The effect of pH on bacterial growth and histamine formation by Klebsiella pneumoniae CK02 and Raoultella ornithinolytica TN01

The present work describes the effect of pH on the growth rate and histamine formation by Klebsiella pneumoniae CK02 and Raoultella ornithinolytica TN01. Bacteria were inoculated on Tuna Fish Infusion Broth media with pH 5, 6, 7, 8 at 30°C for 6 hours. Sampling was conducted at 0, 3, and 6 hours to observe the bacteria number and calculate the histamine content formed in the medium. The number of bacteria was calculated using the Total Plate Count method, and the histamine content was analyzed using Thin Layer Chromatography with a combination of ImageJ software. Growth data and incubation time were plotted in the DMFit program to obtain growth rates. The effect of pH on growth rate and histamine formation was analyzed by ANOVA test and Duncan Multiple Range Test. The results revealed that pH affects the growth rate and histamine formation of K. pneumoniae CK02 and R. ornithinolytica TN01. The optimal growth rate of K. pneumoniae CK02 was in the range of 6-8 (0.304-0.380 log CFU/h), with the highest histamine formation ability at pH 7 (824 ppm). R. ornithinolytica TN01 had an optimal growth rate at pH 6-7 (0.480-0.508 log CFU/ml), with optimal ability to produce histamine at pH 6-8 (620-1,077.5 ppm). At pH 5, the growth rate and the ability of histamine formation by K. pneumoniae CK02 and R. ornithinolytica TN01 were inhibited.

Optimization of Anguilla bicolor oxygen consumption in alkalinity culture media

One potential aquaculture commodity that can be developed is Anguilla bicolor. One effort that can be conducted to maximize the life and growth of A. bicolor by manipulating water quality through alkalinity parameters. Alkalinity is a buffer capacity for changing in water pH, and osmotic pressure of water. Alkalinity levelss in culture media can be managed by the addition of calcium carbonate (CaCO3), calcium oxide (CaO), or calcium hydroxide (CaOH) with a certain dose to the culture media. This study aimed to determine the effect of alkalinity on aquaculture media based on the level of oxygen consumption (OC) that related to growth value. This research was conducted with an experimental design using a completely randomized design (CRD) with four treatments, namely the addition of CaCO3 to maintenance media with different doses (A, 0 mg/L; B, 50 mg/L; C, 100 mg/L; D, 150 mg/L). The results showed that the treatment B (50 mg / L) showed an OC value (0.15 mgO2/g/h) and an optimal Growth Rate (GR) (3.75 g/day), while the Survival Rate (SR) parameter, the treatment had no significant effect. The conclusion was 50 mg/L of calcium carbonate (CaCO3) having the optimum alkalinity level in A. bicolor culture media. At the additional dose of CaCO3, the growth value (GR), and the level of eel fish oxygen consumption were optimal.

Enabling stable coexistence by modifying the environment

In this work coexistence is studied using a model based on two classical population models: the quasispecies of Eigen [1] and the daisyworld presented by Watson and Lovelock [2]. It is assumed that species are able to modify the environment. We show that this ability enables the coexistence between, at most, two species in equilibrium. Given an initial population, the problem arises as to determine which of the many equilibrium populations, i.e. extinction, only one species or coexistence of two species, will be reached as a function of the species characteristics, specifically their capacity to modify the environment and the optimal growth rate. These results are obtained under general assumptions, which broadens its applicability to other fields as evolutionary biology and social sciences.

The growth of seaweed (Eucheuma cottoni) at different fertilizing doses in the waters of the village of Ghonebalano, Duruka District, Muna Regency, Indonesia

The study was conducted aiming to test different fertilizer doses on the optimal growth rate of Eucheuma cottonii seaweed. The study was conducted from July to August 2016 in the waters of Ghonebalano Village, Duruka District, Muna Regency, Southeast Sulawesi. The study used NPK fertilizer with the composition of the element nitrogen (N) 15%, phosphate (P2O5) 15%, and potassium (K2O) 15%. The study used a Randomized Block Design (RBD) with 3 (three) levels of fertilizer doses and 3 (three) groups so that the number of experimental units was 9 (nine) units. While the treatments tested in the study were treatment A (without fertilizer/control), treatment B (fertilizer dose 1 g/L), and treatment C (fertilizer dose 2 g/L). The results showed that the difference in fertilizer dose significantly affected the growth rate of Eucheuma cottonii seaweed. A dosage of 2 g/L of fertilizer gives the best rate of growth of Eucheuma cottonii seaweed while the water quality at the study site shows that it is still in the optimal range for the growth of Eucheuma cottonii seaweed.

Effect of Increased Temperature on Native and Alien Nuisance Cyanobacteria from Temperate Lakes: An Experimental Approach

In response to global warming, an increase in cyanobacterial blooms is expected. In this work, the response of two native species of Planktothrix agardhii and Aphanizomenon gracile, as well as the response of two species alien to Europe—Chrysosporum bergii and Sphaerospermopsis aphanizomenoides—to gradual temperature increase was tested. The northernmost point of alien species distribution in the European continent was recorded. The tested strains of native species were favoured at 20–28 °C. Alien species acted differently along temperature gradient and their growth rate was higher than native species. Temperature range of optimal growth rate for S. aphanizomenoides was similar to native species, while C. bergii was favoured at 26–30 °C but sensitive at 18–20 °C. Under all tested temperatures, non-toxic strains of the native cyanobacteria species prevailed over the toxic ones. In P. agardhii, the decrease in concentration of microcystins and other oligopeptides with the increasing temperature was related to higher growth rate. However, changes in saxitoxin concentration in A. gracile under different temperatures were not detected. Accommodating climate change perspectives, the current work showed a high necessity of further studies of temperature effect on distribution and toxicity of both native and alien cyanobacterial species.

How can we Engineer Stock Markets like NSEIL with BSE SENSEX index data using String Theory

<span class="fontstyle0">This paper considers the problem of sustainably developing<br />stock exchanges like NSEIL and measurable index systems like BSE SENSEX by developing strategies to achieve sales volume which achieve optimal<br />growth rates. Experimental data on BSE SENSEX and Companies over time<br />are used which closely mimics now active NSEIL. This requires consideration<br />of consumer choice in intertemporal markets with endogenous stock market<br />products. A sequence of five steps is derived to characterize the venturing<br />technology which will achieve such desired stock market sales volume with<br />fixed prices and hence the optimal growth rate. It is derived how String Theory is sufficient to build such stock markets in value and volumes by using<br />depositories. </span>

How can we Engineer Stock Markets like NSEIL with BSE SENSEX index data using String Theory

<span class="fontstyle0">This paper considers the problem of sustainably developing<br />stock exchanges like NSEIL and measurable index systems like BSE SENSEX by developing strategies to achieve sales volume which achieve optimal<br />growth rates. Experimental data on BSE SENSEX and Companies over time<br />are used which closely mimics now active NSEIL. This requires consideration<br />of consumer choice in intertemporal markets with endogenous stock market<br />products. A sequence of five steps is derived to characterize the venturing<br />technology which will achieve such desired stock market sales volume with<br />fixed prices and hence the optimal growth rate. It is derived how String Theory is sufficient to build such stock markets in value and volumes by using<br />depositories. </span>

Joint spectral radius, Sturmian measures and the finiteness conjecture

The joint spectral radius of a pair of $2\times 2$ real matrices $(A_{0},A_{1})\in M_{2}(\mathbb{R})^{2}$ is defined to be $r(A_{0},A_{1})=\limsup _{n\rightarrow \infty }\max \{\Vert A_{i_{1}}\cdots A_{i_{n}}\Vert ^{1/n}:i_{j}\in \{0,1\}\}$, the optimal growth rate of the norm of products of these matrices. The Lagarias–Wang finiteness conjecture [Lagarias and Wang. The finiteness conjecture for the generalized spectral radius of a set of matrices. Linear Algebra Appl.214 (1995), 17–42], asserting that $r(A_{0},A_{1})$ is always the $n$th root of the spectral radius of some length-$n$ product $A_{i_{1}}\cdots A_{i_{n}}$, has been refuted by Bousch and Mairesse [Asymptotic height optimization for topical IFS, Tetris heaps, and the finiteness conjecture. J. Amer. Math. Soc.15 (2002), 77–111], with subsequent counterexamples presented by Blondel et al [An elementary counterexample to the finiteness conjecture. SIAM J. Matrix Anal.24 (2003), 963–970], Kozyakin [A dynamical systems construction of a counterexample to the finiteness conjecture. Proceedings of the 44th IEEE Conference on Decision and Control, and the European Control Conference (Seville, Spain, December 2005). IEEE, Piscataway, NJ, pp. 2338–2343] and Hare et al [An explicit counterexample to the Lagarias–Wang finiteness conjecture. Adv. Math.226 (2011), 4667–4701]. In this article, we introduce a new approach to generating finiteness counterexamples, and use this to exhibit an open subset of $M_{2}(\mathbb{R})^{2}$ with the property that each member $(A_{0},A_{1})$ of the subset generates uncountably many counterexamples of the form $(A_{0},tA_{1})$. Our methods employ ergodic theory; in particular, the analysis of Sturmian invariant measures. This approach allows a short proof that the relationship between the parameter $t$ and the Sturmian parameter ${\mathcal{P}}(t)$ is a devil’s staircase.