Investigation on the Metabolic Regulation of pgi gene knockout Escherichia coli by Enzyme Activities and Intracellular Metabolite Concentrations

An integrated analysis of the cell growth characteristics, enzyme activities, intracellular metabolite concentrations was made to investigate the metabolic regulation of pgi gene knockout Escherichia coli based on batch culture and continuous culture which was performed at the dilution rate of 0.2h-1. The enzymatic study identified that pathways of pentose phosphate, ED pathway and glyoxylate shunt were all active in pgi mutant. The glycolysis enzymes i.e glyceraldehyde-3-phosphate dehydrogenase, fructose diphosphatase, pyruvate kinase, triose phosphate isomerase were down regulated implying that the inactivation of pgi gene reduced the carbon flux through glycolytic pathway. Meanwhile, the pentose phosphate pathway was active as a major route for intermediary carbohydrate metabolism instead of glycolysis. The pentose phosphate pathway generates most of the major reducing co-factor NADPH as shown by the increased of NADPH/NADP+ ratio in the mutant when compared with the parent strain. The fermentative enzymes such as acetate kinase and lactate dehydrogenase were down regulated in the mutant. Knockout of pgi gene results in the significant increase in the intracellular concentration of glucose-6-phosphate and decrease in the concentration of oxaloacetate. The slow growth rate of the mutant was assumed to be affected by the accumulation of glucose-6-phosphate and imbalance of NADPH reoxidation

Determination of ultra-morphological changes of trichophyton rubrum treated with hydroxychavicol

Introduction: Trichophyton rubrum is a common pathogenic fungal species that is responsible for causing infection of human skin, hair and nail. The antifungal-resistant strains however, complicate the treatment regime. Hydroxychavicol (HC) is one of the main compounds from the Piper betel leaf that have antifungal potential and its mechanism of action has yet to be studied. This study was carried out to determine the antifungal properties of HC against Trichophyton rubrum using transmission electron microscope (TEM) on gross and ultrastructure of Trichophyton rubrum hypha. Methods: Broth dilution method was used to determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of HC and miconazole (MI) against the Trichophyton rubrum (ATCC 28188). Trichophyton rubrum was treated with HC and MI at concentrations of 1.25, 2.5, 5 and 10 mg/mL for 1, 3, 5 and 7 days continuously. Results: The MIC results of the HC and MI against Trichophyton rubrum were 0.00048 mg/mL and 0.000061 mg/mL respectively. MFC results showed 0.0019 mg/mL for HC and 0.000061 mg/mL for MI. Microscopically, the fungi structures became more severely damaged at increasing treatment duration. The cell wall of the fungi treated with HC showed a rough surface, shrinkage and demolition similar to that of the MI treated group. The fungi organelles were also demolished and disorganized. Conclusions: This study reveals that HC has the ability to inhibit Trichophyton rubrum growth and it has the potential to be an antifungal agent especially in treating dermatitis. KEYWORDS: Piper betel, Trichophyton rubrum, hydroxychavicol, miconazole, antifunga

A simple strategy guides the complex metabolic regulation in Escherichia coli

A way to decipher the complexity of the cellular metabolism is to study the effect of different external perturbations. Through an analysis over a sufficiently large set of gene knockouts and growing conditions, one aims to find a unifying principle that governs the metabolic regulation. For instance, it is known that the cessation of the microorganism proliferation after a gene deletion is only transient. However, we do not know the guiding principle that determines the partial or complete recovery of the growth rate, the corresponding redistribution of the metabolic fluxes and the possible different phenotypes. In spite of this large variety in the observed metabolic adjustments, we show that responses of E. coli to several different perturbations can always be derived from a sequence of greedy and myopic resilencings. This simple mechanism provides a detailed explanation for the experimental dynamics both at cellular (proliferation rate) and molecular level ((13)C-determined fluxes), also in case of appearance of multiple phenotypes. As additional support, we identified an example of a simple network motif that is capable of implementing this myopic greediness in the regulation of the metabolism

The Mediterranean diet for Polish infants: a losing struggle or a battle still worth fighting?

The Mediterranean diet is well known for its health-promoting effects. Among its key ingredients, olive oil is the most characteristic. Processing industries have been successfully manufacturing and marketing jarred baby foods with the use of vegetable oils, including olive oil, as well as other sources of visible fat. We aimed to survey manufacturer claims concerning added fat in jarred infant foods supplied to the Polish market. A total of 124 kinds of infant foods from six suppliers were analyzed. Corn, canola, and soybean oil occupied the first three positions, respectively, in rank order of vegetable oils used in jarred baby foods. In our sample, only one type of ready-to-eat jars with vegetables contained olive oil. 11% of products contained cow milk butter or cream. 61% of jarred “dinners” contained poultry or fish, which are typical sources of animal protein in the Mediterranean diet. Given that commercial baby foods currently available in the Polish market contain no olive oil, we advocate considering home preparation of infant foods with the use of visible fat. Medical professionals should encourage food manufacturers to return to the concepts of the Mediterranean diet for young consumers, aimed at long-term health