Optimal Feeding Strategy Research Articles

Analysis of an optimal control problem related to microorganisms selection

In this work, we consider a minimal time control problem governed by a system describing a continuous bioreactor with one substrate, n ≥ 2 species, and a mutation factor. Our aim is to select in minimal time the fastest species i.e. the one for which the half saturation constant is the lowest. In the case of two species, the optimal feeding strategy consists of a most rapid approach to a singular arc (see Bayen et al. [2014]). The aim of this paper is to study the case of n ≥ 2 species. Thanks to the Pontryagin Maximum Principle, we provide a sub-optimal strategy based on a most rapid approach to a singular arc that depends on the initial condition.

Effects of feeding frequency on the enzymes and genes involved in oxidative stress in juvenile yellow catfishPelteobagrus fulvidraco(Richardson) exposed to ammonia

Optimal feeding strategies improve fish growth and health but may be affected by ammonia stress in closed rearing systems such as tanks or ponds. This study aimed to evaluate the effects of feeding frequency and ammonia levels in rearing water on the enzymes and genes involved in oxidative stress of yellow catfish. Experiment (ammonia exposure) and control groups were randomly assigned to one of three feeding frequencies (1, 2 and 4 times daily) for 8 weeks. Weight gain increased as feeding frequency increased from 1 to 4 times daily, but feed conversion ratio values decreased. The highest survival in ammonia group was found when fish was fed 2 times daily. Glutathione peroxidase activity and total antioxidant capacity in liver and brain of fish exposed to ammonia increased as feeding frequency increased from 1 to 4 times daily. Liver malondialdehyde content in control group decreased as feeding frequency increased from 1 to 4 times daily. The lowest liver malondialdehyde content in ammonia group was observed when fish was fed 2 times daily. Liver mRNA expression of superoxide dismutase and catalase in control group increased as feeding frequency increased from 1 to 4 times daily, but the highest superoxide dismutase and catalase expression in ammonia group were observed when fish were fed 2 times daily. This study indicates that higher feeding frequency of yellow catfish exposed to ammonia could result in oxidative stress and poor survival. The optimal feeding frequency of yellow catfish exposed to ammonia is 2 times daily.

The Speed of Increasing milk Feeds: a randomised controlled trial

BackgroundIn the UK, 1–2% of infants are born very preterm (<32 weeks of gestation) or have very low birth weight (<1500 g). Very preterm infants are initially unable to be fed nutritional volumes of milk and therefore require intravenous nutrition. Milk feeding strategies influence several long and short term health outcomes including growth, survival, infection (associated with intravenous nutrition) and necrotising enterocolitis (NEC); with both infection and NEC being key predictive factors of long term disability. Currently there is no consistent strategy for feeding preterm infants across the UK. The SIFT trial will test two speeds of increasing milk feeds with the primary aim of determining effects on survival without moderate or severe neurodevelopmental disability at 24 months of age, corrected for prematurity. The trial will also examine many secondary outcomes including infection, NEC, time taken to reach full feeds and growth.Methods/designTwo thousand eight hundred very preterm or very low birth weight infants will be recruited from approximately 30 hospitals across the UK to a randomised controlled trial. Infants with severe congenital anomaly or no realistic chance of survival will be excluded. Infants will be randomly allocated to either a faster (30 ml/kg/day) or slower (18 ml/kg/day) rate of increase in milk feeds. Data will be collected during the neonatal hospital stay on weight, infection rates, episodes of NEC, length of stay and time to reach full milk feeds. Long term health outcomes comprising vision, hearing, motor and cognitive impairment will be assessed at 24 months of age (corrected for prematurity) using a parent report questionnaire.DiscussionExtensive searches have found no active or proposed studies investigating the rate of increasing milk feeds. The results of this trial will have importance for optimising incremental milk feeding for very preterm and/or very low birth weight infants. No additional resources will be required to implement an optimal feeding strategy, and therefore if successful, the trial results could rapidly be adopted across the NHS at low cost.Trial registrationISRCTN Registry; ISRCTN76463425 on 5 March, 2013.

Digestive biochemistry as indicator of the nutritional status during early development of the long snouted seahorse (Hippocampus reidi)

The activities of some of the main digestive enzymes of long snouted seahorse (Hippocampus reidi; Ginsburg, 1933) measured during the initial 20days after birth were used to assess the nutritional response to different enrichment of the Artemia salina used as live food. Some significant differences in the activities of trypsin total protease and esterases were observed among the experimental treatments, changes in the activities of acid and alkaline phosphatases, as well as in the trypsin/estaerase ratio, were linked to the different dietary treatments. This provided information both on some characteristics of the digestion process in newborns and the influence of the diet on the maturation of the intestinal epithelium during their early development. The use of a multivariate analysis combining the information of all the enzyme activities highlighted differences between treatments. Results obtained confirm the interest of using digestive enzymes as valuable indicators of nutritional condition in larvae of this species and may help to optimize feeding protocols required for mass-scale production of seahorses in captivity. Statement of relevanceOverexploitation, habitat loss, and incidental bycatch during commercial fishing operations, make seahorses susceptible to decline. The high global demand of seahorses exceeds supply from specimens breeding in captivity, and in this unsustainable situation, the long snouted seahorse, H. reidi, is one of the most frequently commercialized species.Larval rearing remains the bottleneck for successful cultivation of seahorses. In this sense, the design of a suitable feeding regime based on food adapted to the nutritional needs of the species is highly desirable.Due to their key role in nutrient digestion and assimilation, changes in the production patterns of the main digestive enzymes can be used as indicators of the nutritional status helping to assess the adaptation to foods with different content in macronutrients and therefore contributing to optimize feeding strategies for this species.The biochemical parameters proposed as indicators of nutritional status might be good analytic tools, not only to establish the time of change of live prey during the weaning but also to formulate the most digestible biochemical composition of live prey. Phosphatases activities, trypsin/esterase ratio and the clusters of enzyme activities, were consistent in the results and might be considered as good indicators of nutritional status in this species.

Development of an optimal light-feeding strategy coupled with semi-continuous reactor operation for simultaneous improvement of microalgal photosynthetic efficiency, lutein production and CO2 sequestration

In addition to leveraging some environmental and energy benefits, microalgae can also be used as a potentially sustainable source for carotenoids like lutein for healthcare applications. As light influences biosynthesis of lutein in microalgae, it would be interesting to investigate the role of incremental illumination in enhancing photosynthetic efficiency and consequent lutein production, while sequestering CO2 simultaneously. Thus, in this study, an optimal light feeding strategy coupled with a semi-continuous reactor operation was developed for achieving the above-mentioned goals. At a light intensity of 260μmolm−2s−1 as optimized in batch mode, baseline lutein productivity of 4.32mgL−1d−1 was obtained, when culturing Chlorella minutissima under optimal process conditions. On switching over to incremental illumination modes, the linear light-feeding (Strategy-III) resulted in higher lutein productivity of 5.35mgL−1d−1 with photosynthetic efficiency of 8.38%. When Strategy-III was integrated with semi-continuous mode involving 20% medium replenishment, lutein productivity, photosynthetic efficiency and CO2 sequestration rate were further enhanced by 19%, 41% and 34% respectively. Moreover, on this process optimization and integration, light-energy consumption was significantly reduced by 32%, in comparison with constant-illumination. Thus, this optimal production strategy resulted in significantly higher lutein productivity, content and photosynthetic efficiency, as compared to the relevant studies reported in literature.

A theoretical estimate for nucleotide sugar demand towards Chinese Hamster Ovary cellular glycosylation.

Glycosylation greatly influences the safety and efficacy of many of the highest-selling recombinant therapeutic proteins (rTPs). In order to define optimal cell culture feeding strategies that control rTP glycosylation, it is necessary to know how nucleotide sugars (NSs) are consumed towards host cell and rTP glycosylation. Here, we present a theoretical framework that integrates the reported glycoproteome of CHO cells, the number of N-linked and O-GalNAc glycosylation sites on individual host cell proteins (HCPs), and the carbohydrate content of CHO glycosphingolipids to estimate the demand of NSs towards CHO cell glycosylation. We have identified the most abundant N-linked and O-GalNAc CHO glycoproteins, obtained the weighted frequency of N-linked and O-GalNAc glycosites across the CHO cell proteome, and have derived stoichiometric coefficients for NS consumption towards CHO cell glycosylation. By combining the obtained stoichiometric coefficients with previously reported data for specific growth and productivity of CHO cells, we observe that the demand of NSs towards glycosylation is significant and, thus, is required to better understand the burden of glycosylation on cellular metabolism. The estimated demand of NSs towards CHO cell glycosylation can be used to rationally design feeding strategies that ensure optimal and consistent rTP glycosylation.

Exponential feeding strategy of high-density cultivation of a salt-tolerant aroma-producing yeast Zygosaccharomyces rouxii in stirred fermenter

Salt-tolerant yeast Zygosaccharomyces rouxii is a key strain to produce flavor in soy sauce brewing. The aim of this research was to establish the optimal feeding strategy and parameter for high-density culture of Z. rouxii. An exponential feeding strategy was applied where the specific growth rate was fixed by limitation of the fed carbon source. The set point of specific growth rate of exponential feeding for fed-batch culture was chosen to be 0.03–0.07h−1. The optimal set point of specific growth rate (μset) of exponential feeding started after glucose depletion for fed-batch culture was found to be 0.05h−1. Furthermore, a relatively high-dense biomass (72.86g/L dry cell weight) was obtained in the culture of exponential feeding started after glucose was exhausted with μset=0.05h−1. Less than the level of Saccharomyces cerevisiae and Pichia pastoris, however the biomass concentration was much higher than data from other research about Z. rouxii culture.

Effects of Ala-Gln feeding strategies on growth, metabolism, and crowding stress resistance of juvenile Cyprinus carpio var. Jian.

The present study was conducted to evaluate the effects of different L-alanyl-l-glutamine (Ala-Gln) feeding strategies on the growth performance, metabolism and crowding stress resistance related parameters in juvenile Jian carp (Cyprinus carpio var. Jian) under crowded condition (80g/L). Juvenile Jian carp (initial weight 26.1±0.6g) were distributed into five groups which fed with graded concentrations (0% or 1.0%) of Ala-Gln for eight weeks. Control group (I, 0/0) fed with control diet (0% Ala-Gln) throughout the feeding trial. The other four groups employed different control and experimental diet feeding strategies ranging from two weeks control diet fed and two weeks experimental diet (1% Ala-Gln) fed (II, 0/2) to eight weeks experimental diet fed (V, 4/4). Results revealed that Mean weight gain (MEG) under all different feeding strategies of Ala-Gln were significantly higher than that of the control group (p<0.05), and MEG of group II (201.90%) was even higher than that of group IV (184.70%). Liver glycogen and blood total protein of groups II, III and V were significantly higher than that in groups I and IV (p<0.05). The highest level of serum thyroxine (10.07ng/ml), insulin-like growth factor-I (52.40ng/ml) and insulin (9.73μIU/mL) were observed in group V. However, diet supplemented with Ala-Gln did not affect the levels of serum glucose, cortisol and catecholamine in fish. The mRNA expression of GR1a, GR1b and GR2 were also significantly changed in Ala-Gln supplementation groups compared with control group (p<0.05). After fish intraperitoneally injected with virulent Aeromonas hydrophila, the fish survival rates were significantly increased in all Ala-Gln supplementation groups compared with control group (p<0.05). Results from the present experiment showed the importance of dietary supplementation of Ala-Gln in benefaction of the growth performance, metabolism and crowding stress resistance in Jian carp breeding. The optimal feeding strategy was alternatively fed with control diet and then experimental diet at an interval of two weeks for juvenile Jian carp under crowded condition.

Optimal nutrition in the paediatric ICU.

This article describes the current best available evidence on optimal nutrition in the paediatric intensive care based on different levels of outcome, which can be divided in surrogate and hard clinical outcome parameters. Undernutrition is associated with increased morbidity and mortality, whereas in specific cohorts of critically ill children, such as those with burn injury, obesity is associated with more complications, longer length of stay, and decreased likelihood of survival. There is a relation with adequacy of delivery of enteral nutrition and the amount of protein on length of hospital stay, neurological status, and mortality. Studies relating organ function, other than skin healing after thermal injury, with the nutritional status are scarce. There is also a scarcity of data concerning long-term follow-up and health economics. Until now, there are no randomized controlled trials which have investigated a causal relation between different feeding regimens on the nutritional status and short and long-term outcome. As a result current optimal nutritional strategies are based on small trials with surrogate outcome parameters. Prospective randomized studies are needed with nutritional and/or metabolic interventions to come to an optimal feeding strategy for critically ill children.

Optimal Feeding Strategy on Microalgae Growth in Fed-Batch Bioreactor Model

Some countries in the world turn to alternative energy source to fulfill their necessity of fuel. One of the alternative fuels is biodiesel. Raw material of biodiesel can be produced by microalgae cultivation in fed-batch bioreactor. To improve the productivity of microalgae cultivation, we need to determine the optimal control of microalgae growth. This paper discusses mathematical model of microalgae growth in fed-batch bioreactor, and solves the optimal feeding strategy problem by using Pontryagin Minimum Principle. Then we compare the controlled microalgae growth model with the uncontrolled one. Numerical simulation with DOTcvpSB shows that the controlled microalgae growth model yields more harvest and less cost function than the uncontrolled one.

Perioperative feeding management of neonates with CHD: analysis of the Pediatric Cardiac Critical Care Consortium (PC4) registry.

Introduction The optimal perioperative feeding strategies for neonates with CHD are unknown. In the present study, we describe the current feeding practices across a multi-institutional cohort. Inclusion criteria for this study were as follows: all neonates undergoing cardiac surgery admitted to the cardiac ICU for ⩾24 hours preoperatively between October, 2013 and July, 2014 in the Pediatric Cardiac Critical Care Consortium registry. The cohort included 251 patients from eight centres. The most common diagnoses included the following: hypoplastic left heart syndrome (17%), coarctation/aortic arch hypoplasia (18%), and transposition of the great arteries (22%); 14% of the patients were <37weeks of gestational age. The median total hospital length of stay was 21 days (interquartile range (IQR) 14-35) and overall mortality was 8%. Preoperative feeding occurred in 133 (53%) patients. The overall preoperative feeding rates across centres ranged from 29 to 79%. Postoperative feeds started on median day 2 (IQR 1-4); for patients with hypoplastic left heart syndrome postoperative feeds started on median day 4. Postoperative feeds were initiated in 89 (35%) patients before extubation (range across centres: 21-61%). The median cardiac ICU discharge feeding volume was 108 cc/kg/day, varying across centres. The mean discharge weight was 280 g above birth weight, ranging from +100 to 430 g across centres. A total of 110 (44%) patients had discharge feeding tubes, ranging from 6 to 80% across centres, and 40/110 patients had gastrostomy/enterostomy tubes placed. In addition, eight (3.2%) patients developed necrotising enterocolitis - three preoperatively and five postoperatively. In this cohort, neonatal feeding practices and outcomes appear to vary across diagnostic groups and institutions. Only half of the patients received preoperative enteral nutrition; almost half had discharge feeding tubes. Multi-institutional collaboration is necessary to determine feeding strategies associated with best clinical outcomes.

Nutrient timing habits of Division I NCAA athletes

Background It has been suggested that nutrient timing strategies may augment training adaptations in active populations. However, collegiate athletes are often restricted by practice schedules, class times and training sessions and, as a result, may not follow recommendations on optimal feeding strategies. Therefore, a survey questionnaire, which examined the nutrient timing habits of athletes, was designed and administered at selected Division I Institutions within the United States.

A pH shift feeding strategy for increased enduracidin production during fed–batch fermentation by a deep–sea, bacterium, Streptomyces sp. MC079

The aim of this work is to enhance enduracidin production by Streptomyces sp. MC079. Based on the time course analysis of the specific cell growth rate and specific enduracidin formation rate, a two–stage pH control strategy was proposed to improve enduracidin production by shifting the culture pH from 5.5 to 5.8 after 112 h of cultivation. By applying this pH control strategy, enduracidin concentration and productivity was 51.2 and 65.0% higher than results with uncontrolled pH batch fermentation. For further enhancement of enduracidin production, the effects of constant–rate feeding and pH-shift feeding strategy were investigated. The results indicated that the pH-shift feeding strategy increased the maximum concentration and productivity of enduracidin to 61.37 mg/L and 0.697 mg/L/h in the constant–rate feeding fermentation process. This is 73.3 and 88.9% higher than results with uncontrolled pH batch fermentation, respectively. The obtained optimal pH shift feeding strategy may be useful for the industrial–scale microbial production of enduracidin.

Computation of impulsive optimal control for 1,3-PD fed-batch culture

In this paper, in consideration of suddenly increasing of the glycerol and alkali, we propose a nonlinear impulsive system to describe the fed-batch culture of glycerol bioconversion to 1,3-propanediol (1,3-PD) induced by Klebsiella pneumonia (K. pneumonia). To maximize the concentration of 1,3-PD at the terminal time, we present an impulsive optimal control problem in which the final 1,3-PD yield is taken as the cost function, while the feeding volumes of glycerol and the feeding time points are taken as decision variables. Continuous state inequality constraints are imposed to ensure that the concentrations of biomass, glycerol, and reaction products lie within specified limits. We use the time scaling method to handle the variable feeding time points. The impulsive optimal control problem is approximated as a sequence of nonlinear optimization sub-problems through the application of the penalty function and barrier function method. A hybrid algorithm by integrating a particle swarm optimization with gradient-based optimization algorithm is proposed to seek the optimal feeding strategy. From extensive simulation study, it is observed that the obtained optimal strategy is highly satisfactory.

Optimization of CO2 fixation by Chlorella kessleri cultivated in a closed raceway photo-bioreactor

The aim of this study is to optimize biological fixation of CO2 using Chlorella kessleri cultivated in oil sands process water (OSPW). A lab-scale closed raceway photobioreactor was designed and assembled for cultivation of C. kessleri in OSPW. A fed-batch model describing the dynamics of microalgae growth and CO2, phosphate and ammonium uptake rate was developed based on batch kinetics identified in our previous study, and was successfully validated against experimental data. A model-based optimization method was used to calculate the optimal feeding strategies for CO2, phosphate and light intensity which resulted in a 1.5-fold increase in the final biomass concentration and a 2-fold increase in the average CO2 uptake rate in 240h (10days) compared to the initial fed-batch experiment over 432h (18days). Finally, scale-up to large-scale continuous operation was considered, and the optimal hydraulic retention time (HRT) and feeding strategy for maximum productivity were estimated.

Nutrient efficacy of microalgae as aquafeed additives for the adult black tiger prawn,Penaeus monodon

This study used a small amount of several lyophilized microalgae (5% of dry weight in aquafeed) to feed adult black tiger prawns Penaeus monodon for 4 weeks, aiming to promote prawn health and nutritional level. Apart from slight increases in ash content, chlorophyll and β-carotene in the microalgae-added feeds, there was no difference from the commercial diet in their biochemical composition. After 28 days of feeding, prawn body length, body weight, condition index and also total amount of fatty acids and amino acids of the flesh (2nd abdominal segment) were not affected by microalgae additives as compared with the control commercial diet-fed group (P > 0.05). Prawns fed the microalgae diets, however, had a relatively better survival rate than those fed the commercial control diet, although no statistical significance was detected in any except for the diatom Melosira sp. The elevated survival rate was concomitant with a higher phagocytosis rate and superoxide dismutase (SOD) activity in the immune response analysis, and significantly a higher astaxanthin content detected in the tail muscle of microalgae diet-fed prawns (5.36–10.78 ng of astaxanthin per gram of muscle DW). These findings demonstrated that low-inclusion microalgal additives in prawn diets over a short feeding period (4 weeks) can result in healthier adult prawn, and hence could contribute to the development of an optimized feeding strategy for prawn aquaculture close to harvesting.

Optimal control strategy for fed-batch enzymatic hydrolysis of lignocellulosic biomass based on epidemic modeling.

A mathematical optimal control strategy for feeding operation was developed for fed-batch enzymatic hydrolysis of dilute acid pretreated lignocellulosic biomass based on a modified epidemic model. Cellulose conversion was maximized and glucose concentration achieved highest possible value over a fixed hydrolysis time. Boundaries of feeding rate and lignin content were set for feasible controls. Using the optimal control feeding strategy, glucose concentration and accumulated cellulose conversion reached up to 77.31 g/L and 72.08% in 100 h, which are 108.76% and 37.50% higher than in batch hydrolysis with same amount of enzyme consumption. Solids content in feeding source has a significant interference on system mass transfer. Optimal control is a useful tool for guiding operations in fed-batch and continuous processes as it enables process optimization through clear objective functions and feasible controls.

Optimal control of microbial fed-batch culture involving multiple feeds

In this paper, we consider optimal control problem in the fed-batchfermentation of glycerol by Klebsiella pneumoniae with openloop glycerol input and pH logic control, while the feeding volume of glycerol is regardedas the control variable. To maximize the concentration of 1,3-PD at the terminal time, anoptimal control model is established, and a computational approachis constructed to solve the control model. Finally, the numericalsimulations show that the terminal concentration of producing 1,3-PD hasbeen increased obviously by employing the optimal feeding strategy.

Long-Term Production of Fuel Ethanol by Immobilized Yeast in Repeated-Batch Simultaneous Saccharification and Fermentation of Cassava

In this study, a fibrous matrix with chemical modification was used as a support material for the immobilization of Saccharomyces cerevisiae 1308. Cassava hydrolysate without filteration was used for ethanol fermentation. An average utilization rate of starch of 83.5% was obtained by the immobilized cells during the first seven repeated simultaneous saccharification and fermentation. The utilization rate of starch of the immobilized cells was 2.1% higher than that of free cells with an inoculation quantity of 15% (v/v) under the same fermentation conditions. In addition, the effects of enzyme feeding strategies on immobilized yeast fermentation were investigated. The highest utilization rate of starch of 85.9% was obtained at 35 °C with the optimal enzyme feeding strategy. Fermentation performed successfully for about 6 months with 87 batches suggests that ethanol production from cassava using immobilized yeast in a fibrous-bed bioreactor is feasible and may meet the demands of industrial production.

An optimal glucose feeding strategy integrated with step-wise regulation of the dissolved oxygen level improves N-acetylglucosamine production in recombinant Bacillus subtilis

In our previous work, a recombinant Bacillus subtilis strain for the microbial production of N-acetylglucosamine (GlcNAc) was constructed through modular pathway engineering. In this study, to enhance GlcNAc production, glucose feeding approaches and dissolved oxygen (DO) control methods in fed-batch culture were systematically investigated. We first studied the effects of different glucose feeding strategies, including exponential fed-batch culture, pulse fed-batch culture, constant rate fed-batch culture, and glucose control (5g/L, 10g/L, 15g/L) fed-batch culture, on cell growth and GlcNAc synthesis. We found that GlcNAc production in glucose control (5g/L) fed-batch culture reached 26.58g/L, which was 3.10 times that in batch culture. Next, the effect of DO level (20%, 30%, 40%, and 50%) on GlcNAc production was investigated, and a step-wise DO control strategy (0–7h, 30%; 7–15h, 50%; 15–50h, 40%; 50–72h, 30%) was introduced. With the optimal glucose and DO control strategy, GlcNAc production reached 35.77g/L, which was 4.17 times the production in batch culture without DO control.