Response of microbial communities to phytoremediation of nickel contaminated soils

Abstract

Through pot experiment, effects of phytoremediation on microbial communities in soils at different nickel treatment levels were studied. Two Ni hyperaccumulating and one Ni tolerant species were planted in paddy soils different in Ni concentration, ranging from 100 to 1 600 mg/kg. After 110 days of incubation, soil microbial activities were analyzed. Results showed that populations of bacteria, fungus, and actinomycetes and biomass of the microorganisms were stimulated when nickel was added at a rate of 100 mg/kg in non-rhizospheric soil. When the rate was over 100 mg/kg in the soil, adverse effects on the soil microbial communities were observed. The plantation of Ni hyperaccumulating species could increase both the population and biomass of soil microorganisms, because, by absorbing nickel from the soil and excreting root exudates, the plants reduced nickel toxicity and improved the living environment of the microbes. However, different plant species had different effects on microorganisms in soil.Randomly Amplified Polymorphic DNA (RAPD) with five primers was used in this study in 25 soil samples of four types of soils. A total of 947 amplified bands were obtained, including 888 polymorphic bands and 59 non-polymorphic bands. The results indicated that the composition of microbial DNA sequences had changed because of the addition of nickel to the treated soils. Shannon-Weaver index of soil microbial DNA sequences reduced in the nickel contaminated soils with increasing nickel concentration. The changes in ShannonWeaver index in the four types of soils ranged from 1.65 to 2.32 for Alyssum corsicum, 1.37 to 2.27 for Alyssum murale, 1.37 to 1.96 for Brassica juncea, and 1.19 to 1.85 for nonrhizospheric soil. With the same amount of nickel added to soils, the Shannon-Weaver index in rhizospheric soil with plants was higher than that in non-rhizospheric soil.

Effects of lead and zinc mining contamination on bacterial community diversity and enzyme activities of vicinal cropland

“…Due to heavy metal toxicity, sensitive populations would be inhibited and some kinds of populations would decrease and even become extinct, but the less sensitive or resistant population would increase and become the dominant one in a soil community. This result is in accordance with previous references (Li et al 2006;Cai et al 2007;Wang et al 2003).…”

Phytoremediation

“…Aquatic macrophytes may produce many generations of progeny over a very short period of time and multiply their biomass and can remove more than 75 % of total phosphorus and nitrogen in a eutrophied water body (Ansari and Khan 2008Khan , 2009aCheng et al 2002 ). The use of plants for nutrient uptake is especially valuable because following site remediation, it is possible to identify practical and valueadded uses for the plant material (Cheng et al 2002 ;Fang et al 2007 ;Gulcin et al 2010 ).…”

“…For instance, Alyssum corsicum , Alyssum murale and Brassica juncea (Ni hyperaccumulators) have been reported to increase both the population and biomass of soil microorganisms. By absorbing nickel from the soil and excreting root exudates, the plants reduced nickel toxicity and improved the living environment of the microbes (Cai et al 2007 ). Phytoremediation increased the number of phenol-degrading bacteria as well as metabolic diversity of microbial community in semi-coke polluted soil (Truu et al 2003 ).…”

The Microbiology of Metal Mine Waste: Bioremediation Applications and Implications for Planetary Health

“…Nickel is an essential trace element for animals, plants and some microorganisms; Ni deficiency has not been found in humans due to the low concentrations required, while Ni can be toxic at high concentrations (Anke et al, 1995;Mulrooney & Hausinger, 2003;Yusuf et al, 2011). In small amounts Ni enhances the growth of microorganisms; however, high concentrations have negative impacts on microbial communities (Cai et al, 2007). Ni is required for the functioning of certain enzymes in microorganisms, acting for example, as a cofactor in metalloenzymes (Macomber & Hausinger, 2011).…”