Biopolymer production by halotolerant bacteria isolated from Caatinga biome.

Saline environments are extreme habitats with a high diversity of microorganisms source of a myriad of biomolecules. These microorganisms are assigned as extremophiles recognized to be producers of new natural compounds, which can be synthesized by helping to survive under harshness and extreme conditions. In Brazil, in the saline and semi-arid region of Areia Branca (Caatinga biome), halotolerant bacteria (able to growth at high NaCl concentrations) were isolated from rhizosphere of native plants Blutaparon portulacoides and Spergularia sp. and their biopolymer production was studied. A total of 25 bacterial isolates were identified at genus level based on 16S rRNA gene sequence analysis. Isolates were mainly Gram-positive bacteria from Bacillaceae, Staphylococcaceae, Microbacteriaceae, and Bacillales XII incertae sedis families, affiliates to Bacillus, Staphylococcus, Curtobacterium, and Exiguobacterium genera, respectively. One of the Gram-negative isolates was identified as member of the Pseudomonadaceae family, genus Pseudomonas. All the identified strains were halotolerant bacteria with optimum growth at 0.6-2.0 M salt concentrations. Assays for biopolymer production showed that the halotolerant strains are a rich source of compounds as polyhydroxyalkanoates (PHA), biodegradable biopolymer, such as poly(3-hydroxybutyrate) (PHB) produced from low-cost substrates, and exopolysaccharides (EPS), such as hyaluronic acid (HA), metabolite of great interest to the cosmetic and pharmaceutical industry. Also, eight bacterial EPS extracts showed immunostimulatory activity, promising results that can be used in biomedical applications. Overall, our findings demonstrate that these biomolecules can be produced in culture medium with 0.6-2.0 M NaCl concentrations, relevant feature to avoid costly production processes. This is the first report of biopolymer-producing bacteria from a saline region of Caatinga biome that showed important biological activities.

Caulerpa Cupressoides Var. Flabellata.

Green seaweeds are rich sources of sulfated polysaccharides (SPs) with potential biomedical and nutraceutical applications. The aim of this work was to evaluate the immunostimulatory activity of SPs from the seaweed, Caulerpa cupressoides var. flabellata on murine RAW 264.7 macrophages. SPs were evaluated for their ability to modify cell viability and to stimulate the production of inflammatory mediators, such as nitric oxide (NO), intracellular reactive oxygen species (ROS), and cytokines. Additionally, their effect on inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX-2) gene expression was investigated. The results showed that SPs were not cytotoxic and were able to increase in the production of NO, ROS and the cytokines, tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). It was also observed that treatment with SPs increased iNOS and COX-2 gene expression. Together, these results indicate that C. cupressoides var. flabellata SPs have strong immunostimulatory activity, with potential biomedical applications.

Antitumor and immunostimulatory activities of a genotype V recombinant attenuated veterinary Newcastle disease virus vaccine.

Antitumor conventional treatments including chemo/radiotherapy result in several side effects and non-specificity. Therapies including the use of oncolytic viruses, particularly the Newcastle disease virus (NDV), have emerged as an attractive alternative due to their capacity to kill cancer cells directly or through stimulation of the immune system. In the present study, a commercial vaccine composed of a recombinant attenuated NDV strain P05 (rNDV-P05) was assessed for antitumor and immunostimulatory activity. Firstly, hemagglutination activity was evaluated at different pH and temperature conditions. Then, cancer cell lines and peripheral blood mononuclear cells (PBMC) were co-cultured with or without rNDV-P05 and cytoplasmic nucleosomes were measured by enzyme-linked immunosorbent assay (ELISA) as an apoptosis indicator. Antitumor cytokines produced by PBMC in response to the virus were analyzed by ELISA and reverse transcription quantitative polymerase chain reaction. Characterization of rNDV-P05 indicates that the virus is slightly sensible to acid and basic pH, and stable at temperatures no greater than 42°C. The majority of cell lines developed apoptosis in co-culture with rNDV-P05 in a dose-time dependent manner. The highest level of HeLa, HCC1954 and HepG2 cell apoptosis was at 48 h/50 hemagglutination units (HU), and HL-60 was 24 h/50 HU. A549 cell line and PBMC did not show sensitivity to apoptosis by the virus. PBMC from healthy donors stimulated with the rNDV-P05 increased significantly the levels of interferon (IFN)-α, IFN-γ, tumor necrosis factor (TNF)-α and soluble TNF-related apoptosis-inducing ligand in culture supernatants, as well as their mRNA expression. These results demonstrate that the pro-apoptotic effect of rNDV-P05 and its magnitude is specific to particular tumor cell lines and is not induced on PBMC; and the virus stimulates the expression of several key antitumor cytokines. This study promotes the use of rNDV-P05 in an alternate application of different viral strains during virotherapy with NDV.