Two New Alginate Lyases of PL7 and PL6 Families from Polysaccharide-Degrading Bacterium Formosa algae KMM 3553T: Structure, Properties, and Products Analysis

A bifunctional alginate lyase (ALFA3) and mannuronate-specific alginate lyase (ALFA4) genes were found in the genome of polysaccharide-degrading marine bacterium Formosa algae KMM 3553^T. They were classified to PL7 and PL6 polysaccharide lyases families and expressed in E. coli. The recombinant ALFA3 appeared to be active both on mannuronate- and guluronate-enriched alginates, as well as pure sodium mannuronate. For all substrates, optimum conditions were pH 6.0 and 35 °C; Km was 0.12 ± 0.01 mg/ml, and half-inactivation time was 30 min at 42 °C. Recombinant ALFA4 was active predominately on pure sodium mannuronate, with optimum pH 8.0 and temperature 30 °C, Km was 3.01 ± 0.05 mg/ml. It was stable up to 30 °C; half-inactivation time was 1h 40 min at 37 °C. ¹H NMR analysis showed that ALFA3 degraded mannuronate and mannuronate-guluronate blocks, while ALFA4 degraded only mannuronate blocks, producing mainly disaccharides. Products of digestion of pure sodium mannuronate by ALFA3 at 200 µg/ml inhibited anchorage-independent colony formation of human melanoma cells SK-MEL-5, SK-MEL-28, and RPMI-7951 up to 17% stronger compared to native polymannuronate. This fact supports previous data and suggests that mannuronate oligosaccharides may be useful for synergic tumor therapy.

57Fe Mössbauer study of unusual magnetic structure of multiferroic 3R-AgFeO2

We report new results of a ⁵⁷Fe Mössbauer study of hyperfine magnetic interactions in the layered multiferroic 3R-AgFeO₂ demonstrating two magnetic phase transitions at T _N1 and T _N2. The asymptotic value β ^*  ≈  0.34 for the critical exponent obtained from the temperature dependence of the hyperfine field H _hf(T) at ⁵⁷Fe the nuclei below T _N1  ≈  14 K indicates that 3R-AgFeO₂ shows quasi-3D critical behavior. The spectra just above T _N1 (T _N1  <  T  <  T  ^*  ≈  41 K) demonstrate a relaxation behavior due to critical spin fluctuations which indicates the occurrence of short-range correlations. At the intermediate temperature range, T _N2  <  T  <  T _N1, the ⁵⁷Fe Mössbauer spectra are described in terms of collinear spin-density-waves (SDW) with the inclusion of many high-order harmonics, indicating that the real magnetic structure of the ferrite appears to be more complicated than a pure sinusoidally modulated SDW. Below T  <  T _N2  ≈  9 K, the hyperfine field H _hf reveals a large spatial anisotropy (ΔH _anis  ≈  30 kOe) which is related with a local intra-cluster (FeO₆) spin-dipole term that implies a conventional contribution of the polarized oxygen ions. We proposed a simple two-parametric formula to describe the dependence of H _anis on the distortions of the (FeO₆) clusters. Analysis of different mechanisms of spin and hyperfine interactions in 3R-AgFeO₂ and its structural analogue CuFeO₂ points to a specific role played by the topology of the exchange coupling and the oxygen polarization in the delafossite-like structures.

Data supporting functional diversity of the marine bacterium Cobetia amphilecti KMM 296

Data is presented in support of functionality of hyper-diverse protein families encoded by the Cobetia amphilecti KMM 296 (formerly Cobetia marina KMM 296) genome (“The genome of the marine bacterium Cobetia marina KMM 296 isolated from the mussel Crenomytilus grayanus (Dunker, 1853)” [1]) providing its nutritional versatility, adaptability and biocontrol that could be the basis of the marine bacterium evolutionary and application potential. Presented data include the information of growth and biofilm-forming properties of the food-associated isolates of Pseudomonas, Bacillus, Listeria, Salmonella and Staphylococcus under the conditions of their co-culturing with C. amphilecti KMM 296 to confirm its high inter-species communication and anti-microbial activity. Also included are the experiments on the crude petroleum consumption by C. amphilecti KMM 296 as the sole source of carbon in the presence of sulfate or nitrate to ensure its bioremediation capacity. The multifunctional C. amphilecti KMM 296 genome is a promising source for the beneficial psychrophilic enzymes and essential secondary metabolites.