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476 Abstracts / Journal of Biotec
ioleaching of chalcopyrite flotation concentrates with aoderately thermoacidophilic mixed culture and community
nalysis in a stirred tank reactor
ongbo Zhou 1,2,∗, Yingjian Xie 2, Rubing Zhang 2, Weimin Zeng 2,ilang Luo 2, Ying Li 2, Peilei Hu 2, Guanzhou Qiu 1,2
School of Minerals Processing and Bioengineering, Central South Uni-ersity, Changsha, Hunan Province 410083, ChinaKey Laboratory of Biometallurgy, Ministry of Education, Central Southniversity, Changsha, Hunan Province 410083, China
-mail address: [email protected] (H. Zhou).
n this work, the bioleaching of chalcopyrite flotation concentratesas studied in a 2.6 L stirred tank bioreactor with 2 L medium.
he chalcopyrite flotation concentrates mainly consisted of 80%halcopyrite and 5% pyrite. Concentrations of elements in the oreere Fe 30.90%, Cu32.02%, S22.65%, Mg1.06%, Al3.99%, Si 5.1%, K
.16%. A mixed moderately thermophilic microorganisms, includingcidithiobacillus caldus, Leptospirillum ferriphilum and Sulfobacilluscidophilu was inoculated. The reactor was operated at 45 ◦C, initialH 2.0, 1% pulp density. The pulp was aerated at 0.6 L/min, and withrevolution speed of 500 r/min. After being leached for 30 days,
6.2% Cu was dissolved. It was suggested that the flotation reagentsemained in the flotation concentrates suppressed the microor-anisms, which led the lower leaching efficiency. The method ofolymerase chain reaction-restriction fragment length polymor-hism (PCR-RFLP) was used to analyze the successive movementf bacterial population in leachate sampled at 8, 16, 24 and 30 days.ynchronously the changes of pH, Eh and concentration of metalons were determined and the possible influences of these variablesn community composition and population dynamics were evalu-ted. At the initial stage, the amount of At. caldus were outstandingo all populations. With the processing of leaching, L. ferriphilumas increasing and replaced At. caldus as the dominating popula-
ion in the later stages. This may be mostly due to that the mineralsere covered with sulfur intermediate compounds resulted from
he sulfur entity release from minerals dissolution at the initialtage. Finally these compounds are oxidized to elemental sulfur andormed a passivation layer, which will hinder the durative bioleach-ng of chalcopyrite. However, At. caldus can oxidize the elementalulfur to sulfate and remove the passivation layer. Then the L. fer-iphilum can make use of the ferrous iron in the chalcopyrite furthernd grow rapidly. The decrease of pH value in the leachate resultedrom the sulfur oxidation to sulfate acid also favors the growth of. ferriphilum, which can also explain the dominance of this iron-xidizing bacteria.
∗ Corresponding author at: School of Minerals Processing and Bioengineering,entral South University, Changsha, Hunan Province 410083, China.
gy 136S (2008) S460–S495
icrobiological assay for the quantitative determination ofolyoxin B
i Sun, Wenqing Chen, Zixin Deng, Jian-Jiang-Zhong ∗
Key Laboratory of Microbial Metabolism, Ministry of Education, Col-ege of Life Science & Biotechnology, Shanghai Jiao Tong University,hanghai 200240, China
-mail address: [email protected] ( Jian-Jiang-Zhong).
olyoxin B, a high-yield antifungal agro-antibiotic, is often used inhe treatment of a wide range of serious plant diseases (Hori et al.,974). For the enhancement of the product titer in fermentations well as fermentation technology studies, quantitative analysisf polyoxin B is necessary. However, until now there have beeno reports on the accurate quantification of the antibiotics con-entration in liquid. The present work reports a microbiologicalssay, by applying the cylinder-plate method, for the determina-ion of polyoxin B. A strain of Trichosporon cutaneum was used ashe test organism. The results of assay were treated statisticallyy analysis of variance (ANOVA) (Hewitt, 1977; ICH, 1996) andere found to be linear (r = 0.9985) in the range of 10–500 �g/ml,recise (intra-assay: relative standard deviation (R.S.D.) = 0.64;
nter-assay: R.S.D. = 1.70) and accurate (as confirmed by pulse addi-ion of standard sample). We have successfully applied this methodo determine the fermentation titer of the product of Strepto-yces cacaoi var. asoensis with comparison to HPLC analysis. Itas concluded that the microbiological assay was satisfactory for
uantification of in vitro antifungal activity of polyoxin B, and a sim-le, sensitive, cost-effective and specific agar diffusion bioassay forolyoxin B was therefore developed.Acknowledgement
We appreciate the financial support from the National Highechnology Research and Development Program (863 Programroject # 2006AA10A202) of the Ministry of Science & Technologyf China (MOST).
ewitt, W., 1977. Microbiological Assay. An Introduction to Quantitative Principlesand Evolution. Academic Press, New York, pp. 41-42.
ori, M., Eguchi, J., Kakiki, K., Misato, T., 1974. Studies on the mode of action ofpolyoxins. VI. Effect of polyoxin B on chitin synthesis in polyoxin-sensitive andresistant strains of Alternaria Kikuchiana. Journal of Antibiotics 27, 260–266.
CH, 1996. Harmonized Tripartite Guidelines, Validation of Analytical Procedures:Methodology Q2B. ICH, Geneva, pp. 1–8.
ptimization of l-asparaginase production by Pectobacteriumarotovorum using statistical experimental design
rrivukkarasan Sanjeeviroyar, Muthusivaramapandian Muthuraj,ravindan Rajendran ∗, Viruthagiri Thangavelu
Biochemical Engineering Laboratory, Department of Chemical Engi-eering, Annamalai University, Annamalai Nagar 608002, Tamil Nadu,
-mail address: [email protected] (A. Rajendran).
-asparaginase (l-asparagine amido hydrolase E.C.184.108.40.206) is anffective anti tumor agent that has the ability to induce apopto-is in cancerous cells (Narta et al., 2007) and in the production ofcrylamide free food stuffs. Although extensive studies have beenerformed on the isolation, production and on the antileukemiaroperties of l-asparaginase, very little information is available