Cell Mass Concentration Research Articles

Production of Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from CO2 via pH-Stat Jar Cultivation of an Engineered Hydrogen-Oxidizing Bacterium Cupriavidus necator.

The copolyester of 3-hydroxybutyrate (3HB) and 3-hydoxyhexanoate (3HHx), PHBHHx, is a biodegradable plastic characterized by high flexibility, softness, a wide process window, and marine biodegradability. PHBHHx is usually produced from structurally related carbon sources, such as vegetable oils or fatty acids, but not from inexpensive carbon sources such as sugars. In previous studies, we demonstrated that engineered strains of a hydrogen-oxidizing bacterium, Cupriavidus necator, synthesized PHBHHx with a high cellular content not only from sugars but also from CO2 as the sole carbon source in the flask culture. In this study, the highly efficient production of PHBHHx from CO2 was investigated via pH-stat jar cultivation of recombinant C. necator strains while feeding the substrate gas mixture (H2/O2/CO2 = 80:10:10 v/v%) to a complete mineral medium in a recycled-gas, closed-circuit culture system. As a result, the dry cell mass and PHBHHx concentration with the strain MF01/pBPP-ccrMeJAc-emd reached up to 59.62 ± 3.18 g·L-1 and 49.31 ± 3.14 g·L-1, respectively, after 216 h of jar cultivation with limited addition of ammonia and phosphate solutions. The 3HHx composition was close to 10 mol%, which is suitable for practical applications. It is expected that the autotrophic cultivation of the recombinant C. necator can be feasible for the mass production of PHBHHx from CO2.

Study of prevalence of anaemia and haematological parameters in children below 12 years in Northern Karnataka

Anaemia may be defined as a reduction in red blood cell (RBC) mass or blood haemoglobin (HGB) concentration. The most common cause of anaemia in newborns include blood loss, Rh or ABO incompatibility in 3 to 6 months suggests hemoglobinopathy, Nutritional iron deficiency causes after six months hence symptoms of blood examination in children play a significant role below 12 years. 92 children below 12 years of age having anaemia were studied. The blood examination was done to rule out PCV, MCV, MCH, MCHC, RPW, Hb%, PS study, reticulocyte count, and serum iron (Fe), Serum B, folic acids. The types of anaemia were 53(57.6%) anaemia, 13(14.1%) Thalassemia, 10(10.8%) Megablastic anaemia, 8(8.6%) Anaemia of acute haemorrhage, 5(5.4%) sickle cell anaemia, 2(2.1%) aplastic anaemia, 1(1.08%) leukaemia. Clinical manifestations had 92(100%) pallor, 78(84.7%) weakness and fatigability, 36(39.1%) fever, 26(28.2%) Icterus, 19(20.6%) shortness of breathing, 16(17.3%) hepatomegaly, 14(15.2%) cough, 13(14.1%) history of pica, 12(13%) splenomegaly, 10(10.8%) petechiae, 9(9.7%) vomiting, 9(9.7%) Koilonychias, 5(5.4%) hyper-pigmentation, 6(6.5%) tremors, 21(22.8%) was mild anaemia, 42(45.6%) moderate, 29(31.5%) severe anaemia on the basis of haemoglobin level. This pragmatic study of anemia had iron deficiency was a major cause followed by thalassemia, megaloblastic, acute hemorrhagic sickle cell, aplastic anemia. This study will be helpful to the pediatrician to treat such children efficiently to avoid morbidity and mortality.

Stoichiometric models of sucrose and glucose fermentation by oral streptococci: Implications for free acid formation and enamel demineralization.

The objective of this study is to develop stoichiometric models of sugar fermentation and cell biosynthesis for model cariogenic Streptococcus mutans and non-cariogenic Streptococcus sanguinis to better understand and predict metabolic product formation. Streptococcus mutans (strain UA159) and Streptococcus sanguinis (strain DSS-10) were grown separately in bioreactors fed brain heart infusion broth supplemented with either sucrose or glucose at 37°C. Cell mass concentration and fermentation products were measured at different hydraulic residence times (HRT) to determine cell growth yield. Sucrose growth yields were 0.080±0.0078g cell/g and 0.18±0.031g cell/g for S. sanguinis and S. mutans, respectively. For glucose, this reversed, with S. sanguinis having a yield of 0.10±0.0080g cell/g and S. mutans 0.053±0.0064g cell/g. Stoichiometric equations to predict free acid concentrations were developed for each test case. Results demonstrate that S. sanguinis produces more free acid at a given pH than S. mutans due to lesser cell yield and production of more acetic acid. Greater amounts of free acid were produced at the shortest HRT of 2.5hr compared to longer HRTs for both microorganisms and substrates. The finding that the non-cariogenic S. sanguinis produces greater amounts of free acids than S. mutans strongly suggests that bacterial physiology and environmental factors affecting substrate/metabolite mass transfer play a much greater role in tooth or enamel/dentin demineralization than acidogenesis. These findings enhance the understanding of fermentation production by oral streptococci and provide useful data for comparing studies under different environmental conditions.

Nutrient-depended metabolic switching during batch cultivation of Streptomyces coelicolor explored with absolute quantitative mass spectrometry-based metabolite profiling

The well-known secondary metabolite-producing bacterium Streptomyces coelicolor is a natural choice for the development of super-hosts optimized for the heterologous expression of antibiotic biosynthetic gene clusters (BGCs). In this study, we used S. coelicolor M145 and its derivative strain M1146 where all active BGCs have been deleted and generated high-resolution quantitative time series metabolite profiles under two cultivation conditions (phosphate and nitrogen limitation to cease growth and trigger secondary metabolism). Five targeted LC–MS/MS-based methods were used to quantify intracellular primary metabolites covering phosphorylated metabolites, amino acids, organic acids, (deoxy) nucleoside/sugar phosphates, Nicotinamide adenine dinucleotide (NAD), and Coenzyme A (CoA). The nitrogen limitation resulted in a sharp decline in respiration and an immediate drop in the cell mass concentration. Intracellularly, a reduction in the level of the metabolites next to α-ketoglutarate in the tricarboxylic acid cycle and a decrease in the NADH pool were among the most prominent adaptation to this nutrient limitation. Phosphate limitation evoked a different adaptation of the metabolite pools as most of the phosphorylated metabolite pools except 6-phosphogluconic acid (6PG) pool were downregulated. 13C-isotope-labeling experiments revealed the simultaneous activity of both glycolysis and gluconeogenesis during the co-utilization of glucose and glutamate. The S. coelicolor M1146 strain had similar time-series metabolite profile dynamics as the parent M145 strain, except for a visibly increased 6PG pool in the stationary phase. In general, the nutrient limitation had a larger effect on the metabolite pool levels than the absence of secondary metabolite production in M1146. This study provides new insight into the primary carbon metabolism and its link to the secondary metabolism which is needed for further optimization of both super-host genotype and cultivation conditions.

Chemical and Physical Culture Conditions Significantly Influence the Cell Mass and Docosahexaenoic Acid Content of Aurantiochytrium limacinum Strain PKU#SW8.

Thraustochytrids are well-known unicellular heterotrophic marine protists because of their promising ability to accumulate docosahexaenoic acid (DHA). However, the implications of their unique genomic and metabolic features on DHA production remain poorly understood. Here, the effects of chemical and physical culture conditions on the cell mass and DHA production were investigated for a unique thraustochytrid strain, PKU#SW8, isolated from the seawater of Pearl River Estuary. All the tested fermentation parameters showed a significant influence on the cell mass and concentration and yield of DHA. The addition of monosaccharides (fructose, mannose, glucose, or galactose) or glycerol to the culture medium yielded much higher cell mass and DHA concentrations than that of disaccharides and starch. Similarly, organic nitrogen sources (peptone, yeast extract, tryptone, and sodium glutamate) proved to be beneficial in achieving a higher cell mass and DHA concentration. PKU#SW8 was found to grow and accumulate a considerable amount of DHA over wide ranges of KH2PO4 (0.125–1.0 g/L), salinity (0–140% seawater), pH (3–9), temperature (16–36 °C), and agitation (140–230 rpm). With the optimal culture conditions (glycerol, 20 g/L; peptone, 2.5 g/L; 80% seawater; pH 4.0; 28 °C; and 200 rpm) determined based on the shake-flask experiments, the cell mass and concentration and yield of DHA were improved up to 7.5 ± 0.05 g/L, 2.14 ± 0.03 g/L, and 282.9 ± 3.0 mg/g, respectively, on a 5-L scale fermentation. This study provides valuable information about the fermentation conditions of the PKU#SW8 strain and its unique physiological features, which could be beneficial for strain development and large-scale DHA production.

Xylanase Production via Aspergillus niger: Effect of Carbon Source and Composition

Xylanases are secondary metabolite product of variety organisms from various agriculture wastes. Xylanases’ demands in industrial level are increasing. Precisely, the necessity of enzyme such as xylanase to breaks down the xylan into reducing sugar for biofuel production is inevitable. However, the production of xylanases is insufficient to support the market demand. Hence, Aspergillus niger is used as the xylanase producer in this research. In this study, effect of carbon sources (corn cob-based xylan (CCX) and empty fruit bunches (EFB)) and concentrations of carbon source (2.5g/L to 4.0g/L) on xylanase production through One-factor-at-time (OFAT) experimental technique were investigated. The optimum fermentation period of 5 days determined by using mycelial dry cell mass and Bradford protein concentration growth profile is 5 days was set as the incubation period. Among these data, both carbon sources shown the maximum value at concentration of 3.5g/L. CCX showed a higher xylanase concentration (0.882±0.005μg/mL) compared to EFB (0.533 ± 0.006μg/mL). Hence, among these data analysis CCX has a better performance compared to EFB. Hence, among these data analysis CCX has a better performance compared to EFB.

Degradation of aromatic compounds and lignin by marine protist Thraustochytrium striatum

This paper aimed at studying a novel high biomass strain (HBS) of marine protist, Thraustochytrium striatum, for lignin valorization to lipids and carotenoids. In the screening of 15 aromatic compounds, T. striatum HBS can utilize most compounds while achieving the best growth on 3,4-dihydroxybenzoic acid (3,4-DHBA) and 4-hydroxybenzoic acid (4-HBA). The maximum cell mass concentration reached 2−3 g/L under 5 g/L of 3,4-DHBA or 2 g/L of 4-HBA, which was comparable to that under equivalent concentration of glucose. The long-chain fatty acids content was 13 % and 7 % with 3,4-DHBA and 4-HBA, respectively. The adoption of fed-batch fermentation mode improved the degradation of carbon source and prevented the inhibitory effect caused by overloading of aromatic compounds. Both final cellular fatty acids and carotenoids contents were doubled in the fermentation of 3,4-DHBA. T. striatum HBS exhibited limited lignin depolymerization (∼24 %) ability on technical lignins.

Predictive model development and simulation of photobioreactors for algal biomass growth estimation

Abstract In the current scenario of energy requirement and the commercialization aspect of algal biofuel and biomass, it is important that means of predicting the production be available. In this paper, the mathematical models are developed for the tubular, bubble column and airlift photobioreactors to predict the productivity of the algal biomass. A modified Monod kinetic equation, incorporating the effect of nutrient and CO2 concentrations, light availability and oxygen built-up, is used to the estimate specific growth rate of the biomass. The light availability inside the reactor is defined in terms of the modified Beer–Lambert’s law as a function of distance from the surface where light is incident and the cell mass concentration. This allows a more accurate measurement of the shading effect. The equations are solved for different reactor types and their estimated productivities are successfully validated against values available in published literature. The model predicts comparatively better productivity for the tubular reactor (1.5 g/L day) than the bubble column and airlift reactor (1.42 and 1.35 g/L day respectively) because tubular reactor has shorter light/dark cycles and better light availability. The analysis is also done to identify the effect of nutrient, carbon dioxide, light and hydrodynamics on the overall productivity.

Immobilization of Serratia plymuthica by ionic gelation and cross-linking with transglutaminase for the conversion of sucrose into isomaltulose

Isomaltulose is an alternative sugar obtained from sucrose using some bacteria producing glycosyltransferase. This work aimed to optimize conditions for the immobilization of Serratia plymuthica through ionic gelation and cross-linking by transglutaminase using the sequential experimental strategy for the conversion of sucrose into isomaltulose. The effect of five variables (concentrations of cell mass, alginate, gelatin, transglutaminase, and calcium chloride) was studied, as well as the interactions between them on the matrix composition for the S. plymuthica immobilization. Three experimental designs were used to optimize the concentrations of each variable to obtain higher concentration of isomaltulose. A high conversion of sucrose into isomaltulose (71.04%) was obtained by the cells immobilized in a matrix composed of alginate (1.7%), CaCl2 (0.25mol/L), gelatin (0.5%), transglutaminase (3.5%) and cell mass (33.5%). As a result, the transglutaminase application as a cross-linking agent improved the immobilization of Serratia plymuthica cells and the conversion of sucrose into isomaltulose.

Enhanced Production of Astaxanthin by Co-culture of Paracoccus haeundaensis and Lactic Acid Bacteria

This study aimed to determine the increase in astaxanthin production from Paracoccus haeundaensis by optimizing the medium conditions and co-culturing with lactic acid bacteria. In order to select a suitable strain to co-culture with P. haeundaensis, several strains were co-cultured with P. haeundaensis. Lactobacillus fermentum was selected as the optimal strain. Further to optimize the astaxanthin production in the co-culture, various medium conditions were tested and the PMF medium developed in this study was selected as the optimum medium. For the co-culture under optimal conditions, the dried cell mass and astaxanthin concentration were 1.84 ± 0.09 g/L and 821.09 ± 30.98 μg/g-dried cell weight, respectively, which was 2.5 times higher than that of the P. haeundaensis strain in the Luria-Bertani broth medium. In order to confirm the transcription level of the carotenoid biosynthesis genes such as crtE, crtB, crtI, crtY, crtZ, and crtW of P. haeundaensis in the co-culture, real-time qPCR was performed. Among the six carotenoid biosynthesis genes, crtI, crtY, and crtZ showed a significant difference in relative RNA levels. The mass culture was performed using a 5 L jar fermenter and the astaxanthin concentration was the same as that at the laboratory scale. These results may be used as reference for co-culture and astaxanthin production in carotenoid biosynthesis microorganisms.

Dynamical analysis of fractional-order chemostat model

The fractional-order differential equations is studied to describe the dynamic behaviour of a chemostat system. The integer-order chemostat model in the form of the ordinary differential equation is extended to the fractional-order differential equations. The stability and bifurcation analyses of the fractional-order chemostat model are investigated using the Adams-type predictor-corrector method. The result shows that increasing or decreasing the value of the fractional order, α , may stabilise the unstable state of a chemostat system and also may destabilised the stable state of the chemostat system depend on the predefined parameter values. The increasing the value of the initial substrate concentration, S 0 may destabilise the stable state of a chemostat system and stabilise the unstable state of the system. Therefore, the running state of a fractional-order chemostat system is affected by the value of α and the value of the initial substrate concentration, S 0. In actual application, the value of the initial substrate should remain at S 0 ≥ 2.54 to ensure that the chemostat system is unstable state. There will be some change in the amount of the cell mass concentration whether increase or decrease when the system is unstable. Therefore, the chemostat system can be well-controlled for the production of cell mass.

Bioconversion of volatile fatty acids into lipids by the oleaginous yeast Apiotrichum porosum DSM27194

Volatile fatty acids (VFA) derived from waste organics provide economical feedstocks for fuels and oleochemicals production. In this study, the valorization of VFA into microbial lipids by the oleaginous yeast Apiotrichum porosum DSM27194 was investigated. A. porosum DSM 27194 was able to assimilate different VFA mixtures containing acetic, propionic and butyric acid at different ratios for lipid production. By using a two-stage automated fed-batch fermentation strategy with glucose as initial carbon source and VFA mixtures as both carbon source and buffering agent, a dry cell mass concentration of 26.5 g/L with lipid content of 36.2% was achieved with the VFA ratio of 6:1:1 (acetic acid:propionic acid:butyric acid). Fatty acid composition profiles indicated that the lipid derived from VFA is better suited for biodiesel production compared to glucose as carbon source. Moreover, corn stover hydrolysate containing VFA was applied as raw feedstock. Excitingly, A. porosum DSM 27194 could consume all kinds of carbon source within the hydrolysate fast and simultaneously resulting in 28.0 g/L of dry cell mass containing 44.3% of lipid. This study provides a promising oleaginous yeast chassis of A. porosum DSM 27194 and an economical fermentation strategy of two-stage automated fed-batch fermentation for microbial lipid production from low-value VFA derived feedstocks.

Economical lipid production from crude glycerol using Rhodosporidiobolus fluvialis DMKU-RK253 in a two-stage cultivation under non-sterile conditions

To enhance the microbial lipid production through Rhodosporidiobolus fluvialis DMKU-RK253, a two-stage cultivation process with a focus on cost reduction was developed. Low-cost raw materials, which are biodiesel-derived crude glycerol and monosodium glutamate were utilized to produce microbial lipids. A two-stage cultivation process was performed under non-sterile cultivation, and a response surface methodology was used to determine the effects of the interaction among factors in the first and second stages of cultivation while using shaking flask cultivation. In the first stage of cultivation, cells were cultivated in a nitrogen-rich medium for cell mass production. The optimal crude glycerol (30 g/L) and monosodium glutamate (5 g/L) concentrations, and the inoculum age (96 h), were found to improve cell mass production. In the second stage, a non-sterile crude glycerol solution was used to enhance lipid production without any aseptic techniques. An optimal crude glycerol concentration of 57 g/L with an initial pH of 7 and an initial cell concentration of optical density at 600 nm of 20 resulted in a high lipid production of 27.81 ± 1.86 g/L and maximum cell mass of 39.14 ± 0.08 g/L. These high lipid and cell mass concentrations consequent to achieve a high lipid content of 71.42% of the dry cell mass, a lipid yield of 0.34 g/g glycerol and a cell mass yield of 0.48 g/g glycerol. The low-cost raw materials were estimated to be US$0.80/kg for microbial lipid production. Therefore, a potential condition for the cultivation process of yeast that produces a high amount of inexpensive lipids has been demonstrated.

Feeding Strategies of Two-Stage Fed-Batch Cultivation Processes for Microbial Lipid Production from Sugarcane Top Hydrolysate and Crude Glycerol by the Oleaginous Red Yeast Rhodosporidiobolus fluvialis.

Microbial lipids are able to produce from various raw materials including lignocellulosic biomass by the effective oleaginous microorganisms using different cultivation processes. This study aimed to enhance microbial lipid production from the low-cost substrates namely sugarcane top hydrolysate and crude glycerol by Rhodosporidiobolus fluvialis DMKU-SP314, using two-stage fed-batch cultivation with different feeding strategies in a 3 L stirred-tank fermenter. The effect of two feeding strategies of 147.5 g/L crude glycerol solution was evaluated including pulse feeding at different starting time points (48, 24, and 72 h after initiation of batch operation) and constant feeding at different dilution rates (0.012, 0.020, and 0.033 h−1). The maximum lipid concentration of 23.6 g/L and cell mass of 38.5 g/L were achieved when constant feeding was performed at the dilution rate of 0.012 h−1 after 48 h of batch operation, which represented 1.24-fold and 1.27-fold improvements in the lipid and cell mass concentration, respectively. Whereas, batch cultivation provided 19.1 g/L of lipids and 30.3 g/L of cell mass. The overall lipid productivity increased to 98.4 mg/L/d in the two-stage fed-batch cultivation. This demonstrated that the two-stage fed-batch cultivation with constant feeding strategy has the possibility to apply for large-scale production of lipids by yeast.

Black Liquor Valorization by Using Marine Protist Thraustochytrium striatum and the Preliminary Metabolic Mechanism Study

Black liquor that contains various phenolic compounds from lignin solubilization has been the main byproduct of alkaline pretreatment of lignocellulosic biomass in the biorefinery. In this study, black liquor from alkaline pretreatment of corn stover was used as a sole carbon source for the cultivation of a marine protist, Thraustochytrium striatum. It was found that this strain can grow on black liquor and accumulate valuable products (e.g., fatty acids and carotenoids) simultaneously. Under optimal conditions (pH = 7 and NH4Cl = 2 g/L), the cell mass concentration reached 5.2 g/L with total aromatics decreased from 8.18 to 3.09 g/L within 7 day incubation. Fed-batch cultivation was adopted to increase the contents of total fatty acids and carotenoids to 13% and 0.24 mg/g dry cell mass, respectively. Although various compounds such as sugars and organic acids were detected in black liquor and consumed during microbial fermentation as carbon sources, lignin-derived compounds were identified as the major s...

A General Pediatrician's Approach to Anemia in Childhood.

Anemia may be defined as a reduction in red blood cell mass or blood hemoglobin concentration. Physiologically, this represents a hemoglobin level that is too low to meet cellular oxygen demands. Practically, the lower limit of normal is set at 2 standard deviations below the mean based on age, gender, and ethnicity/race. Anemia can lead to impaired growth, development, and poor neurocognitive outcome. As such, it is essential for pediatricians to recognize and conduct appropriate testing for a child with anemia. [Pediatr Ann. 2020;49(1):e10-e16.].

Complete blood count test in the evaluation of anemia: More than a screening test?

Aim: Anemia is defined as a reduction in the red blood cell mass or blood hemoglobin concentration. Complete blood count (CBC) analyses provide comprehensive information with regard to the classification of anemia. We aimed to determine the prevalence and remind the possible etiologies of anemia in our province using CBC analyses.Material and Methods: This retrospective study was conducted in a secondary healthcare center in northern Turkey. A total of 2578 healthy children enrolled. Their sociodemographic features, clinical history, and CBC results were retrospectively reviewed from the hospital records. According to CBC analyses, hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH) and red cell distribution width (RDW) levels were evaluated.Results: The prevalence of anemia in the whole study population was 27.6% (n=713). When stratified according to the age subgroups of the study, the prevalances varied between 21.3% and 41.2%. Among the anemic patients, 42.9% (n=306) had microcytic, 56.1% (n=400) had normocytic and 1% (n=7) had macrocytic anemia Conclusion: The prevalance of anemia was >20% in all the age groups, revealing that anemia is a significant public health problem in our province. Detailed analysis of the CBC provides comprehensive information regarding the classification of anemia. It saves time and money for well−child follow up by facilitating the direct application of etiologic tests.

Stimuli-responsive Biosynthesis of Gold Nanoparticles: Optimization, Kinetics, and Thermodynamics of Biosorption

Green nanotechnology with the goal of producing sustainable nanomaterials in an eco-friendly approach is becoming an increasing necessity for nanomanufacturing industries. In this regards, biosynthesis is well adopted as a viable method for producing benign nanoparticles for biomedical application. The present study aimed at optimization and study of the effects of external stimuli pH and gold ion concentration on the morphology of biosynthesized gold nanoparticles (GNPs) using Fusarium oxysporum. Based on the central composite design, the experimental method was developed at three levels of the operating parameters; the initial gold ion concentration, cell mass, and pH. The X-ray diffraction and transmission electron microscopy showed that the obtained GNPs were impurity-free while the size and shape of particles were a function of the pH and Au3+ concentration. Also, analysis of variance revealed that the cell mass and initial gold ion concentration have a significant effect on biosynthesis of GNPs. The optimal condition was found at the initial gold ion concentration of 550 µM, pH 3.5, and cell mass of 0.047 mg/mL with the obtained gold uptake of 98.29%. Pseudo-second order kinetics model best fitted the experimental results with the activation energy of 73.8 kJ indicating that complex chemisorption is the mechanism of gold biorecovery. Adsorption equilibrium followed Freundlich adsorption model and negative ΔG value at room temperature suggested that the GNPs can be synthesized at ambient temperature and atmosphere via an eco-friendly and economically viable process.

Effects of pH and sugar supplements on bacteriocin-like inhibitory substance production by Pediococcus pentosaceus.

To improve bacteriocin-like inhibitory substance (BLIS) production by Pediococcus pentosaceus ATCC 43200, the influence of pH as well as the addition of sugars-either prebiotic (inulin) or not (sucrose)-on its metabolism were investigated. This strain was grown at pH 5.0 or 6.0 either in glucose-based MRS medium (control) or after addition of 0.5, 1.0 or 1.5% (w/w) sucrose and inulin (GSI-MRS) in the same percentages. In the control medium at pH 5.0, cell mass concentration after 48h of fermentation (Xmax = 2.26g/L), maximum specific growth rate (µmax = 0.180h-1) and generation time (Tg = 3.84h) were statistically coincident with those obtained in supplemented media. At pH 6.0 some variations occurred in these parameters between the control medium (Xmax = 2.68g/L; µmax = 0.32h-1; Tg = 2.17h) and the above supplemented media (Xmax = 1.90, 2.52 and 1.86g/L; µmax = 0.26, 0.33 and 0.32h-1; Tg = 2.62, 2.06 and 2.11h, respectively). Lactate production was remarkable at both pH values (13 and 16g/L) and improved in all supplemented media, being 34 and 54% higher than in their respective control media, regardless of the concentration of these ingredients. Cell-free supernatant of the fermented control medium at pH 5.0 displayed an antimicrobial activity against Enterococcus 101 5.3% higher than that at pH 6.0 and even 20% higher than those of all supplemented media, regardless of the concentration of supplements. BLIS production was favored either at pH 5.0 or in the absence of any additional supplements, which were able, instead, to stimulate growth and lactate production by P. pentosaceus.

Machine learning modelling for the ultrasonication-mediated disruption of recombinant E. coli for the efficient release of nitrilase

The ultrasonication-mediated cell disruption of recombinant E. coli was modeled using three machine learning techniques namely Multiple linear regression (MLR), Multi-layer perceptron (MLP) and Sequential minimal optimization (SMO). The four attributes were cellmass concentration (g/L), acoustic power (A), duty cycle (%) and treatment time of sonication (min). For the three responses (nitrilase, total protein release and cell disruption) MLP model was found to be at par with RSM model in terms of generalization as well as prediction capability. Nitrilase release was significantly influenced by the cellmass concentration so was in case of total protein release. Fraction of cells disrupted was heavily influenced by acoustic power and sonication time. Almost 32 U/mL nitrilase could be released for 300 g/L cellmass concentration when sonicated at 225 W for 1 min with 20% duty cycle.