ABSTRACT
Metabolic flux analysis was used to reveal the metabolic distributions in Gluconacetobacter xylinus (CGMCC no. 2955) cultured on different carbon sources. Compared with other sources, glucose, fructose, and glycerol could achieve much higher bacterial cellulose (BC) yields from G. xylinus (CGMCC no. 2955). The glycerol led to the highest BC production with a metabolic yield of 14.7 g/mol C, which was approximately 1.69-fold and 2.38-fold greater than that produced using fructose and glucose medium, respectively. The highest BC productivity from G. xylinus CGMCC 2955 was 5.97 g BC/L (dry weight) when using glycerol as the sole carbon source. Metabolic flux analysis for the central carbon metabolism revealed that about 47.96 % of glycerol was transformed into BC, while only 19.05 % of glucose and 24.78 % of fructose were transformed into BC. Instead, when glucose was used as the sole carbon source, 40.03 % of glucose was turned into the by-product gluconic acid. Compared with BC from glucose and fructose, BC from the glycerol medium showed the highest tensile strength at 83.5 MPa, with thinner fibers and lower porosity. As a main byproduct of biodiesel production, glycerol holds great potential to produce BC with superior mechanical and microstructural characteristics.
Subject(s)
Cellulose/biosynthesis , Gluconacetobacter xylinus/metabolism , Cellulose/chemistry , Culture Media/metabolism , Fructose/metabolism , Gluconacetobacter xylinus/chemistry , Glucose/metabolism , Glycerol/metabolism , Metabolic Flux AnalysisABSTRACT
The currently accepted approaches to treatment of pulmonary fibrosis are based on the treatment of alveolitis and pulmonary fibrosis, however clinically available anti-inflammatory and antifibrotic agents are not often beneficial. Hu-qi-yin, one of the traditional Chinese herbal formulas, has been used for clinical therapy of pulmonary fibrosis in China. The aim of the present study is to evaluate the preventive effects of Hu-qi-yin on the bleomycin (BLM)-induced pulmonary fibrosis in rats. The degree of fibrosis was evaluated with hydroxyproline contents in serum and lung tissue 28 days post-BLM instillation. The semi-quantitative analyses of lung sections were conducted to evaluate the intensity of alveolitis and fibrosis. Furthermore, the expression of transforming growth factor-beta(1) (TGF-beta(1)) was quantitatively studied at the protein and mRNA levels by immunohistochemistry and in situ hybridization, respectively. Oral treatment with Hu-qi-yin improved the body weight loss of rats in doses of 3.8, 7.6g/kg compared with BLM-treated control group, and significantly inhibited the alveolitis and pulmonary fibrosis in a dose-dependent manner as reflected by decreases of the hydroxyproline contents of serum and lung, and amelioration of alveolitis and pulmonary fibrosis fraction 28 days after BLM administration. The one of the possible mechanisms of the protective effect of Hu-qi-yin was via reduction of the overexpression of TGF-beta(1) protein and mRNA. These results suggested a great potential that Hu-qi-yin might be effective in the treatment of pulmonary fibrosis.
