A weighing method to identify the microbial growth phases in solid-state fermentation tests

A general equation correlating the variation rate of the fermenting medium weight (dry matter) and the cell biomass growth rate in solid-state fermentation tests is proposed with the main purpose of identifying the microbial growth phases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular identification of crocodile species using novel primers for forensic analysis

All crocodilians are under varying degrees of threat due to over exploitation and these species have been listed in Appendix I or II of CITES. The lack of molecular techniques for the identification of confiscated samples makes it difficult to enforce the law. Conclusive forensic identification of species requires a complete gene sequence which is difficult in case of degraded samples. We have developed two novel sets of primers to amplify two partial cytochrome b gene sequences of six crocodile species i.e. Crocodylus palustris, Crocodylus porosus, Crocodylus siamensis, Crocodylus niloticus, Gavialis gangeticus and Caiman crocodilus. These partial sequences were edited to give a complete cyt b gene sequence, which can be used as an effective tool for forensic authentication of crocodile species. A phylogeny of crocodile species was reconstructed using these sequences. The described primers hold great promise in forensic identification of crocodile species, which can aid in the effective enforcement of law and conservation of these ancient species.     

绿洲农业生态经济系统的结构与功能分析以张掖绿洲为例

通过分析张掖绿洲农业生态经济系统的结构与功能,发现其种群结构单一、产业结构不甚合理、空间结构脆弱,决定了绿洲功能较差,产投比低下的特点,并据此从可持续发展的角度提出了改善绿洲农业生态经济系统结构、提高其功能的对策与建议     

Biostructural analysis of the metal-sensor domain of CnrX from <Emphasis Type="Italic">Cupriavidus metallidurans</Emphasis> CH34

In Cupriavidus metallidurans CH34, the proteins CnrX, CnrY, and CnrH regulate the expression of the cnrCBA operon that codes for a cation-efflux pump involved in cobalt and nickel resistance. The periplasmic part of CnrX can be defined as the metal sensor in the signal transduction complex composed of the membrane-bound anti-sigma factor CnrY and the extra-cytoplasmic function sigma factor CnrH. A soluble form of CnrX was overproduced and purified. This protein behaves as a dimer in solution as judged from gel filtration, sedimentation velocity experiments, and NMR. Native crystals diffracting to 2.3 A using synchrotron radiation were obtained using the hanging-drop vapor-diffusion method. They belong to the primitive monoclinic space group P2(1), with unit cell parameters a = 31.87, b = 74.80, c = 93.67 A, beta = 90.107 degrees. NMR data and secondary structure prediction suggest that this protein is essentially formed by helices.     

Antimicrobial activity in cultures of endophytic fungi isolated from Garcinia species

The aim of the present study was to screen for antimicrobial activity in endophytic fungi isolated from surface sterilized leaves and branches of five Garcinia plants, G. atroviridis, G. dulcis, G. mangostana, G. nigrolineata and G. scortechinii, found in southern Thailand. Fermentation broths from 377 isolated fungi were tested for antimicrobial activity by the agar diffusion method. Minimum inhibitory concentrations (MICs) were obtained for crude ethyl acetate extracts. Seventy isolates (18.6%) displayed antimicrobial activity against at least one pathogenic microorganism, such as Staphylococcus aureus, a clinical isolate of methicillin-resistant S. aureus, Candida albicans and Cryptococcus neoformans. The results revealed that 6-10%, 1-2% and 18% of the crude ethyl acetate extracts inhibited both strains of S. aureus (MIC 32-512 microg mL(-1)), Ca. albicans and Cr. neoformans (MIC 64-200 microg mL(-1)), and Microsporum gypseum (MIC 2-64 microg mL(-1)), respectively. Isolates D15 and M76 displayed the strongest antibacterial activity against both strains of S. aureus. Isolates M76 and N24 displayed strong antifungal activity against M. gypseum. Fungal molecular identification based on internal transcribed spacer rRNA gene sequence analysis demonstrated that isolates D15 (DQ480353), M76 (DQ480360) and N24 (DQ480361) represented Phomopsis sp., Botryosphaeria sp. and an unidentified fungal endophyte, respectively. These results indicate that some endophytic fungi from Garcinia plants are a potential source of antimicrobial agents.     

A biochemical protocol for the isolation and identification of current species of Vibrio in seafood

AIMS: We report a biochemical method for the isolation and identification of the current species of vibrios using just one operative protocol. METHODS AND RESULTS: The method involves an enrichment phase with incubation at 30 degrees C for 8-24 h in alkaline peptone water and an isolation phase on thiosulphate-citrate-salt sucrose agar plates incubating at 30 degrees C for 24 h. Four biochemical tests and Alsina's scheme were performed for genus and species identification, respectively. All biochemical tests were optimized as regards conditions of temperature, time of incubation and media composition. The whole standardized protocol was always able to give a correct identification when applied to 25 reference strains of Vibrio and 134 field isolates. CONCLUSIONS: The data demonstrated that the assay method allows an efficient recovery, isolation and identification of current species of Vibrio in seafood obtaining results within 2-7 days. SIGNIFICANCE AND IMPACT OF THE STUDY: This method based on biochemical tests could be applicable even in basic microbiology laboratories, and can be used simultaneously to isolate and discriminate all clinically relevant species of Vibrio.     

A structural perspective on copper uptake in eukaryotes

Over a decade ago, genetic studies identified a family of small integral membrane proteins, commonly referred to as copper transporters (CTRs) that are both required and sufficient for cellular copper uptake in a yeast genetic complementation assay. We recently used electron crystallography to determine a projection density map of the human high affinity transporter hCTR1 embedded into a lipid bilayer. At 6 Å resolution, this first glimpse of the structure revealed that hCTR1 is trimeric and possesses the type of radial symmetry that traditionally has been associated with the structure of certain ion channels such as potassium or gap junction channels. Representative for this particular type of architecture, a region of low protein density at the center of the trimer is consistent with the existence of a copper permeable pore along the center three-fold axis of the trimer. In this contribution, we will briefly discuss how recent structure–function studies correlate with the projection density map, and provide a perspective with respect to the cellular uptake of other transition metals.     

High-throughput sex identification by melting curve analysis in blue-breasted quail and chicken

The objective was to develop a high-throughput method of identifying sex in both Coturnix chinensis and Gallus gallus, which would be useful for biomedical research and hatcheries. Because chromo-helicase-DNA binding protein (CHD)-based Griffiths P2/P8 primers do not produce polymerase chain reaction (PCR) products with distinguishable sex-specific curves in melting curve analysis (MCA), these primers are unsuitable for high throughput application in either species. Conserved regions were identified by basic local alignment search tool (BLAST) analyses of cloned CHD-Z and CHD-W genes of C. chinensis. Based on sequence alignment, a female-specific CHD-W primer (W-cot-F1) and a female/male (or CHD-W/CHD-Z)-common primer (ZW-cot-F1) were redesigned for use in combination with the Griffiths P2 primer for MCA-based PCR reaction. In C. chinensis and G. gallus, W-cot-F1/P2 and ZW-cot-F1/P2 had amplicon lengths of 315/318 and 114 base pairs and melting temperatures (Tm) of approximately 79.5 °C to 80 °C and approximately 78.5 °C to 79°C, respectively. Thus, MCA distinguished sex based on two distinct Tm peaks in females versus only one Tm peak in males. The MCA-based real-time PCR combined with the proposed primer redesign provided a high-throughput method of identifying sex in C. chinensis and G. gallus.