Prevalence and genomic characterization of Group A Streptococcus dysgalactiae subsp. equisimilis isolated from patients with invasive infections in Toyama prefecture,Japan

Streptococcus dysgalactiae subsp. equisimilis (SDSE) causes severe invasive streptococcal infections, especially in elderly people. Between 2013 and 2018, 88 streptococci were isolated from clinical blood culture in a hospital in Toyama prefecture, Japan. The collection included six Group A SDSE (ASD) strains, which are rarely isolated. Multilocus sequence typing categorized five of the six strains into ST128 and the remaining strain into a new type. Maximum-likelihood phylogenetic analysis revealed that the six ASD strains had highly similar genome sequences. Bayesian analysis indicated that the most recent common ancestor of the strains appeared 39 years ago. The ASD strains possessed carbohydrate synthase genes that are conserved in Streptococcus pyogenes strains, whereas one strain featured a different arrangement of the gene cluster. The carbohydrate synthase genes varied by Lancefield type (A, C, and G).     

Macrophage ubiquitin-specific protease 2 modifies insulin sensitivity in obese mice

We previously reported that ubiquitin-specific protease (USP) 2 in macrophages down-regulates genes associated with metabolic diseases, suggesting a putative anti-diabetic role for USP2 in macrophages. In this study, we evaluate this role at both cellular and individual levels. Isolated macrophages forcibly expressing Usp2a, a longer splicing variant of USP2, failed to modulate the insulin sensitivity of 3T3-L1 adipocytes. Similarly, macrophage-selective overexpression of Usp2a in mice (Usp2a transgenic mice) had a negligible effect on insulin sensitivity relative to wild type littermates following a three-month high-fat diet. However, Usp2a transgenic mice exhibited fewer M1 macrophages in their mesenteric adipose tissue. Following a six-month high-fat diet, Usp2a transgenic mice exhibited a retarded progression of insulin resistance in their skeletal muscle and liver, and an improvement in insulin sensitivity at an individual level. Although conditioned media from Usp2a-overexpressing macrophages did not directly affect the insulin sensitivity of C2C12 myotubes compared to media from control macrophages, they did increase the insulin sensitivity of C2C12 cells after subsequent conditioning with 3T3-L1 cells. These results indicate that macrophage USP2A hampers obesity-elicited insulin resistance via an adipocyte-dependent mechanism.     

Direct production of 4-hydroxybenzoic acid from cellulose using cellulase-displaying Pichia pastoris

4-hydroxybenzoic acid (4-HBA) is an industrially important aromatic compound, and there is an urgent need to establish a bioprocess to produce this compound in a sustainable and environmentally friendly manner from renewable feedstocks such as cellulosic biomass. Here, we developed a bioprocess to directly produce 4-HBA from cellulose using a recombinant Pichia pastoris strain that displays heterologous cellulolytic enzymes on its cell surface via the glycosylphosphatidylinositol (GPI)-anchoring system. β-glucosidase (BGL) from Aspergillus aculeatus, endoglucanase (EG) from Trichoderma reesei, and cellobiohydrolase (CBH) from Talaromyces emersonii were co-displayed on the cell surface of P. pastoris using an appropriate GPI-anchoring domain for each enzyme. The cell-surface cellulase activity was further enhanced using P. pastoris SPI1 promoter- and secretion signal sequences. The resulting strains efficiently hydrolyzed phosphoric acid swollen cellulose (PASC) to glucose. Then, we expressed a highly 4-HBA-resistant chorismate pyruvate-lyase (UbiC) from Providencia rustigianii in the cellulase-displaying strain. This strain produced 975 mg/L of 4-HBA from PASC, which corresponding to 36.8% of the theoretical maximum yield, after 96 h of batch fermentation without the addition of commercial cellulase. This 4-HBA yield was over two times higher than that obtained from glucose (12.3% of the theoretical maximum yield). To our knowledge, this is the first report on the direct production of an aromatic compound from cellulose using cellulase-displaying yeast.     

Vulnerability of a large monomictic lake (Lake Biwa) to warm winter event

Detailed cross-sectional temperature and oxygen distributions during winter were examined over 5 years (2003–2007) in large, warm, monomictic Lake Biwa. The distribution patterns showed year-to-year variation in the degree of spatial heterogeneity and indicated that both convective mixing and gravity currents contributed to the delivery of oxygen to the profundal zone. We encountered a warm winter in 2007, when deep-water oxygenation was delayed by more than a month relative to normal years. Data obtained during the period of oxygenation in 2007 suggest that the timing of complete oxygenation of the bottom water (or lower layers of the hypolimnion) was controlled by physical processes responsible for destruction of the weak thermal stratification near the bottom. This study revealed that Lake Biwa is sensitive to year-to-year variations in winter meteorological conditions. Specifically, the bottom environments are highly susceptible to a warm winter, especially when it follows a cold winter.