The afsRS(cla) global regulatory genes from Streptomyces clavuligerus activate the production of two antibiotics in Streptomyces lividans. In this study, we gained an increase of 38% in the production of natamycin (3.56 g/L) in an industrial strain Streptomyces gilvosporeus TZ1401 through the integration of pHL851 that bears the afsRS(cla) global regulatory genes into its genome. We discovered by quantitive real-time reverse transcription PCR (qRT-PCR) that the expression of 6 genes of the natamycin biosynthetic gene cluster were improved from 1.9 to 2.7 times. This suggests that afsRS(cla) improve the production of natamycin through increased transcription. This study provides a good example for applying afsRS(cla) in high yield breeding of industrial antibiotic producers.
Anti-Bacterial Agents ; biosynthesis ; Genes, Regulator ; Industrial Microbiology ; Multigene Family ; Natamycin ; biosynthesis ; Streptomyces ; genetics

The flanking fragments of the whiE(a) gene cluster was PCR amplified, cloned and used to construct the gene replacement plasmid pHL643. pHL643 was conjugated into Streptomyces avermitilis NRRL8165 followed by screening for double crossover event, yielding three apramycin resistance and thiostrepton sensitive isolates named ZJ1, ZJ2 and ZJ3, which were deficient in biosynthesis of the grey spore pigment. The whiE(a) gene replacement of these isolates was confirmed by Southern hybridization. Fermentation of the mutant strains in shaking flasks and HPLC analyses showed that the production of avermectins increased by 47% compared with that of the wild type, indicating that the spore pigment biosynthesis competes with the avermectins biosynthetic pathway.
Bacterial Proteins ; biosynthesis ; genetics ; metabolism ; Cloning, Molecular ; Ivermectin ; analogs & derivatives ; metabolism ; Mutation ; Peptides ; genetics ; metabolism ; Spores, Bacterial ; genetics ; Streptomyces ; cytology ; genetics ; metabolism

Tunicamycin, a potent reversible translocase I inhibitor, is produced by several Actinomycetes species. The tunicamycin structure is highly unusual, and contains an 11-carbon dialdose sugar and an α, β-1″,11'-glycosidic linkage. Here we report the identification of a gene cluster essential for tunicamycin biosynthesis by high-throughput heterologous expression (HHE) strategy combined with a bioassay. Introduction of the genes into heterologous non-producing Streptomyces hosts results in production of tunicamycin by these strains, demonstrating the role of the genes for the biosynthesis of tunicamycins. Gene disruption experiments coupled with bioinformatic analysis revealed that the tunicamycin gene cluster is minimally composed of 12 genes (tunA-tunL). Amongst these is a putative radical SAM enzyme (Tun B) with a potentially unique role in biosynthetic carbon-carbon bond formation. Hence, a seven-step novel pathway is proposed for tunicamycin biosynthesis. Moreover, two gene clusters for the potential biosynthesis of tunicamycin-like antibiotics were also identified in Streptomyces clavuligerus ATCC 27064 and Actinosynnema mirums DSM 43827. These data provide clarification of the novel mechanisms for tunicamycin biosynthesis, and for the generation of new-designer tunicamycin analogs with selective/enhanced bioactivity via combinatorial biosynthesis strategies.
Actinobacteria ; enzymology ; genetics ; Base Sequence ; Biological Assay ; Carbohydrate Sequence ; Carbohydrates ; biosynthesis ; genetics ; Cloning, Molecular ; Gene Deletion ; Gene Library ; High-Throughput Screening Assays ; Molecular Sequence Data ; Multigene Family ; Recombinant Proteins ; biosynthesis ; genetics ; Sequence Analysis, DNA ; Streptomyces ; enzymology ; genetics ; Tunicamycin ; biosynthesis ; chemistry ; genetics

Objective To explore efficacy and safety of simulated artificial pancreas in modulating stress hyperglycemia in critically ill patients. Methods A prospective randomized controlled study was performed. Seventy-two critically ill patients with stress hyperglycemia, aged 18-85 years, acute physiology and chronic health evaluationⅡ(APACHEⅡ) score over 15, two consecutive random blood glucose 11.1 mmol/L or higher, glycated hemoglobin (HbA1C) below 0.065, unable to eat food for 3 days after inclusion, or only accepting parenteral nutrition, admitted to intensive care unit (ICU) in Shanghai Punan Hospital of Pudong New District from January 1st, 2015 to June 30th, 2017 were enrolled. The patients were divided into three groups according to the random number table method, high-intensity group and low-intensity group were injected Novolin R (high-intensity group 2/3 dosage, low-intensity group 1/3 dosage) to modulate stress hyperglycemia by simulated artificial pancreas. Simulated artificial pancreas consisted of Guardian real time glucose monitoring system (GRT system), close-circle control algorithm and micro-pump;subcutaneous injection of Humulin 70/30 was applied to modulate stress hyperglycemia in humulin group. Real-time glucose levels of interstitial fluid in abdominal wall, equivalent to blood glucose levels, 10 minutes each time, were monitored by using of GRT system for all patients in three groups. Fasting serum levels of stress hormones including epinephrine and cortisol and insulin resistance index (IRI) were recorded within 24 hours after inclusion. Mean blood glucose, blood glucose variation coefficient, blood glucose target-reaching rate, blood glucose target-reaching time, hypoglycemia rate and 6-month mortality were measured. Twenty healthy adults from health administration department of the hospital were recruited as healthy control group. Results A total of 60 eligible critically ill patients were included in this study, each group with 20 patients. There was no significant difference in gender, age, APACHE Ⅱ scores among three groups. The levels of serum epinephrine, cortisol and IRI within 24 hours after inclusion in the three groups were significantly higher than those in healthy control group. The mean blood glucose levels of humulin group, low-intensity group, high-intensity group were decreased (mmol/L: 10.2±3.2, 8.4±2.6, 8.1±2.2), the blood glucose target-reaching rate were increased [40.2% (3 295/8 196), 71.1% (5 393/7 585), 80.4% (6 286/7 818)], the blood glucose target-reaching time were shortened (hours: 49.1±5.8, 24.6±4.6, 17.5±4.2), the hypoglycemia rates were increased respectively [1.3% (108/8 196), 2.8% (211/7 585), 4.0% (313/7 818)], with statistically significant differences (all 1 = 0.000). There was no significant difference in blood glucose variation coefficient and 6-month mortality among three groups [blood glucose variation coefficient: (29.4±3.7)%, (28.5±5.3)%, (26.1±4.6)%, 6-month mortality: 55.0%, 45.0%, 40.0%, all 1 > 0.05]. Conclusions Simulated artificial pancreas could effectively and safely modulate stress hyperglycemia in critically ill patients, high-intensity modulation could bring about better efficacy in the regulation of hyperglycemia. High-frequency blood glucose monitoring by using GRT system could promptly identify hypoglycemia and help it to be corrected.