Effect of pII key nitrogen regulatory gene on strain growth and butenyl-spinosyn biosynthesis in Saccharopolyspora pogona.

PII signal transduction proteins are widely found in bacteria and plant chloroplast, and play a central role in nitrogen metabolism regulation, which interact with many key proteins in metabolic pathways to regulate carbon/nitrogen balance by sensing changes in concentrations of cell-mediated indicators such as α-ketoglutarate. In this study, the knockout strain Saccharopolyspora pogona-ΔpII and overexpression strain S. pogona-pII were constructed using CRISPR/Cas9 technology and the shuttle vector POJ260, respectively, to investigate the effects on the growth and secondary metabolite biosynthesis of S. pogona. Growth curve, electron microscopy, and spore germination experiments were performed, and it was found that the deletion of the pII gene inhibited the growth to a certain extent in the mutant. HPLC analysis showed that the yield of butenyl-spinosyn in the S. pogona-pII strain increased to 245% than that in the wild-type strain while that in S. pogona-ΔpII decreased by approximately 51%. This result showed that the pII gene can promote the growth and butenyl-spinosyn biosynthesis of S. pogona. This research first investigated PII nitrogen metabolism regulators in S. pogona, providing significant scientific evidence and a research basis for elucidating the mechanism by which these factors regulate the growth of S. pogona, optimizing the synthesis network of butenyl-spinosyn and constructing a strain with a high butenyl-spinosyn yield. KEY POINTS: • pII key nitrogen regulatory gene deletion can inhibit the growth and development of S. pogona. • Overexpressed pII gene can significantly promote the butenyl-spinosyn biosynthesis. • pII gene can affect the amino acid circulation and the accumulation of butenyl-spinosyn precursors in S. pogona.

Enhanced triacylglycerol metabolism contributes to the efficient biosynthesis of spinosad in Saccharopolyspora spinosa.

Triacylglycerol (TAG) is crucial for antibiotic biosynthesis derived from Streptomyces, as it serves as an important carbon source. In this study, the supplementation of exogenous TAG led to a 3.92-fold augmentation in spinosad production. The impact of exogenous TAG on the metabolic network of Saccharopolyspora spinosa were deeply analyzed through comparative proteomics. To optimize TAG metabolism and enhance spinosad biosynthesis, the lipase-encoding genes lip886 and lip385 were overexpressed or co-expressed. The results shown that the yield of spinosad was increased by 0.8-fold and 0.4-fold when lip886 and lip385 genes were overexpressed, respectively. Synergistic co-expression of these genes resulted in a 2.29-fold increase in the yield of spinosad. Remarkably, the combined overexpression of lip886 and lip385 in the presence of exogenous TAG elevated spinosad yields by 5.5-fold, led to a drastic increase in spinosad production from 0.036 g/L to 0.234 g/L. This study underscores the modification of intracellular concentrations of free fatty acids (FFAs), short-chain acyl-CoAs, ATP, and NADPH as mechanisms by which exogenous TAG modulates spinosad biosynthesis. Overall, the findings validate the enhancement of TAG catabolism as a beneficial strategy for optimizing spinosad production and provide foundational insights for engineering secondary metabolite biosynthesis pathways in another Streptomyces.

Hospitalization rate of respiratory syncytial virus-associated acute lower respiratory infection among young children in Suzhou, China, 2010-2014.

BACKGROUND: There is a limited amount of data in China on the disease burden of respiratory syncytial virus- (RSV) associated acute lower respiratory infection (ALRI) among young children. This study aimed to estimate the hospitalization rate of RSV-associated ALRI (RSV-ALRI) among children aged 0-59 months in Suzhou, China. METHODS: All cases from children hospitalized with ALRI who were aged 0-59 months in Suzhou University Affiliated Children's Hospital during January 2010 to December 2014 were retrospectively identified. Detailed diagnosis and treatment data were collected by reviewing each individual's medical chart. In accordance with the World Health Organization (WHO) influenza disease burden estimation, the hospitalization rate of RSV-ALRI among children aged 0-59 months in Suzhou, China, was then estimated. RESULTS: Out of the 28,209 ALRI cases, 19,317 (68.5%) were tested for RSV, of which the RSV positive proportion was 21.3% (4107/19,317). The average hospitalization rate of RSV-ALRI for children aged 0-59 months was 14 (95% confidence interval [CI]:14-14)/1000 children years, and that for children aged 0-5, 6-11, 12-23, and 24-59 months were 70 (95% CI: 67-73), 31 (95% CI: 29-33), 11 (95% CI: 10-12), and 3 (95% CI: 3-3)/1000 children years, respectively. CONCLUSION: A considerable degree of RSV-ALRI hospitalization exists among children aged 0-59 months, particularly in those under 1 year of age. Therefore, an effective monoclonal antibody or vaccine is urgently needed to address the substantial hospitalization burden of RSV infection.

Effectiveness of 13-valent pneumococcal conjugate vaccine against community acquired pneumonia among children in China, an observational cohort study.

BACKGROUND: In China, 13-valent pneumococcal conjugate vaccine (PCV13) has been available since 2017, but only via the private market with low uptake rate. We assessed the direct effectiveness of PCV13 against community acquired pneumonia (CAP) associated with PCV13 serotype carriage (VT-CAP). METHODS: We conducted an observational cohort study of children born during 12-Dec-2016 to 30-Nov-2018 identified in the Suzhou Centers for Disease Control vaccine registry database, and who had at least one inpatient or outpatient record at the Suzhou University Affiliated Children's hospital (SCH) health-information-system (HIS) database. The vaccine registry cohort was followed through the HIS database through 30-Jun-2019 to identify hospitalized VT-CAP. Pneumococci were isolated from deep upper respiratory aspirates and serotyped with Quellung reactions. RESULTS: We included 139,127 children of whom 9024 (6.5%) received 1 + PCV13 doses (95.8% received 2 + doses). Within the total cohort, we identified 548 children hospitalized at SCH for VT-CAP, of whom 10 had received 2 + PCV13 doses. Adjusted for demographics, receipt of other childhood vaccines, and underlying medical conditions, the first visit vaccine effectiveness among children who had received 2 + PCV13 doses was 60.9% (95% CI: 25.8% to 79.4%) for VT-CAP and 17.9% (95% CI: 5.5% to 28.6%) for clinical CAP. Incidence rate reductions per 100,000 child-years of observation for all visits were 208 (95% CI: 118 to 298) for VT-CAP and 720 (95% CI: 304 to 1135) for clinical CAP. CONCLUSIONS: PCV13 was protective against hospitalized VT-CAP and clinical CAP with large associated incidence rate reductions among children living in Suzhou, China.