title: [Effects of ammonium sulfate on the metabolism and K-feldspar weathering of two potassium-bearing mineral-solubilizing bacteria].
abstract: OBJECTIVE
  To determine the best conditions for Bacillus globisporus Q12 and Rhizobium sp. Q32 to produce organic acids and extracellular polysaccharides, respectively, and further elucidate the weathering mechanism of the two potassium-bearing mineral-solubilizing bacteria.
  
  
  METHODS
  Different contents (0-1.2 g/L) of (NH4)2SO4 were added to media to analyze the ability of the strains to produce organic acids and extracellular polysaccharides, and assess the ability of Q12, Q32 and their mixture to dissolve potassium feldspar. Scanning electron microscope (SEM) was also used to observe the distribution of the bacterial cells on the surfaces of the feldspar and the mineral weathering.
  
  
  RESULTS
  Results show that Bacillus globisporus Q12 produced more organic acids, when the contents of (NH4)2SO4 were 0.6 g/L; Rhizobium sp. Q32 produced more extracellular polysaccharides, when there was no (NH4)2SO4 in the media; and the mixture of two strains produced more organic acids and extracellular polysaccharides, when the contents of (NH4)2SO4 were 0.3 g/L. Mineral dissolution experiment showed that Bacillus globisporus Q12, Rhizobium sp. Q32 and the mixture (Q12 + Q32) significantly dissolved the feldspar and released the elements from the mineral, of which the mixture of Q12 and Q32 had the best weathering ability than strain Q12 or Q32; SEM also indicated that the mixture of Q12 and Q32 had more ability to weather feldspar than each tested strain.
  
  
  CONCLUSIONS
  The contents of (NH4)2SO4 in the media could affect the growth and metabolites of the strains Q12 and Q32 and the mineral bioweathering, the mixture of strains Q12 and Q32 had the more potential of feldspar weathering through the combined action of organic acids and extracellular polysaccharides produced by strains Q12 and Q32.
authors.affiliation: College of Life Science, Nanjing Agriculture University, Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Nanjing 210095, China. zhuang@njau.edu.cn
authors.forename: Zhi
authors.initials: Z
authors.lastname: Huang
authors.forename: Guangyou
authors.initials: G
authors.lastname: Ma
authors.forename: Linyan
authors.initials: L
authors.lastname: He
authors.forename: Xiafang
authors.initials: X
authors.lastname: Sheng
mesh_terms: D000538:Aluminum Silicates / Q000378:metabolism*; D000645:Ammonium Sulfate / Q000494:pharmacology*; D001407:Bacillus / Q000378:metabolism*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D011188:Potassium / Q000378:metabolism*; D017680:Potassium Compounds / Q000378:metabolism*; D012231:Rhizobium / Q000378:metabolism*; D012995:Solubility
chemical_list: D000538:Aluminum Silicates; D003470:Culture Media; D017680:Potassium Compounds; C016447:feldspar; D011188:Potassium; D000645:Ammonium Sulfate