Production of the siderophore lysochelin in rich media through maltose-promoted high-density growth of sp. 3655.

Siderophores are produced by bacteria in iron-restricted conditions. However, we found maltose could induce the biosynthesis of the siderophore lysochelin in sp. 3655 in rich media that are not compatible with siderophore production.

An Antifungal Polycyclic Tetramate Macrolactam, Heat-Stable Antifungal Factor (HSAF), Is a Novel Oxidative Stress Modulator in Lysobacter enzymogenes.

Polycyclic tetramate macrolactams (PoTeMs) are a fast-growing family of antibiotic natural products found in phylogenetically diverse microorganisms. Surprisingly, none of the PoTeMs have been investigated for potential physiological functions in their producers. Here, we used heat-stable antifungal factor (HSAF), an antifungal PoTeM from , as a model to show that PoTeMs form complexes with iron ions, with an association constant ( ) of 2.

Identification of the Biosynthetic Gene Cluster for the anti-MRSA Lysocins through Gene Cluster Activation Using Strong Promoters of Housekeeping Genes and Production of New Analogs in sp. 3655.

The Gram-negative gliding bacteria represent a new and rich source for bioactive natural products. In an effort to discover new antibiotics, we found a cryptic biosynthetic gene cluster (BGC) in sp. 3655 that shared a high similarity with the putative lysocin BGC identified previously from sp.

LeTetR Positively Regulates 3-Hydroxylation of the Antifungal HSAF and Its Analogs in OH11.

The biocontrol agent OH11 produces several structurally distinct antibiotic compounds, including the antifungal HSAF (Heat Stable Antifungal Factor) and alteramides, along with their 3-dehydroxyl precursors (3-deOH). We previously showed that the 3-hydroxylation is the final step of the biosynthesis and is also a key structural moiety for the antifungal activity. However, the procedure through which OH11 regulates the 3-hydroxylation is still not clear.

Numerical study on the impact response of aircraft fuselage structures subjected to large-size tire fragment.

By applying finite element software ANSYS/LS-DYNA, finite element models of front bulkhead and main cabin are established, which aims to assess the dynamic response of fuselage structures impacted by tire fragment under bursting mode. Besides, dynamic characteristics of the two fuselage structures impacted by tire fragment are simulated and critical damage velocities of each working condition are obtained. The results show that composite front bulkhead cannot bear the impact load of front tire fragment at the velocity of 100 m/s, but aluminum alloy front bulkhead can.

Initial Crack Propagation and the Influence Factors of Aircraft Pipe Pressure.

In aircraft engineering, an increase of internal pressure in a hydraulic pipe increases the probability of pipe damage, leading to crack propagation becoming a serious issue. In this study, the extended finite element method (XFEM) is applied to simulate initial crack propagation in hydraulic pipes and to investigate the influence factors. Stress intensity factors are extracted to verify the mesh independence of XFEM, which is based on the level set method and unit decomposition method.

Systematic optimization for production of the anti-MRSA antibiotics WAP-8294A in an engineered strain of Lysobacter enzymogenes.

WAP-8294A is a group of cyclic lipodepsipeptides and considered as the first-in-class new chemical entity with potent activity against methicillin-resistant Staphylococcus aureus. One of the roadblocks in developing the WAP-8294A antibiotics is the very low yield in Lysobacter. Here, we carried out a systematic investigation of the nutritional and environmental conditions in an engineered L.

Spermidine-Regulated Biosynthesis of Heat-Stable Antifungal Factor (HSAF) in OH11.

Heat-Stable Antifungal Factor (HSAF) and its analogs are antifungal natural products produced by the biocontrol agent . The production of HSAF is greatly influenced by environmental stimuli and nutrients, but the underlying molecular mechanism is mostly unclear. Here, we found that HSAF production in OH11 is strictly controlled by spermidine, which is the most prevalent triamine in bacteria.

Yield Improvement of the Anti-MRSA Antibiotics WAP-8294A by CRISPR/dCas9 Combined with Refactoring Self-Protection Genes in Lysobacter enzymogenes OH11.

The cyclic lipodepsipeptides WAP-8294A are antibiotics with potent activity against methicillin-resistant Staphylococcus aureus (MRSA). One member of this family, WAP-8294A2 (Lotilibcin), was in clinical trials due to its high activity and distinct chemistry. However, WAP-8294A compounds are produced in a very low yield by Lysobacter and only under very stringent conditions.

A Regulatory Gene SCO2140 is Involved in Antibiotic Production and Morphological Differentiation of Streptomyces coelicolor A3(2).

Streptomyces coelicolor is the soil-dwelling bacterium with a complex life cycle and a strong ability to produce plenty of secondary metabolites which are strictly regulated by a variety of regulators. Amino acid alignment shows that the deduced protein of SCO2140 belongs to the family of Leucine-responsive regulatory proteins (Lrps). Disruption of SCO2140 significantly decreased the yields of actinorhodin and calcium-dependent antibiotics, and the complemented strain restored the antibiotic productions to the wild-type level.

GntR family regulator SCO6256 is involved in antibiotic production and conditionally regulates the transcription of myo-inositol catabolic genes in Streptomyces coelicolor A3(2).

SCO6256 belongs to the GntR family and shows 74% identity with SCO6974, which is the repressor of myo-inositol catabolism in Streptomyces coelicolor A3(2). Disruption of SCO6256 significantly enhanced the transcription of myo-inositol catabolic genes in R2YE medium. The purified recombinant SCO6256 directly bound to the upstream regions of SCO2727, SCO6978 and SCO6985, as well as its encoding gene.

Nanocomposite of Au Nanoparticles/Helical Carbon Nanofibers and Application in Hydrogen Peroxide Biosensor.

A combined sol-gel/hydrogen reduction method has been developed for the mass production of helical carbon nanofibers (HCNFs) by the pyrolysis of acetylene at 425 degrees C in the presence of NiO nanoparticles. The synthesized HCNFs were characterized with scanning electron microscopy (SEM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The helical-structured carbon nanofibers have a large specific surface area and excellent biocompatibility.

Regulation of myo-inositol catabolism by a GntR-type repressor SCO6974 in Streptomyces coelicolor.

Myo-inositol is important for Streptomyces growth and morphological differentiation. Genomic sequence analysis revealed a myo-inositol catabolic gene cluster in Streptomyces coelicolor. Disruption of the corresponding genes in this cluster abolished the bacterial growth on myo-inositol as a single carbon source.

Disruption of rimP-SC, encoding a ribosome assembly cofactor, markedly enhances the production of several antibiotics in Streptomyces coelicolor.

Background: Ribosome assembly cofactor RimP is one of the auxiliary proteins required for maturation of the 30S subunit in Escherichia coli. Although RimP in protein synthesis is important, its role in secondary metabolites biosynthesis has not been reported so far. Considering the close relationship between protein synthesis and the production of secondary metabolites, the function of ribosome assembly cofactor RimP on antibiotics production was studied in Streptomyces coelicolor and Streptomyces venezuelae.

Synthesis of four natural prenylflavonoids and their estrogen-like activities.

Four prenylflavonoids, bavachin 1, isobavachin 2, 7,4'-dihydroxy-8-prenylflavone 3, and 8-prenylapigenin 4 were synthesized and recognized for possessing estrogen-like activity in MCF-7/BOS cells, as evaluated by an estrogen-screening assay. All compounds significantly stimulated the proliferation of MCF-7/BOS cells in a dose-dependent manner. Isobavachin 2 showed the most potent activity, while bavachin 1 was the weakest.