Genomic insights into Staphylococcus equorum KS1039 as a potential starter culture for the fermentation of high-salt foods

Abstract Background Our previous comparative genomic analysis of Staphylococcus equorum KS1039 with five S. equorum strains illuminated the genomic basis of its safety and salt tolerance. However, a comprehensive picture of the cellular components and metabolic pathways involved in the degradation of macromolecules and development of sensory properties has not been obtained for S. equorum. Therefore, in this study, we examined the general metabolism of S. equorum based on information obtained from published complete genome sequences of six S. equorum strains isolated from different niches. Additionally, the utility of strain KS1039 as a starter culture for high-salt food fermentations was examined. Results All six S. equorum strains contained genes involved in glycolysis, the tricarboxylic acid cycle, and amino acid metabolic pathways, as well as color development. Moreover, the strains had the potential to produce acetoin, butanediol, and branched chain fatty acids, all of which are important flavor compounds. None of the strains contained decarboxylase genes, which are required for histamine and tyramine production. Strain KS1039 contained bacteriocin and CRISPR/Cas gene clusters, and experimental results suggested that these genes were functional in vitro. Conclusions The comparative genomic analysis carried out herein provides important information on the usefulness of S. equorum KS1039 as a starter culture for the fermentation of high-salt foods in terms of safety, salt tolerance, bacteriocin production, and foreign plasmid restriction

Structural Evolution in Polymer Nanocomposite Fibers—A Molecular Dynamics Simulation Approach

Carbon nanotube (CNT)-based polymer nanocomposites have often been processed into fibers because fibrous shapes are one of the best methods of fully exploiting the anisotropies and structures of CNTs. Among various types of polymer-CNT nanocomposite fiber, polyacrylonitrile (PAN) has been among the most studied polymeric system because it strongly interacts with CNTs and is the most common source of high-performance carbon fibers. In order to understand the structural evolution and related mechanical properties under extensional flow, molecular dynamics (MD) simulations were performed on polyacrylonitrile–single-wall carbon nanotube (PAN-SWNT) nanocomposites, to a draw ratio of two, which mimics fiber-spinning and drawing processes. Two SWNT(5,5)- and SWNT(10,10)-containing nanocomposite systems, as well as a control PAN, were constructed. Higher stresses were observed in both nanocomposite systems. In addition, higher Young???s (4.76 GPa) and bulk (4.09 GPa) moduli were observed when the smaller-diameter SWNT(5,5) was used, compared to those of PAN-SWNT(10,10) (4.41 GPa and 3.96 GPa, respectively), suggesting that SWNT(5,5) resists stress better. Furthermore, we also observed the formation of void structures at both ends of the SWNTs, especially for the large-diameter SWNT(10,10); these voids became larger in the drawing direction with increasing draw ratio and may adversely affect the mechanical properties of the nanocomposite fibers

Evaluacion fitosociologica y etnobotanica de un bosque secundario cerca de Pucalipa- Ucayali, Amazonz peruana

A study was carried out in a 20 year-old secondary forest situated on the campus of the University of Ucayali, 4 km from the city of Pucallpa, Peruvian Amazon. Botanical and ethno-botanical inventories were made of all trees greater than 10 cm dbh growing on an half hectare plot on very demineralised and acid soil. One hundred and ninety two trees were counted belonging to 22 families and 33 species. The dominant families were (in order of abundance): Euphorbiaceae, Melastornataceae, Leguminosae, Apocynaceae, Combretaceae and Guttiferae. At the species level the following pioneer, fast growing species were most abundant: Croton matourensis, Inga thibaudiana, Miconja eriocalyx, Vismia amazonica and Buchenavia oxycarpa. The total basal area measured was 70 448 cm2. The ethno-botanical survey was made with two informants of the shipibo conibo ethnic group who named 70% of the tree species. One individual knew one or several uses for 66% of the species and the other 73 % of the species

Transcriptomic Analysis of <i>Staphylococcus equorum</i> KM1031, Isolated from the High-Salt Fermented Seafood <i>Jeotgal</i>, under Salt Stress

Staphylococcus equorum is a potential starter for Korean high-salt fermented foods because of its salt tolerance and enzymatic activities that contribute to enhanced sensory properties of the food products. However, the mechanisms of salt tolerance of S. equorum are not fully understood. Here, RNA sequencing was performed on S. equorum strain KM1031 exposed to 7% NaCl (w/v) for 2 and 4 h to determine global gene expression changes. Salt pressure for 2 and 4 h resulted in significant differential expression of 4.8% (106/2209) and 6.1% (134/2209) of S. equorum KM1031 genes, respectively. Twenty-five core genes were differentially expressed on salt treatment for both 2 and 4 h, seven of which were related to osmoprotectant uptake and synthesis. We analyzed the genome of strain KM1031 and identified osmoprotectant uptake (Opu) systems, potassium importers, sodium exporters, and the glycine betaine synthesis system. The RNA sequencing results indicated that the OpuD system and glycine betaine synthesis might play the main roles in the salt tolerance of strain KM1031. Finally, the results of RNA sequencing were validated by quantitative real-time PCR of likely salt stress-related genes. This transcriptomic analysis provides evidence regarding the osmotic stress responses of S. equorum strain KM1031

Additional file 9: of Genomic insights into Staphylococcus equorum KS1039 as a potential starter culture for the fermentation of high-salt foods

Figure S3. Genetic organization of nitrogen metabolism in S. equorum. (DOCX 51 kb

Additional file 10: of Genomic insights into Staphylococcus equorum KS1039 as a potential starter culture for the fermentation of high-salt foods

Figure S4. Growth inhibition of S. aureus by S. equorum strains. S. aureus RN4220 was used as an indicator strain. (DOCX 336 kb

Additional file 1: of Genomic insights into Staphylococcus equorum KS1039 as a potential starter culture for the fermentation of high-salt foods

Table S1. List of genes involved in sugar transport systems. (DOCX 25 kb

Additional file 8: of Genomic insights into Staphylococcus equorum KS1039 as a potential starter culture for the fermentation of high-salt foods

Table S6. List of the genes involved in protein and peptide transport systems. (DOCX 19 kb