A new concept of biocatalytic synthesis of acrylic monomers for obtaining water-soluble acrylic heteropolymers

Rhodococcus strains were designed as model biocatalysts (BCs) for the production of acrylic acid and mixtures of acrylic monomers consisting of acrylamide, acrylic acid, and N-alkylacrylamide (N-isopropylacrylamide). To obtain BC strains, we used, among other approaches, adaptive laboratory evolution (ALE), based on the use of the metabolic pathway of amide utilization. Whole genome sequencing of the strains obtained after ALE, as well as subsequent targeted gene disruption, identified candidate genes for three new amidases that are promising for the development of BCs for the production of acrylic acid from acrylamide. New BCs had two types of amidase activities, acrylamide-hydrolyzing and acrylamide-transferring, and by varying the ratio of these activities in BCs, it is possible to influence the ratio of monomers in the resulting mixtures. Based on these strains, a prototype of a new technological concept for the biocatalytic synthesis of acrylic monomers was developed for the production of water-soluble acrylic heteropolymers containing valuable N-alkylacrylamide units. In addition to the possibility of obtaining mixtures of different compositions, the advantages of the concept are a single starting reagent (acrylamide), more unification of processes (all processes are based on the same type of biocatalyst), and potentially greater safety for personnel and the environment compared to existing chemical technologies.

Draft Genome Sequence of Rhodococcus sp. Strain M8, Which Can Degrade a Broad Range of Nitriles

Rhodococcus sp. strain M8 is a nitrile-degrading bacterium isolated from acrylonitrile-contaminated sites. This strain produces the enzymes for sequential nitrile degradation, cobalt-type nitrile hydratase, and amidase in large amounts. Its draft genome sequence, announced here, has an estimated size of 6.3 Mbp.

The complete genome of the oil emulsifying strain Thalassolituus oleivorans K-188 from the Barents Sea

Gammaproteobacterium Thalassolituus oleivorans plays an important role in oil degradation in sea water through emulsifying crude oil and alkanes at low temperatures in polar sea environment. Here we report the complete genome sequence of K-188 strain (VKPM B-9394) isolated in the Barents Sea and compare it with other known Thalassolituus oleivorans strains. The Thalassolituus strains are differed in orthologs number of the genes of alkane degradation, transport proteins, genes of sugar utilization, endonucleases, signaling proteins, transcriptional regulators and presence of CRISPR/Cas locus. Also only the genome of K-188 contains the 3-hydroxyalkanoate synthetase.

Unexpected Effects of Activator Molecules' Polarity on the Electroreological Activity of Titanium Dioxide Nanopowders

Titanium dioxide nanoparticles, obtained using the sol-gel method and modified with organic solvents, such as acetone, acetonitrile, benzene, diethyl ether, dimethyl sulfoxide, toluene, and chloroform, were used as the filler of polydimethylsiloxane-based electrorheological fluids. The effect of electric field strength on the shear stress and yield stress of electrorheological fluids was investigated, as well as the spectra of their dielectric relaxation in the frequency range from 25 to 10⁶ Hz. Modification of titanium dioxide by polar molecules was found to enhance the electrorheological effect, as compared with unmodified TiO₂, in accordance with the widely accepted concept of polar molecule dominated electrorheological effect (PM-ER). The most unexpected result of this study was an increase in the electrorheological effect during the application of nonpolar solvents with zero or near-zero dipole moments as the modifiers. It is suggested that nonpolar solvents, besides providing additional polarization effects at the filler particles interface, alter the internal pressure in the gaps between the particles. As a result, the filler particles are attracted to one another, leading to an increase in their aggregation and the formation of a network of bonds between the particles through liquid bridge contacts. Such changes in the electrorheological fluid structure result in a significant increase in the mechanical strength of the structures that arise when an electric field is applied, and an increase in the observed electrorheological effect in comparison with the unmodified titanium dioxide.

[Wide distribution of transposable phages in natural Pseudomonas aeruginosa populations]

Five phages (PH2, PH51, PH59, PH93 and PH132) which have some characteristics common with D3112, the transposable phage of Pseudomonas aeruginosa, were isolated from clinical P. aeruginosa isolates. The phages were distributed into 4 different immunity groups. The basic criteria used for selection of transposable phages have been: 1) Morphology of a phage particle, host range, similar inactivation with antiserum; 2) Similar sizes of phage genomes; 3) The presence of a variable non-phage nucleotide sequences covalently linked to phage genome DNA, which could be identified using restriction endonucleases or by heteroduplex analyses. The DNAs of the new phages are resistant to treatment with BamH1 endonuclease, like the DNAs of phages D3112, B39 and B3 described earlier. The restriction maps of the phage genomes are constructed.