Uptake Of Organic Molecules Research Articles

Screening, isolation and characterization of biosurfactant-producing Bacillus tequilensis strain ANSKLAB04 from brackish river water

Biosurfactants are amphiphilic compounds produced by micro-organisms that are excreted extracellularly and contain hydrophobic as well as hydrophilic moieties which reduce surface tension. These extracellular membrane vesicles aid in the uptake of organic molecules that are used as a source of energy for growth of micro-organisms. These micro-organisms have the ability to grow and proliferate on the oil-based medium like petro-contaminated soil and water. Oil spills and discharge from industry contaminates the water bodies and surrounding land. Many chemical-based technologies and manual cleaning are involved to reduce water and land pollution. Chemicals used are the surfactants that lead to the generation of toxic by-products. Hence, considerable attention has been given to surface-active molecules of biological origin called biosurfactants, produced by microbial species in and around the contaminated area. The present study focuses on identifying a novel biosurfactant-producing bacterial strain from brackish water. The bacterial consortium was isolated from targeted brackish water site. Each bacterial species was tested for its biosurfactant production ability using various assays. Haemolysis, oil spreading, cetyltrimethyl ammonium bromide agar plate, drop collapse, hydrocarbon overlay agar, hydrocarbon assay and lipase production were a few qualitative methods performed. Further, the most efficient biosurfactant producer was identified by measuring emulsification index, quantifying biosurfactant production and efficient reduction in surface tension. 16S rRNA gene sequencing was performed for phenotypic characterization of the biosurfactant-producing strain, using Sanger dideoxy sequencing method followed by the phylogenetic assessment. The isolate was found to be a novel Bacillus tequilensis strain, named as ANSKLAB04. The novel isolate was deposited in GenBank with Accession number KU529483.

HEPES inhibits the conversion of prion protein in cell culture

HEPES is a well-known buffering reagent used in cell-culture medium. Interestingly, this compound is also responsible for significant modifications of biological parameters such as uptake of organic molecules, alteration of oxidative stress mechanisms or inhibition of ion channels. While using cell-culture medium supplemented with HEPES on prion-infected cells, it was noticed that there was a significant concentration-dependent inhibition of accumulation of the abnormal isoform of the prion protein (PrP(Sc)). This effect was present only in live cells and was thought to be related to modification of the PrP environment or biology. These results could modify the interpretation of cell-culture assays of prion therapeutic agents, as well as of previous cell biology results obtained in the field using HEPES buffers. This inhibitory effect of HEPES could also be exploited to prevent contamination or propagation of prions in cell culture.

Ecological advantages from light adaptation and heterotrophic-like behavior in Synechococcus harvested from the Gulf of Trieste (Northern Adriatic Sea)

A preliminary study was carried out on a picocyanobacterial mixed culture harvested from the Gulf of Trieste (Northern Adriatic) and identified as Synechococcus spp. both by transmission electron microscopy observations, biliprotein composition and molecular analyses. Absorption and fluorescence spectra revealed phycourobilin and phycoerythrobilin chromophores, suggesting the presence of both CU- and C-phycoerythrin, besides phycocyanobilin chromophores typical for phycocyanins and allophycocyanins. Both biliprotein analyses and molecular identification indicated the presence of at least two Synechococcus subgroups presumably differing either in phycoerythrin type or in physiological traits. Among the exoenzymatic activities acting on different substrates, only aminopeptidase showed high hydrolysis rates and the uptake of organic molecules was positive for leucine but not for thymidine. The protein carbon mobilized was high compared with the leucine incorporation rates, resulting in low percentages of newly mobilized carbon utilized by cultures. The organic carbon incorporated as leucine was compared with the photosynthetically produced one, and the balance between the phototrophic- and heterotrophic-like processes was c. 3 : 1. Our findings suggest that the Synechococcus heterotrophy plays an important role in cell's metabolism, and that the photoheterotrophic behavior, together with their chromatic adaptation capability, might represent the key for the absolute dominance of this genus in the Adriatic Sea.

Solubilization of Benzoic Acid Derivatives by Nonionic Surfactants: Location of Solubilizates in Hydrocarbon Core of Micelles and Polyoxyethylene Mantle

The micelles that nonionic surfactants containing polyoxyethylene head groups form in aqueous solution have a hydrocarbon core surrounded by a mantle, which can be described as a dense solution of polyoxyethylenes. Solubilization, or the uptake of organic molecules in such micelles, may involve two broadly defined loci: (a) the hydrocarbon core along with its interface, and (b) the polyoxyethylene mantle. It is shown that the solubilization of many benzoic acid derivatives and phenolic preservatives in such micelles can be described in terms of the two loci of solubilization. The relative importance of the two loci can be derived in an approximate fashion from solubilization data in systems where the polyoxyethylene chain length is varied on the basis of two simplifying assumptions. The distribution of the solubilized species between the two loci is related to the chemical structure of the solubilizate, and it is important in understanding the physical and chemical reactivities of the solubilized species.