[Objective] The aim was to study the effects of heavy metal stress on the protein content of microorganisms.[Method] By using traditional microbiological culture method,four typical microorganisms(including Escherichia coli,Bacillus subtilis,Saccharomyces cerevisiae Hansen and Streptomycetaceae) were cultured under the stress of heavy metal ions(like Hg2+,Cd2+,Cr6+ and Pb2+) with different concentrations,and the effects of heavy metal stress on the synthesis of protein in four typical microorganisms were discussed through measuring protein content.[Result] Heavy metals with low concentration were beneficial to the synthesis of protein in four typical microorganisms to a certain extent,but the synthesis of protein in four typical microorganisms was inhibited differently with the increase of heavy metal concentration.The tolerance of B.subtilis to four heavy metals was stronger compared with other three microorganisms,and the four heavy metals with concentration of 5-50 mg/L promoted the protein synthesis of B.subtilis.Cr6+ with low concentration promoted the protein synthesis of E.coli greatly;Pb2+ inhibited the protein synthesis of E.coli obviously,and promoted the protein synthesis of other three microorganisms under certain concentration;Cd2+ with low concentration was beneficial to the protein synthesis of four microorganisms.[Conclusion] The study could provide theoretical foundation for discussing the physiological response of microorganism to heavy metal stress.
LI Shu-yingDONG Shi-haoSU Ya-liZHOU Yuan-qingLI Hong-mei
[Objective] The aim was to study on the effects of heavy metal stress on the growth curves of Escherichia coli and Bacillus subtili. [Method] Using traditional culture method,Escherichia coli and Bacillus subtili were cultured under heavy metal stress including Cu2+,Hg2+,Pb2+,Cd2+ and Cr6+ in different concentrations. Then the growth curves of the bacteria were determined to investigate the effects of exogenous heavy metals on the growth of the two kinds of bacteria. [Result] The proliferation of the two bacteria was inhibited at high concentrations of Hg2+ and Cd2+ respectively,and G+ is more sensitive to them than G-; when the heavy metal concentration was 50 mg/L,the toxicity of the five kinds of heavy metals on the two bacteria was Hg2+Cd2+Cu2+Cr6+≈Pb2+. [Conclusion] The research will provide a basis to explore the effects of heavy metal on environment and ecological system.
Using traditional microbiological culture method,under laboratory conditions,different concentrations of Cr6+ were selected for stress culture on Pistia stratiote,Sagittaria sagittifolia and Myriophyllum spicatum.Through determination of the rhizosphere microorganism and the nitrogen cycle bacteria change of three kinds of aquatic macrophytes,the tolerance of rhizosphere microorganism to Cr6+ was studied.The results showed that the sensitivity of microorganisms could be summarized as:actinomycete bacteria fungi,it has no obvious regularity about tolerance of 3 microorganisms;while the effects demonstrated their specificity on ammonification bacteria,nitrifying bacteria,nitrosococcus bacteria and denitrifying bacteria.