B. longum CKD1 enhances the efficacy of anti-diabetic medicines through upregulation of IL- 22 response in type 2 diabetic mice.

The gut microbiota plays a pivotal role in metabolic disorders, notably type 2 diabetes mellitus (T2DM). In this study, we investigated the synergistic potential of combining the effects of Bifidobacterium longum NBM7-1 (CKD1) with anti-diabetic medicines, LobeglitazoneⓇ (LO), SitagliptinⓇ (SI), and MetforminⓇ (Met), to alleviate hyperglycemia in a diabetic mouse model. CKD1 effectively mitigated insulin resistance, hepatic steatosis, and enhanced pancreatic ß-cell function, as well as fortifying gut-tight junction integrity. In the same way, SI-CKD1 and Met- CKD1 synergistically improved insulin sensitivity and prevented hepatic steatosis, as evidenced by the modulation of key genes associated with insulin signaling, ß-oxidation, gluconeogenesis, adipogenesis, and inflammation by qRT-PCR. The comprehensive impact on modulating gut microbiota composition was observed, particularly when combined with MetforminⓇ. This combination induced an increase in the abundance of Rikenellaceae and Alistipes related negatively to the T2DM incidence while reducing the causative species of Cryptosporangium, Staphylococcaceae, and Muribaculaceae. These alterations intervene in gut microbiota metabolites to modulate the level of butyrate, indole-3-acetic acid, propionate, and inflammatory cytokines and to activate the IL-22 pathway. However, it is meaningful that the combination of B. longum NBM7-1(CKD1) reduced the medicines' dose to the level of the maximal inhibitory concentrations (IC50). This study advances our understanding of the intricate relationship between gut microbiota and metabolic disorders. We expect this study to contribute to developing a prospective therapeutic strategy modulating the gut microbiota.

Protective effect of the mixture of Lactiplantibacillus plantarum KC3 and Leonurus Japonicas Houtt extract on respiratory disorders.

Air pollutants, such as particulate matter (PM) and diesel exhaust particles (DEP), are associated with respiratory diseases. Therefore, preventive and therapeutic strategies against PM-and DEP (PM10D)-induced respiratory diseases are needed. Herein, we evaluate the protective effects of a mixture of Lactiplantibacillus plantarum KC3 and Leonurus Japonicas Houtt (LJH) extract against airway inflammation associated with exposure to PM10D. To determine the anti-inflammatory effects of the LJH extract, reactive oxygen species (ROS) production and the expression of inflammatory pathways were determined in PM10-induced MH-S cells. For the respiratory protective effects, BALB/c mice were exposed to PM10D via intranasal injection, and a mixture of L. plantarum KC3 and LJH extract was administered orally for 12 days. LJH extract inhibited ROS production and the phosphorylation of downstream factors of NF-κB in PM10-stimulated MH-S cells. The mixture of L. plantarum KC3 and LJH repressed the infiltration of neutrophils, reduced the immune cells number, and suppressed the proinflammatory mediators and cyclooxygenase (COX)-2 expressions in PM10D-induced airway inflammation with reduced phosphorylation of downstream factors of NF-κB. In addition, these effects were not observed in an alveolar macrophage depleted PM10D-induced mouse model using clodronate liposomes. The extract mixture also regulated gut microbiota in feces and upregulated the mRNA expression of Foxp3, transforming growth factor (TGF)-ß1, and interleukin (IL)-10 in the colon. The L. plantarum KC3 and LJH extract mixture may inhibit alveolar macrophage- and neutrophil-mediated inflammatory responses and regulate gut microbiota and immune response in PM10D-induced airway inflammation, suggesting it is a potential remedy to prevent and cure airway inflammation and respiratory disorders.

Transcriptome profiles of Streptomyces clavuligerus strains producing different titers of clavulanic acid.

Streptomyces clavuligerus NRRL 3585 is a native producer of clavulanic acid (CA), a clinically used ß-lactamase inhibitor, and is widely used as an industrial strain for the production of antibiotics. Selective random mutagenesis has successfully generated the improved CA-producing S. clavuligerus mutant strains as well as the strain with the loss of CA biosynthesis. To understand the molecular mechanisms associated with the improved CA-production potential, genome-scale RNA-sequencing-based transcriptional data were obtained for the wild-type S. clavuligerus strain and its three mutant strains. Total RNA samples for each strain were collected across four different growth stages, and all 32 sequencing data points exhibited an average Phred score of 36. The high-quality genome-scale transcriptional profile of S. clavuligerus strains with varied CA biosynthetic potential provides valuable insights and new opportunities for discovering efficient metabolic engineering strategies for the development of improved industrial strains.

Enhanced production of clavulanic acid by improving glycerol utilization using reporter-guided mutagenesis of an industrial Streptomyces clavuligerus strain.

Clavulanic acid (CA) produced by Streptomyces clavuligerus is a clinically important ß-lactamase inhibitor. It is known that glycerol utilization can significantly improve cell growth and CA production of S. clavuligerus. We found that the industrial CA-producing S. clavuligerus strain OR generated by random mutagenesis consumes less glycerol than the wild-type strain; we then developed a mutant strain in which the glycerol utilization operon is overexpressed, as compared to the parent OR strain, through iterative random mutagenesis and reporter-guided selection. The CA production of the resulting S. clavuligerus ORUN strain was increased by approximately 31.3% (5.21 ± 0.26 g/l) in a flask culture and 17.4% (6.11 ± 0.36 g/l) in a fermenter culture, as compared to that of the starting OR strain. These results confirmed the important role of glycerol utilization in CA production and demonstrated that reporter-guided mutant selection is an efficient method for further improvement of randomly mutagenized industrial strains.

Improved production of clavulanic acid by reverse engineering and overexpression of the regulatory genes in an industrial Streptomyces clavuligerus strain.

Genomic analysis of the clavulanic acid (CA)-high-producing Streptomyces clavuligerus strains, OL13 and OR, developed through random mutagenesis revealed a frameshift mutation in the cas1 gene-encoding clavaminate synthase 1. Overexpression of the intact cas1 in S. clavuligerus OR enhanced the CA titer by approximately 25%, producing ~ 4.95 g/L of CA, over the OR strain in the flask culture. Moreover, overexpression of the pathway-specific positive regulatory genes, ccaR and claR, in the OR strain improved CA yield by approximately 43% (~ 5.66 g/L) in the flask. However, co-expression of the intact cas1 with ccaR-claR did not further improve CA production. In the 7 L fermenter culture, maximum CA production by the OR strain expressing the wild-type cas1 and ccaR-claR reached approximately 5.52 g/L and 6.01 g/L, respectively, demonstrating that reverse engineering or simple rational metabolic engineering is an efficient method for further improvement of industrial strains.

Establishment of a cryopreservation method for the industrial use of D-amino acid oxidase-overexpressing Escherichia coli.

A cryopreservation condition for D-amino acid oxidase (DAAO)-overexpressing Escherichia coli (E. coli BL21(DE3)/pET-DAAO) was established. Ten percent was the optimum concentration of glycerol as a cryoprotectant, and its diffusion into stationary phase cells was superior to that into log cells. The results also showed that rather than fast cooling, a slow cooling method was appropriate to our recombinant E. coli. In addition, 15 min was the best equilibration period, at which higher than 90% of recovery rates were maintained at all test points. Most importantly, the relative recovery rates, product yield, and fermentation pattern of the cell banks (CBs) constructed according to our cryopreservation method did not change over 12 months, confirming that our method not only permits exceptional cryopreservation, but offers prolonged productivity. Taken together, our results demonstrating a cryopreservation method for E. coli BL21(DE3)/pET-DAAO provide insight into an improvement in the industrial production of DAAO.

An approach to strain improvement and enhanced production of clavulanic acid in Streptomyces clavuligerus.

To develop a strategy for improved production of clavulanic acid (CA), we investigated the effect of using oils on cell growth and CA production during the fermentation of Streptomyces clavuligerus NRRL 3585. In this analysis, triolein, whose fatty acid is oleic acid only, was the best oil source for CA production, but free fatty acids generated from the hydrolysis of oils in a culture broth negatively impacted CA production and cell growth. Hence, we screened for mutants that were resistant to high concentrations of oleic acid. From this screen we identified a mutant S. clavuligerus, OL13, that had a minimum inhibitory concentration (MIC) to oleic acid of 2.1 g/l, much higher than that of S. clavuligerus NRRL 3585, at 0.4 g/l. Not only was cell growth improved, but maximum CA production, at 1,950 mg/l, was approximately 2.0-fold higher than that of the parent strain.

Characterization of pbpA and pbp2 encoding penicillin-binding proteins located on the downstream of clavulanic acid gene cluster in Streptomyces clavuligerus.

Two genes, pbpA (orf18) and pbp2 (orf19) located on the downstream of clavulanic acid (CA) gene cluster of Streptomyces clavuligerus were cloned into pET-28a(+), and confirmed to encode a family of high molecular-weight penicillin-binding proteins (PBPs). Both genes were amplified from genomic DNA by PCR and expressed in E. coli BL21 (DE3). Hydropathy plots of the proteins revealed a single stretch of hydrophobic amino acids indicating them to be transmembrane proteins. Pbp2 had lower affinity to penicillin G compared to PbpA, and was essential to the cell growth in contrast to PbpA.