Streptomycetes are Gram-positive bacteria of Actinomycetales. These organisms can produce many economically important secondary metabolites. With the development of molecular biology, gene sequencing technology and synthetic biology, people gained a better understanding of the Streptomyces family. The means to transform genome on the molecular level is also increasing. By simplifying the Streptomyces genome rationally and efficiently, it will improve the yield and quality of the metabolites as well as reduce the consumption of the substrates. Markerless knockout is an important way to carry out genetic modification. Here we describe novel genome modification techniques developed for Streptomyces in recent years with focus on the markerless knockout technologies.
Chromosomes, Bacterial ; genetics ; Gene Knockout Techniques ; methods ; Genes, Bacterial ; genetics ; Streptomyces ; genetics

Polymalic acid, known as a bioactive material, is completely biodegradable, and has far reaching application potential in medical field. Combined with our own findings, we summarized advances in polymalic acid metabolism, microbial fermentation synthesis, and application research in the medical field. Finally, prospect for further research was addressed.
Fermentation ; Industrial Microbiology ; Malates ; chemistry ; Polymers ; chemistry

Objective To investigate the clinical characteristics of methylmalonic academia in adolescence cases. Methods 4 cases were diagnosed methylmalonic academia by gas chromatography- masss pectrogram whose clinical, manifestations and treatment process were analyzed. Results The main clinical manifestations in 4 cases with methylmalonic academia were intellect impairment,epilepsy, pyramid signs; 2 of them suffered with hypopsia and optic atrophy, one of them suffered with papilledema. Symptoms were improved after treated with cobamamide and L-carnitine in all the 4 cases 1 months later. Conclusions The main clinical characteristics of methylmalonic academia in adolescence were intellect impairment, epilepsy and pyramid signs. The symptoms could be improved after treatment.

Objective To investigate the pathological features of sural nerve biopsy in patients with motor neuron disease （MND）. Methods 22 patients with amyotrophic lateral sclerosis (ALS) underwent sural nerve biopsy and routine electrophysiological examination. The transected images were captured and morphometrically analyzed.Results The myelinated fiber density decreased in ALS patients' sural nerves, and larger fibers were involved mostly. The thinly myelinated fibers increased. Conclusion The sural nerves of ALS patients shows mild but definite pathological changes.

In this study, we found that when Pseudomonas mendocina NK-01 accumulated intracellular carbon reserve, medium chain length poly (3-hydroxyalkanoates), it also synthesized extracellular saccharides, alginate oligosaccharides. The high carbon nitrogen ratio of culture medium facilitated alginate oligosaccharides production. We analyzed the structure of alginate oligosaccharide by Ultraviolet-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy, 1H and 13C of Nuclear Magnetic Resonance, and found that it was compounded in line from beta-D-mannuronic acids and alpha-L-gluronic acids via beta-(1-->4)/ alpha-(1-->4) bonds, which acetylated partly on the 2- and/or 3-hydroxy. In addition, we determined the weight-average molecular weight of alginate oligosaccharides by gel permeation chromatography to be 2054.
Alginates ; chemistry ; Glucuronic Acid ; biosynthesis ; chemistry ; genetics ; Hexuronic Acids ; chemistry ; Molecular Weight ; Oligosaccharides ; biosynthesis ; chemistry ; genetics ; Pseudomonas mendocina ; metabolism