Identification And Characterization Of Manganese-resistant Endophytic Bacteria From Manganese Hyperaccumulator Phytolacca Acinosa

With the developing of industrial and agricultural production and the growth in the living standard, the types and amount of various pollutants in environment have increased rapidly, mainly including heavy metal and organic pollutants pollutants.Heavy metal pollution is one of the important content of environmental pollution prevention.In recent years, there are numerous reports about heavy metal pollution. Thus, heavy metal pollution is an environmental and social problem that nots allow to ignoreTo solve the heavy metal pollution problem thoroughly, it is very difficult to achieve the purpose and meet requirement only depending on one or more techniques such as physical technologies and/or chemical technologies. For the past few years, some bioremediation technologies including micro-remediation, phytoremediation and animal remediation have got a rapid development because they are filling in gaps in the defections for the latter followed as high cost, halfway treatment, vulnerable secondary pollution and so on. Based on it, the phytoremediation technology with some characteristics about high efficiency, wide application and faster remediation has been built by many researchers at home and abroad. Among them, phytoremediation of heavy metal is often used hyperaccumulators to accumulate heavy metal. One of hyperaccumulators ofte can assimilate one or more heavy metals in excess of the general plants.so it can effectively repair of heavy metal pollution.We got the results as following:Many studies have found that microbial closely associated with plants, microbes can effectively improve the plant resistance to heavy metal toxicity, improve the removal efficiency of heavy metals. Phytolacca acinosa is one a kind of manganese hyperaccumulators, the current, the screening of manganese-resistant endophytic bacteria of Phytolacca acinosa reported less, the purpose of this study is to investigate whether the endophytic bacteria have resistance to manganese and manganese removal features.We isolated and characterized Mn-resistant endophytic bacteria(MEB) from hyperaccumulators Phytolacca acinos. A total of 19 MEB were Preliminary isolated from the root, stem and leaf respectively. And we constructed phylogeny tree based on 16S rDNA sequences and nucleotide blast.The leaf only represented 1 genera while the root and stem both comprised of 4 genera, with Bacillus sp. being the most dominant bacteria from each part of plant. Meanwhile, we detected their ability to promote plant growth. this result suggested that MEB from both each part of plants all could product IAA.4 strains (G-1,G-6,J-9 and J-11) were selected according to their classifying of genera and abillity of removing Mn. Then we analyzed their biochemical characters and basic characteristics by Gram stain,Scanning electron micrograph and Puncture training.In order to further evaluate the resistant manganese ability of the four strains,they are compared with the determination of manganese resistance ability.The experimental results show that the G-land G-6 tolerated 600 mg/L bivalent manganese ion and is not affected, and J-9 and J-11 growth significantly suppressed in bivalent manganese ion increased to 400 mg/L.G-1 and G-6 come from the Phytolacca acinosa root, so endophyte’s manganese resistance ability of root is far higher than that of stems and leaves. So choose G-1 and G-6 follow-up study.G-1 and G-6 are the best two strains of Phytolacca acinosa to resistance to manganese and manganese removal. Therefore, we study on growth characteristics and manganese removal system optimization of the two strains. So, we set different conditions of physical and chemical factors to study the growth and manganese removal ability of G-l and G-6. The results showed that the G-1 strain in sodium succinate or glucose as carbon source, pH 7 and 30℃, speed 150 RPM, inoculum size 3% of the cases, the strain growth best and the most strong manganese removal ability. And the G-6 strain in sodium succinate or glucose as carbon source, pH 7 and 30　℃, speed 150 RPM, inoculum size 5% of the cases, the strain growth best and the most strong manganese removal ability.Manganese-resistant bacteria 4-05 for reference is filtrated by our team in the early. Study that the G-1 affect manganese removal ability of Phytolacca acinosa. Results show that adding exogenous bacteria not restrain the germination of Phytolacca acinosa,but significant impact on its growth. The difference is that under the condition of soil culture, both promote the growth of Phytolacca acinosa and its manganese enrichment. Above conclusion shows that the manganese resistant bacteria and plant compete nutrition in 1/2 MS culture medium.But nutrient in soil is less, so the added exogenous bacteria has a promoting effect on the Phytolacca acinosa growth and the ability of enrichment manganese.