Genome sequencing and systems biology analysis of a lipase-producing bacterial strain.

Lipase-producing bacteria are naturally-occurring, industrially-relevant microorganisms that produce lipases, which can be used to synthesize biodiesel from waste oils. The efficiency of lipase expression varies between various microbial strains. Therefore, strains that can produce lipases with high efficiency must be screened, and the conditions of lipase metabolism and optimization of the production process in a given environment must be thoroughly studied. A high efficiency lipase-producing strain was isolated from the sediments of Jinsha River, identified by 16S rRNA sequence analysis as Serratia marcescens, and designated as HS-L5. A schematic diagram of the genome sequence was constructed by high-throughput genome sequencing. A series of genes related to lipid degradation were identified by functional gene annotation through sequence homology analysis. A genome-scale metabolic model of HS-ML5 was constructed using systems biology techniques. The model consisted of 1722 genes and 1567 metabolic reactions. The topological graph of the genome-scale metabolic model was compared to that of conventional metabolic pathways using a visualization software and KEGG database. The basic components and boundaries of the tributyrin degradation subnetwork were determined, and its flux balance analyzed using Matlab and COBRA Toolbox to simulate the effects of different conditions on the catalytic efficiency of lipases produced by HS-ML5. We proved that the catalytic activity of microbial lipases was closely related to the carbon metabolic pathway. As production and catalytic efficiency of lipases varied greatly with the environment, the catalytic efficiency and environmental adaptability of microbial lipases can be improved by proper control of the production conditions.

Relationship between abnormal NOS expression and the pathogenesis of cerebral aneurysm.

We sought to investigate the relationship between abnormal expression of nitric oxide synthase (NOS) and pathogenesis of cerebral aneurysm. Brain tissues were collected from 36 patients with cerebral aneurysm confirmed by computer tomography with angiography or neurosurgical therapy. The control group consisted of 25 patients of similar age who had no vascular diseases, as confirmed by magnetic resonance imaging. Samples of cortical arterioles were collected. The structure of the aneurysms was detected by hematoxylin and eosin staining, and the expression of inducible NOS was detected by immunohistochemistry. NOS expression was significantly higher in the patient group than in the control group (patients: 30/36 strongly positive; control: 0/25 strongly positive; P < 0.05). In conclusion, the pathogenesis underlying cerebral aneurysm may be due to abnormal expression of NOS, degradation of the extracellular matrix, aggravation of a pro-inflammatory reaction, or a deficiency in arterial elasticity layer synthesis. These changes may result in a deficiency in vascular remodeling.