Similar Specific Growth Rates Research Articles

Engineering Bacillus subtilis J46 for efficient utilization of galactose through adaptive laboratory evolution

Efficient utilization of galactose by microorganisms can lead to the production of valuable bio-products and improved metabolic processes. While Bacillus subtilis has inherent pathways for galactose metabolism, there is potential for enhancement via evolutionary strategies. This study aimed to boost galactose utilization in B. subtilis using adaptive laboratory evolution (ALE) and to elucidate the genetic and metabolic changes underlying the observed enhancements. The strains of B. subtilis underwent multiple rounds of adaptive laboratory evolution (approximately 5000 generations) in an environment that favored the use of galactose. This process resulted in an enhanced specific growth rate of 0.319 ± 0.005 h−1, a significant increase from the 0.03 ± 0.008 h−1 observed in the wild-type strains. Upon selecting the evolved strain BSGA14, a comprehensive whole-genome sequencing revealed the presence of 63 single nucleotide polymorphisms (SNPs). Two of them, located in the coding sequences of the genes araR and glcR, were found to be the advantageous mutations after reverse engineering. The strain with these two accumulated mutations, BSGALE4, exhibited similar specific growth rate on galactose to the evolved strain BSGA14 (0.296 ± 0.01 h−1). Furthermore, evolved strain showed higher productivity of protease and β-galactosidase in mock soybean biomass medium. ALE proved to be a potent tool for enhancing galactose metabolism in B. subtilis. The findings offer valuable insights into the potential of evolutionary strategies in microbial engineering and pave the way for industrial applications harnessing enhanced galactose conversion.

Abstract B147: Preclinical evaluation of XPO1 inhibition with topoisomerase-I (topo-I) inhibition in colorectal cancer (CRC) cell lines and patient-derived xenograft (PDX) models

Abstract Background: Resistance to topo-I inhibitors is of significant importance in treating patients with metastatic CRC (mCRC). Selinexor and eltanexor are selective inhibitors of nuclear export, by binding to exportin 1 (XPO1, the primary nucleic export receptor, and is overexpressed in CRC). Eltanexor is an investigational XPO1 inhibitor, with similar mechanism and potency but improved tolerability in animal models. XPO1 inhibition results in nuclear localization of tumor suppressor proteins, oncoprotein mRNAs, and topoisomerases, and decreases DNA damage repair (DDR) response. Irinotecan is a topo-I inhibitor which induces DNA damage and is commonly used in mCRC. We hypothesized that XPO1 inhibition may improve response to topo-I inhibitor in mCRC by impairing the DDR response. Methods: The synergism of XPO1 inhibition (selinexor or eltanexor) with SN38 was assessed in CRC cell lines by CellTiter-Glo 2.0 and quantitated using Bliss Additivity Model using Synergy Finder 2.0. Each condition was plated either concurrent (both drugs for 72 hours) or sequential (SN38 for 24 hours then removed, followed by XPO1 inhibitor for 48 hours). Nude mice were implanted with one microsatellite stable CRC PDX model in the flanks followed by treatment with vehicle, XPO1 inhibitor, irinotecan (15 mg/kg intraperitoneal weekly), or combination. Tumor growth was measured by specific growth rate (SGR), within an IACUC-approved protocol. Tumor tissue was collected at day 7 for molecular analysis. Tissues were lysed and protein was run on 4%-12% SDS-PAGE Gel. p21 Waf/Cip and P-Histone H2A.X were used to determine DNA damage by western blot. P-Histone H2AX (pH2AX) was evaluated by immunofluorescence using primary conjugated P-Histone H2A.X antibody and DAPI for nuclear counter stain. Slides were imaged using Olympus iX83 microscope and analysis was performed using Olympus CellSens software. Results: In CRC cell lines, concurrent combination eltanexor and SN38 did not synergistically decrease viability but increased pH2AX compared to SN38 alone (~30-fold). However, sequential SN38 followed by eltanexor synergistically decreased viability at multiple dose levels; evaluation of pH2AX is ongoing. In PDX model CRC254, eltanexor (10 mg/kg and reduced to 7.5 mg/kg on day 8 to improve tolerability, orally 5 days per week) with irinotecan decreased SGR compared to irinotecan alone (SGR=0.007 vs 0.026, respectively, p=0.0003) and compared to eltanexor alone (SGR=0.029, p <0.0001). Combination treatment increased pH2AX and increased p21 expression compared to either single-agent treatment. Similar SGR results were observed with selinexor (5 mg/kg orally twice weekly). Conclusions: XPO1 inhibition and topo-I inhibition decreased CRC tumor growth in PDX models, presumably by increasing DNA double strand breaks. Cell line data suggests sequential dosing of topo-I inhibition followed by XPO1 inhibition may be effective. This work supports continued development of this combination in mCRC. Citation Format: Robert W Lentz, Adrian Dominguez, Stacey Bagby, Cameron Binns, Alexis Leal, Sunnie Kim, Sarah Lindsey Davis, Christopher H Lieu, Wells A Messersmith, Todd M Pitts. Preclinical evaluation of XPO1 inhibition with topoisomerase-I (topo-I) inhibition in colorectal cancer (CRC) cell lines and patient-derived xenograft (PDX) models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B147.

Cyanobacteria cultivation on human urine for nutrients recovery

Urine is a nutrient rich stream; it accounts for 70% of the nitrogen load and 40% of the phosphorus load present in domestic wastewater while in volume it only represents 1%. Given the high concentrations of nitrogen (5–7 g N∙L−1) and phosphorus (0.2–0.3 g P∙L−1) in urine, it is more efficient to recover these nutrients from this concentrated stream than from domestic wastewater where they are more diluted. These nutrients can be recovered in form of biomass that could be a source of biobased compounds or could also be used as soil amendment or fertilizer. In this study, the model cyanobacterium Synechocystis sp. PCC6803 was cultivated on synthetic and real, source-separated human urine with different pretreatments to determine if real urine inhibits cyanobacterial growth. Additionally, the nutrient content of urine, including trace elements, was assessed to determine if these are sufficient to support growth to the biomass concentration needed for complete nitrogen and phosphorus recovery. Cultivation of Synechocystis sp. PCC6803 on source separated urine recovered up to 87% of the nitrogen and 99% of the phosphorus in form of biomass, reaching N:P ratios up to 43:1. The biomass reached similar specific growth rates on synthetic urine and source-separated urine demonstrating that there are no negative effects of real urine on growth of Synechocystis sp. PCC6803. Supplementing urine with sulfate, magnesium, iron and trace elements is necessary for balanced growth of Synechocystis sp. PCC6803 and high nutrient recovery.

Aqua-Ento-Ponics: Effect of Insect Meal on the Development of Sea Bass, Dicentrarchus labrax, in Co-Culture with Lettuce

The aim of this study is to investigate the effect of 10 and 20% replacement of fishmeal (FM dietary group) with the superworm Zophobas morio larvae meal (ZM10 and ZM20 dietary groups) on the growth performance of sea bass (Dicentrarchus labrax) and lettuce plants (Lactuca sativa) reared in aquaponics. Ninety juvenile sea bass with an average body weight of 21.55 g/individual were placed in aquaponic fish tanks, together with 24 lettuce plants with an average initial height of 8.90 cm/plant and an average number of leaves of 5.75/plant over a 45-day trial period. At the end of that period, all feeding groups exhibited high survival. In fact, ΖΜ10 and ZM20 groups showed similar fish weight gain and specific growth rate (SGR) (p > 0.05), but significantly lower SGR (p < 0.05) than the FM group. Nevertheless, final fish body weight and length were similar (p > 0.05) for all feeding groups. No plant mortality was observed during the 45-day study period. All three aquaponic systems resulted in similar leaf fresh weight, as well as fresh and dry aerial biomass. At the end of the experimental period, plants in the third system showed higher fresh leaf weight, total weight of fresh leaves, total dry aerial biomass, and total produced biomass compared to the other two systems. The results of the present study show that fish fed with the ZM10 diet had higher weight gain (WG) than fish fed with the ZM20 diet, while the SGRs for ZM10 and ZM20 were similar. Both ZM10 and ZM20 diets result in efficient lettuce production. This study also provides data that enlighten the feasibility of integrating insect meals as fish feeds for aquaponics which helps towards the development of an ento-aquaponic approach.

A subdermal tagging technique for juvenile sturgeon using a new self-powered acoustic tag

BackgroundA new technology for a self-powered acoustic tag (SPT) was developed for active tracking of juvenile fish, intended to avoid the typical battery life constraints associated with active telemetry technology. We performed a laboratory study to evaluate a subdermal tagging technique for the SPT and effects of the tag on survival, tag retention, and growth in juvenile white sturgeon (Acipenser transmontanus).ResultsSurvival was associated with tag retention. White sturgeon implanted with the SPT (n = 30) had 93% survival and tag retention by day 28, 67% by day 101, and 38% by day 595 post-tagging. Sturgeon implanted with a passive integrated transponder (PIT) tag only (control group) had 96% survival and tag retention by day 28, and through day 101 post-tagging. Fish in the PIT group were repurposed after day 101, so no comparisons with this group were made at day 595 post-tagging. Specific growth rate (SGR) for fork length was a median of 0.25% day−1 by day 28 for the SPT group, which was significantly lower than the PIT group (median: 0.42% day−1; n = 27). The SPT and PIT groups had similar SGR fork length by day 101 post-tagging (0.22 and 0.25% day−1, respectively). SGR weight was also lower for the SPT group compared to the PIT group on day 28 (1.39 and 2.11% day−1, respectively), but the difference again dissipated by day 101 (0.79 and 0.88% day−1, respectively).ConclusionThe tagging technique and placement of the SPT allowed the tag to remain upright along the flank of the sturgeon to ensure maximum battery output of the SPT; however, retention rates of the SPT were not ideal. We provided suggestions to improve the tagging technique. Suggestions included tagging fish that are > 400 mm FL, moving the incision location to extend the cavity and create a pocket for the placement of the SPT, and performing a quantitative wound-healing evaluation. Future studies are therefore recommended to evaluate these suggestions.

Effects of acclimation temperature regime on the thermal tolerance, growth performance and gene expression of a cold-water fish, Schizothorax prenanti.

Acclimation temperature is crucial for the optimization of a condition in aquaculture; we experimentally investigated the effects of temperature acclimation on the thermal tolerance, growth performance and gene expression levels of heat shock proteins (hsp70), growth hormone (gh) and insulin-like growth factors (igf-1) in Schizothorax prenanti, a cold-water fish in the Yangtze River basin. Critical thermal maximum (CTmax), critical thermal minimum (CTmin), lethal thermal maximum (LTmax), lethal thermal minimum (LTmin), feeding intake (FI), feeding efficiency (FE), and specific growth rate (SGR) were assessed at three stable temperatures (17, 22 and 27°C) and one variable temperature (22±5°C) for 28d. Better growth performance was observed under variable treatment compared to stable treatments. However, fish under the 27°C treatment exhibited much weaker growth performance than those in the 17°C treatment. Fish under variation temperature treatment fed like those under 22°C treatment; the fish exhibited similar SGR but a higher gh and hsp70 level under variation temperature treatment. This may be due in part to a trade-off energy expenditure to deal with the temperature fluctuation. Together, these findings suggest that juvenile Schizothorax prenanti are resilient to daily fluctuations within the temperature tested here.

Water temperature effects on growth performance, proximate body and tissue composition, morphometric characteristics and gastrointestinal evacuation processes of juvenile meagre, Argyrosomus regius (Asso 1801)

The effect of 4 temperature levels, 17, 20, 23 and 26 °C was investigated on growth performance, feed and nutrient utilization, body, fillet and liver composition and morphometric characteristics of meagre, of initial mean weight 36.46 g, after a 12-week trial, fed on a practical diet composed of 49% crude protein and 16% lipids (dry weight). Furthermore, the gastrointestinal evacuation processes of meagre were monitored by subjecting fish to 48-h fasting period, followed by force-feeding and collecting the stomach and intestinal contents at 1 h, 2 h, 4 h, 6 h, 8 h, 12 h and 24 h post-feeding. Meagre growth parameters significantly improved with the increase in temperature, resulting in double the thermal growth coefficient (TGC) at 23 and 26 °C compared to 17 °C. Maximum weight (122.5 g) was achieved at 26 °C. Daily feed intake (DFI) increased from 17 to 26 °C, whereas nutrient efficiency and utilization parameters were significantly lower only at 17 °C. A time effect was also evident on the growth-related parameters and feed conversion ratio (FCR), resulting in similar specific growth rate (SGR) and TGC values between 23 and 26 °C and lower FCR only in 17 °C by the 3rd month, despite the initial difference amongst the 4 treatments. Intestine length increased as fish grew bigger with temperature increase, but the relative intestine length to fish total length remained constant. No effect of temperature was found on condition index (CI), hepatosomatic index (HSI), body proximate composition, fillet lipids and liver glycogen content. Liver lipid content significantly increased from 17 °C to 26 °C. Temperature influenced gastric evacuation patterns, but not the digesta moisture in each gastrointestinal tract (GIT) segment. Hydration within the GIT was affected by temperature with lower content obtained at 17 °C. Stomach digesta moisture and hydration significantly elevated 4 h post-feeding in all treatments. Within the intestine, unlike in the stomach, digesta were mostly comprised of moisture. Gastric evacuation rate (GER) became faster with temperature increase. Meagre juveniles required 4.3–7.4 h to half-empty their stomachs depending on temperature and more than 24 h to completely evacuate their GIT. 23–27 °C was determined as the best water temperature range for growth of meagre of 36-123 g under the specific culture conditions. At 17 °C growth and feed efficiency were impaired, while gastric evacuation processes deviated from the rest.

Continuous biohydrogen production by a degenerated strain of Clostridium acetobutylicum ATCC 824

Degenerated strains of Clostridium acetobutylicum lack the ability to produce solvents and to sporulate, allowing the continuous production of hydrogen and organic acids. A degenerated strain of Clostridium acetobutylicum was obtained through successive batch cultures. Its kinetic characterization showed a similar specific growth rate than the wild type (0.25 h−1), a higher butyric acid production of 6.8 g·L−1 and no solvents production. A steady state was reached in a continuous culture at a dilution rate of 0.1 h−1, with a constant hydrogen production of 507 mL·h−1, corresponding to a volumetric rate of 6.10 L·L−1 d−1, and a yield of 2.39 mol of H2 per mole of glucose which represents 60% of the theoretical maximum yield. These results suggest that the degeneration is an interesting alternative for hydrogen production with this strain, obtaining a high hydrogen production in a continuous culture with cells in a permanent acidogenic state.

Black Soldier Fly Larvae Meal as a Fishmeal Substitute in Juvenile Dusky Kob Diets: Effect on Feed Utilization, Growth Performance, and Blood Parameters

Using black soldier fly larvae meal (BSFM) in place of fishmeal is an ingenious strategy for sustainable fish aquaculture. However, BSFM has not been evaluated for dusky kob (Argyrosomus japonicus), an economically important fish in South Africa. Therefore, this five-week study investigated the effect of partially replacing fishmeal with BSFM on feed utilization, growth performance, and blood parameters of juvenile dusky kob in a recirculating aquaculture system. Four diets were formulated by replacing fishmeal in a commercial dusky kob diet with BSFM at the rate of 0 (BSFM0), 50 (BSFM50), 100 (BSFM100), and 200 g/kg (BSFM200). Fish length and weights were measured weekly, while blood analyses were performed at the end of Week 5. For fish length and weight gain, there were neither linear nor quadratic responses in Weeks 1–4, while quadratic trends (y = 14.77 (± 0.19)−0.11 (± 0.05)x + 0.01 (± 0.00) x2; R2 = 0.35 and y = 49.85 (± 1.53)−1.22 (± 0.39)x + 0.06 (± 0.02) x2; R2 = 0.47, respectively) were observed in Week 5 in response to BSFM levels. Quadratic effects (y = 1.75 (± 0.15) + 0.10 (± 0.04)x − 0.01 (± 0.00) x2; R2 = 0.39) were also observed for feed conversion ratio (FCR) in response to BSFM inclusion levels. Fish fed BSFM200 had a similar overall FCR and specific growth rate as those reared on BSFM0. All blood parameters fell within the normal range for the dusky kob. We concluded that 20% dietary replacement of fishmeal with BSFM does not compromise feed utilization and growth performance of juvenile dusky kob.

Evaluation of high-density tank cultivation of the live-feed cyclopoid copepod Apocyclops royi (Lindberg 1940)

Copepods are considered relevant live feed for fish larval marine aquaculture. They promote fish larval survival and growth rate and reduce deformities when used as food source. The cyclopoid copepod Apocyplops royi are among others used in extensive Taiwanese aquaculture. However, knowledge on its performance in intensive cultures is limited. This study investigates parameters that are relevant prerequisites before initiating intensive tank cultures with A. royi. We found that the biochemical profile of A. royi is promising and relevant when used as live feed with a C:N ratio of 4.7 and a fatty acid ratio (DHA/EPA 3.2 ± 0.7) that fulfil the minimum quantitatively dietary requirement of essential FAs for marine fish larvae and early juveniles. The size range of nauplii (78 - 245 μm) is evaluated to be a feasible size for small mouthed first feeding marine fish larvae. The copepod exhibits similar specific growth rates as other cyclopoids (10% DW d−1). Further, we tested A. royi populations relative composition (nauplii, copepodites, males, females and ovigerous females) as an effect of culture densities and found no change within the test range (300 to 3800 ind. L−1). To evaluate the recruitment into the population we conducted an experiment with densities from a few hundred to 10,000 ind. L−1. We observed no density limitation on the female ovigerous rate = ((ovigerous females) / copepodites + adults) x 100) ~6%) even at very high densities. We demonstrated, that A. royi is a promising candidate for intensive copepod cultures and a relevant live feed for marine larval fish culture.

Effects of berberine supplementation in high starch diet on growth performance, antioxidative status, immune parameters and ammonia stress response of fingerling black sea bream (Acanthopagrus schlegelii)

Berberine (BBR) is an isoquinoline alkaloid with hepatoprotective, anti-obesity, antibacterial and anti-inflammatory properties. The present study investigated berberine supplementation in high starch diet on growth performance, antioxidative status, immune parameters, and ammonia stress response of black sea bream (Acanthopagrus schlegelii). Three isonitrogenous diets were prepared as Con: control diet (14% starch), HS: high starch diet (23% starch), and HSB: high starch diet with 50 mg/kg berberine. After the 8-week feeding trial, HS and HSB groups had similar specific growth rate and weight gain, but they were significantly lower than that of the Con group (P < .05). Fish fed HS diet had excessive lipid deposition and nuclear polarization in hepatocytes, as well as higher serum activities of aspartate transaminase and alanine aminotransferase. In contrast, fish fed HSB diet showed significantly reduced serum aspartate transaminase and alanine aminotransferase activities and alleviated hepatic lipid accumulation. Significantly lower serum glucose and lactate contents were observed in the HSB group. After the ammonia stress test (0.5 mg/L unionized ammonia), serum acid phosphatase and lysozyme activities, and total antioxidant capacity decreased significantly in all groups. Additionally, the highest hepatic glutathione peroxidase activity was found in fish fed HSB diet both before and after the ammonia stress test, whereas the HS group obtained the highest malondialdehyde in liver. In conclusion, berberine supplementation in high starch diet could reduce hepatic lipid accumulation, improve liver health and antioxidative status.

Formate Utilization by the Crenarchaeon Desulfurococcus amylolyticus.

Formate is one of the key compounds of the microbial carbon and/or energy metabolism. It owes a significant contribution to various anaerobic syntrophic associations, and may become one of the energy storage compounds of modern energy biotechnology. Microbial growth on formate was demonstrated for different bacteria and archaea, but not yet for species of the archaeal phylum Crenarchaeota. Here, we show that Desulfurococcus amylolyticus DSM 16532, an anaerobic and hyperthermophilic Crenarchaeon, metabolises formate without the production of molecular hydrogen. Growth, substrate uptake, and production kinetics on formate, glucose, and glucose/formate mixtures exhibited similar specific growth rates and similar final cell densities. A whole cell conversion experiment on formate revealed that D. amylolyticus converts formate into carbon dioxide, acetate, citrate, and ethanol. Using bioinformatic analysis, we examined whether one of the currently known and postulated formate utilisation pathways could be operative in D. amylolyticus. This analysis indicated the possibility that D. amylolyticus uses formaldehyde producing enzymes for the assimilation of formate. Therefore, we propose that formate might be assimilated into biomass through formaldehyde dehydrogenase and the oxidative pentose phosphate pathway. These findings shed new light on the metabolic versatility of the archaeal phylum Crenarchaeota.

A fasting period during grow-out make juvenile pacu (Piaractus mesopotamicus) leaner but does not impair growth

We evaluated the effect of a 30-day fast followed by 30 days of feeding on the dynamics of energy mobilization and the growth performance in juvenile pacu (Piaractus mesopotamicus). Pacu is a freshwater fish known for its high amount of body fat, an undesirable marketing trait. This study was conducted to determine whether a fasting strategy could reduce fat stores without impairing fish growth. For that, a total of 300 juvenile fish (41.5 ± 12.9 g) were distributed into 12 tanks (six tanks per experimental group), and sorted in two feeding strategies: continuous feeding during 60 days (control group) and 30 days of fasting followed by 30 days of refeeding (30/30 group). Growth, nutritional and biometric parameters were evaluated: final weight, weight gain, specific growth rate (SGR), feed conversion ratio, protein efficiency rate, feed intake, hepatosomatic index (HSI) and mesenteric fat index (MFI). Also tissues metabolic indicators were assayed in liver (lipids and glycogen) and muscle (lipids and protein) as well as blood metabolites (glucose, triglycerides, cholesterol, non-esterified fatty acids (NEFA) and total serum protein). After experimental time the results displayed that, fasting period of 30 days decreased the glucose and triglycerides and increased the serum cholesterol and NEFA concentrations. In liver, fasting reduced glycogen and total lipid concentrations, as well as the HSI. Total lipid in muscle and in viscera (MFI) also reduced along the fasting and remained lower than in control during the refeeding. The refeeding promoted hyperphagia and full growth compensation in fasted fish, which reached similar weight gain and specific growth rate to those of continuously fed fish. The long-term fasting in pacu may favour the production of a leaner fish, without compromising its growth, and additionally reduce feeding cost.

Adaptation of Mammalian Cells to Chemically Defined Media.

In order to circumvent ethical, technical, and economic drawbacks regarding the use of animal serum in cell culturing, it is possible to adapt mammalian cells to serum-free media. Nowadays, there are several serum-free formulations available, including fully animal derived-free and chemically defined media, and different adaptation techniques. This article focuses on the gradual adaptation of a mammalian suspension cell culture to a chemically defined medium. The first step is to transfer the cells cultured in medium supplemented with fetal bovine serum (FBS) to a chemically defined medium of your choice, containing the same amount of FBS. The next steps consist of progressively reducing the amount of FBS, while monitoring cell growth and viability up to the complete elimination of FBS. This protocol has been successfully used to adapt THP-1 cells to a chemically defined medium with similar maximum specific growth rate as those cultured with FBS. © 2019 by John Wiley & Sons, Inc. Basic Protocol: Gradual adaptation to chemically defined medium Alternate Protocol: Direct adaptation to chemically defined medium Support Protocol 1: Determining maximum specific growth rate of a cell culture Support Protocol 2: Cell freezing and thawing.

Culture Miniaturization of Lipase Production by Yarrowia lipolytica

Background::The proposal to perform scale-down of culture systems (2 to 4 mL) could be more efficient for screen multiple formulations and operational conditions. For such, is important to evaluate if the kinetic parameters of a bioprocess are comparative to conventional lab-scale reactors. In the present study, the effects of different miniaturized systems were evaluated on growth and lipase production of Yarrowia lipolytica IMUFRJ 50682.Methods::Cultivations were conducted in a mini-scale version of Erlenmeyer flask of 10 mL (10EF); 24 deep-well microplate of 11 ml (24MTP/11 mL) and 24 deep-well microplate of 25 ml (24MTP/25 mL).Results::Similar specific growth rate (μ) was observed between miniaturized cultivations (0.27 h-1). Different lipase productivities values were obtained, the highest was achieved in 10EF (181 U.L-1.h-1). Volumetric oxygen transfer coefficient (kLa) and maximum lipase production were improved with culture miniaturization in comparison with conventional shake-flasks. Bioreactor (1.5 L) cultivation showed similar growth kinetic, pH profile and kLa values, but an increase in the maximum productivity was observed. These finding showed the advantages of Y. lipolytica cultivations scale-down.Conclusion::These findings show the advantages of Y. lipolytica scale-down cultivations, and to perform scale-up for benchtop bioreactor directly from these miniaturized cultivations, without the need of gradual scale-up, representing a reduction in costs and working time. Taking into consideration the rare works about miniaturized cultivation with Y. lipolytica, this work opens the way to a better understanding of bioprocess and alternatives for process conduction.

In-pond strain selection of euryhaline Tetraselmis sp. strains for reliable long-term outdoor culture as potential sources of biofuel and other products

Studies on microalgae species and strain selection have demonstrated the potential of a broad range of algal species suitable for large-scale mass production, but provided little data on the reliability and productivity of the cultures under outdoor conditions over a long period. Long-term studies as part of the development of large-scale microalgae mass production are essential at small scale to minimise expenditure in scaling-up and large-scale operations. The current study describes the long-term semi-continuous culture of 4 wild-type isolates of euryhaline Tetraselmis sp. grown in 1 m2 raceway ponds outdoors in 7% (w/w NaCl) saline water enriched with N and P without any additional carbon source under the environmental conditions in Perth, Western Australia. The long-term investigation indicated that Tetraselmis MUR-231 was not able to grow outdoors, while Tetraselmis strains MUR-167, MUR-230 and MUR-233 grew outdoors over long periods. Tetraselmis MUR-167 was cultured for over 16 months outdoors before terminated due to cell clump formation and heavy biofilm development on the pond walls, whereas Tetraselmis strains MUR-230 and MUR-233 were cultured in semi-continuous culture over 20 months. The latter two strains grew at high solar irradiance with daily maximum values of 58890 W m−2 and temperatures ranging from about 40 to 0 °C. Both strains had a similar average specific growth rate of 0.19 day−1 over the experimental period. Maximum biomass productivities were 9.11 g m−2 day−1 and 9.99 g m−2 day−1 for Tetraselmis MUR-230 and MUR-233, respectively. The maximum total lipid productivity of 4.30 g m−2 day−1 of Tetraselmis MUR-230 was slightly higher than Tetraselmis MUR-233 (4.05 g m−2 day−1). These results clearly indicate the potential of these two Tetraselmis strains for commercial application, such as a high lipid yielding feedstock under minimal culture management conditions in arid and semi-arid coastal regions such as northern Western Australia.

EFFECT OF PROBIOTICS AND CARBON SOURCES ON GROWTH PERFORMANCE AND SURVIVAL OF INDIAN WHITE SHRIMP (FENNEROPENAEUS INDICUS) UNDER BIOFLOC TECHNOLOGY

The aim of this study was to determine the influence of different sources of carbon with and without addition of probiotics on growth performance, and feed utilization of Indian white shrimp (Fenneropenaeus indicus), in addition to water quality of biofloc production system. Control diet (35% CP), in addition to eight treatments based on partial and complete substitution of artificial feeds were used. The biofloc used in the treatments were collected from different reactors with different carbon source (Corn flour and Barley flour) with and without probiotics addition. The experiment lasted for 28 days. At the end of the experiment, the results indicated that there were significant differences between treatments in growth performance and feed utilization. The highest survival was shown by the shrimp fed with barley flour fed biofloc without probiotics and control treatments (100 ± 0.0%), while the lowest survival was shown by the shrimp fed with corn flour fed biofloc with probiotics (54 ± 1.0%). The highest specific growth rate was obtained in the control treatment (1.66 ± 0.02%) while, the shrimp fed with biofloc from barley flour carbon source without probiotics showed almost similar specific growth rate (1.61± 0.02) to that of the control treatment. The biofloc fed shrimp showed promising growth values indicating that the biofloc was sufficient for supporting shrimp growth under commercial farming conditions. Hence, the overall experiments allow concluding that based on its nutritional value; the biofloc offers an alternative strategy for an efficient use of nutrient input in aquaculture systems.

Glucose and lipid metabolic adaptations during postprandial starvation of Japanese flounder Paralichthys olivaceus previously fed different levels of dietary carbohydrates

Exogenous glucose loading is generally used to assess the capacity of glucose utilization in carnivorous fish. Examining the use of endogenous glucose during fasting provides a new perspective on assessing glucose metabolism in fish. Japanese flounder Paralichthys olivaceus, a marine carnivorous fish species, were starved for 3, 9, 24, 48 h, and 3, 7, 14, 21, 28 days, respectively, after a 10-week feeding trial with 12% (C12: 49.49% crude protein, 9.65% crude lipid and gross energy of 18.98 kJ g−1) and 20% (C20: 49.99% crude protein, 9.75% crude lipid and gross energy of 19.11 kJ g−1) of dietary carbohydrates (alpha-starch and corn starch). After feeding trial, fish fed different diets showed similar specific growth rate (3.62 vs 3.61) (P > .05). During starvation period, compared with 3 h, plasma glucose and insulin concentration increased at 9 h in both groups. A similar trend was found for the glycogen content and the mRNA levels of genes involved in glycolysis and pentose phosphate pathway in liver. And the gluconeogenic genes mRNA levels significantly increased since 9 h in C12 and 24 h in C20 (P < .05). Subsequently, liver glycogen in C12 fell significantly on the 3 d compared with 48 h and was depleted on the 7 d (P < .05). It significantly decreased on the 7 d compared with 3 d and was minimized on the 14 d in C20 (P < .05). Plasma glucose peaked at 48 h and 7 d in both groups. As for lipid metabolism, high levels of plasma triglyceride, cholesterol concentration and lipogenetic genes mRNA levels were observed within 9 h. Compared with 3 h, liver lipid significantly decreased on the 14 d in both groups (P < .05). The mRNA levels of genes related to beta-oxidation and ketogenesis was enhanced in later stages in both groups. In addition, in C20, greater changes of mRNA levels of genes involved in gluconeogenesis and lipolysis in liver were observed. It was concluded that primary substrate of energy sources switched from glycogen to lipid occurring on the 3 d-7 d in C12 and 7 d-14 d in C20. Besides, high dietary carbohydrate (C20) feeding activated greater gluconeogenesis and lipolysis during starvation. These observations demonstrated glucose and lipid metabolic responses of Japanese flounder during starvation were influenced by previous feeding with different levels of dietary carbohydrates.

Body size and population dynamics of annual fishes from temporary wetlands in Southern Brazil

Annual fishes live exclusively in temporary wetlands where several species coexist. Understanding how annual fishes cohabit in small and isolated pools is still a challenge. In this study, we aimed to examine the prediction that annual fish assemblages in temporary pools in Southern Brazil are structured by temporal differences in body size, specific growth rate and density. Two–three fish species coexisted in each pool. The most abundant and frequent species were Cynopoecilus melanotaenia and Austrolebias nigrofasciatus, while A. wolterstorffi was less abundant and rare. The species differed significantly in body size throughout the flooding phase and showed similar growth patterns, with higher specific growth rates in the first months of flooding and a reduction in growth rate thereafter. The monthly average densities of A. nigrofasciatus and C. melanotaenia did not differ over time, but they were higher than values observed for A. wolterstorffi. Our results provide evidence for hatching synchrony, similar specific growth rates and densities among the most abundant species and differences in body sizes among all species that are more evident after adulthood, suggesting that differences in body size mediate the coexistence of annual fishes in temporary pools.

Does graded substitution of soy protein concentrate by an insect meal respond on growth and N-utilization in Nile tilapia (Oreochromis niloticus)?

Besides fishmeal, soybean protein is the most common protein source in aquafeed. However, the sustainability of soybean production is criticized. Due to the rapid development of aquaculture, the increasing demand for high value feed proteins has initiated research into alternative and more sustainable proteins for aquafeeds. In order to evaluate one promising alternative protein source, a growth study (56 days) was conducted with juvenile Nile tilapia (Oreochromis niloticus, 35 g on average) with a partial substitution of soybean protein by a partly defatted insect meal from black soldier fly larvae (Hermetia illucens). Growth performance, feed utilization and dietary protein quality parameters were evaluated based on analysed body protein deposition.A control feed (8% fish meal, 37% soy protein concentrate (SPC)) and three iso-nitrogenous and iso-energetic experimental feeds with 25, 50 or 100% replacement of SPC by partly defatted Hermetia meal (HM) were formulated. All feeds supplied essential amino acids as recommended for Nile tilapia. Growth response and protein utilization were examined in a semi-closed in-door water recirculation system. A comparative slaughter technique was applied to generate N deposition data for protein quality evaluation based on the standardized net protein utilization (NPUstd) according to the “Goettingen approach”. All feeds were very well accepted. Replacement of SPC by HM up to 50% improved feed protein quality and result in similar specific growth rate and feed conversion ratio, respectively. However, a higher inclusion rate of HM tended to impair growth, but not the observed protein quality. In conclusion, the replacement of SPC by partly defatted HM up to a level of 50% had no negative effect on growth performance and improved the dietary protein quality of tilapia feeds under study. Insect protein from Hermetia illucens could be a promising option to make aquafeed formulation more flexible and sustainable.