The Cellulose Utilization Characteristic Of Fe(Ⅲ) Reduction Microbe In Paddy Soil

Microbial communities from different paddy soil are tested with anaerobic cultivations, and researches on the effect when using Fe (OH) 3 as the sole electron acceptor, the use of cellulose as the electron donor have on the iron reduction. By comparing the relationship of the electron donor concentration and iron reducibility, and try to clarify the utilization characteristics of different sources of iron reducing microbial when cellulose are used as the carbon source. Pure cultivation experiments are operated to further explore some of the isolation and purification of iron reducing strain on the potential for the use of cellulose powder. Test soil mud cultivation, study the impacts that cellulose from different sources under the condition of flooding have on the iron reduction of soil microbial, and compare the difference of organics of different resources during the iron reduction process which offer the necessary theoretical basis to further clarify the organic metabolism in the rice ecosystem and its relationship with microbial iron reduction. Main conclusions are drawn as follows:1. There are notable differences between microbial iron irreducibilities of different paddy soil microbial communities when use cellulose. Seen from the overall trend, the use of cellulose by different sources of microbial communities is proportional to the cellulose concentration, the performance of the final cumulant of Fe (II) are: treatment 20 g / L>treatment 10 g / L> treatment 2 g / L, with the exception of TJ, the remaining three kinds of microbial communities use concentration of 20 g / L starch Fe (II) concentration can be reached 500 mg / L, nearly added total Fe (III). With the addition of increasing concentrations of cellulose, Fe (III) reduction maximum rate (Vmax) also showed increasing trend. From the maximum rate of reaction time, Jilin and Hunan paddy soil microbial community, with the addition of increasing concentrations of cellulose, showed a turnaround from TVmax. The higher the adding cellulose concentration is the sooner it reaches its maximum rate. Microbial communities from Sichuan paddy soil took almost equal time to reach the maximum rate in dealing with different concentrations of cellulose.2. The reducibility of different iron reduction strains of using showed certain distinctions. When using cellulose as the sole carbon source, strain JX-a06,SC-a04,SC-a16 and SC-a20 all have large value of a, which respectively reached 71.82,76.68,79.92 and 71.07 mg / L, Fe (III) reduction is also high with the rate of respectively 21.16%, 22.59%, 23.55% and 20.94%, the iron of the strains JX-a12, JX-a17, SC -a09, SC-a11, SC-a14 and SC-a24 are among the middle, which respectively reached 16.17 percent to 19.94 percent, and strains JX-a03 and a08 JX-iron suffered with poor iron reducibility, among which the Fe (III) reduction rate was significantly lower than the other strains, with only 9.64 percent and 9.66 percent. The changes of maximum rate (Vmax) and the change rate of Fe (III) reduction are identical. TVmax of 12 strains are distributed between 3.8 d~ 5.7d, and which showed the role the long-term process of pure cultivation play in promoting cellulose decomposition is not obvious. Compared to the iron reduction which are inoculated with different soil microbial community from paddy soil, Fe (II) accumulation was significantly lower, which implies the capability of the 12 strains with iron reducing ability have limit direct use of cellulose carbon source, and the decomposition of cellulose may need the process of metabolism to strengthen, so in the paddy soil microbial community in the process of reduction of iron is with high iron reduction efficiency.3. Compare the extent of iron reduction, the abilities of using four different kinds of cellulose sources are: clover> corncob> corn straw> wheat straw. Between different treatments of soil microbial community in dealing with wheat straw and corn-cob are of some differences, and clover and corn straw in its handling of Fe (II) accumulation are basically the same. Four kinds of microbial communities from paddy soil, when use different sources of cellulose, Fe (III) reduction rates are as follows: The use of wheat straw are at an average of 35.28±8.05%, clover treatment are 76.38±3.32%, corn-cob treatment are 65.39±9.28%, and corn stalks treatment are 48.64±7.58%, the coefficient of variation (CV%) were 22.83%, 4.34%, 14.19% and 15.59% respectively. From the changes of the coefficient of variation, clover is a more easily used carbon source among four kinds of paddy soil microbial communities. The utilization of wheat straw for four kinds of paddy soil microbial community is relatively small, but among different paddy soil microbial communities, large difference are shown. When use maize stalks and corn-cob as carbon source, although Fe (III) reduction rate are of 48.64% and 65.39%, with high utilization of carbon sources, between different microbial communities, coefficient of variation also reached 15.59% and 14.19%, and the difference of utilization is more obvious.4. The impact of the addition of Fe (OH) 3 and different organic materials is significantly greater on TJ paddy soil than the impact on the soil of SC paddy soil; which reflect the intrinsic characteristics of different iron paddy soil microbial reduction. Changes of treatments with different sources of cellulose of Sichuan paddy soil are not significant. A value of CK is 6.130 mg / g, with Fe (OH) 3 adding in is 6.513 mg / g, treatment with organic material adding in are of an average of 6.233±0.215 mg / g, with Fe (OH) 3 and different organic materials adding in are 6.450±0.066 mg / g, on the whole, CK increases, but the change is not apparent. Seen from the changes of Vmax, different treatments all increased significantly than CK, while TVmax, after adding Fe (OH) 3 and different organic compounds all shortened than CK. For TJ paddy soil, treatments with different straws adding in, all appear increasing of the previous 10 days of Fe (II) concentrations, and then slow to change, addition of Fe (OH) 3 with Fe (II) produced significantly greater than in CK (natural soil); with straw added in can significantly enhance the cumulative production and producing rate of Fe (II), which played great role in improving rate of iron microbial reduction. TJ paddy soil added Fe (OH) 3 is with Fe (II) accumulation (a) from the CK 5.631 mg / g to 5.905 mg / g, that the accession of Fe (OH) 3 can be restored quickly, Vmax increased from 0.137 mg / (g ? d) to 0.245 mg / (g ? d). After adding wheat straw, clover, corn cob and corn straw, a value change to 6.046,6.209,6.461 and 6.467 mg / g, which show more increase than adding Fe (OH) 3, demonstrates the organic have great impacts on promoting Iron reduction in TJ paddy soil. Adding straw and Fe (OH) 3 at the same time, there is same increase in both the Fe (II) accumulation (6.701 to 7.0 mg / g), and Vmax (0.595 ~ 1.048 mg / g ? d).Through anaerobic mud test, mixed culture of different microbial community and the pure culture system, we study the different sources of cellulose, and the impact different sources cellulose have on paddy soil iron reduction. The main results of the study provided the necessary theoretical basis in understanding iron reduction in paddy soil.