Generation behavior of extracellular polymeric substances and its correlation with extraction efficiency of valuable metals and change of process parameters during bioleaching of spent petroleum catalyst.

The vital functions of extracellular polymeric substances (EPS) have been well recognized in bioleaching of sulfide ores. However, no report is available about the role of EPS in bioleaching of spent catalyst. To completely and deeply understand the functions of EPS in bioleaching of spent catalyst, the generation behavior of EPS at various pulp densities during bioleaching was characterized by three-dimensional excitation-emission matrix (3DEEM), and its relevance with bioleaching performance and process parameters were analyzed using mathematical means. The results showed that the EPS contain humus-like substances as main component (>70%) and protein-like substances as minor component (<30%). Both total EPS and humus-like substances mainly keep growing over the whole duration of bioleaching at low pulp density of 5.0% or lower; whereas total EPS and humus-like fraction keep declining at high pulp density of 7.5% or higher. Among the total EPS and its components, humus-like substances only have a positive significant correlation with bioleaching efficiencies of both Co and Mo and affect bioleaching process more greatly due to greater correlation coefficient. Biofilm appears at the spent catalyst surface under 2.5% of pulp density mediated by EPS while no biofilm occurs at 10% of pulp density due to shortage of EPS, accounting for the great difference in bioleaching efficiencies between high and low pulp densities which are 48.3% for Mo and 50.0% for Co at 10% of pulp density as well as 75.9% for Mo and 78.8% for Co at 2.5% of pulp density, respectively.

Nocardioides jishulii sp. nov.,isolated from faeces of Tibetan gazelle (Procapra picticaudata).

Two novel Gram-stain-positive, irregular rod-shaped bacterial strains, dk3136T and dk3543, were isolated from the faeces of Tibetan gazelle (Procapra picticaudata) in the Qinghai-Tibet Plateau of PR China. The cells were aerobic, oxidase-negative and catalase-positive. Colonies were yellowish, circular without any observable aerial mycelium after culturing at 28 ℃ for 3 days on brain-heart infusion (BHI) agar with 5 % sheep blood. The cells grew optimally at 28 °C, pH 7.5 and with 1 % (w/v) NaCl on BHI agar supplemented with 5 % sheep blood. Phylogenetic analysis of the 16S rRNA gene sequences revealed that their nearest phylogenetic relative was Nocardioides solisilvae Ka25T (97.9 % similarity). The results of 16S rRNA gene sequence and phylogenetic/phylogenomic analyses illustrated that N. solisilvae Ka25T, Nocardioides gilvus XZ17T, Nocardioides houyundeii 78T and Nocardioides daphniae D287T were their nearest phylogenetic neighbours. The DNA G+C contents of strains dk3136T and dk3543 were 70.3 mol% and 70.4 mol%, respectively. Their genomes exhibit lower than threshold (95-96 %) average nucleotide identity to known species of the genus Nocardioides. ll-2,6-diaminopimelic acid was the diagnostic diamino acid and MK-8(H4) was the predominant respiratory quinone. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The two strains had C18 : 1 ω9c, iso-C16 : 0 and C17 : 1 ω8c as the major fatty acids, and rhamnose and galactose as the main whole-cell sugars. On the basis of the results of our genotypic, phenotypic and biochemical analyses, we conclude that strains dk3136T and dk3543 represent a novel species in genus Nocardioides, for which the name Nocardioides jishulii sp. nov. is proposed. The type strain is dk3136T (=CGMCC 4.7570T=JCM 33496T=KCTC 49314T).

[Traditional medicine CDP and promoter demethylation in breast cancer cell lines].

OBJECTIVE: To investigate the demethylation effect of CDP on P16 and E-CADHERIN genes. METHODS: Breast cancer cell lines T47D and MDA-MB-435 were treated with CDP and DNA methyltransferase inhibitor 5-azacytidine (5-aza-C). The methylation of P16 and E-CADHERIN gene promoters were measured by methylation-specific PCR (MSP). The RNA transcription was determined by reverse transcription-PCR(RT-PCR). RESULTS: 1) The methylation-specific fragments of P16 gene promoter existed in T47D cells after 25, 50 and 75 micromol/L of CDP treatment for 6 days. An absolute demethylation on P16 gene occurred after treatment with 100 micromol/L of CDP. The unmethylation-specific fragments appeared in T47D cells after being treated with 25, 50, 75 and 100 micromol/L of CDP for 6 days. The RNA expression of P16 was detected after treatment with 75 and 100 micromol/L of CDP. 2) After being treated with 50 micromol/L of CDP, the methylation-specific fragments of CpG island in P16 gene promoter still existed in T47D cells. The unmethylation-specific fragments in T47D cells started to appear after 24 hours of treatment and lasted until 144 hour of treatment. The RNA expression was detected after 144 hours of treatment. 3) The demethylation on E-CADHERIN gene and genomic DNA or RNA transcription were not detected in MDA-MB-435 cells. CONCLUSION: CDP has concentration- and time-dependent demethylation effect on P16 gene in T47D cells, but not on E-CADHERIN gene in MDA-MB-435 cells, which indicates that CDP has substantial diversity in molecular activities.