ABSTRACT
Attachments of Acidithiobacillus ferrooxidans ATCC 23270 onto elemental sulfur, quartz and complex chalcopyrite were investigated by analysis of its extracellular polymeric substances as well as applying Langmuir and Freundlich equations. The two equations fitted the adsorption equilibrium data with significant correlation coefficient over 0.9. This indicated that bacterial attachment is complicated and involves Langmuir and Freundlich characterizations. Sulfur-grown cells showed the highest affinity for the three solid substrates. The investigated complex chalcopyrite possessed a higher maximum adsorption capacity for A. ferrooxidans than elemental sulfur or quartz. The Freundlich fitting parameters suggested that quartz had a weaker adsorption capacity and smaller adsorption areas than elemental sulfur or the complex chalcopyrite. It is not the content of total carbohydrates or proteins in EPS but their ratios that determine the affinity differences between cells and substrates.
Subject(s)
Acidithiobacillus/metabolism , Bacterial Adhesion/physiology , Copper/metabolism , Models, Theoretical , Quartz/metabolism , Sulfur/metabolism , Acidithiobacillus/chemistry , Acidithiobacillus/cytology , Adsorption , Extracellular Space/chemistry , Extracellular Space/metabolism , Kinetics , Linear Models , Polysaccharides, Bacterial/chemistry , Polysaccharides, Bacterial/metabolismABSTRACT
Pileus and stipe of mushroom Russula griseocarnosa from South China were analyzed separately for chemical composition and antioxidant activities. The wild mushroom species proved to have antioxidant potential, using assays of reducing power, chelating effect on ferrous ions, scavenging effect on hydroxyl free radicals, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The mushroom contained very useful phytochemicals such as phenolics, flavonoids, ergosterol, and beta-carotene. The phenolic composition of R. griseocarnosa was analyzed by high-performance liquid chromatography (HPLC). The major component in R. griseocarnosa was quercetin (95.82 microg/g). The combination of bioactive substances and rich nutritional composition (high contents in protein and carbohydrates, low content in fat) in the mushroom should be useful to consumers in encouraging them to utilize the nutritive potential of this edible wild mushroom.
