Microbial remediation of cadmium-contaminated soils and its mechanisms: a review / 生物工程学报

Excessive levels of cadmium (Cd) in soil exert serious negative impacts on soil ecosystems. Microorganisms are a common component of soil and show great potential for mitigating soil Cd. This review summarizes the application and remediation mechanisms of microorganisms, microbial-plants, and microbial-biochar in Cd-contaminated soil. Microorganisms such as Bacillus, Acinetobacter, Pseudomonas, and arbuscular mycorrhizal fungi (AMF) can change the biological validity of Cd through adsorption, mineralization, precipitation and dissolution. Different factors such as pH, temperature, biomass, concentration, and duration have significant effects on Cd bioavailability by microorganisms. Pseudomonas, Burkholderia, and Flavobacterium can promote the uptake of Cd2+ by hyperaccumulator through promotion and activation. Biochar, a soil amendment, possesses unique physicochemical properties and could act as a shelter for microorganisms in agriculture. The use of combined microbial-biochar can further stabilize Cd compared to using biochar alone.

Levels of Th1/Th2 type cytokines in TNBS and OXZ colitis without or with Trichinella spiralis infection / 中华微生物学和免疫学杂志

Objective To study the levels of Th1 and Th2 type cytokines in 3-nitrobenzene sulfonate(TNBS) and oxazolone(OXZ) colitis without or with Trichinella spiralis( T. spiralis) infection. Methods Female BALB/c mice were randomly divided into 4 groups: 50% Ethanol, T. spiralis only, TNBS or OXZ,T. spiralis +TNBS or OXZ(at least 6 in each group when mice were killed). The levels of IFN-γ, IL-12,IL-4, IL-10 in colon in mice with colitis induced by TNBS or OXZ without or with T. spiralis infection 3 d and 7 d post-induction were assessed using ELISA method. Results Colonic protein levels of IFN-γand IL-12 were significantly increased 3 d and 7 d after intra-colonic injection of TNBS( P ＜0.05 ). Concurrent infection with T. spiralis prevented this rise in IFN-γand IL-12 secretion and tended to induce a rise in colonic IL-4 and IL-10 content(P ＜0. 05). The levels of IFN-γ, IL-4 and IL-10 protein in colitic mice colon with prior nematode infection on days 3 and 7 post-induction of colitis were significantly higher than that seen in colitic mice without prior nematode infection ( P ＜ 0.05 ). Conclusion T. spiralis infection significantly attenuates TNBS-induced colitis in mice. The local immunologic mechanism is that T. spiralis can down-regulate strongly Th1-type immune response of colitis and up-regulate Th2 response, Tr1-cytokines. According to the change of Th1/Th2 cytokines, prior T. spiralis infection doesn't reduce the severity of OXZ-induced colitis, but without aggravating colitis. The exactly immunologic mechanism deserve to be explored deeply.