title: Short-time effect of heavy metals upon microbial community activity.
abstract: Microcalorimetry was applied to assess and compare the toxic effect of heavy metals, such as As, Cu, Cd, Cr, Co, Pb and Zn, on the soil microbial activities and community. About 1.0 g soil spiked 5.0mg glucose and 5.0mg ammonium sulfate, the microbial activities were recorded as power-time curves, and their indices, microbial growth rate constant k, total heat evolution Q(T), metabolic enthalpy Delta H(met) and mass specific heat rate J(Q/S), were calculated. Comparing these thermodynamic parameters associated with growth yield, a general order of toxicity to the soil was found to be Cr>Pb>As>Co>Zn>Cd>Cu. When soil was exposed to heavy metals, the amount of bacteria and fungi decreased with the incubation time, and the bacterial number diminished sharply. It illustrates that fungi are more tolerant, and bacteria-fungi ratio would be altered under metal stress. To determine the status of the glucose consumed, a glucose biosensor with eggshell membrane was used to measure the remaining glucose in soil sample. Results showed that the time at which glucose was consumed completely was agreed with the microcalorimetric time to a large extent, and depended on the toxicity of heavy metals as well.
authors.affiliation: Key Laboratory of Biogeology and Environmental Geology of Chinese Ministry of Education, China University of Geosciences, 430074 Wuhan, PR China.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Yao
authors.forename: Yang
authors.initials: Y
authors.lastname: Si
authors.forename: Huilun
authors.initials: H
authors.lastname: Chen
authors.forename: Mohammad
authors.initials: M
authors.lastname: Russel
authors.forename: Ke
authors.initials: K
authors.lastname: Chen
authors.forename: Yiguang
authors.initials: Y
authors.lastname: Qian
authors.forename: Gyula
authors.initials: G
authors.lastname: Zaray
authors.forename: Emilia
authors.initials: E
authors.lastname: Bramanti
mesh_terms: D000645:Ammonium Sulfate / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D001673:Biodegradation, Environmental; D018533:Biomass; D002151:Calorimetry; D004784:Environmental Monitoring; D004800:Enzymes, Immobilized; D005658:Fungi / Q000187:drug effects / Q000254:growth & development; D005947:Glucose / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D019216:Metals, Heavy / Q000633:toxicity*; D010100:Oxygen / Q000032:analysis / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D004800:Enzymes, Immobilized; D007202:Indicators and Reagents; D019216:Metals, Heavy; D005949:Glucose Oxidase; D005947:Glucose; D010100:Oxygen; D000645:Ammonium Sulfate