Comparison Of Growth Kinetics Research Articles

Short communication: Comparison of growth kinetics at different temperatures of Streptococcus macedonicus and Streptococcus thermophilus strains of dairy origin

Within the genus Streptococcus, S. thermophilus and S. macedonicus are the 2 known species related to foods. Streptococci are widely used as starter cultures to rapidly lower milk pH. As S. macedonicus has been introduced quite recently, much less information is available on its technological potential. Because temperature is an important factor in fermented food production, we compared the growth kinetics over 24 h of 8 S. thermophilus and 7 S. macedonicus strains isolated from various dairy environments in Italy, at 4 temperatures, 30°C, 34°C, 37°C and 42°C. We used the Gompertz model to estimate the 3 main growth parameters; namely, lag phase duration (λ), maximum growth rate (µmax), and maximum cell number at the stationary phase (Nmax). Our results showed significant differences in average growth kinetics between the 2 species. Among the strains tested, 37°C appeared to be the optimal temperature for the growth of both species, particularly for S. macedonicus strains, which showed mean shorter lag phases and higher cell numbers compared with S. thermophilus. Overall, the growth curves of S. macedonicus strains were more similar to each other whereas S. thermophilus strains grew very differently. These results help to better define and compare technological characteristics of the 2 species, in view of the potential use of S. macedonicus in place of S. thermophilus in selected technological applications.

Comparison of growth kinetics between static and dynamic cultures of human induced pluripotent stem cells

Understanding the fundamental mechanisms that govern the growth kinetics of human induced pluripotent stem cells (hiPSCs) contributes to culture design strategies to improve large-scale production. Two hiPSC lines (Tic and 253G1) were cultured under static and dynamic suspension conditions, and growth kinetics were compared during early (24-48h), middle (48-72h), and late (72-96h) stages. In 2D static culture, similar growth profiles were observed for both hiPSC lines. However, there were significant differences in growth profile patterns and aggregate morphologies between hiPSC lines grown in 3D static and dynamic cultures. Based on immunostaining comparing the two hiPSC lines, surface distribution of collagen type I was observed in aggregates of the Tic line, but not in those of the 253G1 line. Compared to that in 3D static culture, the numbers of cells at 96h were significantly decreased in 3D dynamic culture. The apparent specific growth rate (μapp) of the Tic line was maintained continuously throughout culture, whereas that of the 253G1 line decreased gradually with culture until the late phase, at which time this parameter was reduced to μapp=(0.85±0.71)×10-2h-1. This indicates that during the growth of hiPSCs in 3D dynamic culture, cells were damaged by liquid flow, which disrupted the cell-synthesized extracellular matrix (ECM). These results demonstrate that cell-synthesized ECM is an important factor affecting cell growth and morphology, and that changes to the ECM within aggregates lead to reduced growth abilities in dynamic culture.

Evolution of attenuating mutations in dengue-2 strain S16803 PDK50 vaccine and comparison of growth kinetics with parent virus

A live-attenuated dengue-2 virus strain S16803 vaccine candidate that is immunogenic and safe in humans was derived by 50 passages in primary dog kidney (PDK) cells. To identify mutations associated with attenuation of the dengue-2 PDK50 vaccine strain, we determined the nucleotide changes that arose during PDK passage of the dengue-2 virus. Thirteen mutations distinguished the PDK50 virus from low-passage parent resulting in amino acid substitutions in the premembrane (E89G), envelope (E202K, N203D), nonstructural proteins NS1 (A43T), NS2A (L181F), NS2B (I26V), and NS4B (I/T108T, L112F). In addition, the PDK50 virus contained a C to T change of nucleotide 57 in the 5' non-coding region and four silent mutations of nucleotides 591, 987, 6471, and 8907. An infectious PDK50 cDNA clone virus was produced and characterized for growth kinetics in monkey (LLC-MK(2), Vero) and mosquito (C6/36) cells. Identification of mutations in the vaccine strain and availability of an infectious clone will permit systematic analysis of the importance of individual or collective mutations on attenuation of dengue virus.

Fuhrman Grade Provides Higher Prognostic Accuracy Than Nucleolar Grade for Papillary Renal Cell Carcinoma

Recent evidence suggests that nucleolar grade but not Fuhrman grade is applicable to papillary renal cell carcinoma. We tested this hypothesis in an independent large series from a single institution. One dedicated uropathologist regraded 158 cases of papillary renal cell carcinoma by nucleolar and Fuhrman grades. The prognostic value and predictive accuracy of these grading systems to predict disease specific survival were analyzed by Cox proportional hazards models and the concordance index. There were 39 papillary renal cell carcinoma related deaths (25%) at a mean followup of 50 months. On univariate analysis nucleolar grade predicted disease specific survival with a concordance index of 67.8% but the survival difference between grades 1 and 2 did not attain statistical significance (p = 0.1441). Fuhrman grade predicted disease specific survival significantly better (concordance index 74.7%, p <0.001). Comparison of survival estimates between the grades revealed statistical significance across each grade category (each p <0.05). Fuhrman but not nucleolar grade was retained as an independent prognostic factor on multivariate analysis (p = 0.027 and 0.128, respectively). Each grading system performs well but the predictive accuracy of Fuhrman grade is statistically superior to that of nucleolar grade and only Fuhrman grade provides independent prognostic information on patients with papillary renal cell carcinoma. Thus, Fuhrman grade should be the standard grading system for papillary renal cell carcinoma.

The growth behaviours of IMC layers in solid‐liquid interfacial reactions of Sn1.5Cu/Cu in high magnetic fields

PurposeThe aim of this paper is to investigate the growth behaviours of intermetallic compound (IMC) layers in solid‐liquid interfacial reactions of Sn1.5Cu/Cu in various intensities of high‐magnetic field.Design/methodology/approachSn1.5Cu solder was prepared and melted in a vacuum furnace at 873 K and cast into solder bars. Samples were mounted using resin and etched after being carefully polished. Then the IMC layers were observed by using scanning electron microscopy.FindingsThe results show that the growth of IMC layers has been accelerated by high‐magnetic field through the comparison of growth kinetics of IMC layers among 0‐2.5 T magnetic filed. IMC grains in high‐magnetic field are much bigger than that in 0 T. By the analyzing of X‐ray diffractometer patterns of IMC layers, it can be found that the orientations of IMC have been changed by magnetic field.Originality/valueThis paper investigates the growth behaviour of IMC layers during the solid‐liquid interfacial reactions of Sn1.5Cu/Cu in a high magnetic field.

In Vitro Cultivation of an Insect Microsporidian Tubulinosema ratisbonensis in Mammalian Cells

Tubulinosema ratisbonensis is a microsporidian pathogen of Drosophila melanogaster belonging to the family Tubulinosematidae. The microsporidia in this family mainly cause infections in invertebrate hosts, but two members of this family, Brachiola vesicularum and Brachiola algerae, have been found to cause infections in humans as well. Moreover, B. algerae can be transmitted to immunodeficient mice and grows in mammalian cell cultures. Thus, the examination of the opportunistic properties of other members of the family Tubulinosematidae is important. Spores of T. ratisbonensis, isolated from infected fruit flies, were used to inoculate mammalian and insect cell cultures. Parasite growth was only seen in human lung fibroblasts. No growth was seen in Vero cells or insect cell cultures. Comparison of growth kinetics at 31 degrees C and 37 degrees C showed that there were fewer and smaller parasitic foci in cultures incubated at 37 degrees C. Transmission electron microscopy revealed the typical ultrastructure of T. ratisbonensis, and scanning electron microscopy showed oval or slightly pyriform spores, with some spores having extruded their polar tubes. The PCR-amplified sequences of rDNA fragments from infected cell cultures were 100% identical to the original T. ratisbonensis rRNA sequence. As T. ratisbonensis is able to proliferate in mammalian cell cultures, it may have the opportunistic properties of other members of the family Tubulinosematidae.

Comparison of growth kinetics and phenol metabolizing enzymes of Trichosporon cutaneum R57 and mutants with modified degradation abilities

The model kinetic coefficients of the growth and phenol degradation processes of Trichosporon cutaneum R57 strain and the investigated mutants in culture media containing phenol as a sole carbon and energy source are reported. Successfully simulated phenol degradation profiles in all studied strains were obtained by Haldane-type kinetics. The data presented in the paper showed no direct correlation between efficiency of phenol degradation by the strains studied and biomass productivity. The observed significant increase of inhibitory coefficients in both 2R ( K i=0.46 g l −1) and 4R ( K i=0.44 g l −1) mutants corresponded with their improved capacity to degrade phenol and increased phenol hydroxylase activity. The intracellular specific activities of phenol hydroxylase (EC 1.14.13.7) and catechol 1,2-dioxygenase (EC 1.13.11.1) in T. cutaneum R57 strain and its mutants are measured. The comparison of data for phenol hydroxylase and catechol 1,2-dioxygenase activities in cell-free extracts obtained by ultrasonication and in permeabilized cells showed that the method of cell permeabilization was more favorable for enzyme analyses. The obtained specific activity of phenol hydroxylase in T. cutaneum R57 was 0.8 U mg −1 protein while those in 2R and 4R mutant strains were 1.47 U mg −1 protein and 1.28 U mg −1 protein, respectively. The value of catechol 1,2-dioxygenase activity showed quite less variability and was kept about 0.2 U mg −1 protein in all investigated strains. The results received in these experiments demonstrated that the increased rate of the initial phenol degradation reaction enhanced phenol utilization by cells and vice versa.

Comparison of Growth Kinetics in Pseudomonas using Two Different Sets of Conditions

The aim of this study was to compare the growth kinetic responses to two different sets of conditions by investigating the growth kinetic response of Pseudomonas sp. which was isolated by an enrichment technique using a shaking water bath and a biosimulator. The viable count of the Pseudomonas sp. was initially determined on a small scale using sterile nutrient broth alone, plus broth supplemented with malathion (8.55 mg ml−1) incubated in a shaking water bath. A biosimulator was used on a larger scale to compare the growth kinetics of the Pseudomonas sp. using sterile undiluted and diluted (1:10) nutrient broth. The viable count was measured by the standard plate count (SPC) technique for both the sets of conditions (shaking water bath; biosimulator) and reported as colony forming units (CFU ml−1). In the shaking water bath experiments, the culture grew very well in the presence of 8.55 mg ml−1 malathion, as indicated by good growth response in comparison to that of nutrient broth alone. Similar studies were also performed using the same culture in the biosimulator, using undiluted and diluted (1:10) nutrient broth, results of which revealed, that at each sampling hour the viable population density was greater in the presence of undiluted nutrient broth, than in the presence of diluted (1:10) nutrient broth. A critical evaluation of data presented indicated that the growth performance of Pseudomonas sp. was better in the biosimulator when compared to the shaking water bath. As the Pseudomonas sp. is highly aerobic, it performed better in the biosimulator, where a greater quantity of oxygen (DO 4.0 mg l−1) was more readily available in comparison to the shaking water bath. The total quantity of nutrients available also affected the total viable population density. The study revealed that the wild isolate, when studied on a laboratory scale, could be effective in bioremediation of environmental pollution caused by pesticides.

Morphologic typing of papillary renal cell carcinoma: Comparison of growth kinetics and patient survival in 66 cases

Whereas papillary renal cell carcinoma is now established as a subtype of renal cell neoplasia, division of these tumors into 2 distinctive morphotypes has been proposed. Type 1 tumors have cells with scanty pale cytoplasm arranged in a single layer on the basement membrane of papillary cores. In these tumors, psammoma bodies and foamy macrophages are frequently seen, and the tumors frequently express cytokeratin 7. Type 2 tumor cells have pseudostratified nuclei and usually have voluminous eosinophilic cytoplasm. Recent studies have supported this subclassification of papillary renal cell carcinoma by demonstrating differing genotypes for type 1 and 2 tumors. To further study the subclassification of papillary renal carcinoma, we compared clinical features, nuclear grade, stage, tumor growth kinetics, and survival in a series of 50 type 1 and 16 type 2 papillary renal cell carcinomas. Comparison of patient age at presentation, sex, and primary tumor size shows no significant difference between the 2 tumor types. Type 1 tumors were of significantly lower Fuhrman grade (P =.0001) and higher Robson stage (P =.009) than type 2 tumors. There was no significant difference when tumors were staged according to the TNM classification. Assessment of tumor growth kinetics showed significantly different mean silver-staining nucleolar organizer region (AgNOR) scores and Ki-67 indices (AgNOR type 1, 3.83, type 2, 7.24, P =.0001; Ki-67 type 1, 3.17%, type 2, 6.01%, P =.0002). Multivariate analysis showed tumor type (P =.03), presence of metastases (P =.04), AgNOR score (P =.001), and Ki-67 index (P =.03) to be independently associated with survival. These results provide evidence of the clinical utility of dividing papillary renal cell carcinomas into 2 types according to histologic characteristics. HUM PATHOL 32:590-595. Copyright © 2001 by W.B. Saunders Company

Population dynamics of thermophilic lactobacilli in mixed starter whey cultures

The starter used in the production of Parmesan cheese consists of mixed-strain whey cultures of thermophilic rod lactic acid bacteria, where several strains of each species can be found. The present work was undertaken to demonstrate the effects on the strain composition of interactions among individual lactobacilli grown together in cheese whey. Three strains belonging to Lactobacillus helveticus and Lactobacillus delbrueckii subsp. bulgaricus and subsp. lactis were cultured in Parmesan cheese whey and counted by a molecular approach based on Random Amplified Polymorphic DNA (RAPD) fingerprinting. Results showed interactions among the three lactobacilli as confirmed by comparison of growth kinetics and pH behaviour of the respective strains in mixed-strain culture with single-strain cultures. The present work underlines the importance of noting strain-to-strain interactions among thermophilic lactobacilli in whey co-cultures.

Comparison of Growth Kinetics and Source Material Utilization Efficiency in MBE under Conventional and Ale Conditions

Comparison of Growth Kinetics and Source Material Utilization Efficiency in MBE under Conventional and Ale Conditions