Production of extracellular polymeric substances from Rhodopseudomonas acidophila in the presence of toxic substances.
A hydrogen-producing photosynthetic bacteria strain, Rhodopseudomonas acidophila, was used to investigate the production of extracellular polymeric substances (EPS) in the presence of toxic substances and the effect of toxicants on bacterial surface characteristics. Addition of the toxic substances including Cu(II), Cr(VI), Cd(II) and 2,4-dichlorophenol (2,4-DCP) stimulated the production of EPS but reduced the cell dry weight. At concentrations of 30 mg l(-1) Cu(II), 40 mg l(-1) Cr(VI), 5 mg l(-1) Cd(II) and 100 mg l(-1) 2,4-DCP, the EPS content increased by 5.5, 2.5, 4.0 and 1.4 times, respectively, than the control. These toxic substances also greatly influenced the proteins/carbohydrates ratio of EPS. The ratios in the presence of toxic substances were always higher than that of control. Furthermore, under toxic conditions, the increase in the protein content far exceeded than that of others in EPS, suggesting that extracellular proteins could protect cells against toxic substances. The toxic substances significantly changed the surface characteristics and flocculation ability of R. acidophila, such as surface energy, relative hydrophobicity and free energy of adhesion.
Sheng
Guo-Ping
GP
Laboratory of Environmental Biotechnology, School of Chemistry, University of Science and Technology of China, Hefei, Anhui.
Yu
Han-Qing
HQ
Yue
Zheng-Bo
ZB
D001419:Bacteria / Q000254:growth & development; D001422:Bacterial Adhesion / Q000502:physiology; D001704:Biopolymers / Q000096:biosynthesis* / Q000737:chemistry*; D002104:Cadmium / Q000737:chemistry; D002733:Chlorophenols / Q000737:chemistry; D002857:Chromium / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D012241:Rhodopseudomonas / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D012722:Sewage / Q000737:chemistry*; D013499:Surface Properties; D013816:Thermodynamics; D014874:Water Pollutants, Chemical
D001704:Biopolymers; D002733:Chlorophenols; D012722:Sewage; D014874:Water Pollutants, Chemical; D002104:Cadmium; D002857:Chromium; D003300:Copper; C004762:2,4-dichlorophenol