Research On The Cell Wall Related Proteins Of Acidiphilium DX1-1

The Acidiphilium sp. are chemoheterotrophic, acidophilic and aerobic bacteria, the bacteria are capable of iron respiration, using organic compounds or H₂ reduction Fe³⁺ to the growth. In the leaching process, often live with acidophilic Thiobacillus ferrooxidans (Acidithiobacillus ferrooxidans). It plays an important role in interaction with the interface between microbe and mineral. In this thesis, the cell wall related proteins of Acidiphilium sp. have been studied. The surface structures researched at the aspect of Proteomics would be helpful to clarify the mechanisms of Acidiphilium sp. attaching to minerals.This paper studies, form the Transmission electron microscope (TEM) result, we found that bacteria in vivo accumulation of a large number of transparent particles, identified as poly-β-hydroxybutyrate (PHB). Interestingly, we discovered that the amout of PHB accumulated bu the strain DX1-1, which were cultivated in growth medium without Fe₂(SO₄)₃ (about 40.9%/CDW), is a lot more than DX1-1 (only 14.2%/CDW) grown with Fe₂(SO₄)₃ in the growth medium.In this study, the cell wall related proteins of Acidiphilium sp. were extracted and separated by SDS-PAGE. Liquid chromatography coupled with tandem mass spectrometry was applied to identify the proteins. Firstly, the proteins which were subjected to in-gel digestion with trypsin, were separated by liquid chromatography, and then were online analyzed by the coupled tandem mass spectrometry. The acquired 286 MS and MS/MS spectras were sent for searching in the proteins database with Mascot search engine for protein identification. The export signal and subcellular location of each obtained protein was also predicted. Portion of the aimed proteins were obtained. Among the identified proteins, 51.4% of them possess export of the Sec type, 16.8% of them show a twin arginine translocation (Tat) signal, 27.3% have lipoprotein signal peptides. 18.2% are non-classically secreted proteins, and 32.5% could be exported with their subcellular location prediction. According to their functional categories, 38.14% of them belong to Cell Envelope, 11.51% belong to Transport and binding proteins, 12.61% belong to Hypothetical Proeteins, 4.9% belong to Conserved Hypothetical Proteins, and 8.41% belong to Unknown Functions. Also, there are a few other functional proteins. Furthermore, the molecular weights of these proteins are distributed in the range of 4000 to 160000Da. Their isoelectric points are between 4 and 12, among which 32.52% of which show the pH values below 7, 67.48% higher than 7, and 24.83% over pH values of 10. This work provides fundamental research of the cell wall related protein of Acidiphilium sp. by revealing the total expressed proteins.