[Diversity of the Microbial Community in Rice Paddy Soil with Biogas Slurry Irrigation Analyzed by Illumina Sequencing Technology].

In order to explore the variation in soil microbial community diversity in paddy fields with different irrigation periods, we collected in situ rice field soils during different biogas irrigation periods and analyzed the microbial community structures of these soils by high-throughput sequencing. The results showed that as the biogas irrigation period increased, the soil pH decreased gradually, while organic matter, nitrate nitrogen, phosphate, and other nutrients were accumulated. Years of continued biogas irrigation was not conducive to improving rice yields. The results showed that as the biogas irrigation period increased, the richness in microbial species in paddy soils decreased gradually, and the diversity in the microbial communities was also reduced. Proteobacteria accounts for the largest proportion in rice paddy soil with biogas slurry irrigation. With the increase of biogas irrigation years, the proportion of ß-Proteobacteria, Bacteroidia, Bacteroidales, Burkholderiales, Bacteroides, and Thiobacillus increased, while the proportion of Gemmatimonadetes and α-Proteobacteria decreased gradually. Dissolved organic carbon (F=2.67, P=0.09) had the greatest effect on microbial community structures in the studied paddy soils.

Accumulation and tolerance to cadmium heavy metal ions and induction of 14-3-3 gene expression in response to cadmium exposure in Coprinus atramentarius.

Cadmium (Cd), one of the most toxic heavy-metal pollutants, has a strong and irreversible tendency to accumulate. Bioremediation is a promising technology to remedy and control heavy metal pollutants because of its low cost and ability to recycle heavy metals. Coprinus atramentarius is recognized as being able to accumulate heavy metal ions. In this work, C. atramentarius is cultivated on a solid medium containing Cd2+ ions to analyze its ability to tolerate different concentrations of the heavy metal ion. It is found that the growth of C. atramentarius is not significantly inhibited when the concentration of Cd2+ is less than 0.6mgL-1. The accumulation capacity of C. atramentarius at different Cd2+ concentrations also was determined. The results show that 76% of the Cd2+ present can be accumulated even when the concentration of the Cd2+ is 1mgL-1. The different proteins of C. atramentarius exposed to Cd2+ were further analyzed using gel electrophoresis. A 14-3-3 protein was identified and shown to be significantly up-regulated. In a further study, a full-length 14-3-3 gene was cloned containing a 759bp open reading frame encoding a polypeptide consisting of 252 amino acids and 3 introns. The gene expression work also showed that the 14-3-3 was significantly induced, and showed coordinated patterns of expression, with Cd2+ exposure.

[Effects of applying pig manure on lettuce yield and nitrate content and soil nutrients].

A pot experiment with two representative soils (purple soil and yellow soil) in Southwest China was conducted to study the effects of applying pig manure on the lettuce (Lactuca sativa L. var. capitata L. ) yield and nitrate content and the soil nutrients. Applying pig manure increased the lettuce yield significantly, and the increment was higher for yellow soil than for purple soil. The nitrate and total nitrogen, phosphorus, and potassium contents in lettuce plants were closely related to soil type and pig manure application rate. According to the evaluation standards of the nitrate pollution level of vegetables formulated by the Chinese Academy of Agricultural Sciences, the nitrate content in lettuce plants growing on purple soil was lower than the grade I (< or = 432 mg x kg(-1), slight pollution) in treatments CK (no pig manure application) and M1 ( applying 200 kg N x hm(-2) of pig manure), but generally higher than the grade II (< or = 758 mg x kg(-1), moderate pollution) while not exceeded the grade III (< or = 1440 mg x kg(-1), heavy pollution) in other treatments. The nitrate content in lettuce plants growing on yellow soil was lower than the grade I, except that in the treatments of chemical fertilizations and of M8 (applying 1600 kg N x hm(-2) of pig manure) where the plant nitrate content was exceeded the grade II. The critical value of Olsen-P characterizing the apparent leaching risk level of phosphorous in yellow soil and purple soil was 96.3 and 107.7 mg x kg(-1), respectively. The environmental safety capacity of pig manure was higher for yellow soil than for purple soil. Applying pig manure increased the organic carbon and total nitrogen contents of the two soils significantly.

[Bioremediation of heavy metal pollution by edible fungi: a review].

Bioremediation is the method of using organisms and their derivatives to absorb heavy metals from polluted environment, with the characteristics of low cost, broad sources, and no secondary pollution. Heavy metals enrichment by edible fungi is an important research focus of bioremediation, because it can decrease the eco-toxicity of heavy metals via the uptake by edible fungi, and thereby, take a definite role in heavy metal remediation. This paper reviewed the research progress on the enrichment of heavy metal copper, cadmium, lead, zinc, arsenic, and chromium by edible fungi and the possible enrichment mechanisms, and prospected the development and applications of heavy metal enrichment by edible fungi in the management of polluted environment.