 cm of the AMD microbial community. Although supersaturated with respect to cinnabar and metacinnabar, microcosms inoculated with the AMD microbial community were capable of releasing significantly more Hg into solution compared to inactivated or abiotic controls. Four different Hg‐containing materials were tested for bacterially enhanced HgS dissolution: pure cinnabar, pure metacinnabar, mine tailings, and calcine material (processed ore). In the microcosm with metacinnabar, the presence of the AMD microbial community resulted in an increase of dissolved Hg concentrations up to 500 μg L^‐1 during the first 30 days of incubation. In abiotic control microcosms, dissolved Hg concentrations did not increase above 100 ng L^?1. When Hg concentrations were below 50 μg L^‐1, the Fe‐oxidizing bacteria in the AMD microbial community were still capable of oxidizing Fe(II) to Fe(III) in the AMD solution, whereas concentrations above 50 μg L^?1 resulted in inhibition of microbial iron oxidation. Our experiments show that the AMD microbial community contributes to the dissolution of mercury sulfide minerals. These findings have major implications for risk assessment and future management of inoperative Hg mines worldwide.     

Effect of dietary dextrin levels on the growth performance,blood chemistry,body composition,hepatic triglicerides and glycogen of Lebranche mullet juveniles (Mugil liza Valenciennes 1836, Mugilidae)

The effects of increasing levels of dietary dextrin on growth performance, body composition, blood chemistry and hepatic triglycerides and glycogen levels were evaluated for juvenile Lebranche mullet, Mugil liza Valenciennes 1836, Mugilidae). Five diets were formulated to be isonitrogenous (350 g kg^?1) and isolipidic (6 g kg^?1) with increasing dextrin levels (D150: 150 g kg^?1; D200: 200 g kg^?1; D250: 250 g kg^?1; D300: 300 g kg^?1; D350: 350 g kg^?1). The experimental diets were offered to the fish for 34 days, four times per day, until apparent satiation. Each treatment was tested in triplicate, with nine fish per tank (mean weight 4.69 ± 0.31 g). Fish were reared in a recirculating aquatic system of 15 fibreglass tanks each containing 50 L of saltwater. Growth parameters and body composition of the mullets were not significantly affected (P > 0.05) by the dietary treatments. Plasma glucose concentration declined (P < 0.05) when dietary dextrin increased from D250 to D300, but recovered to the previous values (in reference to D150 and D200) when fish were fed with D350. Glycated haemoglobin, plasma proteins, triglycerides and cholesterol showed no significant differences among these treatments. Hepatic glycogen reached a maximum in treatment D250, followed by D350, D200 and D300, with the lowest concentration of liver glycogen found in D150 (P < 0.05). The concentration of liver triglycerides showed an increase (P < 0.05) in treatments D300 and D350 compared with D200. In conclusion, Mugil liza juveniles can be fed diets with high levels of dietary dextrin with no deleterious effects to their growth or plasma biochemistry, hepatic glycogen or triglycerides.     

Estimation of Lipid Hydroperoxide Levels in Tropical Marine Macroalgae

The incipient levels of lipid hydroperoxides (LHPOs) were determined in selected green, brown, and red macroalgae by the FOX assay using hydroperoxy HPLC mix. The LHPOs contents varied between the investigated species and showed relatively low values in this study. Among the greens, it varied from 12 ± 6.2 μg · g^?1 (Codium sursum) to 31.5 ± 2.8 μg · g^?1 (Ulva lactuca), whereas in reds, from 5.7 ± 1.6 μg · g^?1 (Gracilaria corticata) to 46.2 ± 6 μg · g^?1 (Sarconema filiforme), and in browns, from 4.6 ± 4.4 μg · g^?1 (Dictyota bartayresiana) to 79 ± 5.0 μg · g^?1 (Sargassum tenerrimum), on fresh weight basis. These hydroperoxides represented a minor fraction of total lipids and ranged from 0.04% (S. swartzii) to 1.1% (S. tenerrimum) despite being a rich source of highly unsaturated fatty acids. The susceptibility of peroxidation was assessed by specific lipid peroxidazibility (SLP) values for macroalgal tissues. The LHPO values were found to be independent of both the PUFAs contents and their degree of unsaturation (DBI), as evident from the PCA analysis. SLP values were positively correlated with the LHPOs and negatively with DBI. The FOX assay gave ≥20‐fold higher values for LHPOs as compared to the TBARS method for all the samples investigated in this study. Furthermore, U. lactuca cultured in artificial seawater (ASW) enriched with nutrients (N, P, and NP) showed a sharp decline in LHPOs contents relative to those cultured in ASW alone P ≤ 0.05. It is inferred from this study that the FOX assay is an efficient, rapid, sensitive, and inexpensive technique for detecting the incipient lipid peroxidation in macroalgal tissues.     

Using CO2 to enhance carbon capture and biomass applications of freshwater macroalgae

A major limiting factor in the development of algae as a feedstock for the bioenergy industry is the consistent production and supply of biomass. This study is the first to access the suitability of the freshwater macroalgal genus Oedogonium to supply biomass for bioenergy applications. Specifically, we quantified the effect of CO₂ supplementation on the rate of biomass production, carbon capture, and feedstock quality of Oedogonium when cultured in large‐scale outdoor tanks. Oedogonium cultures maintained at a pH of 7.5 through the addition of CO₂ resulted in biomass productivities of 8.33 (±0.51) g DW m^?2 day^?1, which was 2.5 times higher than controls which had an average productivity of 3.37 (±0.75) g DW m^?2 day^?1. Under these productivities, Oedogonium had a carbon content of 41–45% and a higher heating value of 18.5 MJ kg^?1, making it an ideal biomass energy feedstock. The rate of carbon fixation was 1380 g C m^?2 yr^?1 and 1073.1 g C m^?2 yr^?1 for cultures maintained at a pH of 7.5 and 8.5, and 481 g C m^?2 yr^?1 for cultures not supplemented with CO₂. This study highlights the potential of integrating the large‐scale culture of freshwater macroalgae with existing carbon waste streams, for example coal‐fired power stations, both as a tool for carbon sequestration and as an enhanced and sustainable source of bioenergy.     

Different fermentation strategies by Schizochytrium mangrovei strain pq6 to produce feedstock for exploitation of squalene and omega‐3 fatty acids

Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L^?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g^?1 · L^?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g^?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium .