Zinc oxide nanoparticle-reinforced pectin/starch functionalized films: A sustainable solution for biodegradable packaging

Environmental pollution caused by non-biodegradable plastic pollutants adversely affects various ecosystems. This study proposes the development of novel functional and biodegradable films based on corn starch (CST) and pectin (PEC) containing zinc oxide nanoparticles (ZnONPs) from the casting method. The films exhibited processability, transparency, low water vapor permeation, and desirable mechanical properties for food packaging and coating applications. The ZnONPs acted as a plasticizer, enhancing the film elongation at the break, increasing the pec25-1 (PEC 25 wt% and ZnONPs 1 wt%) elongation from 79.85 to 162.32 %. The improved film elasticity supported by ZnONPs reduced the material stiffness. However, the films still demonstrated an average tensile strength (0.69 MPa) 17-fold higher than the tensile strength (0.04 MPa) of the non-biodegradable commercial film based on poly(vinyl chloride). Furthermore, the ZnONPs enhanced the UV-blocking capabilities of the films, leading to wettable materials with water contact angles lower than 90°. The films showed high biodegradation rates under natural disposal conditions. The results indicated that the pec25-1/ZnONPs film is a promising eco-friendly coating in food preservation due to its biodegradability, suitable mechanical properties, low water vapor permeability, and UV-blocking properties.

Antiviral Effect of Caulerpin Against Chikungunya

The discovery of new substances that present innumerable biological activities for the development of drugs is increasingly difficult. Natural marine products are a source of substances with a diversified chemical structure, a broad spectrum of biological activities and low cytotoxicity, which are the essential characteristics for the development of a new drug. An increasing number of reports of Chikungunya virus (CHIKV) infections, in addition to the lack of specific antiviral therapy or vaccines, emphasizes the importance of searching for effective therapy. Studies with the marine green alga Caulerpa racemosa showed antiviral potential. Hence, the aim of this work was to evaluate the anti-CHIKV activity of a marine alkaloid isolated from green alga C. racemosa. Vero cells were used in antiviral assays, submitted to CHIKV, and treated with different concentrations of caulerpin. In the antiviral activity, we observed that the isolated compound showed a much significant and promising EC50 inhibitory effect of 0.8 µM. When evaluating the virucidal activity, we observed that caulerpin was very efficient against CHIKV, being able to inhibit around 90% of the viral infectivity when treated with 5 μM of the compound. We observed that caulerpin added at times 0, 1, 2, and 3 postinfection still maintains a 100% inhibitory potential of viral replication for CHIKV. These studies suggest that the said compounds might be potentially studied for use in the prevention and treatment of CHIKV infections. Derivatives can be considered as a promising new anti-CHIKV drug and can be used for clinical testing.

Update of the Brazilian floristic list of Algae and Cyanobacteria

Abstract An updated synthesis of cyanobacteria and algae information is presented for Brazil aiming to refine the data gathered to date and evaluate the progress of the biodiversity knowledge about these organisms in the country since the publication of the Catálogo de Plantas e Fungos do Brasil. The results of 2015 showed an increase of 1,250 species (35.7%) when compared to 2010, reaching a total of 4,747 species. The most diverse classes in species number were the Bacillariophyceae, Conjugatophyceae, Florideophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae. Bacillariophyceae and Cyanophyceae had the highest increase in species number in the five-year interval. The Southeast and South regions were the most diverse, however, the Northeast, with the states of Piauí and Sergipe, and the Central-west region, with Mato Grosso, Goiás and Distrito Federal, also stood out in the national algal biodiversity scenario. Despite the shortage of taxonomists and limited infrastructure, the results showed a significant improvement in the knowledge regarding the diversity of cyanobacteria and algae in the country during the study period, starting to even out regional geographical differences caused by subsampling.

Xylella and Xanthomonas Mobil'omics

The gamma-proteobacterium Xanthomonadales groups two closely related genera of plant pathogens, Xanthomonas and Xylella. Whole genome sequencing and comparative analyses disclosed a high degree of identity and co-linearity of the chromosome backbone between species and strains. Differences observed are usually clustered into genomic islands, most of which are delimited by genetic mobile elements. Focus is given in this paper to describe which groups of mobile elements are found and what is the relative contribution of these elements to Xanthomonas and Xylella genomes. Insertion sequence (IS) elements have invaded the Xanthomonas genome several times, whereas Xylella is rich in phage-related regions. Also, different plasmids are found inhabiting the bacterial cells studied here. Altogether, these results suggest that the integrative elements such as phages and transposable elements as well as the episomal plasmids are important drivers of the genome evolution of this important group of plant pathogens.

Genetic discovery in Xylella fastidiosa through sequence analysis of selected randomly amplified polymorphic DNAs

Xylella fastidiosa causes many important plant diseases including Pierce's disease (PD) in grape and almond leaf scorch disease (ALSD). DNA-based methodologies, such as randomly amplified polymorphic DNA (RAPD) analysis, have been playing key roles in genetic information collection of the bacterium. This study further analyzed the nucleotide sequences of selected RAPDs from X. fastidiosa strains in conjunction with the available genome sequence databases and unveiled several previously unknown novel genetic traits. These include a sequence highly similar to those in the phage family of Podoviridae. Genome comparisons among X. fastidiosa strains suggested that the "phage" is currently active. Two other RAPDs were also related to horizontal gene transfer: one was part of a broadly distributed cryptic plasmid and the other was associated with conjugal transfer. One RAPD inferred a genomic rearrangement event among X. fastidiosa PD strains and another identified a single nucleotide polymorphism of evolutionary value.

Comparative Analysis of the Complete Plastid Genome Sequence of the Red Alga Gracilaria tenuistipitata var. liui Provides Insights into the Evolution of Rhodoplasts and Their Relationship to Other Plastids

We sequenced to completion the circular plastid genome of the red alga Gracilaria tenuistipitata var. liui. This is the first plastid genome sequence from the subclass Florideophycidae (Rhodophyta). The genome is composed of 183,883 bp and contains 238 predicted genes, including a single copy of the ribosomal RNA operon. Comparisons with the plastid genome of Porphyra pupurea reveal strong conservation of gene content and order, but we found major genomic rearrangements and the presence of coding regions that are specific to Gracilaria. Phylogenetic analysis of a data set of 41 concatenated proteins from 23 plastid and two cyanobacterial genomes support red algal plastid monophyly and a specific evolutionary relationship between the Florideophycidae and the Bangiales. Gracilaria maintains a surprisingly ancient gene content in its plastid genome and, together with other Rhodophyta, contains the most complete repertoire of plastid genes known in photosynthetic eukaryotes.

The genome sequence of the gram-positive sugarcane pathogen Leifsonia xyli subsp. xyli

The genome sequence of Leifsonia xyli subsp. xyli, which causes ratoon stunting disease and affects sugarcane worldwide, was determined. The single circular chromosome of Leifsonia xyli subsp. xyli CTCB07 was 2.6 Mb in length with a GC content of 68% and 2,044 predicted open reading frames. The analysis also revealed 307 predicted pseudogenes, which is more than any bacterial plant pathogen sequenced to date. Many of these pseudogenes, if functional, would likely be involved in the degradation of plant heteropolysaccharides, uptake of free sugars, and synthesis of amino acids. Although L. xyli subsp. xyli has only been identified colonizing the xylem vessels of sugarcane, the numbers of predicted regulatory genes and sugar transporters are similar to those in free-living organisms. Some of the predicted pathogenicity genes appear to have been acquired by lateral transfer and include genes for cellulase, pectinase, wilt-inducing protein, lysozyme, and desaturase. The presence of the latter may contribute to stunting, since it is likely involved in the synthesis of abscisic acid, a hormone that arrests growth. Our findings are consistent with the nutritionally fastidious behavior exhibited by L. xyli subsp. xyli and suggest an ongoing adaptation to the restricted ecological niche it inhabits.

In vitro assay and light regulation of nitrate reductase in red alga Gracilaria chilensis

Nitrate reductase (NR) is the first enzyme in the nitrogen assimilation pathway. The in vitro NR activity of Gracilaria chilensis was assayed under different conditions to reveal its stability and biochemical characteristics, and an optimized in vitro assay is described. Maximal NR activities were observed at pH 8.0 and 15 degrees C. The apparent Km value for NADH was 8 microM and for nitrate 680 microM. Crude extracts of G. chilensis stored at 4 degrees C showed a 50% decrease of NR activity after 24 h. The highest NR activity value (253.20+/-2.60 x 10(-3) U g(-1)) was obtained when 100% von Stosch medium (500 microM NO3-) was added before extraction of apical parts. Algae under light:dark cycles of 12:12h exhibited circadian fluctuation of NR activity and photosynthesis with more than 2 times higher levels in the light phase. No evidence of endogenous diel rhythm controlling NR activity or photosynthesis was observed. Light pulses lasting 10 or 60 min during the darkness increased the NR activity by 30% and 45%, respectively. The results indicate that NR and photosynthesis are regulated mainly by light and not by a biological clock.