Biologia最新文献

Streptococcus agalactiae stands out as a significant bacterial pathogen, causing substantial economic losses in the aquaculture sector. Given the challenges posed by multidrug resistance, this study explores the potential of phage therapy as an alternative to antibiotics in biocontrol strategies. The focus is on evaluating the multidrug resistance profile of S. agalactiae isolated from a tilapia aquaculture farm, with particular attention to the strain KSA/01, which exhibits resistance to seven structurally different classes of antibiotics and a notable MAR index of around 0.6. In response to this challenge, the study successfully identifies and isolates the specific and lytic phage SAP-13 targeting the multidrug-resistant strain KSA/01. Transmission electron microscopy reveals that SAP-13 shares morphological characteristics with the Siphoviridae family. In a one-step growth curve, the phage demonstrates a substantial burst size of approximately 610 PFU/cell over a short burst period and the phage exhibited stability across various physicochemical parameters such as temperature, pH, and salinity. In vitro lytic ability of SAP-13 at different multiplicity of infection underscores its potential to effectively eliminate S. agalactiae, particularly at an MOI of 0.01. Consequently, these findings suggest that phage SAP-13 exhibits high infectivity against S. agalactiae, presenting a promising avenue for addressing multidrug-resistant strains in aquaculture.

Antimicrobial peptides (AMPs) are natural ribosomal synthesized small peptides and are crucial effectors in all living organisms. AMPs are diverse polypeptides with varying amino acid composition and structure that often exhibit broad-spectrum and fast-acting antibacterial properties. As a result, AMPs offer a great deal of promise for restorative application in medicine, agriculture, and the environment. The maritime, industrial, and healthcare sectors all suffer major losses as a result of biofouling. This article will review antimicrobial peptides (AMPs), their structure and major class of AMPs that are reported as anti-biofouling agents, evolutionary concept of AMP, mechanism of action of AMPs against biofilm formation, intracellular active AMPs, synthetic AMPs, promising AMP modifications reported and AMP databases to understand AMPs specificity and activity for rational designing.

Therefore, this review will provide a comprehensive assessment of AMPs numerous functions as well as to detect their therapeutic potential and avoid industry losses incurred by biofilms.

Levan is a type of fructan with β-(2, 6) fructosyl linkage. In recent years, levan has been used in the medicinal, food and chemical industries for its excellent physicochemical properties of good thermal stability, low viscosity, pseudoplasticity, and non-swelling in water. The levansucrase is key enzyme responsible for biosynthesis of levan from substrate sucrose. In the present study cell lysate of Escherichia coli was used as support for convenient immobilization of Ba-SacB (i.e., Ba-SacB-Cell-Lysate) under the action of dopamine. Compared with the free Ba-SacB, the Ba-SacB-Cell-Lysate showed surprisingly enhanced pH stability in the pH range 6–9, and improved relative activities in the pH ranges 4–5 and 7–10. With the presence of 10% (v/v) butyl alcohol, 5mmol/L Fe³⁺, and after vortex for 90 min, the Ba-SacB-Cell-Lysate showed up to 14.32 times, 4.63 times, and 9.2 times higher relative activities than the free Ba-SacB. The Ba-SacB-Cell-Lysate kept nearly 81% of the residual activity after 9 cycles of reuse. The fructo-oligosaccharide syrup (FOS) was efficiently produced through the catalysis of levanase with the substrate of levan produced by Ba-SacB-Cell-Lysate, and the preparation conditions were optimized by Box-Behnken response surface methodology.

Earthworms are natural soil quality indicators that are highly responsive to their living environment. Due to the recent rapid expansion of oil palm in tropical countries, there are raised concerns on possible negative impacts on the soil environment. This study aims to examine the earthworm distribution through the shallow soil profile and its relation to soil characteristics using oil palm and rubber plantations, compared with a natural forest in Galle District, Sri Lanka, to understand impacts of vegetation alterations. Soil samples were collected from 0 to 10, 10–20, and 20–30 cm depths (9 points/layer/site). The earthworm count was taken manually to determine the earthworm density (EWD). The C stock of forest soil in three soil layers was significantly higher than that of rubber and oil palm. In all sites, the topsoil showed the highest C stock, however, the differences between layers were not significant. Forest soils showed the highest EWD, although there was no significant difference between the three sites. The topsoil layer of all sites showed significantly higher EWD. In forest soil, EWD showed a strong negative correlation (R² = 0.81) with bulk density, a strong positive correlation with porosity (R² = 0.78), and a moderate positive correlation (R² = 0.57) with organic matter content. The EWD in rubber and oil palm soils showed positive correlations with organic matter content, which were not statistically significant. Literature shows that the earthworm abundance has strong positive correlations with N fertilizer. The forest has intact soil environments while the tested oil palm and rubber plantations annually receive high amounts of N. Accordingly, the creation of a favorable soil environment for the growth and development of earthworms with the addition of N fertilizer might be the reason for these results.

The increasing population and demand for food and feed have increased the urge to find protein sources from waste products. Due to poor management of waste valorization, it has become a pollutant to the environment. This waste can be converted into a valuable product by microbial degradation. Feather waste from poultry farms can be efficiently processed into hydrolysates, serving as an additive or in its crude form for animal feed and detergents. This approach not only reduces pollution but also boosts the economy of a country. Keratin is a hard fibrous protein, insoluble in water and organic solvents. They are accumulated in nature and are major components of feathers, nails, hairs, and wool. Microorganisms like bacteria, fungi, and actinomycetes can degrade keratin by producing the keratinase enzyme. Keratinases are thought to be promising biocatalysts for the production of animal nutrients, protein supplements, leather processing, fibre modification, detergent formulations, and pharmaceutical, cosmetic, and biomedical industries. An overview of keratin structure and composition, the mechanism of microbial hydrolysis of keratin, and their possible uses in biotechnological sectors are presented in this review.

Xiphocentronidae comprises eight genera found across tropical regions. In Brazil, two genera are present: Xiphocentron Brauer, 1870 and Machairocentron Schmid, 1982. Xiphocentron is further divided into five subgenera: Xiphocentron (Antillotrichia) Banks, 1941, X. (Glyphocentron) Schmid, 1982, X. (Rhamphocentron) Schmid, 1982, X. (Sphagocentron) Schmid, 1982, and X. (Xiphocentron). Xiphocentron (Antillotrichia) is the most species-rich subgenus and the only one occurring in South America. In Brazil, there are 18 species of X. (Antillotrichia), mainly distributed in the Atlantic Forest, with one species recorded in the Brazilian Amazon. Machairocentron, another Neotropical genus, comprises nine species, but only one species is known in Brazil. Recent research in the Brazilian Amazon led to the discovery of three new species of Xiphocentron: Xiphocentron (Antillotrichia) moa sp. n., Xiphocentron tapajos sp. n., and Xiphocentron (Antillotrichia) xingu sp. n. This study describes and illustrates these species, focusing on adult males, and highlighting the distinctive morphology of segment IX and inferior appendages. New distribution records are provided for X. (Antillotrichia) sclerothrix Pes & Hamada, 2013 and M. falciforme Pes & Hamada, 2013 . Additionally, M. amahuaca Vilarino, Salles & Bispo, 2023 and X. (Antillotrichia) surinamense Flint, 1974 are reported for the first time in Brazil.

The summer of 2022 has been the so far hottest summer on record in Central Europe. High temperatures negatively affect the physiology of plants and cause considerable thermal stress in particular on the leaf level. The assessment of the temperature-dependent decline of the quantum use efficiency of the photosystem II (Fv/Fm) has gained much popularity to quantify the leaf-level sensitivity to thermal stress. An open question is whether leaves heat to those in vitro estimated threshold temperatures on hot days or if plants can avoid heat stress through transpirational cooling. Therefore, leaf temperatures were monitored on a non-native Austrian oak (Quercus cerris) during a heatwave in July 2022 and compared to observed air temperature and leaf thermal traits assessed with a chlorophyll fluorometer. The highest air temperature recorded during the heatwave was 42.5 °C and surpassed the breaking point temperature (temperature at 5% decline of Fv/Fm; T5) by 0.3 °C, but was 6.1 °C lower than T50 (temperature at 50% decline of Fv/Fm). However, during the hottest day, the maximum leaf temperature was significantly below the air temperature. Even the directly illuminated leaf facing south reached a maximum temperature of only 38.7 °C but reached 39.8 °C on the second hottest day when the air temperature went up to 39.6 °C. All leaves showed a certain degree of homeothermy as the slope between leaf temperature and air temperature was 0.83 (P < 0.05). In conclusion, Austrian oak can buffer thermal stress during heatwaves to a certain degree, however, leaf temperatures are only marginally below critical threshold temperatures.

The first records in the literature compiled on the parasitic fauna of amphibians in Northeastern Brazil date back to the 1990s. Since then, several new studies have been published on parasite-host relationships, parasite communities, and descriptions of new taxa. However, only in the last decade has there been a significant increase in these studies. Given this growth, we aim to provide a complete and updated compilation of helminth records associated with amphibians from the Brazilian Northeastern region and to analyse the dynamics and network structure formed between parasites and their hosts. Therefore, 33 studies were found in the specialized literature that addressed data from eight families, 15 genera, and 34 species of anuran amphibians, distributed mainly in areas of the morphoclimatic domain of the Caatinga and Atlantic Forest remnants in the Brazilian Northeast. These data correspond to 35% of the total known species of the Caatinga, with Leptodactylidae being the most representative taxon. Regarding helminths, 51 species were recorded, belonging to 20 families and 32 genera. To evaluate the structure of the network, we used measures of connectivity, nestedness, modularity, and centrality, that were considered to identify key species. The web presented 247 interactions with a highly connected structure formed by two parasite generalist species, non-nested and non-modular. We concluded that anuran amphibians from the Brazilian Northeast possess a high parasitic diversity, being Bufonidae and Leptodactylidade taxa considered fundamental for the network structure. Herein, we provided the first analysis of the global framework of parasite communities in amphibians from Brazilian Northeast, by using antagonistic network interactions.

Iris sibirica is a threatened plant species of the Central European flora, but its distribution and vegetation ecology in Slovakia have not been studied so far. Therefore, we aimed to compile a complex chorology of this species and to analyse phytosociological plots with the species occurrence. Our results suggest that Iris sibirica occurs almost in the whole Slovakia, with two distributional centres situated in the south-western region (Pannonian bioregion) and in the southern regions of central Slovakia (Carpathian bioregion), but a higher proportion of recent records was identified in the Carpathians. Vegetation classification using the TWINSPAN algorithm divided 80 vegetation plots into 5 clusters. They were interpreted syntaxonomically as follows: i) Calthion palustris alliance, ii) Deschampsion cespitosae alliance, iii) Molinion caeruleae alliance, iv) vegetation of the successional stages and transitional status between wet meadows (Calthion palustris and Molinion caeruleae) and fens (Scheuchzerio palustris-Caricetea fuscae), and v) vegetation with a transitional status between hygrophilous, fen vegetation of the alliances Molinion caeruleae, Caricion davallianae, Caricion fuscae and mesic habitats. Variation in the species composition of vegetation plots, analysed using detrended correspondence analysis (DCA) and interpreted using Ellenberg indicator values for vascular plants, showed a shift along the first DCA axis from taxa typical for nutrient-rich and shaded but thermophilic sites to taxa of open and relatively cold habitats on nutrient-poor soils. The second DCA axis corresponded to the moisture gradient, which controlled the pattern of plant species richness.

The complete mitochondrial DNA sequence of a deep-sea eel Congriscus megastoma (Anguilliformes: Congridae) was determined by high throughput sequencing technology. As the first mitogenome of the genus Congriscus up to now, its entire mtDNA sequence was 17,616 bp in length, including 37 mitochondrial genes (13 protein-coding genes, 2 rRNA genes, 22 tRNA genes) and 2 control regions, which was inconsistent with that of the typical vertebrate mitogenomes. In addition, the genes of C. megastoma exhibited an obvious rearrangement. ND6 and tRNA-Glu were transferred between tRNA-Thr and tRNA-Pro, as well as a doubled control region appeared. The tandem duplication-random loss (TDRL) model was an ideal explanation for this irregular gene reorganization phenomenon. The Bayesian phylogenetic tree showed that Congridae species were divided into four clades, suggesting their non-monophyletic origin. Congriscus had the closest relationships with Thalassenchelys and Coloconger. Species with gene rearrangement separately clustered as one clade. The results provided a basis for future studies of mitochondrial DNA structure and phylogeny of Anguilliformes.