Isolation and Identification of Selenium-tolerant Strains from Selenium-rich Soil in Guangxi

To provide reference for selenium resource exploitation of soil,many selenium-tolerant strains were isolated from selenium-rich soil in Guangxi. The dilution spread plate method and selenium-added culture method were used to screen the selenium-tolerant strains from the soils which were sampled from the main Selenium-rich areas such as Yongfu,Bama,Yulin Hanshan,Guiping and Tengxian. The results showed that 8 strains with high selenium tolerance were obtained,which could tolerate the selenium concentration above 10 000 μg/m L in solid medium. Among the 8 strains,YLB1-33 showed the highest selenium tolerance,and it could still grow weakly in the solid medium with selenium concentration of 29 000 μg/m L. The sequencing of 16 S rD NA and phylogenetic analysis showed that YLB1-6 was identified as Bacillus cereus,BMB2-1 and TXB1-8 were identified as Bacillus pumilus,GPB2-5 was identified as Bacillus thuringiensis,YLB1-26 and YLB1-33 were identified as Bacillus licheniformis,and YLB1-2 and YFB1-8 were identified as Serratia marcescens. The finding of selenium-tolerance strains had potential application value on promoting the utilization of selenium soil resources and the development of selenium-rich agricultural products in Guangxi.

Dietary supplement of selenium-rich yeast may relieve lipopolysaccharide-induced growth depression in piglets via improving immune and antioxidant status

Selenium protects cells from oxidative damage and reduces lipopolysaccharide （LPS）-induced expression of inflammatory cytokines. Because inflammatory cytokines induce growth depression, we hypothesized that selenium-rich yeast （SeY） would inhibit growth depression caused by LPS. Twenty Meishan weanling pigs [28 （s.d. 2 d）, 7.6 （s.d. 0.3 kg） body weight （BW）] were used in a 2×2 factorial design （n=5）. The main factors were dietary Se sources [selenium-rich yeast （SeY） vs. sodium selenite （SSe）] with supplement level at 0.3 mg Se/kg, and immunological stress （LPS vs. saline）. The experiment lasted for 28 d. On d 14 and d 21, half of pigs in each dietary treatment were intramuscularly injected with either 50 μg/kg BW LPS or an equivalent amount of sterile saline. Blood samples were collected at 3 h post-injection. There were no interactions between dietary Se sources and immunological stress on growth performance. LPS depressed average daily gain （ADG） （d 14-21, P〈0.05; d 21-28, P〈 0.01）, and elevated feed to gain ratio （F/G） （d 21-28, P〈0.05）, while SeY elevated ADG （d 0-14, P〈0.05; d 21-28 and d 0-28, P〈0.01）, and decreased F/G （P〈0.01）. Interactions were observed on interleukin-1β（IL-1β） and interleukin-6 （IL-6） from serum samples of d 14 and d 21 （P〈0.01）, as well as superoxide dismutase （SOD） and insulin like growth factor （IGF-1） of d 21 （P〈0.05）. In conclusion, SeY relieved the growth depression of piglets immunologically stressed by LPS, which maybe resulted from the decreased externalization of inflammatory cytokines and improved antioxidant status.

Ecological Geochemistry of Selenium in the Production Base of Zhangqiu Green Chinese Onion

Based on the achievement of local ecological geochemical survey,the selenium in surface layer soil of Zhangqiu green Chinese onion within production area is systematically studied in this study.And the ecological geochemical characters of selenium both in surface layer soil and in green Chinese onions are analyzed,and the relationship between the selenium in plant and soil is discussed.The results show that soil in Zhangqiu is rich in selenium,and it is suitable to develop the selenium-rich green Chinese onion products.

Preliminary Study on the Standard of Selenium Content in Agricultural Products

With the improvement of living standards, people pay more attention to the agricultural products with health protection function, and the selenium-rich agricultural products attract more and more consumers. The main biological role of selenium is to resist oxidation and inflammatory response, mainly focusing on resisting aging, preventing cardiovascular disease, protecting eyesight, counteracting or destroying the toxic properties, preventing cancer and thyroid disease. In most areas of China, there is a widespread shortage of selenium, thus producing selenium-rich agricultural products to provide natural selenium-rich health food to the areas in need of selenium, has gradually become a new hot spot of China's health food industry, but high content of selenium in food is detrimental to human body, even leads to selenium intoxication, and artificially adding inorganic selenium is difficult to guarantee that the selenium content of agricultural products is not exceeded. According to human body's daily demand for selenium in dietetics and the content of selenium in agricultural products in the Chinese food composition table, we put forward the recommendations on the standard of selenium in agricultural products, in order to provide the basis for China to formulate the health standard of selenium content in selenium-rich agricultural products.

Effects of Plant-derived Humic Acid Organic Fertilizer on Selenium Content of Rice in Northern Guangxi

This study was to find out the suitable application amount of plant-derived humic acid organic fertilizer for selenium-rich rice production in northern Guilin area by applying the fertilizer at different amounts.The results showed that plant-derived humic acid organic fertilizer could effectively activate selenium in selenium-rich soil,and then promote the uptake of selenium by rice.With costs,selenium enrichment and rice yield as the main evaluation indicators,A4 was chosen as the best treatment,that is,the application of 4 500 kg/hm^2 of plant-derived humic acid organic fertilizer as base fertilizer could achieve the best benefit.

Characteristics of B,Zn and Se in stream sediments of Tanzania and their agricultural applications:Based on 1∶1000000 geochemical survey

Tanzania is located in eastern Africa with a predominantly agricultural ecomomy,the potential for developing and utilizing cultivated land are promising,but scientific guidance is required.B,Zn and Se are essential micronutrients for plants and human body with crucial biological functions,in particular,Se is significant for human health and considered as“the king of anti-cancer”.As these elements required by human or plants are mainly absorbed from soil directly or indirectly,therefore,it is important to understand the contents and distributions of them in the soil of cultivated land for guiding agricultural production.In this work,low-density geochemical survey at the scale of 1∶1000000 was carried out in Tanzania,and the results show that the concentrations of B,Zn and Se in stream sediments are low and their distributions are heterogeneous.According to the distributions of geological units,the existing cultivated land resources can be divided into five regions in Tanzania.Compared with the national background values,the concentrations of B,Zn and Se are insufficient overall but enriched locally in these regions.In general,element concentrations in stream sediments and soil have a positive correlation because of their similar sources,which is essential in agriculture application.Based on the information provided by low-density geochemical data and maps,the Se-sufficient and Se-rich regions were delineated in Tanzania,where can be used to develop Se-rich industries.Finally,this paper believes that geochemical survey is a powerful tool for cultivated land evaluation,agriculture management and land development.

Distribution of Soil Nutrients in Se-rich Areas of Hainan Island

[Objectives] The aim was to reveal the distribution of soil nutrients in Se-rich area of Hainan and to clarify their specific contents, so as to provide references for the development of Se-rich area agriculture in Hainan.[Methods] With the se-rich area in Hainan as the object, field investigation and indoor analysis were combined to elucidate the nutrient status of cultivated soil in the area and analyze its nutrient distribution.[Results] The soil in the se-rich area in Hainan province was generally acidic with the average soil pH value of 5.0. The difference in soil pH between different landforms and different altitudes was not significant, ranging from 4.9 to 5.3. Soil available P and available K contents were low to intermediate, and the soil available N content was moderate. The farming system, chemical fertilizer application structure and meteorological factors were the main causes of the distribution of soil nutrient elements. The soil exchangeable calcium and magnesium content was rich, and the distribution of trace elements in the arable soil of different terrains and elevations was closely related to the distribution of soil parent material in the region. The increase of soil organic matter content in arable land could be achieved by increasing the application of organic fertilizer and guiding the farmers to enhance the application of straws to fields.[Conclusions] The application of soil N, P and K fertilizers should be combined with the application of soil organic fertilizers to improve the soil fertility of cultivated land.