Antiproliferative activity of biomass extract from Pseudomonas cedrina

BackgroundThe study of plant-associated microorganisms is very important in the discovery and development of bioactive compounds. Pseudomonas is a diverse genus of Gammaproteobacteria comprising more than 60 species capable of establishing themselves in many habitats, which include leaves and stems of many plants. There are reports of metabolites with diverse biological activity obtained from bacteria of this genus, and some of the metabolites have shown cytotoxic activity against cancer cell lines.Because of the high incidence of cancer, research in recent years has focused on obtaining new sources of active compounds that exhibit interesting pharmacodynamic and pharmacokinetic properties that lead to the development of new therapeutic agents.ResultsA bacterial strain was isolated from tumors located in the stem of Pinus patula, and it was identified as Pseudomonas cedrina. Extracts from biomass and broth of P. cedrina were obtained with chloroform:methanol (1:1). Only biomass extracts exhibited antiproliferative activity against human tumor cell lines of cervix (HeLa), lung (A-549), and breast (HBL-100). In addition, a biomass extract from P. cedrina was fractioned by silica gel column chromatography and two diketopiperazines were isolated: cyclo-(l-Prolyl-l-Valine) and cyclo-(l-Leucyl-l-Proline).ConclusionsThis is the first report on the association of P. cedrina with the stems of P. patula in Mexico and the antiproliferative activity of extracts from this species of bacteria against human solid tumor cell lines.How to cite: Sánchez-Tafolla L, Padrón JM, Mendoza G, et al. Antiproliferative activity of biomass extract from Pseudomonas cedrina. Electron J Biotechnol 2019;40. https://doi.org/10.1016/j.ejbt.2019.03.010.     

Production,characterization and kinetic model of biosurfactant produced by lactic acid bacteria

BackgroundBiosurfactants are surface active molecules produced by microorganisms which have the ability to disrupt the plasma membrane. Biosurfactant properties are important in the food, pharmaceutical and oil industries. Lactic acid bacteria can produce cell-bound and excreted biosurfactants.ResultsThe biosurfactant-producing ability of three Lactobacillus strains was analyzed, and the effects of carbon and nitrogen sources and aeration conditions were studied. The three species of lactobacillus evaluated were able to produce biosurfactants in anaerobic conditions, which was measured as the capacity of one extract to reduce the surface tension compared to a control. The decreasing order of biosurfactant production was L. plantarum>Lactobacillus sp.>L. acidophilus. Lactose was a better carbon source than glucose, achieving a 23.8% reduction in surface tension versus 12.9% for glucose. Two complex nitrogen sources are required for growth and biosurfactant production. The maximum production was reached at 48 h under stationary conditions. However, the highest level of production occurred in the exponential phase. Biosurfactant exhibits a critical micelle concentration of 0.359 ± 0.001 g/L and a low toxicity against E. coli. Fourier transform infrared spectroscopy indicated a glycoprotein structure. Additionally, the kinetics of fermentation were modeled using a logistic model for the biomass and the product, achieving a good fit (R² > 0.9).ConclusionsL. plantarum derived biosurfactant production was enhanced using adequate carbon and nitrogen sources, the biosurfactant is complex in structure and because of its low toxicity could be applied to enhance cell permeability in E. coli.How to cite: Montoya Vallejo C, Florez Restrepo MA, Guzmán Duque FL, et al. Production, characterization and kinetic model of biosurfactant produced by lactic acid bacteria. Electron J Biotechnol 2021;53. https://doi.org/10.1016/j.ejbt.2021.06.001     

Mechanism of hypercholesterolemia produced by some antibiotics

Rats administered antibiotics showed increased hepatic cholesterogenesis as was evident from the increased activity of HMG-CoA reductase and increased incorporation of labelled acetate into liver cholesterol. But hepatic degradation of cholesterol to bile acids was decreased. There was increased release of lipoproteins into the circulation but their clearance from the circulation was lower as was evident from the decreased activity of lipoprotein lipase of the extrahepatic tissues. Activity of plasma LCAT was also decreased.     

Injuries produced by contact with electric circuits

This paper discusses the results of a series of experimental investigations that have been conducted at The Johns Hopkins University on the effects of electric shock. Rats and dogs were used as the experimental animals. They were completely anesthetized before the experiments. Studies of the effects produced by electric current upon the nervous system and upon the heart are reported. Three types of circuits were used in the work, namely, direct current, alternating current, and the discharge of an impulse generator.In the first series of experiments, the effect of voltage was studied and it was found that low voltage alternating current circuits are much more deadly than direct current circuits of the same voltage. At voltages of 1,000 and higher the reverse is the case. In this work, the importance of the size of the animal as related to the injury was definitely established, larger animals being able to withstand a greater current than those small in size.The resistance offered by a body in an electrical circuit was determined. The resistance is made up of two parts—the contact resistance, and the ohmic resistance of the body proper. The resistances offered at the contacts are of the nature of a voltage drop and are largely independent of the current flowing. The importance of contact resistances in industrial accidents is emphasized.In a second series of experiments the effect of the current path through the     

Microfluidic concentration of bacteria by on-chip electrophoresis

In this contribution, we present a system for efficient preconcentration of pathogens without affecting their viability. Development of miniaturized molecular diagnostic kits requires concentration of the sample, molecule extraction, amplification, and detection. In consequence of low analyte concentrations in real-world samples, preconcentration is a critical step within this workflow. Bacteria and viruses exhibit a negative surface charge and thus can be electrophoretically captured from a continuous flow. The concept of phaseguides was applied to define gel membranes, which enable effective and reversible collection of the target species. E. coli of the strains XL1-blue and K12 were used to evaluate the performance of the device. By suppression of the electroosmotic flow both strains were captured with efficiencies of up to 99%. At a continuous flow of 15 μl/min concentration factors of 50.17 ± 2.23 and 47.36 ± 1.72 were achieved in less than 27 min for XL1-blue and K12, respectively. These results indicate that free flow electrophoresis enables efficient concentration of bacteria and the presented device can contribute to rapid analyses of swab-derived samples.     

Characterization and properties of the biosurfactant produced by Candida lipolytica UCP 0988

BackgroundBiotechnological processes are costly, especially for the production of biosurfactants. The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. Considering the importance of the characteristics of a biosurfactant to facilitate its industrial application, the properties of the biosurfactant produced by Candida lipolytica through previously optimized medium have been established.ResultsThe yeast was grown for 72 h to determine the kinetics of growth and production. The surface tension of the cell-free broth was reduced from 55 to 25 mN/m. The yield of biosurfactant was 8.0 g/l with a CMC of 0.03%. The biosurfactant was characterized as an anionic lipopeptide composed of 50% protein, 20% lipids, and 8% of carbohydrates.ConclusionsThe isolated biosurfactant showed no toxicity against different vegetable seeds: Brassica oleracea, Solanum gilo and Lactuca sativa L. and the micro-crustacean Artemia salina. The properties of the biosurfactant produced suggest its potential application in industries that require the use of effective compounds at low cost.