Cd胁迫对淹水稻田土壤微生物种群数量的影响

Effects of Cd2+ on Microbial Populations in Submerged Paddy Soil

采用传统培养方法及改良的亨格特(Hungate)厌氧技术,在实验室条件下,通过液体培养MPN法及滚管固体培养法系统研究了不同浓度重金属Cd对稻田土壤中各好氧、厌氧微生物类群的种群数量影响及其动态变化过程。结果表明,好氧微生物中以放线菌所受抑制最大,真菌次之,细菌最小,在最大抑制期其抑制率分别为71.65%、60.62%、50.73%。在厌氧微生物类群中,各类菌群的变化趋势不尽相同,以产甲烷细菌对Cd最为敏感,厌氧固氮菌、产氢产乙酸细菌次之,而反硝化细菌、水解发酵性细菌影响相对较小。针对淹水稻田土壤特殊的生态环境,可以选择敏感厌氧菌群产甲烷细菌、厌氧固氮菌、产氢产乙酸细菌作为稻田土壤受重金属Cd胁迫的指标。

With traditional culture method and improved Hungate anaerobic technique, the influence of Cd2+ on the numbers of anaerobic and aerobic microbial populations in submerged paddy soil was studied by the MPN (the Most Probable Number) method and the roll tube method. The results showed that the order of the aerobic microorganisms inhibited by cadmium was actinomycetes>fungi>bacteria, with the maximum inhibition rates of 71.65%, 60.62% and 50.73, respectively. Among the anaerobic bacteria populations, the methane-producing bacteria were most sensitive to Cd2+, the second was the anaerobic nitrogen-fixing bacteria and the hydrogen-producing acetogenic bacteria. The inhibition of Cd2+ to the denitrifying and the hydrolytic-fermentative bacteria was slightly weaker. Hydrogen-producing acetogenic bacteria, anaerobic nitrogen-fixing bacteria and methane-producing bacteria could be known as the sensitive anaerobic bacteria population indexes to indicate the contamination degree of paddy soil by Cd2+.